Single battery, battery pack and power utilization device

Abstract

The invention discloses a single battery, a battery pack and a power utilization device, and belongs to the technical field of batteries. The cover plate is connected with the shell and covers the accommodating cavity, and the cover plate is provided with an anti-explosion hole; the explosion-proof valve and the explosion-proof valve cover seal the explosion-proof hole, the explosion-proof valve comprises a bearing part, a weak part, a protruding part and a concave part which are sequentially connected in a surrounding mode from outside to inside, the bearing part is connected with the cover plate, the weak part is configured to be damaged when impacted by preset pressure, and the protruding part protrudes towards the side away from the electrode assembly; the concave part sinks towards one side close to the electrode assembly from the joint of the concave part and 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 S2 / (S1 + S2) is more than or equal to 0.1 and less than or equal to 0.4. By limiting the proportion 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 anti-explosion valve can fully absorb and disperse stress, and the problem that the anti-explosion valve deforms and cracks or is opened in advance due to local stress concentration is solved.

Description

Technical Field

[0001] The present application belongs to the field of battery technology, and specifically relates to a single cell, a battery pack and an electrical device. Background Art

[0002] Lithium-ion batteries are currently widely used in various fields such as transportation power supply, electric energy storage power supply, new energy storage power supply, aerospace and military industry due to their large capacity, high operating voltage, strong charge retention ability and long cycle life. The cover plate in the battery is usually integrated with poles, explosion-proof valves and other structures. Among them, the main function of the explosion-proof valve is to release pressure and exhaust. It is used for the directional release of internal high-temperature and high-pressure gas when the battery cell has thermal runaway due to mechanical impact, internal abnormal lap short circuit and other reasons, thereby improving the safety performance of the battery pack. However, in the processes of liquid injection, pre-charging formation, and capacity division in the single cell process, there is a repeated positive and negative alternating pressure difference between the inside of the battery and the outside world, which causes deformation, cracking, premature opening of the explosion-proof valve and other problems, seriously affecting the battery process yield and safety performance. Summary of the invention

[0003] Purpose of the invention: The embodiments of the present application provide 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 the battery preparation process.

[0004] Technical solution: The present application embodiment provides a single battery, including:

[0005] A housing having a receiving cavity;

[0006] An electrode assembly, the electrode assembly is located in the accommodating cavity;

[0007] A cover plate, which is connected to the shell and covers the accommodating cavity, and is provided with an explosion-proof hole;

[0008] An explosion-proof valve, the explosion-proof valve cover seals the explosion-proof hole, the explosion-proof valve comprises a bearing portion, a weak portion, a protruding portion and a concave portion which are connected in sequence from the outside to the inside, the bearing portion is connected to the cover plate, the weak portion is configured to be destroyed when subjected to a preset pressure impact, the protruding portion protrudes from the connection with the weak portion toward a side away from the electrode assembly, and the concave portion is concave toward a side close to the electrode assembly;

[0009] The area of ​​the protrusion is S1 mm 2 The area of ​​the concave portion is S2 mm 2 , satisfying: 0.1≤S2 / (S1+S2)≤0.4.

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

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

[0012] In some embodiments, the single battery 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 bearing portion in the thickness direction is A mm, satisfying: C>A, 0.4≤A≤0.6.

[0015] In some embodiments, the bearing portion is connected to a side of the cover plate close to the electrode assembly, and the protruding portion protrudes into the explosion-proof hole.

[0016] In some embodiments, a limiting groove is opened on one side of the cover plate close to the electrode assembly, the limiting groove is arranged around the explosion-proof hole, the limiting groove is opened on one side of the cover plate close to the electrode assembly, and the bearing part is arranged in the limiting groove.

[0017] Accordingly, an embodiment of the present application provides a battery pack, comprising the above-mentioned single battery.

[0018] Correspondingly, an embodiment of the present application provides an electrical device, including the above-mentioned single battery, or including the above-mentioned battery pack.

[0019] Beneficial effects: The single cell of the embodiment of the present application includes a shell, an electrode assembly, a cover plate and an explosion-proof valve. The shell has a receiving cavity; the electrode assembly is located in the receiving cavity; the cover plate is connected to the shell and covers the receiving cavity, and the cover plate is provided with an explosion-proof hole; the explosion-proof valve covers the explosion-proof hole, and the explosion-proof valve includes a bearing part, a weak part, a protruding part and a recessed part connected in sequence from the outside to the inside, the bearing part is connected to the cover plate, the weak part is configured to be destroyed when subjected to a preset pressure impact, the protruding part protrudes from the connection with the weak part toward the side away from the electrode assembly, and the recessed part is recessed toward the side close to the electrode assembly; wherein the area of ​​the protruding part is S1 mm 2 The area of ​​the concave portion is S2 mm 2 , satisfying: 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 portion and the convex portion, it is ensured that the arrangement of the convex portion and the concave portion can fully absorb and disperse the stress caused by the pressure difference between the accommodating cavity and the outside of the shell to the explosion-proof valve during the production of the single battery, avoiding the deformation of the explosion-proof valve caused by local stress concentration, and then causing the explosion-proof valve to crack or open prematurely, thereby effectively improving the production yield of the single battery and improving the safety and reliability of the single battery.

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

[0021] The electrical device of the embodiment of the present application includes the above-mentioned single cell or the above-mentioned battery pack, so the electrical device can have all the technical features and beneficial effects of the above-mentioned single cell or battery pack, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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.

[0023] Figure 1 is an exploded diagram of a single cell of an embodiment of the present application;

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

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

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

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

[0028] Figure numerals: 1, shell; 2, electrode assembly; 3, cover plate; 4, explosion-proof valve; 10, accommodating chamber; 30, explosion-proof hole; 31, limiting groove; 40, bearing part; 41, weak part; 42, protruding part; 43, recessed part; 310, bottom wall; 410, first surface; 411, notch; X, thickness direction. DETAILED DESCRIPTION

[0029] 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.

[0030] In the description of the present application, it should be understood that the terms "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot 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, "multiple" means two or more, and at least one means one, two or more, unless otherwise clearly and specifically defined. In the description of this application, "vertical" means completely vertical at 90° or almost completely vertical, for example, an angle within the range of 80° to 100° is considered vertical. Similarly, "parallel" means completely parallel or almost completely parallel, for example, an angle within 10° of completely parallel is considered parallel.

[0031] The applicant noted that lithium-ion batteries are currently widely used in various fields such as transportation power supply, electric energy storage power supply, new energy storage power supply, aerospace and military industry due to their large capacity, high operating voltage, strong charge retention ability and long cycle life. The cover plate in the battery is usually integrated with poles, explosion-proof valves and other structures. Among them, the main function of the explosion-proof valve is to release pressure and exhaust. It is used for the directional release of internal high-temperature and high-pressure gas when the battery cell has thermal runaway due to mechanical impact, internal abnormal lap short circuit and other reasons, thereby improving the safety performance of the battery pack. However, in the processes of liquid injection, pre-charging formation, and capacity division in the single cell process, there is a repeated positive and negative alternating pressure difference between the inside of the battery and the outside world, which causes deformation, cracking, premature opening of the explosion-proof valve and other problems, seriously affecting the battery process yield and safety performance.

[0032] In view of this, the single cell of the embodiment of the present application includes a shell, an electrode assembly, a cover plate and an explosion-proof valve. The single cell of the embodiment of the present application includes a shell, an electrode assembly, a cover plate and an explosion-proof valve. The shell has a accommodating cavity; the electrode assembly is located in the accommodating cavity; the cover plate is connected to the shell and seals the accommodating cavity, and the cover plate is provided with an explosion-proof hole; the explosion-proof valve seals the explosion-proof hole, and the explosion-proof valve includes a bearing portion, a weak portion, a protruding portion and a recessed portion that are sequentially connected from the outside to the inside, the bearing portion is connected to the cover plate, the weak portion is configured to be destroyed when subjected to a preset pressure shock, the protruding portion protrudes from the connection with the weak portion toward the side away from the electrode assembly, and the recessed portion is recessed toward the side close to the electrode assembly; wherein the area of ​​the protruding portion is S1 mm 2 , the area of ​​the concave portion is S2mm 2, satisfying: 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 portion and the convex portion, it is ensured that the convex portion and the concave portion can fully absorb and disperse the stress caused by the pressure difference between the accommodating cavity and the outside of the shell to the explosion-proof valve during the production of the single battery, avoiding the deformation of the explosion-proof valve caused by local stress concentration, and then causing the explosion-proof valve to crack or open prematurely, thereby effectively improving the production yield of the single battery and improving the safety and reliability of the single battery.

[0033] In the present application, a single cell may include a lithium-ion secondary battery, a lithium-ion primary battery, a lithium-sulfur battery, a sodium-lithium-ion battery, a sodium-ion battery or a magnesium-ion battery, etc., and the embodiments of the present application do not limit this. A single cell may be cylindrical, flat, rectangular or other shapes, etc., and the embodiments of the present application do not limit this. Single cells are generally divided into three types according to the packaging method: cylindrical single cells, square single cells and soft-pack single cells, and the embodiments of the present application do not limit this.

[0034] The following is a detailed description of the single cell, battery pack and electrical device of the present application in conjunction with the accompanying drawings. The features of the following embodiments and implementations can be combined with each other if there is no conflict.

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

[0036] refer to Figures 1 to 5The embodiment of the present application provides a single cell, comprising a shell 1, an electrode assembly 2, a cover plate 3 and an explosion-proof valve 4. The shell 1 has a housing chamber 10; the electrode assembly 2 is located in the housing chamber 10; the cover plate 3 is connected to the shell 1 and covers the housing chamber 10, the cover plate 3 is provided with an explosion-proof hole 30, the explosion-proof valve 4 covers the explosion-proof hole 30, and the explosion-proof valve 4 includes a bearing portion 40, a weak portion 41, a protruding portion 42 and a recessed portion 43 which are connected in sequence from the outside to the inside. Specifically, the bearing portion 40 is connected to the weak portion 41, the weak portion 41 is connected to the protruding portion 42, and the protruding portion 42 is connected to the recessed portion 43. The weak portion 41 is configured to be destroyed when impacted by a preset pressure. When the internal pressure of the single cell is too large (for example, the internal pressure is too large 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, thereby reducing the internal pressure of the single cell and preventing the single cell from exploding due to excessively rapid pressurization inside the single cell. The protrusion 42 protrudes from the connection with the weak portion 41 toward the side away from the electrode assembly 2, and the recess 43 is recessed toward the side close to the electrode assembly 2. The arrangement of the protrusion 42 and the recess 420 can avoid stress concentration. The area of ​​the protrusion 42 is S1 mm 2 , the area of ​​the concave portion 43 is S2 mm 2 , satisfying: 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 caused by the pressure difference between the inside of the accommodating chamber 10 and the outside of the shell 1 to the explosion-proof valve 4 during the production of the single battery, avoiding the deformation of the explosion-proof valve 4 caused by the local stress concentration, and then causing the explosion-proof valve 4 to crack or open prematurely, thereby effectively improving the production yield of the single battery and improving the safety and reliability of the single battery.

[0037] It is understandable that when the relative area of ​​the recess 43 is too small, the recess 43 cannot fully absorb and disperse the internal pressure of the single cell, resulting in that the explosion-proof valve 4 is subject to certain restrictions when it should be opened normally to release the pressure, and cannot open the valve in time and effectively, which may cause the internal pressure of the single cell to be unable to be released in time, increasing the risk of danger to the single cell. When the relative area of ​​the recess 43 is too large, it may cause the protrusion 42 to deform abnormally and crack during the single cell process. The ratio of the area of ​​the recess 43 to the total area of ​​the recess 43 and the protrusion 42 can avoid the problem of constrained valve opening and abnormal deformation and cracking of the protrusion 42. In the single cell 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, so that the explosion-proof valve 4 can be opened in time and accurately when it is impacted by the preset pressure, preventing the single cell from catching fire and exploding, and improving the safety performance of the single cell.

[0038] In some embodiments, the area of ​​the protrusion 42 is S1 mm 2 , the area of ​​the concave portion 43 is S2 mm 2 , the area of ​​explosion-proof valve 4 is S mm 2 , satisfying: 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 can be understood that the area occupied by the protrusion 42 and the recess 43 in the explosion-proof valve 4 is too large, thereby occupying the space of the weak part 41. This may cause the weak part 41 to fail to be destroyed normally when subjected to a preset pressure, affecting the function of the explosion-proof valve 4 to release 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 to fully absorb and disperse the pressure difference stress from the production process of the single cell, which can 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 range 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 the stress, and the stress will not be effectively dispersed due to the protrusion 42 being too small, nor will the pressure relief function of the explosion-proof valve 4 be affected due to the area being too large. A reasonable area ratio helps the explosion-proof valve 4 to quickly release the internal gas when the internal pressure of the single battery is too high, reduce the internal pressure, and improve the safety and reliability of the single battery.

[0039] In some embodiments, the area of ​​the explosion-proof valve 4 is S mm 2 The area of ​​the protrusion 42 is S1 mm 2 , satisfying: 0.35≤S1 / S≤0.6. That is, the area of ​​the protrusion 42 on the explosion-proof valve 4 accounts for between 35% and 60%. When the area of ​​the protrusion 42 is too large, since the protrusion 42 usually bears the main role of absorbing and dispersing stress, but when the area of ​​the protrusion 42 is too large, excessive elastic deformation may occur during the production process due to the stress caused by the internal and external pressure difference, which may exceed the bearing limit of the material of the explosion-proof valve 4, thereby causing the explosion-proof valve 4 to have abnormal external deformation problems, or even cracking, affecting the safety and reliability of the single cell. When the area of ​​the protrusion 42 is too small, the protrusion 42 with an area that is too small cannot fully exert its stress absorption and dispersion functions, making it easy for depression problems to occur in the single cell manufacturing process. By reasonably 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, the stress can be effectively dispersed and absorbed to ensure the structural stability of the explosion-proof valve 4 and reduce the risk of deformation and cracking of the explosion-proof valve 4; on the other hand, the explosion-proof valve 4 can be prevented from opening prematurely, and can be opened normally when the internal pressure of the battery reaches a preset value, thereby releasing the pressure in time and 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 concave portion 43 is S2 mm 2 , satisfying: 0.1≤S2 / S≤0.2. That is, the area of ​​the concave portion 43 on the explosion-proof valve 4 accounts for between 10% and 20%. When the area of ​​the concave portion 43 is too small, it may cause the problem of constrained valve opening after the single cell produces gas in the capacity separation process. It can be understood that the capacity separation process refers to the process of capacity sorting of single cells. By charging and discharging the single cells, measuring their actual capacity, and classifying batteries with similar capacity into one category, the single cells may produce gas due to chemical reactions and apply pressure to the explosion-proof valve during the charging and discharging process. The insufficient area of ​​the concave portion 43 makes it impossible for the concave portion 43 to fully absorb and disperse the internal pressure of the single cell, resulting in certain restrictions when the explosion-proof valve 4 should be opened normally to release the pressure, and the valve cannot be opened in time and effectively, which may cause the internal pressure of the single cell to be unable to be released in time, increasing the risk of danger to the single cell. When the area of ​​the concave portion 43 is too large, it will occupy the area of ​​the protrusion 42, which may cause the protrusion 42 to deform abnormally and crack during the single cell manufacturing process. By reasonably 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 constrained 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, thereby ensuring the stable performance of the explosion-proof valve 4, and being able to open normally when the internal pressure of the battery reaches the preset value, releasing the pressure in time, and improving the safety and reliability of the single battery.

[0041] In the embodiments of the present application, different explosion-proof valves S, S1 and S2 are provided and welded to the cover plate 3 for actual measurement and verification, and the abnormal conditions of the explosion-proof valves in the cell manufacturing process are tracked. The verification results are shown in Table 1.

[0042] Table 1:

[0043]

[0044]

[0045] Referring to Example 1 to Example 9 in Table 1, the monomer cells all meet 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 is no abnormal cracking problem of the explosion-proof valve 4 in the process of the monomer cell. It can be understood that by reasonably setting the size of the area of ​​the recess 43, the area of ​​the protrusion 42 and the area of ​​the explosion-proof valve 4, 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 accommodating cavity 10 and the outside of the shell 1 during the production of the monomer cell, avoiding the deformation of the explosion-proof valve 4 due to local stress concentration, and then causing the explosion-proof valve 4 to crack or open the valve in advance, thereby effectively improving the production yield of the monomer cell and improving the safety and reliability of the monomer cell.

[0046] Referring to Table 1, Example 1, the single cell meets the requirements of 0.4≤(S1+S2) / S≤0.8, 0.35≤S1 / S≤0.6, but S2 / (S1+S2) is less than 0.1, S2 / S is less than 0.1, and does not meet the requirements of 0.1≤S2 / (S1+S2)≤0.4 and 0.1≤S2 / S≤0.2. The verification result is that the concave part area of ​​the concave portion 43 is too small. In the process of dividing the capacity of the single cell, there is a problem of cracking of the explosion-proof valve 4 due to the high internal air pressure, and the proportion is about 0.245%. It can be understood that since the area of ​​the concave portion 43 is relatively small, it cannot fully absorb and disperse the internal pressure of the single cell. When the internal pressure cannot be effectively dispersed by the concave portion 43, the local pressure borne by the explosion-proof valve 4 will be too large. As the internal air pressure continues to rise, the weak portion 41 is prone to cracking.

[0047] Referring to Table 1, Example 2, the single cell meets the requirements of 0.1≤S2 / (S1+S2)≤0.4, 0.4≤(S1+S2) / S≤0.8, 0.35≤S1 / S≤0.6, but S2 / S is less than 0.1, which does not meet the requirement of 0.1≤S2 / S≤0.2. The verification result is that the concave part area of ​​the concave portion 43 is too small, and the single cell still has the problem of constrained valve opening after internal gas production in the volume separation process. 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 single cell, resulting in the explosion-proof valve 4 being restricted when it should be opened normally to release the pressure, and the valve cannot be opened effectively in time.

[0048] Referring to Table 1, Example 3, the single cell meets the requirements of 0.1≤S2 / (S1+S2)≤0.4, 0.4≤(S1+S2) / S≤0.8, 0.35≤S1 / S≤0.6, but S2 / S is greater than 0.2, which does not meet the requirement of 0.1≤S2 / S≤0.2. The verification result is that the concave part area of ​​the concave portion 43 is too large, and the single cell process has the problem of the explosion-proof valve 4 being sunken. It can be understood that the area of ​​the concave portion 43 is relatively large, which will occupy the area of ​​the protrusion 42, resulting in the problem of abnormal deformation and cracking of the protrusion 42 in the single cell process.

[0049] Referring to Table 1, Example 4, the single cell meets the requirements of 0.4≤(S1+S2) / S≤0.8, 0.35≤S1 / S≤0.6, but S2 / (S1+S2) is greater than 0.4, S2 / S is greater than 0.2, and does not meet the requirements of 0.1≤S2 / (S1+S2)≤0.4 and 0.1≤S2 / S≤0.2. The verification result is that the concave part area of ​​the concave portion 43 is too large, and the single cell process has the problem of the explosion-proof valve 4 being sunken. It can be understood that the area of ​​the concave portion 43 is relatively large, which will occupy the area of ​​the protrusion 42, resulting in the problem of abnormal deformation and cracking of the protrusion 42 in the single cell process.

[0050] Referring to Comparative Examples 5 and 6 in Table 1, the single cell meets the requirements of 0.1≤S2 / (S1+S2)≤0.4, 0.4≤(S1+S2) / S≤0.8 and 0.1≤S2 / S≤0.2, but S1 / S is less than 0.35, and does not meet the requirement of 0.35≤S1 / S≤0.6. The verification result is that the area of ​​the convex part of the protrusion 42 is too small, and the explosion-proof valve 4 in the process of the single cell has a dent problem. It can be understood that the area of ​​the protrusion 42 is relatively small relative to the total area of ​​the explosion-proof valve 4, and it is unable to fully absorb and disperse the pressure difference stress from the process of the single cell, which leads to the stress being concentrated in other areas of the explosion-proof valve 4, causing the explosion-proof valve 4 to have a dent problem.

[0051] Referring to Comparative Examples 7 and 8 in Table 1, the single cell meets the requirements of 0.1≤S2 / (S1+S2)≤0.4, 0.4≤(S1+S2) / S≤0.8 and 0.1≤S2 / S≤0.2, but S1 / S is greater than 0.6, and does not meet the requirement of 0.35≤S1 / S≤0.6. The verification result is that the area of ​​the convex part of the protrusion 42 is too large, and the single cell process has the problem of cracking of the explosion-proof valve 4 due to the high internal air pressure. It can be understood that the area of ​​the protrusion 42 is relatively large relative to the total area of ​​the explosion-proof valve 4. In the single cell process, due to the stress caused by the internal and external pressure difference, excessive elastic deformation occurs, which exceeds the bearing limit of the material of the explosion-proof valve 4, resulting in the problem of abnormal convex deformation of the explosion-proof valve 4, and even cracking, which affects the safety and reliability of the single cell.

[0052] 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, and 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 can be understood that the difference range 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 too large, the height of the protrusion 42 is 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, and there is a risk of the explosion-proof valve 4 being crushed in the single cell process. On the other hand, the height of the concave part of the concave portion 43 is relatively high, and it may be deformed due to local stress concentration during the production process, increasing the risk of abnormal 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 concave portion 43 and the first surface 410 is too small, the protrusion 42 and the concave portion 43 may not be able to absorb and disperse the pressure in time and effectively, thereby increasing the risk of the explosion-proof valve 4 being concave and convex, and then cracking or opening the valve in advance. The present application reasonably controls the difference range of 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 concave portion 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 in the accommodating cavity 10 and outside the shell 1 during the production of the single cell, avoids the problem of the explosion-proof valve 4 being concave and convex due to local stress concentration, and then causes the explosion-proof valve 4 to crack or open the valve in advance, thereby effectively improving the production yield of the single cell and improving the safety and reliability of the single cell.

[0053] In some embodiments, the maximum dimension of the bearing 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 bearing 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 of values ​​between any two of them. Such a setting can ensure the connection stability between the bearing portion 40 and the cover plate 3, avoid loosening or falling off of the explosion-proof valve 4 due to unstable connection during the single cell manufacturing process or normal use, and improve the safety and reliability of the single cell. When the minimum dimension C between the concave portion 43 and the first surface 410 in the thickness direction X is smaller than the maximum dimension A of the bearing portion 40 in the thickness direction X, the stress cannot be effectively dispersed to the protrusion 42, and the explosion-proof valve 4 has the risk of concave. In the embodiment of the present application, 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 the stress, and fully absorb and disperse the stress brought to the explosion-proof valve 4 by the pressure difference inside the accommodating cavity 10 and outside the shell 1 during the production of the single battery, thereby avoiding the problem of local stress concentration causing the explosion-proof valve 4 to become concave inside and convex outside, and further causing the explosion-proof valve 4 to crack or open prematurely.

[0054] In some embodiments, a notch 411 is provided on the weak portion 41, and the notch 411 is provided around the protrusion 42. By providing the notch 411, the weak portion 41 can be more accurately ruptured at the notch 411 when subjected to a preset pressure, ensuring that the explosion-proof valve 4 releases the internal gas of the single cell in time at an appropriate pressure, thereby effectively reducing the internal pressure and preventing the single cell from being in danger.

[0055] In some embodiments, the notch 411 may be disposed on a side of the weak portion 41 away from the electrode assembly 2 and recessed in a direction toward the electrode assembly 2. In other embodiments, the notch 411 may be disposed on a side of the weak portion 41 close to the electrode assembly 2 and recessed in a direction away from the electrode assembly 2. Figure 3 , Figure 5 In the illustrated embodiment, the notch 411 is disposed on a side of the weak portion 41 away from the electrode assembly 2 and is recessed toward the electrode assembly 2. The notch 411 may be formed by laser etching or by mechanical processing, and the present application does not limit this.

[0056] exist Figure 2 and Figure 5In the illustrated embodiment, the bearing portion 40 is connected to the side of the cover plate 3 close to the electrode assembly 2, and the protruding portion 42 protrudes into the explosion-proof hole 30. The explosion-proof valve 4 is arranged on the side of the cover plate 3 close to the electrode assembly 2, which can avoid the problem of the explosion-proof valve 4 being easily damaged by scratches when welding the explosion-proof valve 4 on the outer wall of the cover plate 3, and ensure the connection stability between the explosion-proof valve 4 and the cover plate 3.

[0057] exist Figure 2 and Figure 5 In the illustrated embodiment, a limiting groove 31 is provided on one side of the cover plate 3 close to the electrode assembly 2, the limiting groove 31 is arranged around the explosion-proof hole 30, the limiting groove 31 is provided on one side of the cover plate 3 close to the electrode assembly 2, and the bearing portion 40 is arranged in the limiting groove 31. The limiting groove 31 can play a role in positioning and fixing the explosion-proof valve 4. By providing the limiting groove 31 on the cover plate 3 and arranging the explosion-proof valve 4 in the limiting groove 31, in this arrangement, the explosion-proof valve 4 will not occupy the space of the electrode assembly 2 in the accommodating cavity 10, thereby improving the energy density and performance of the single battery.

[0058] The present application embodiment provides a battery pack, including the above-mentioned single battery, so the battery pack can have all the technical features and beneficial effects of the above-mentioned single battery, which will not be repeated here. The battery pack also includes a box body, wherein at least one single battery is accommodated inside the box body.

[0059] Correspondingly, the embodiment of the present application also provides an electrical device, including the above-mentioned single cell, or, including the above-mentioned battery pack, so the electrical device can have all the technical features and beneficial effects of the above-mentioned single cell or battery pack, which will not be repeated here. The electrical device can be a mobile phone, a portable device, a laptop computer, an electric car, an electric car, a ship, a spacecraft, an electric toy, and an electric tool. For example, spacecraft include airplanes, rockets, space shuttles, and spacecrafts; electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys; electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers.

[0060] 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.

[0061] The above is a detailed introduction to a single cell battery, a battery pack and an electrical device provided in the embodiments of the present application, and specific examples are used to illustrate the principles and implementation methods of the present application. 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 solution deviate from the scope of the technical solution of the embodiments of the present application.

Claims

1. A single cell battery, characterized in that: include: A housing having a receiving cavity; an electrode assembly, wherein the electrode assembly is located in the accommodating cavity; A cover plate, the cover plate is connected to the shell and covers the accommodating cavity, and the cover plate is provided with an explosion-proof hole; an explosion-proof valve, the explosion-proof valve covers the explosion-proof hole, the explosion-proof valve comprises a bearing portion, a weak portion, a protruding portion and a concave portion which are connected in sequence from the outside to the inside, the bearing portion is connected to the cover plate, the weak portion is configured to be destroyed when impacted by a preset pressure, the protruding portion protrudes from the connection with the weak portion toward a side away from the electrode assembly, and the concave portion is recessed toward a side close to the electrode assembly; The area of ​​the protrusion is S1 mm 2 The area of ​​the concave portion is S2 mm 2 , satisfying: 0.1≤S2 / (S1+S2)≤0.

4.

2. The single cell according to claim 1, characterized in that: The area of ​​the explosion-proof valve is Smm 2 , satisfying: 0.4≤(S1+S2) / S≤0.

8.

3. The single cell according to claim 2, characterized in that: The single cell satisfies: 0.35≤S1 / S≤0.

6.

4. The single cell according to claim 2, characterized in that: The single cell satisfies: 0.1≤S2 / S≤0.

2.

5. The single cell 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.

6. The single cell according to claim 5, characterized in that: The maximum dimension of the bearing portion in the thickness direction is A mm, satisfying the following conditions: C>A, 0.4≤A≤0.

6.

7. The single cell according to claim 1, characterized in that: The bearing portion is connected to a side of the cover plate close to the electrode assembly, and the protruding portion protrudes into the explosion-proof hole.

8. The single cell according to claim 1, characterized in that: A limiting groove is provided on one side of the cover plate close to the electrode assembly, the limiting groove is arranged around the explosion-proof hole, the limiting groove is provided on one side of the cover plate close to the electrode assembly, and the bearing part is arranged in the limiting groove.

9. A battery pack, characterized in that: The invention comprises the single cell according to any one of claims 1 to 8.

10. An electrical device, characterized in that: The method comprises the single cell according to any one of claims 1 to 8, or comprises the battery pack according to claim 9.

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