Battery monomer, battery and electric device

Abstract

The invention relates to a battery monomer which comprises a shell, a battery cell, a cover plate and a collector plate, an annular first weak part is formed on the cover plate, and an annular second weak part is formed on the flow collecting disc. When thermal runaway occurs and the pressure in the shell exceeds a threshold value, the first weak part and the second weak part are broken through, so that the first rupture disk and the second rupture disk are respectively separated from the cover plate and the main body of the collector plate and are jointly pushed outwards. And after the first rupture disk is pushed out, a pressure relief hole is formed in the cover plate, so that pressure relief is realized. After the second rupture disk is pushed out, a through hole is formed in the position, corresponding to the pressure relief hole, of the flow collecting disc. The formation of the through holes can prevent the flow collecting disc from shielding the pressure relief holes, so that the smoothness of the exhaust channel is ensured, and quick pressure relief is realized. Therefore, the pressure relief effect of the battery monomer is remarkably improved. In addition, the invention also provides a battery and an electric device.

Description

Technical Field

[0001] The present invention relates to the field of new energy technology, and in particular to a battery cell, a battery and an electrical device. Background Art

[0002] The cover of a cylindrical battery is usually provided with a circle of notches or grooves as a weak part. When the battery experiences thermal runaway, the air pressure inside the battery will increase sharply. When the pressure exceeds the threshold, the weak part will be torn open, thereby forming a pressure relief hole on the cover to achieve pressure relief. However, since the end face of the cylindrical battery cell is generally connected to a current collecting plate, the pressure relief hole may be blocked to a certain extent, resulting in poor pressure relief and the risk of battery fire and explosion. Summary of the invention

[0003] Based on this, it is necessary to provide a battery cell, a battery and an electrical device that can improve the pressure relief effect in order to solve the above problems.

[0004] On the one hand, the present application provides a battery cell, including a shell, a battery cell, a cover plate and a current collecting plate, wherein the cover plate is covered on one end of the shell, the battery cell and the current collecting plate are accommodated in the shell, a first annular weak portion is formed on the cover plate, and a portion of the cover plate located inside the first weak portion forms a first bursting piece; the current collecting plate is arranged on a side of the cover plate facing the battery cell, a second annular weak portion is formed on the current collecting plate, and a portion of the current collecting plate located inside the second weak portion forms a second bursting piece; wherein the projection of the second weak portion on the surface of the cover plate does not exceed the area enclosed by the first weak portion.

[0005] In one embodiment, the first weak portion is configured as an annular hollow groove, and the second weak portion is configured as a notched groove.

[0006] In one embodiment, the second weak portion is located within the range of the first weak portion.

[0007] In one embodiment, the second weak portion is formed on a surface of the collecting plate facing the cover plate.

[0008] In one embodiment, the cover plate portions located on both sides of the first weak portion are welded to the current collecting plate.

[0009] In one embodiment, the width of the hollow groove is W1, and the distance between the notched groove and the side wall of the hollow groove is W2; wherein, 2W2≤W1≤3W2, and 1mm≤W1≤3mm.

[0010] In one of the embodiments, an annular protrusion extending into the hollow groove is formed on the surface of the collecting plate, and the second weak portion is located on the annular protrusion and extends along the annular protrusion.

[0011] In one embodiment, the side walls on opposite sides of the annular protrusion are inclined toward each other.

[0012] In one of the embodiments, the hollow groove is filled with a cured adhesive layer.

[0013] In one of the embodiments, a avoiding boss is formed on a side of the cover plate facing away from the battery cell.

[0014] In one embodiment, the current collecting plate includes a first metal layer and a second metal layer stacked on each other, the first metal layer is located on a side of the current collecting plate facing the battery cell and is welded to the tab of the battery cell, and the second metal layer is located on a side of the current collecting plate facing away from the battery cell and is welded to the cover plate.

[0015] Compared with the prior art, this application has at least the following beneficial effects:

[0016] When thermal runaway occurs in the battery cell and the pressure in the shell exceeds the threshold, the first weak part and the second weak part will be broken through, so that the first bursting disc and the second bursting disc are separated from the cover plate and the main body of the current collecting plate, respectively, and pushed out together. After the first bursting disc is pushed out, a pressure relief hole will be formed on the cover plate to achieve pressure relief. After the second bursting disc is pushed out, a through hole will be formed at the position corresponding to the pressure relief hole on the current collecting plate. The formation of the through hole can prevent the current collecting plate from blocking the pressure relief hole, thereby ensuring the smooth flow of the exhaust channel to achieve rapid pressure relief. Therefore, the pressure relief effect of the above-mentioned battery cell is significantly improved.

[0017] On the other hand, the present application provides a battery, comprising a plurality of battery cells as described in any one of the above preferred embodiments.

[0018] In addition, the present application also provides an electrical device, comprising a plurality of battery cells as described in any one of the above preferred embodiments or a battery as described in the above embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1A schematic diagram of the structure of a battery cell in one embodiment of the present invention;

[0021] Figure 2 for Figure 1 An exploded view of the battery cell shown;

[0022] Figure 3 for Figure 1 The battery cell is shown in a cross-sectional view along AA;

[0023] Figure 4 for Figure 3 An enlarged schematic diagram of a part B in the battery cell shown;

[0024] Figure 5 A schematic diagram of the structure of a battery cell in another embodiment of the present invention;

[0025] Figure 6 for Figure 5 A cross-sectional view of the battery cell shown;

[0026] Figure 7 for Figure 6 An enlarged schematic diagram of a local area C in the battery cell shown. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0028] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0029] In addition, 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 the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0030] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0032] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0033] The present invention discloses an electric device, a battery and a battery cell. The electric device includes the battery or the battery cell, and can be provided with electric energy by the battery or the battery cell. The electric device can be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, an energy storage device, an amusement equipment, an elevator and a lifting device, etc. The vehicle can be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. The spacecraft includes an airplane, a rocket, a space shuttle and a spacecraft, etc. The electric toy includes a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy or an electric airplane toy, etc. The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool and an electric tool for railways, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact drill, a concrete vibrator and an electric planer, etc. The energy storage device can be an energy storage wall, a base station energy storage, a container energy storage, etc. The amusement equipment can be a carousel, a jumping machine, etc. This application does not impose any special restrictions on the above-mentioned electrical devices.

[0034] For new energy vehicles, the above batteries can be used as a driving power source, thereby replacing fossil fuels to provide driving power.

[0035] The above-mentioned battery can be a battery pack or a battery module. When the above-mentioned battery is a battery pack, the battery pack specifically includes a battery management system (BMS) and a plurality of the above-mentioned battery cells. The plurality of battery cells can be electrically connected in series, in parallel, or in a mixture of series and parallel, and communicated with the battery management system to form a battery pack, and the above-mentioned battery management system controls and monitors the working status of each battery cell. In addition, the plurality of battery cells can also be first connected in series and / or in parallel, and form a battery module with the module management system, and then the plurality of battery modules are electrically connected in series, in parallel, or in a mixture of series and parallel, and together with the battery management system form a battery pack.

[0036] The battery pack or battery module may be mounted on a supporting structure such as a box, a frame, or a bracket, and the battery cells and the battery management system may be electrically connected to each other through a busbar, such as a bar. The battery cells may be lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries. Specifically, in the present embodiment, the battery cells are lithium-ion cylindrical batteries.

[0037] See also Figure 1 , Figure 2 and Figure 3 In one embodiment of the present invention, a battery cell 10 includes a housing 100 , a battery cell 200 , a cover plate 300 and a current collecting plate 400 .

[0038] The shell 100 is a tubular structure, specifically a cylindrical shape. The shell 100 can be an aluminum shell or a steel shell. The present embodiment adopts a steel shell, which has a higher structural strength. The shell 100 is usually provided with an opening at one end, and the opening can allow the battery cell 200 and the current collecting plate 400 to be installed, and the cover plate 300 is covered at one end of the opening of the shell 100 and closes the opening. In addition, a pole 500 is generally provided at one end of the shell 100 away from the cover plate 300. The battery cell 200 is the core component of the battery cell and is accommodated in the shell 100. The battery cell 200 is generally formed by winding a positive electrode sheet, a negative electrode sheet and a diaphragm that acts as an insulator between the negative electrode sheet and the positive electrode sheet. Specifically, the battery cell 200 in the present embodiment is cylindrical, and a positive electrode ear and a negative electrode ear are respectively provided at both ends.

[0039] Normally, the positive pole ear of the battery cell 200 is electrically connected to the pole 500 through the second current collecting plate 600, and the negative pole ear is electrically connected to the cover plate 300 through the current collecting plate 400, so the pole 500 and the cover plate 300 will respectively serve as the positive terminal and negative terminal of the battery cell 10. Of course, the positions of the positive pole ear and the negative pole ear of the battery cell 200 can also be reversed. That is, the positive pole ear is electrically connected to the cover plate 300 through the current collecting plate 400, and the negative pole ear is electrically connected to the pole 500 through the second current collecting plate 600, so the pole 500 and the cover plate 300 will respectively serve as the negative terminal and positive terminal of the battery cell 10.

[0040] The material of the cover plate 300 is the same as that of the shell 100, so the welding effect with the shell 100 is better. An annular first weak portion 301 is formed on the cover plate 300, and the portion of the cover plate 300 located inside the first weak portion 301 forms the first bursting piece 310. The structural strength of the first weak portion 301 is lower than that of other portions. Specifically, the first weak portion 301 can be a hollow groove, a notched groove or a thinning area. Optionally, the first weak portion 301 is in the shape of a circular ring, so the first bursting piece 310 is in the shape of a circular plate. When the pressure on one side of the cover plate 300 exceeds a threshold value, the first weak portion 301 ruptures and separates the first bursting piece 310 from the main body of the cover plate 300, thereby forming a pressure relief hole (not shown) on the cover plate 300.

[0041] The current collecting plate 400 is arranged on the side of the cover plate 300 facing the battery cell 200. Specifically, the current collecting plate 400 can be welded to the cover plate 300 by penetration welding, caulking welding, etc., so as to realize the electrical connection between the pole ear of the battery cell 200 and the cover plate 300. Among them, a ring-shaped second weak portion 401 is formed on the current collecting plate 400, and the part of the current collecting plate 400 located inside the second weak portion 401 forms a second bursting piece 410. The second weak portion 401 has a lower structural strength than other parts. Specifically, the first weak portion 301 can be a notched groove or a thinning area. Optionally, the second weak portion 401 is in the shape of a circular ring, so the second bursting piece 410 is in the shape of a circular plate. When the pressure on one side of the current collecting plate 400 exceeds the threshold value, the second weak portion 401 ruptures and separates the second bursting piece 410 from the main body of the current collecting plate 400, thereby forming a through hole (not shown) on the current collecting plate 400.

[0042] Furthermore, the projection of the second weak portion 401 on the surface of the cover plate 300 does not exceed the area enclosed by the first weak portion 301. In other words, the projection of the second weak portion 401 on the surface of the cover plate 300 is located in the area enclosed by the first weak portion 301, or partially overlaps with the first weak portion 301 but does not exceed the outer edge of the first weak portion 301. In this way, the size of the second bursting disc 410 can be made smaller than the size of the pressure relief hole formed on the cover plate 300, ensuring that the second bursting disc 410 can smoothly pass through the cover plate 300 through the pressure relief hole.

[0043] When thermal runaway occurs and causes the pressure in the housing 100 to exceed a threshold, the first weak portion 301 and the second weak portion 401 will be broken, so that the first bursting disc 310 and the second bursting disc 410 are separated from the cover plate 300 and the main body of the current collecting plate 400 respectively, and are pushed out together. The pressure relief hole formed by the first bursting disc 310 being pushed out can achieve pressure relief, and the through hole formed by the second bursting disc 410 being pushed out can prevent the current collecting plate 400 from blocking the pressure relief hole, thereby ensuring the smoothness of the exhaust passage to achieve rapid pressure relief.

[0044] Moreover, the tabs of the battery cell 200 are generally welded to the second bursting disc 410 . As the second bursting disc 410 rushes out, the connection between the battery cell 200 and the current collecting plate 400 will be disconnected, thereby cutting off the current to further ensure safety.

[0045] Please also read Figure 4 In this embodiment, the first weak portion 301 is configured as an annular hollow groove, and the second weak portion 401 is configured as a notched groove. In other words, the first bursting disc 310 is not connected to the cover plate 300 body, and the first bursting disc 310 is fixed by the collecting plate 400. When thermal runaway occurs, it is only necessary to tear the second weak portion 401, and the second bursting disc 410 and the first bursting disc 310 can be pushed out at the same time, thereby ensuring that pressure relief can be achieved smoothly.

[0046] It should be noted that in other embodiments, the first weak portion 301 and the second weak portion 401 may also be configured as notched grooves. In this case, the threshold for pressure relief of the battery cell 10 is equal to the sum of the thresholds for rupture of the first weak portion 301 and the second weak portion 401. In addition, in order to ensure the integrity of the cover plate 300 and facilitate assembly, a connecting portion may be provided in the hollow groove to connect the first bursting disc 310 with the main body of the cover plate 300.

[0047] Furthermore, in this embodiment, the second weak portion 401 is located within the range of the first weak portion 301. That is, the projection of the notched groove on the collecting plate 400 on the cover plate 300 is located within the hollow groove. In this way, when the second weak portion 401 is broken, the size of the through hole formed on the collecting plate 400 is larger, which can further ensure the smooth flow of the exhaust passage.

[0048] Furthermore, in this embodiment, the second weak portion 401 is formed on the surface of the current collecting plate 400 facing the cover plate 300. In this way, the notched groove can be exposed in the hollow groove, so that the notched groove can be observed from the outside of the cover plate 300 during the welding operation between the current collecting plate 400 and the cover plate 300, thereby facilitating the identification and positioning of the notched groove during welding and reducing assembly errors.

[0049] Specifically, in this embodiment, the cover plate 300 is located at the first weak portion 301, that is, both sides of the hollow groove are welded to the current collecting plate 400. The two sides of the hollow groove are the first bursting disc 310 and the main body of the cover plate 300, which can be welded to the second bursting disc 410 and the main body of the current collecting plate 400 respectively. In this way, two annular weld marks will be formed between the current collecting plate 400 and the cover plate 300, and the two weld marks are respectively located on both sides of the hollow groove, thereby ensuring the sealing performance between the current collecting plate 400 and the cover plate 300.

[0050] More specifically, in this embodiment, the width of the hollow groove is W1, and the distance between the notched groove and the side wall of the hollow groove is W2; wherein 2W2≤W1≤3W2, and 1mm≤W1≤3mm. It should be noted that W2 refers to the distance between the opening edge of the notched groove and the side wall of the hollow groove.

[0051] If W2 is too small, the space available for welding on both sides of the notched groove is small, so the welding area is insufficient, resulting in poor weld strength, and the sealing between the collector plate 400 and the cover plate 300 is affected; if W2 is too large, the exposed area of ​​the collector plate 400 is large, which is easy to cause damage to the collector plate 400. In particular, when the collector plate 400 is formed of metal such as copper, it is easy to rust and corrode.

[0052] In addition, in this embodiment, the hollow groove is filled with a cured glue layer (not shown). Specifically, the cured glue layer can be made by first filling the hollow groove with UV glue or other common glue and then curing it into shape. The cured glue layer can form a protective layer in the hollow groove, thereby preventing the notched groove from being deformed or scratched by foreign objects. Moreover, the cured glue layer can fill the gap between the cover plate 300 and the collecting plate 400, and can also play a role in improving the sealing performance. Optionally, the top surface of the cured glue layer is flush with the outer surface of the cover plate 300.

[0053] Please refer again Figure 2 and Figure 3 In this embodiment, a side of the cover plate 300 facing away from the battery cell 200 is formed with an avoidance boss 320. The avoidance boss 320 can be formed by stamping, and is generally located in the middle of the cover plate 300 and is concentrically arranged with the first bursting piece 310. The avoidance boss 320 can play a role of outstanding protection, effectively preventing the first weak portion 301 and the second weak portion 401 from being scratched by foreign objects.

[0054] In addition, in the present embodiment, the current collecting plate 400 includes a first metal layer (not shown) and a second metal layer (not shown) stacked on each other. The first metal layer is located on the side of the current collecting plate 400 facing the battery cell 200 and is welded to the pole ear of the battery cell 200. The second metal layer is located on the side of the current collecting plate 400 facing away from the battery cell 200 and is welded to the cover plate 300.

[0055] The second metal layer is usually a steel layer, which is the same material as the cover plate 300, so it can reduce the difficulty of welding with the cover plate 300. The material of the first metal layer can be specifically set according to the material of the pole ear to be welded thereto. Specifically, when the pole ear welded to the first metal layer is a negative pole ear, the first metal layer can be a copper layer; and when the pole ear welded to the first metal layer is a positive pole ear, the first metal layer can be an aluminum layer. Therefore, it can be ensured that a reliable weld mark is formed between the first metal layer and the pole ear of the battery cell 200.

[0056] Moreover, the second metal layer can also protect the first metal layer, thereby reducing the risk of rusting of the first metal layer. The second metal layer can be thicker than the first metal layer, and the notch groove can be only opened in the second metal layer without extending to the first metal layer.

[0057] See also Figure 5 , Figure 6 and Figure 7 In another embodiment, the surface of the collector plate 400 is formed with an annular protrusion 420 extending into the hollow groove, and the second weak portion 401 is located on the annular protrusion 420 and extends along the annular protrusion 420. In this embodiment, the second weak portion 401 is set as a notched groove, and in the thickness direction of the collector plate 400, the bottom surface of the notched groove is located between the surfaces on opposite sides of the collector plate 400, ensuring that the second weak portion 401 is smoothly broken in the event of thermal runaway.

[0058] The end surface of the annular protrusion 420 is usually lower than the outer surface of the cover plate 300, which can prevent the annular protrusion 420 from being scratched by foreign objects. The annular protrusion 420 can play the role of a reinforcing rib, thereby reducing the risk of deformation of the cover plate 300 and ensuring the stability and consistency of the valve opening pressure value of the second weak portion 401, thereby ensuring that the first weak portion 301 and the second weak portion 401 are successfully broken through during thermal runaway, and the first bursting disc 310 and the second bursting disc 410 can be smoothly pushed out. In addition, the annular protrusion 420 can also cooperate with the hollow groove to play a positioning role during the assembly process.

[0059] Furthermore, in this embodiment, the side walls on both sides of the annular protrusion 420 are inclined toward each other. On the one hand, the inclined side walls can avoid stress concentration; on the other hand, when the cover plate 300 and the current collecting plate 400 are welded by caulking welding, the inclined side walls can also avoid laser during laser welding, reducing the difficulty of welding.

[0060] When thermal runaway occurs in the battery cell 10 and the pressure in the housing 100 exceeds the threshold, the first weak portion 301 and the second weak portion 401 will be broken through, so that the first bursting piece 310 and the second bursting piece 410 are separated from the main body of the cover plate 300 and the current collecting plate 400, respectively, and pushed out together. After the first bursting piece 310 is pushed out, a pressure relief hole will be formed on the cover plate 300, thereby achieving pressure relief. After the second bursting piece 410 is pushed out, a through hole will be formed at a position corresponding to the pressure relief hole in the current collecting plate 400. The formation of the through hole can prevent the current collecting plate 400 from blocking the pressure relief hole, thereby ensuring the smooth flow of the exhaust channel to achieve rapid pressure relief. Therefore, the pressure relief effect of the battery cell 10 is significantly improved.

[0061] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0062] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A battery cell, comprising a shell, a battery cell, a cover plate and a current collecting plate, wherein the cover plate is arranged on one end of the shell, and the battery cell and the current collecting plate are accommodated in the shell, characterized in that: A first annular weak portion is formed on the cover plate, and a portion of the cover plate located inside the first weak portion forms a first bursting piece; the current collecting plate is arranged on a side of the cover plate facing the battery cell, and a second annular weak portion is formed on the current collecting plate, and a portion of the current collecting plate located inside the second weak portion forms a second bursting piece; wherein the projection of the second weak portion on the surface of the cover plate does not exceed the area enclosed by the first weak portion.

2. The battery cell according to claim 1, characterized in that: The first weak portion is configured as an annular hollow groove, and the second weak portion is configured as a notched groove.

3. The battery cell according to claim 2, characterized in that: The second weak portion is located within the range of the first weak portion.

4. The battery cell according to claim 3, characterized in that: The second weak portion is formed on a surface of the collecting plate facing the cover plate.

5. The battery cell according to claim 3, characterized in that: Portions of the cover plate located on both sides of the first weak portion are welded to the current collecting plate.

6. The battery cell according to claim 3, characterized in that: The width of the hollow groove is W1, and the distance between the notched groove and the side wall of the hollow groove is W2; wherein, 2W2≤W1≤3W2, and 1mm≤W1≤3mm.

7. The battery cell according to claim 2, characterized in that: An annular protrusion extending into the hollow groove is formed on the surface of the collecting plate, and the second weak portion is located on the annular protrusion and extends along the annular protrusion.

8. The battery cell according to claim 7, characterized in that: The side walls on opposite sides of the annular protrusion are arranged to be inclined toward each other.

9. The battery cell according to claim 2, characterized in that: The hollow groove is filled with a cured adhesive layer.

10. The battery cell according to claim 1, characterized in that: A avoiding boss is formed on a side of the cover plate facing away from the battery core.

11. The battery cell according to claim 1, characterized in that: The current collecting plate includes a first metal layer and a second metal layer stacked on each other, the first metal layer is located on a side of the current collecting plate facing the battery cell and welded to the tab of the battery cell, and the second metal layer is located on a side of the current collecting plate facing away from the battery cell and welded to the cover plate.

12. A battery, characterized in that: The invention comprises a plurality of battery cells as claimed in any one of claims 1 to 11.

13. An electrical device, characterized in that: The invention comprises a battery cell as claimed in any one of claims 1 to 11 or a battery as claimed in claim 12.

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