Battery cell and electrical device

Abstract

Disclosed in the present application are a battery cell and an electrical device. The battery cell comprises a casing and a pressure relief assembly; the casing is provided with an accommodation space and a liquid injection hole communicated with the accommodation space; the pressure relief assembly covers the liquid injection hole; the pressure relief assembly comprises an adapter component, a sealing component and a pressure relief component; the casing, the adapter component, the sealing component and the pressure relief component are sequentially stacked in a first direction; the adapter component comprises a first main body part and a first weld mark part; the projection of the sealing component on the adapter component in the first direction is a first projection; the first projection is located within the first main body part; the first weld mark part is arranged around the peripheral side of the first projection; the first weld mark part and the first projection are spaced apart; and the first weld mark part is welded to the casing. The battery cell provided by the present application is highly safe.

Description

Battery cells and electrical devices

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on January 29, 2024, with application number 202410121864.2 and invention name “Battery Cell and Electrical Device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of electric energy storage, and in particular to a battery cell and an electric device. Background Art

[0003] A battery cell is a device that converts external energy into electrical energy and stores it inside the cell to power external electrical devices (such as portable electronic devices, etc.) when needed. In related technologies, a battery cell includes a shell with an injection hole provided on the shell, through which electrolyte can be injected into the shell, and then a pressure relief assembly is used to seal the injection hole. If the pressure relief assembly is damaged during the assembly of the battery cell, when the battery cell is in a thermal runaway state, a large amount of gas will be generated inside the battery. The damaged pressure relief assembly will not be able to immediately relieve the air pressure inside the shell, which will cause the battery to explode, affecting the safety of the user.

[0004] In summary, it is necessary to design a battery cell and an electrical device to solve the above technical problems. Summary of the Invention

[0005] Embodiments of the present application provide a battery cell and an electrical device, wherein the safety of the battery cell is improved.

[0006] In a first aspect, an embodiment of the present application provides a battery cell, comprising:

[0007] The shell has a receiving space and a liquid injection hole communicating with the receiving space;

[0008] A pressure relief assembly covers the liquid injection hole. The pressure relief assembly includes an adapter, a seal and a pressure relief assembly. The shell, the adapter, the seal and the pressure relief assembly are stacked in sequence along a first direction. The adapter includes a first main body and a first weld mark. The projection of the seal on the adapter along the first direction is the first projection. The first projection is located in the first main body. The first weld mark is arranged around the circumference of the first projection, and the first weld mark is spaced apart from the first projection. The first weld mark is welded to the shell.

[0009] In some embodiments, the minimum spacing distance between the first projection and the first welding mark portion is d3, and d3 satisfies 0.02 mm to 0.25 mm.

[0010] In some embodiments, d3 satisfies 0.05 mm to 0.18 mm.

[0011] In some embodiments, the adapter further includes an edge portion, and the first main body portion, the first welding mark portion, and the edge portion are arranged in sequence from the inside to the outside.

[0012] In some embodiments, the shell includes a shell wall and a second weld mark portion, wherein the second weld mark portion is embedded in the shell wall and connected to the first weld mark portion.

[0013] In some embodiments, the first welding mark portion includes a first surface close to the shell and a second surface facing away from the shell, and a projection of the first surface along the first direction is located within a projection of the second surface along the first direction.

[0014] In some embodiments, a projection of the first surface along the first direction covers the second welding mark portion.

[0015] In some embodiments, the length of the first weld mark portion along the second direction is the width of the first weld mark portion, and the width of the first weld mark portion gradually decreases along the direction from the pressure relief piece to the shell. The length of the second weld mark portion along the second direction is the width of the second weld mark portion, and the width of the second weld mark portion gradually decreases along the direction from the pressure relief piece to the shell. The second direction is perpendicular to the first direction.

[0016] In some embodiments, the width of the second surface is d1, and d1 satisfies 70 um to 150 um.

[0017] In some embodiments, a width of the second welding mark portion away from the surface of the housing is d2, and d2 satisfies 30 um to 80 um.

[0018] In some embodiments, the length of the second welding mark along the first direction is H2, the length of the shell wall along the first direction is H3, and H2 and H3 satisfy 30um≤H2≤0.8*H3.

[0019] In some embodiments, the minimum spacing distance between the edge of the adapter and the first welding mark portion is d4, and d4 satisfies 0.02 mm to 0.22 mm.

[0020] In some embodiments, the adapter has a first through hole connected to the liquid injection hole, the sealing component has a second through hole connected to the liquid injection hole, and the pressure relief component covers the second through hole.

[0021] In some embodiments, a projection of the sealing member on the adapter along the first direction falls into the first through hole.

[0022] In some embodiments, the edge of the sealing member is located outside a projection of the pressure relief member on the sealing member along the first direction.

[0023] In some embodiments, a projection of the adapter on the housing along the first direction falls into the liquid injection hole.

[0024] In some embodiments, the outer diameter of the seal is 2.5 mm to 3.0 mm, the inner diameter of the seal is 0.6 mm to 1.0 mm, and the thickness of the seal along the first direction is 0.03 mm to 0.07 mm.

[0025] In some embodiments, the seal comprises a first adhesive layer, a second adhesive layer, and a third adhesive layer sequentially arranged along a first direction, wherein the melting point of the second adhesive layer is greater than that of the first adhesive layer, and the melting point of the second adhesive layer is greater than that of the third adhesive layer.

[0026] In a second aspect, an embodiment of the present application further provides an electrical device, comprising a battery cell provided according to the second aspect, wherein the battery cell is used to provide electrical energy.

[0027] In some embodiments, the electrical device includes a housing, the housing includes a receiving space and an escape space that are connected to each other, the battery cell portion is engaged in the receiving space, and the recess is engaged in the escape space.

[0028] Compared with the related art, in the battery cell and electrical device provided in the embodiments of the present application, the first weld mark portion and the shell are welded, so that the connection between the shell and the adapter is stable, and the electrolyte is prevented from flowing out of the shell from between the shell and the first weld mark portion; the seal is stacked between the first main body and the pressure relief member, so that the connection between the adapter and the pressure relief member is stable, and the electrolyte is prevented from flowing out of the shell from between the adapter and the pressure relief member; the projection of the seal along the first direction on the adapter is located inside the first main body and is spaced apart from the first weld mark portion, so that when welding the first weld mark portion and the shell, the welding area is spaced apart from the seal by a certain distance, which can avoid or reduce the impact of the welding operation on the connection between the seal and the adapter and the pressure relief member when welding the first weld mark portion and the shell, avoid or reduce damage to the pressure relief assembly, and thus improve the safety of the prepared battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application. 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 creative work.

[0030] FIG1 is a schematic diagram of the three-dimensional structure of a battery cell provided in one embodiment of the present application;

[0031] FIG2 is a schematic diagram of the disassembled structure of a battery cell provided in one embodiment of the present application;

[0032] FIG3 is a schematic diagram of a partial cross-sectional structure of a battery cell provided in one embodiment of the present application;

[0033] FIG4 is a schematic diagram of a partial cross-sectional structure of a battery cell provided in one embodiment of the present application;

[0034] FIG5 is a schematic diagram of a partial cross-sectional structure of a battery cell provided in one embodiment of the present application;

[0035] FIG6 is an electron microscope image of a partial cross-sectional structure of a sealing member provided in one embodiment of the present application.

[0036] FIG7 is a schematic diagram of the three-dimensional structure of a battery cell provided in one embodiment of the present application;

[0037] FIG8 is an enlarged structural schematic diagram of portion A shown in FIG7 ;

[0038] FIG9 is an electron microscope image of a partial cross-sectional structure of a battery cell provided in one embodiment of the present application.

[0039] In the accompanying drawings: 1. Shell; 11. Liquid injection hole; 12. Shell wall; 13. Second weld mark portion; 14. Accommodation space; 15. Upper cover; 16. Lower cover; 17. Recess; 2. Pressure relief assembly; 21. Adapter; 211. First main body; 212. First weld mark portion; 2121. First surface; 2122. Second surface; 213. Edge portion; 214. First through hole; 22. Sealing member; 221. Second through hole; 224. First adhesive layer; 222. Second adhesive layer; 223. Third adhesive layer; 23. Pressure relief member; X, first direction; Y, second direction; Z, third direction. DETAILED DESCRIPTION

[0040] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In the detailed description below, many specific details are proposed to provide a comprehensive understanding of the present application. However, it will be apparent to those skilled in the art that the present application can be implemented without the need for some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present application by illustrating the examples of the present application.

[0041] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The embodiments will be described in detail below with reference to the accompanying drawings.

[0042] In one aspect, the present application provides a battery cell. In order to better understand the technical solution and technical effects of the present application, specific embodiments will be described in detail below with reference to the accompanying drawings.

[0043] Please refer to Figures 1, 2 and 3. A battery cell includes a shell 1 and a pressure relief assembly 2. The shell 1 has a receiving space 14 and a liquid injection hole 11 connected to the receiving space 14; the pressure relief assembly 2 covers the liquid injection hole 11, and the pressure relief assembly 2 includes an adapter 21, a seal 22 and a pressure relief member 23. The shell 1, the adapter 21, the seal 22 and the pressure relief member 23 are stacked in sequence along a first direction X. The adapter 21 includes a first main body 211 and a first welding mark 212. The projection of the seal 22 on the adapter 21 along the first direction X is a first projection. The first projection is located within the first main body 211. The first welding mark 212 is arranged around the circumference of the first projection, and the first welding mark 212 is spaced apart from the first projection. The first welding mark 212 is welded to the shell 1.

[0044] The battery cells provided in this application may specifically be lithium-ion secondary battery cells, lithium-ion primary battery cells, lithium-sulfur battery cells, sodium-lithium-ion battery cells, sodium-ion battery cells or magnesium-ion battery cells, etc., and the embodiments of this application are not limited to this.

[0045] The housing 1 has an upper cover 15 and a lower cover 16, which together form a receiving space 14 of the housing 1. A battery cell can be placed in the receiving space 14. The battery cell includes a positive electrode sheet, a negative electrode sheet, and a separator. The portion of the battery cell containing active material constitutes the positive and negative electrode sheets of the battery cell, and the portion without active material constitutes the tab. Electrolyte can also be injected into the receiving space 14 through the injection hole 11, and the positive electrode sheet, negative electrode sheet, and separator are immersed in the electrolyte. In some embodiments, the positive electrode sheet, negative electrode sheet, and separator are wound to form a wound structure. In other embodiments, the positive electrode sheet, separator, and negative electrode sheet are stacked in sequence to form a laminated structure. Those skilled in the art can select a suitable battery cell as needed. During the charge and discharge process of the battery cell, the positive electrode active material and the negative electrode active material react with the electrolyte. The tab is used to connect the electrode terminal to form a current circuit, and the electrode terminal is led out from one end of the housing 1.

[0046] The housing 1 may include a top wall and a bottom wall arranged along a thickness direction Z, and a side wall connecting the top wall and the bottom wall. The injection hole 11 may be arranged on the side wall. The first direction X may be a length direction or a width direction of the housing 1.

[0047] The pressure relief assembly 2 is welded to the housing 1 via the adapter 21, allowing the pressure relief assembly 2 to seal the injection hole 11 and prevent leakage of the electrolyte in the housing 1. The seal 22 is made of a material with a preset melting point, which can be lower than the melting point of the adapter 21 and / or lower than the melting point of the pressure relief member 23. When the battery cell is in a thermal runaway state, the temperature of the seal 22 reaches the preset melting point, the seal 22 melts, and a pressure relief channel is formed between the adapter 21 and the pressure relief member 23. The pressure in the housing 1 is relieved through the pressure relief channel, thereby preventing or reducing the risk of battery cell explosion.

[0048] The adapter 21 can be in the shape of a metal plate to facilitate welding the adapter 21 and the housing 1. The adapter 21 can be a nickel sheet with a passivation layer, and the passivation layer can be chromium oxide. The pressure relief member 23 can also be in the shape of a metal plate to facilitate the sealing member 22 to connect the adapter 21 and the pressure relief member 23. The pressure relief member 23 can be a nickel sheet with a passivation layer, and the passivation layer can be chromium oxide. The nickel sheet after the surface is cleaned can be immersed in a chromate solution to form a passivation layer of chromium oxide on the surface of the nickel sheet. Optionally, the thickness of the passivation layer is 10nm to 150nm. The passivation layer can reduce or prevent the electrolyte from corroding the adapter 21 and the pressure relief member 23. The adapter 21 and the pressure relief member 23 can be made of different materials so that the adapter 21 and the pressure relief member 23 have different physical and chemical properties. The adapter 21 and the pressure relief member 23 can also be made of the same material to simplify the preparation steps.

[0049] When preparing a battery cell, the adapter 21 , the seal 22 and the pressure relief member 23 can be stacked in sequence to pre-assemble the pressure relief component 2 , and then the assembled pressure relief component 2 can be welded to the shell 1 , and the pressure relief component 2 can seal the liquid injection hole 11 .

[0050] Exemplarily, when preparing a battery cell, the adapter 21, the seal 22 and the pressure relief member 23 are stacked in sequence to pre-assemble the pressure relief assembly 2; the battery cell is placed in the shell 1, and the electrolyte is injected into the shell 1 through the injection hole 11; an image showing the injection hole 11 is obtained, the injection hole 11 in the image is identified, and the first coordinate information of the injection hole 11 is obtained, and the second coordinate information is obtained based on the preset offset coordinate and the first coordinate information; according to the second coordinate information, the pre-assembled pressure relief assembly 2 is controlled to be located on one side of the injection hole 11 so that the pressure relief assembly 2 covers the injection hole 11; an image showing the adapter 21 is obtained, the adapter 21 in the image is identified, and the third coordinate information of the welding is obtained; the carrier carrying the shell 1 is moved to be opposite to the laser galvanometer, and the welding gun is controlled to shoot the laser to the position corresponding to the first weld mark 212 in the adapter 21 according to the third coordinate information to weld to form the first weld mark 212 welded to the shell 1.

[0051] In this embodiment, by arranging the first welding mark portion 212 and the shell 1 for welding, the connection between the shell 1 and the adapter 21 is stable, and the electrolyte is prevented from flowing out of the shell 1 from between the shell 1 and the first welding mark portion 212; by arranging the sealing member 22 to be stacked between the first main body portion 211 and the pressure relief member 23, the connection between the adapter 21 and the pressure relief member 23 is stable, and the electrolyte is prevented from flowing out of the shell 1 from between the adapter 21 and the pressure relief member 23; the projection of the sealing member 22 along the first direction X on the adapter 21 is located inside the first main body portion 211 and is spaced apart from the first welding mark portion 212, so that when welding the first welding mark portion 212 and the shell 1, the welding area is spaced apart from the sealing member 22 by a certain distance, which can avoid or reduce the impact of the welding operation on the connection between the sealing member 22 and the adapter 21 and the pressure relief member 23 when welding the first welding mark portion 212 and the shell 1, thereby avoiding or reducing damage to the pressure relief assembly 2, thereby improving the safety of the prepared battery cell.

[0052] In some embodiments, the adapter 21 further includes an edge portion 213 , and the first main body portion 211 , the first welding mark portion 212 and the edge portion 213 are arranged in sequence from the inside to the outside.

[0053] The first weld mark portion 212 can penetrate the adapter 21 along the first direction X. The first weld mark portion 212 is arranged around the first main portion 211, and the edge portion 213 is arranged around the first weld mark portion 212. The seal 22 does not block the first weld mark portion 212 and the edge portion 213 in the first direction X. Therefore, when welding the adapter 21 and the housing 1, the welding gun can directly act on the area where the first weld mark portion 212 is located, thereby facilitating the welding operation. During the welding operation, the welding gun can weld the housing 1 and the adapter 21 along the intersection of the first main portion 211 and the edge portion 213, thereby forming the first weld mark portion 212 at the intersection of the first main portion 211 and the edge portion 213.

[0054] An edge portion 213 is provided on the outer side of the first weld mark portion 212 so that the area where the welding gun can operate to form the first weld mark portion 212 is large enough to avoid welding positioning errors during welding that result in the first weld mark portion 212 not being stably connected to the housing 1.

[0055] Please refer to FIG. 4 . In some embodiments, the housing 1 includes a housing wall 12 and a second welding mark portion 13 . The second welding mark portion 13 is embedded in the housing wall 12 and connected to the first welding mark portion 212 .

[0056] When the welding torch is applied to adapter 21, high temperature is transferred through adapter 21 to housing 1, causing some of the housing 1 material to melt, forming a second weld mark 13 connected to first weld mark 212. The welding torch parameters are controlled so that the formed second weld mark 13 is embedded in housing wall 12, but does not penetrate through it. This prevents over-welding and prevents the welding operation from affecting the electrolyte, battery cells, etc. within housing 1.

[0057] In some embodiments, the first welding mark 212 includes a first surface 2121 close to the shell 1 and a second surface 2122 away from the shell 1 , and the first welding mark 212 includes a projection of the first surface 2121 along the first direction X located within a projection of the second surface 2122 along the first direction X.

[0058] The area of ​​second surface 2122 is larger than that of first surface 2121. During welding, the welding torch can be applied to the surface of adapter 21 facing away from housing 1. Heat generated by the welding torch is transferred from the surface of adapter 21 facing away from housing 1 to the surface of adapter 21 closer to housing 1, causing the projection of first surface 2121 on housing 1 along the first direction X to lie within the projection of second surface 2122 on housing 1 along the first direction X. This means that first weld mark 212 forms a structure with one end larger than the other along the first direction X. The welding torch acts on second surface 2122 to facilitate welding.

[0059] In some embodiments, a projection of the first surface 2121 along the first direction X covers the second welding mark portion 13 .

[0060] The first surface 2121 is connected to the second weld mark 13, increasing the area of ​​the first surface 2121 to improve the stability of the connection between the adapter 21 and the housing 1. During welding, the welding gun can act on the second surface 2122, and heat energy is transferred from the first weld mark 212 to the second weld mark 13, so that the projection of the first surface 2121 along the first direction X covers the second weld mark 13 on the housing 1. In other words, the width of the first weld mark 212 is greater than the width of the second weld mark 13. The first weld mark 212 is smaller than the second weld mark 13 to prevent the formation of the second weld mark 13 from affecting the electrolyte and electrode assembly.

[0061] In some embodiments, the length of the first weld mark portion 212 along the second direction Y is the width of the first weld mark portion 212, and the width of the first weld mark portion 212 gradually decreases along the direction from the pressure relief member 23 to the shell 1. The length of the second weld mark portion 13 along the second direction Y is the width of the second weld mark portion 13, and the width of the second weld mark portion 13 gradually decreases along the direction from the pressure relief member 23 to the shell 1. The first direction X is perpendicular to the second direction Y.

[0062] When the adapter 21 is annular, the second direction Y can be the radial direction of the adapter 21. The width of the first weld mark 212 gradually decreases along the direction from the pressure relief member 23 to the housing 1, and the width of the second weld mark 13 gradually decreases along the direction from the pressure relief member 23 to the housing 1, so that the cross-section of the first weld mark 212 along the first direction X and the cross-section of the second weld mark 13 along the first direction X can form a triangle. From the first weld mark 212 to the second weld mark 13, the width of the second weld mark 13 of the first weld mark 212 gradually decreases along the direction from the pressure relief member 23 to the housing 1, thereby reducing the impact of the formation of the second weld mark 13 on the electrolyte and battery cells.

[0063] Please refer to FIG. 5 . In some embodiments, the width of the second surface 2122 is d1 , and d1 satisfies 70 um to 150 um.

[0064] The width of the second surface 2122 is d1. If d1 is too narrow, it will affect the conduction of heat energy from the first weld mark 212 to the second weld mark 13, affecting the connection area between the first weld mark 212 and the second weld mark 13. If d1 is too wide, it will affect the spacing between the first weld mark 212 and the sealing member 22. d1 is set to 70um to 150um to ensure that the connection between the first weld mark 212 and the second weld mark 13 formed during the welding process is stable, and at the same time, the spacing between the first weld mark 212 and the sealing member 22 is large enough to avoid or reduce the possibility of the sealing member 22 being heated and melted during the welding operation, resulting in structural changes in the sealing member 22. Optionally, d1 is 90um to 120um.

[0065] In some embodiments, the width of the second weld mark 13 away from the surface of the housing 1 is d2, and d2 is 30 μm to 80 μm, which can further ensure the stable connection between the first weld mark 212 and the second weld mark 13 while reducing the heat impact on the sealing member 22.

[0066] The width of the second weld mark 13 away from the surface of the shell 1 is d2. If d2 is too narrow, it will affect the stability of the connection between the first weld mark 212 and the second weld mark 13. If d2 is too wide, the second weld mark 13 will be too deep, easily penetrating the shell wall 12 and contacting the electrolyte, affecting the quality of the battery cell. d1 is set to 30um to 80um to ensure that the connection between the first weld mark 212 and the second weld mark 13 formed during the welding process is stable, and the size of the second weld mark 13 is small enough to avoid or reduce the impact of the formation of the second weld mark 13 on the electrolyte and battery cells. Optionally, d2 is 40um to 70um.

[0067] In some embodiments, the length of the second welding mark 13 along the first direction X is H2, the length of the shell wall 12 along the first direction X is H3, and 30 μm≤H2≤0.8*H3.

[0068] The length of the first weld mark 212 along the first direction X is H1. Since the first weld mark 212 passes through the first main body 211, H1 can be equal to the length of the adapter 21 along the first direction X. The second weld mark 13 is embedded in the shell 1 to form the shell wall 12 of the liquid injection hole 11, so that the length H2 of the second weld mark 13 along the first direction X is less than the length H3 of the shell wall 12 along the first direction X. If H2 is too small, it will affect the stability of the connection between the shell 1 and the second weld mark 13. If H2 is too large, the second weld mark 13 will be too deep, resulting in over-welding. 30um≤H2≤0.8*H3 is set to ensure that the connection between the first weld mark 212 and the second weld mark 13 formed during the welding process is stable, and the size of the second weld mark 13 is small enough to avoid or reduce the formation of the second weld mark 13 affecting the electrolyte and battery cells. Optionally, 30um≤H2≤80um.

[0069] In some embodiments, a minimum spacing distance d3 between the first projection and the first welding mark portion 212 is 0.02 mm to 0.25 mm.

[0070] If d3 is too narrow, the heat generated by welding during the process of forming the first weld mark 212 will be easily transferred to the sealing layer, reducing the reliability of the sealing layer. If d3 is too wide, the adapter 21 will be too large or the seal 22 will be too small. If the adapter 21 is too large, it will be unfavorable for the miniaturization of the battery cell. If the seal 22 is too small, the pressure relief channel formed by the melted seal 22 will have insufficient pressure reduction capacity in the event of electrical runaway. Set d3 to 0.02mm to 0.25mm to reduce or avoid the heat generated during the welding process affecting the reliability of the sealing layer. The size of the adapter 21 and the size of the seal 22 are appropriate. Optionally, d3 meets the requirements of 0.05mm to 0.18mm.

[0071] In some embodiments, the minimum spacing distance d4 between the edge of the adapter 21 and the first welding mark portion 212 is 0.02 mm to 0.22 mm.

[0072] The edge of the adapter 21 can be the edge of the edge portion 213 away from the first main body portion 211. If d4 is too narrow, the positioning requirements for the edge of the adapter 21 during welding are high, and the working position of the welding gun is easily deviated to the outside of the adapter 21, resulting in a cold weld or no weld between the adapter 21 and the shell 1, thereby reducing the welding sealing effect between the adapter 21 and the shell 1. If d4 is too wide, the size of the adapter will be too large, which is not conducive to the miniaturization of the battery cell. Setting d4 to 0.02mm to 0.22mm can reduce or avoid cold welds or no welds between the adapter 21 and the shell 1.

[0073] In some embodiments, the adapter 21 has a first through hole 214 communicating with the liquid injection hole 11 , the sealing member 22 has a second through hole 221 communicating with the liquid injection hole 11 , and the pressure relief member 23 covers the second through hole 221 .

[0074] The injection hole 11, first through hole 214, and second through hole 221 can be coaxially arranged. The receiving space 14, injection hole 11, first through hole 214, and second through hole 221 are sequentially connected. The diameter of the injection hole 11 can be greater than or equal to the diameter of the first through hole 214, and the diameter of the first through hole 214 can be greater than the diameter of the second through hole 221. In the event of thermal runaway of the battery cell, the pressure relief channel formed by the melting of the seal 22 communicates with the second through hole 221, allowing the pressure relief channel to exhaust the high-pressure gas in the receiving space 14.

[0075] In some embodiments, a projection of the sealing member 22 along the first direction X onto the adapter 21 falls into the first through hole 214 .

[0076] The seal 22 and adapter 21 can be annular. The outer diameter Φ1 of the adapter 21 is greater than the outer diameter Φ2 of the seal 22. That is, the projection of the outer edge of the seal 22 onto the adapter 21 along the first direction X is located inward of the outer edge of the adapter 21, allowing the first projection of the seal 22 stacked on the adapter 21 to be spaced apart from the first weld mark 212. The inner diameter ψ1 of the adapter 21 is greater than the inner diameter ψ1 of the seal 22. This allows the projection of the seal 22 onto the adapter 21 along the first direction X to partially fall into the first through-hole 214, thereby improving the sealing performance of the seal 22 between the adapter 21 and the pressure relief member 23.

[0077] In some embodiments, an edge of the sealing member 22 is located outside a projection of the pressure relief member 23 along the first direction X onto the sealing member 22 .

[0078] The outer diameter Φ3 of the pressure relief member 23 is smaller than the outer diameter Φ2 of the sealing member 22, so that the edge of the sealing member 22 is located outside the projection of the pressure relief member 23 on the sealing member 22 along the first direction X. The pressure relief member 23 can be stacked on the sealing member 22, ensuring an effective seal between the sealing member 22 and the pressure relief member 23. The outer diameter Φ3 of the pressure relief member 23 is larger than the inner diameter ψ1 of the sealing member 22, so that the pressure relief member 23 can cover the second through hole 221 along the first direction X, thereby sealing the liquid injection hole 11.

[0079] In some embodiments, a projection of the adapter 21 on the housing 1 along the first direction X falls into the liquid injection hole 11 .

[0080] The outer diameter Φ1 of the adapter 21 is larger than the diameter r1 of the liquid injection hole 11, allowing the adapter 21 to cover one side of the liquid injection hole 11. The inner diameter ψ1 of the adapter 21 is smaller than the diameter r1 of the liquid injection hole 11, allowing the projection of the adapter 21 on the housing 1 along the first direction X to fall into the liquid injection hole 11, facilitating liquid injection into the receiving space 14 through the liquid injection hole 11. This reduces the diameters of the first through hole 214 and the second through hole 221, and reduces the size of the pressure relief member 23, thereby improving the sealing performance between the adapter and the seal 22, and between the seal 22 and the pressure relief member 23. The projection of the adapter 21 on the housing 1 along the first direction X into the liquid injection hole 11 ensures that liquid injection is not affected while also improving the sealing performance of the pressure relief assembly 2.

[0081] The diameter D1 of the liquid injection hole 11 may be 0.5 to 3 mm to ensure the efficiency of liquid injection through the liquid injection hole 11 .

[0082] In some embodiments, the outer diameter Φ1 of the adapter 21 is 3 to 4 mm, the inner diameter ψ1 of the adapter 21 is 0.5 to 2 mm, and the thickness of the adapter 21 along the first direction X is 0.05 to 1.5 mm. The inner diameter ψ1 of the adapter 21 is the diameter of the first through hole 214. If the inner diameter ψ1 of the adapter 21 is too large, the area required for the adapter 21 to connect with the housing 1 increases, which is not conducive to sealing between the adapter 21 and the housing 1. If the inner diameter ψ1 of the adapter 21 is too small, the diameter of the first through hole 214 is reduced, which is not conducive to pressure relief through the first through hole 214 in the event of thermal runaway.

[0083] In one embodiment, the initial outer diameter of the seal 22 before the adapter 21 and the pressure relief member 23 are bonded is 2 to 4 mm, the initial inner diameter of the seal 22 is 0.8 to 1.9 mm, and the initial thickness of the seal 22 along the first direction X is 0.05 to 1.5 mm. The seal 22 is hot-pressed to connect the adapter 21 and the pressure relief member 23. After the hot-pressing, the outer diameter Φ2 of the seal 22 is 2.5 to 3.0 mm, the inner diameter ψ2 of the seal 22 is 0.6 to 1.0 mm, and the thickness of the seal 22 along the first direction X is 0.03 to 0.07 mm. The inner diameter ψ2 of the seal 22 is the aperture of the second through hole 221. If the inner diameter ψ2 of the seal 22 is too large, the connection area between the seal 22 and the pressure relief component 23 will be reduced, which is not conducive to the sealing between the seal 22 and the pressure relief component 23; if the inner diameter ψ2 of the seal 22 is too small, the aperture of the second through hole 221 will be reduced, and the seal 22 after melting will easily overflow excessively, which is not conducive to forming a pressure relief channel and not conducive to pressure relief in the case of thermal runaway.

[0084] In one embodiment, the outer diameter Φ3 of the pressure relief member 23 is 2 to 3 mm, and the thickness of the pressure relief member 23 along the first direction X is 0.1 to 0.2 mm. If the outer diameter Φ3 of the pressure relief member 23 is too large, it is not conducive to forming a pressure relief channel in the melted seal 22, which is not conducive to pressure relief in the event of thermal runaway. If the outer diameter Φ3 of the pressure relief member 23 is too small, the area of ​​the pressure relief member 23 available for connection with the seal 22 is reduced, which is not conducive to the sealing between the seal 22 and the pressure relief member 23.

[0085] The outer diameter Φ1 of the adapter 21 is 3.4 mm, the inner diameter ψ1 of the adapter 21 is 1 mm, and the thickness of the adapter 21 along the first direction X is 0.08 mm. The outer diameter Φ2 of the seal 22 is 2.2 mm, the inner diameter ψ2 of the seal 22 is 1.2 mm, and the thickness of the seal 22 along the first direction X is 0.08 mm. The outer diameter Φ3 of the pressure relief member 23 is 2.5 mm, and the thickness of the pressure relief member 23 along the first direction X is 0.08 mm. The diameter D1 of the injection hole 11 is 1 to 2 mm. The initial outer diameter of the seal 22, without the adapter 21 and the pressure relief member 23 bonded together, is 2.2 mm, the initial inner diameter of the seal 22 is 1.2 mm, and the initial thickness of the seal 22 along the first direction X is 0.08 mm.

[0086] The seal 22 can be single-layer or multi-layer. A single-layer seal 22 is made of the same material so that the melting point of the seal 22 is consistent. A multi-layer seal 22 is made of different materials so that different layers have different melting points.

[0087] In some embodiments, the sealant 22 is a single layer, and the melting point of the sealant 22 is 123±5°C.

[0088] In some embodiments, the seal 22 is double-layered, including a first adhesive layer 224 and a second adhesive layer 222 . The first adhesive layer 224 is located on a side of the second adhesive layer 222 close to the adapter 21 . The melting point of the first adhesive layer 224 is 123±5° C.

[0089] Referring to Figure 6, in some embodiments, the seal 22 includes a first adhesive layer 224, a second adhesive layer 222 and a third adhesive layer 223 arranged in sequence along the first direction X, the melting point of the second adhesive layer 222 is greater than the melting point of the first adhesive layer 224, and the melting point of the second adhesive layer 222 is greater than the melting point of the third adhesive layer 223.

[0090] The first adhesive layer 224 and the third adhesive layer 223 can be made of the same material. Optionally, the melting point of the first adhesive layer 224 and the third adhesive layer 223 is 123±5°C. The melting point of the second adhesive layer 222 is 145±10°C. In the event of thermal runaway, the first adhesive layer 224 and the third adhesive layer 223 melt before the second adhesive layer 222, so that the second adhesive layer 222 can support the first adhesive layer 224 and the third adhesive layer 223. The first adhesive layer 224 melts, forming a pressure relief channel between the second adhesive layer 222 and the adapter 21; the third adhesive layer 223 melts, forming a pressure relief channel between the second adhesive layer 222 and the pressure relief member 23.

[0091] 7 , in some embodiments, the maximum length of the pressure relief assembly 2 along the second direction Y is greater than the maximum length of the pressure relief assembly 2 along the third direction Z, and the first direction X, the second direction Y, and the third direction Z are perpendicular to each other.

[0092] The reference plane in the second direction Y and the third direction Z can be parallel to the shell wall 12 forming the liquid injection hole 11. The pressure relief assembly 2 can be rectangular, and the maximum length of the pressure relief assembly 2 along the second direction Y is greater than the maximum length along the third direction Z. The third direction Z can be the thickness direction of the battery cell.

[0093] The maximum length of the pressure relief assembly 2 along the second direction Y is greater than its maximum length along the third direction Z to increase the contact area between the pressure relief assembly 2 and the housing 1. The adapter 21 can have a length in the third direction Z of 1.0 to 6 mm. Alternatively, the adapter 21 can have a length in the third direction Z of 1.0 to 3.5 mm. The housing 1 can have a length in the third direction Z of 1.1 to 5 mm, and the thickness of the housing wall 12 along the first direction X is 0.075 to 0.20 mm.

[0094] Please refer to Figure 8. In some embodiments, the shell 1 has a recess 17, which is recessed relative to the outer surface of the shell 1 in a direction closer to the battery cell. The liquid injection hole 11 is opened in the recess 17, and the pressure relief assembly 2 is arranged in the recess 17. The surface of the pressure relief member 23 facing away from the adapter is coplanar with the outer surface of the shell 1, or the surface of the pressure relief member 23 facing away from the adapter is located on the side of the outer surface of the shell 1 close to the battery cell.

[0095] Please refer to Figure 9, which is an electron microscope image of a partial cross-sectional structure of a battery cell. As can be seen from Figure 9, laser welding can form a first weld mark 212 on the adapter 21 and a second weld mark 13 in the housing 1.

[0096] In the second aspect, the present application further provides an electrical device, please refer to the figure, the electrical device includes the battery cell provided in the first aspect, and the battery cell is used to provide electrical energy.

[0097] There can be multiple battery cells, which can be connected in series, in parallel, or in hybrid connection to form a whole, through which charging and discharging are carried out. Hybrid connection means that multiple battery cells are connected in both series and in parallel.

[0098] Specific product types of electrical devices include but are not limited to mobile terminals, smart wearables, power tools, electric vehicles, mobile power supplies, etc.

[0099] Since the battery cell has the aforementioned beneficial effects, the electrical device is safe and reliable to use.

[0100] The above-mentioned beneficial effects are further illustrated below through examples and comparative examples.

[0101] Battery cells were manufactured using the parameters listed in Tables 1, 2, and 3. Unless otherwise specified, the adapter, seal, and pressure relief member of Experimental Examples 1-26 and Comparative Example 1 were coaxially arranged. The width of the second surface 2122 was d1, the minimum spacing between the first projection and the first weld mark 212 was d3, the width of the first surface 2122 was d2, and the minimum spacing between the edge of the adapter 21 and the first weld mark 212 was d4.

[0102] The prepared battery cells were subjected to bonding strength testing. With the housing 1 fixed, a pin fitted with the injection port 11 was used to apply varying thrusts F1 to the adapter 21. The bonding strength between the adapter 21 and the housing 1 was measured. With the housing 1 and adapter 21 fixed, a pin fitted with the injection port 11 was used to apply thrusts F2 to the pressure relief member 23. The bonding strength between the seal 22 connecting the adapter 21 and the pressure relief member 23 was measured. Each experimental example or comparative example was repeated 100 times. The average bonding strength of the battery cells in the same group was calculated and recorded as the bonding strength for that experimental example or comparative example.

[0103] The prepared battery cells were subjected to a high-temperature, high-humidity test. The fully charged battery cells were placed in an open circuit at (65±2)°C and 90-95% humidity for 42 days. The cells were removed every 7 days and inspected for leakage. If no leakage was observed, the fully charged battery cell was recorded as having passed the test. Each experimental example or comparative example was repeated 100 times. The probability of each battery cell in the same group passing the test was calculated as the high-temperature, high-humidity test pass rate.

[0104] Table 1

[0105] F2 represents the bond strength between the seal 22, adapter 21, and pressure relief member 23. Experiments 1-8 show that, while d1 and d4 remain constant, increasing d3 also increases F2. This indicates that a greater distance between the seal 22 and the first weld mark 212 improves the bond strength between the seal 22, adapter 21, and pressure relief member 23, and increases the structural stability of the pressure relief assembly 2. As d3 increases, the leakage test pass rate of the battery cells in high-temperature and high-humidity environments increases, indicating improved battery cell safety.

[0106] In Comparative Example 1, d3 is 0, and the adapter 21 and housing 1 are welded along the edge of the seal 22, resulting in a first weld mark 212 positioned along the edge of the seal 22. A comparison of Comparative Example 1 and Example 1 shows that when the first weld mark 212 is not spaced from the first projection of the seal 22, F2 is small, resulting in a low leakage test pass rate. This indicates that the formation of the first weld mark 212 affects the seal 22, resulting in poor bonding strength between the seal 22, the adapter 21, and the pressure relief member 23, and low battery cell safety.

[0107] By comparing Example 1 and Example 9, it can be seen that when d3 is less than 20um, F2 decreases, indicating that the welding process affects the structure of the seal 22. The battery cell has a leakage test pass rate of less than 90% in a high temperature and high humidity environment, indicating poor safety. By comparing Example 8 and Example 10, it can be seen that when d3 is greater than 250um, F2 remains unchanged. The battery cell has a leakage test pass rate in a high temperature and high humidity environment, indicating that after d3 is greater than 250um, the increase in d3 has no effect on F2 and the leakage test pass rate. The larger the value of d1+d3+d4, the larger the outer diameter of the adapter 21, which is not conducive to the miniaturization of the pressure relief assembly.

[0108] Table 2

[0109] F1 represents the bonding strength between adapter 21 and housing 1. Experiments 4 and 11-16 show that, while d3 and d4 remain constant, increasing d1 also increases F1. This indicates that a larger width of second surface 2122 improves the bonding strength between adapter 21 and housing 1, and a more stable connection between pressure relief assembly 2 and housing 1. As d1 increases, the leakage test pass rate of battery cells in high-temperature and high-humidity environments increases, indicating improved battery cell safety.

[0110] By comparing Example 16 and Example 17, it can be seen that when d1 is greater than 150um, F1 continues to increase, and the leakage test pass rate of the battery cell remains unchanged in a high temperature and high humidity environment, indicating that after d1 is greater than 150um, the increase in d3 has little effect on the leakage test pass rate. The larger the value of d1+d3+d4, the larger the outer diameter of the adapter 21, which is not conducive to the miniaturization of the pressure relief component. By comparing Example 11 and Example 18, it can be seen that when d1 is less than 60um, F1 decreases, and the leakage test pass rate of the battery cell in a high temperature and high humidity environment is less than 90%, and the safety of the battery cell is poor.

[0111] Table 3

[0112] It can be seen from Experimental Examples 19-24 that when d1 remains unchanged, d2 increases, and F1 increases, indicating that the width of the first surface 2122 increases, the bonding strength between the adapter 21 and the shell 1 is better, and the connection between the pressure relief assembly 2 and the shell 1 is more stable. It can be seen from Experimental Examples 26 and 19-22 that when d2 is between 20um and 60um, the greater the increase in d2, the greater the pass rate of the leakage test of the battery cell in a high temperature and high humidity environment, and the better the safety of the battery cell. It can be seen from Experimental Examples 22-25 that when d2 is between 60um and 90um, the greater the increase in d2, the lower the pass rate of the leakage test of the battery cell in a high temperature and high humidity environment, and the worse the safety of the battery cell, indicating that when d2 is greater than a certain threshold, the welding process affects the structure of the seal 22, affecting the safety of the battery cell in a high temperature and high humidity environment.

[0113] By comparing Example 25 and Example 26, it can be seen that when d3 is less than 250 μm or d3 is greater than 250 μm, the leakage test pass rate of the battery cell is less than 90% under a high temperature and high humidity environment, and the safety of the battery cell is poor.

[0114] In this document, the term "and / or" simply describes a relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document generally indicates that the related objects are in an "or" relationship.

[0115] It should be understood that in the embodiments of the present application, "B corresponding to A" means that B is associated with A and B can be determined based on A. However, it should also be understood that determining B based on A does not mean determining B based solely on A, but B can also be determined based on A and / or other information.

[0116] The above are only specific embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and such modifications or substitutions should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A battery cell, characterized in that: include: A shell having a receiving space and a liquid injection hole communicating with the receiving space; A pressure relief assembly covers the liquid injection hole, and the pressure relief assembly includes an adapter, a seal and a pressure relief assembly. The shell, the adapter, the seal and the pressure relief assembly are stacked in sequence along a first direction. The adapter includes a first main body and a first weld mark. The projection of the seal on the adapter along the first direction is a first projection. The first projection is located in the first main body. The first weld mark is arranged around the circumference of the first projection, and the first weld mark is spaced apart from the first projection. The first weld mark is welded to the shell.

2. The battery cell according to claim 1, wherein: The minimum spacing distance between the first projection and the first welding mark portion is d3, and d3 satisfies 0.02 mm to 0.25 mm.

3. The battery cell according to claim 2, characterized in that: d3 satisfies 0.05mm to 0.18mm.

4. The battery cell according to any one of claims 1 to 3, characterized in that: The adapter also includes an edge portion, and the first main body portion, the first welding mark portion and the edge portion are arranged in sequence from the inside to the outside.

5. The battery cell according to any one of claims 1 to 3, characterized in that: The shell includes a shell wall and a second welding mark portion, wherein the second welding mark portion is embedded in the shell wall and connected to the first welding mark portion.

6. The battery cell according to claim 5, characterized in that The first welding mark portion includes a first surface close to the shell and a second surface away from the shell, and a projection of the first surface along the first direction is located within a projection of the second surface along the first direction.

7. The battery cell according to claim 6, characterized in that A projection of the first surface along the first direction covers the second welding mark portion.

8. The battery cell according to claim 7, characterized in that The length of the first weld mark portion along the second direction is the width of the first weld mark portion, and the width of the first weld mark portion gradually decreases along the direction from the pressure relief piece to the shell. The length of the second weld mark portion along the second direction is the width of the second weld mark portion, and the width of the second weld mark portion gradually decreases along the direction from the pressure relief piece to the shell. The second direction is perpendicular to the first direction.

9. The battery cell according to claim 8, characterized in that The width of the second surface is d1, and d1 satisfies 70um to 150um.

10. The battery cell according to claim 8, characterized in that The width of the second welding mark away from the surface of the shell is d2, and d2 satisfies 30um to 80um.

11. The battery cell according to claim 5, characterized in that The length of the second welding mark along the first direction is H2, the length of the shell wall along the first direction is H3, and H2 and H3 satisfy 30um≤H2≤0.8*H3.

12. The battery cell according to any one of claims 1 to 3, characterized in that: The minimum spacing distance between the edge of the adapter and the first welding mark portion is d4, and d4 satisfies 0.02 mm to 0.22 mm.

13. The battery cell according to any one of claims 1 to 3, characterized in that: The adapter has a first through hole connected to the liquid injection hole, the sealing component has a second through hole connected to the liquid injection hole, and the pressure relief component covers the second through hole.

14. The battery cell according to claim 13, characterized in that A projection of the sealing member on the adapter along the first direction falls into the first through hole.

15. The battery cell according to any one of claims 1 to 3, characterized in that: The edge of the sealing member is located outside a projection of the pressure relief member on the sealing member along the first direction.

16. The battery cell according to any one of claims 1 to 3, characterized in that: A projection of the adapter on the housing along the first direction falls into the liquid injection hole.

17. The battery cell according to any one of claims 1 to 3, characterized in that: The outer diameter of the sealing member is 2.5 mm to 3.0 mm, the inner diameter of the sealing member is 0.6 mm to 1.0 mm, and the thickness of the sealing member along the first direction is 0.03 mm to 0.07 mm.

18. The battery cell according to any one of claims 1 to 3, characterized in that: The sealing member includes a first adhesive layer, a second adhesive layer and a third adhesive layer sequentially arranged along the first direction, the melting point of the second adhesive layer is greater than that of the first adhesive layer, and the melting point of the second adhesive layer is greater than that of the third adhesive layer.

19. An electrical device, characterized in that: The invention comprises a battery cell according to any one of claims 1 to 18, wherein the battery cell is used to provide electric energy.

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