Battery cell casing, pressure relief mechanism of battery cell, battery cell, and electrical apparatus

Abstract

A battery cell casing, a pressure relief mechanism (2) of a battery cell, a battery cell (10), and an electrical apparatus. The battery cell casing comprises a casing body (1) and a pressure relief mechanism (2); a through hole (20) is formed in the casing body (1); the pressure relief mechanism (2) is arranged in the through hole (20); the pressure relief mechanism (2) comprises an adhesive film (21) and a cover piece (22); the cover piece (22) is bonded to the casing body (1) by means of the adhesive film (21) and covers the through hole (20); the adhesive film (21) can be heated and melted to form a pressure relief channel communicating the interior and the exterior of the casing body (1); the bonding area of the cover piece (22) and the casing body (1) is A, and the cross-sectional area of the through hole (20) covered by the cover piece (22) is B, wherein 1.778≤A / B≤16.361. According to the structure, the range of the ratio of the bonding area A of the cover piece (22) and the casing body (1) to the cross-sectional area B of the pressure relief channel covered by the cover piece (22) is limited, so that when the internal pressure of the battery cell (10) reaches a preset value, the cover piece (22) can fall off in time to form a pressure relief channel, and the internal pressure of the battery cell (10) is reduced in time, and thus, the battery cell (10) can has good reliability while achieving overheating pressure relief.

Description

Battery cell casing, battery cell pressure relief mechanism, battery cell and electrical device

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on November 23, 2023, with application number 202311580556.8 and invention name “Battery cell casing, battery cell pressure relief mechanism, 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 field of batteries, and in particular to a battery cell casing, a battery cell pressure relief mechanism, a battery cell, and an electrical device. Background Art

[0003] Rechargeable batteries, also known as secondary batteries, are batteries that can be recharged after discharge to reactivate the active materials and continue to be used. Rechargeable batteries are widely used in electronic devices such as mobile phones, laptops, electric bicycles, electric cars, electric airplanes, electric boats, electric toy cars, electric toy boats, electric toy airplanes, and power tools.

[0004] Currently, battery cell covers typically feature notches to relieve excess pressure inside the cell. However, these notches have poor thermal sensitivity, resulting in poor pressure relief reliability. Improving the reliability of pressure relief in battery cells has long been a concern for those skilled in the art.

[0005] Summary of the Invention

[0006] The present application provides a battery cell casing, a battery cell pressure relief mechanism, a battery cell, and an electrical device. The battery cell casing can improve the reliability of battery cell pressure relief.

[0007] In a first aspect, the present application provides a battery cell casing, comprising a shell and a pressure relief mechanism, wherein the shell is provided with a through hole; the pressure relief mechanism is provided in the through hole, the pressure relief mechanism comprising an adhesive film and a cover sheet, the cover sheet being bonded to the shell and covering the through hole via the adhesive film, the adhesive film being capable of melting under heat to form a pressure relief channel connecting the interior and exterior of the shell; the bonding area between the cover sheet and the shell is A, the cross-sectional area of ​​the through hole covered by the cover sheet is B,

[0008] Since the bonding force between the cover sheet and the shell is proportional to the bonding area A between the cover sheet and the shell, the pressure exerted on the cover sheet by the pressure relief material inside the shell through the through hole is proportional to the cross-sectional area B of the through hole covered by the cover sheet. When the pressure exerted on the cover sheet by the pressure relief material inside the shell is greater than the bonding force between the cover sheet and the shell, the cover sheet will detach from the through hole or even fall off. By setting the ratio of the bonding area A between the cover sheet and the shell to the cross-sectional area B of the through hole covered by the cover sheet within a reasonable range, when the internal pressure of the battery cell reaches a preset value, the pressure exerted on the cover sheet by the pressure relief material inside the shell is greater than the bonding force between the cover sheet and the shell, and the cover sheet can fall off in time to form a pressure relief channel, thereby releasing the internal pressure of the battery cell in a timely manner. This allows the battery cell to achieve overheating pressure relief while also having good reliability.

[0009] According to some embodiments of the present application, the battery cell housing includes a side wall, and the through hole includes a first through hole provided on the side wall, so that the first through hole on the side wall can serve as a through hole in the housing for discharging substances. The cover is bonded to the side wall and covers the first through hole via an adhesive film, thereby sealing the first through hole and isolating the battery cell from the outside under normal operating conditions. In the case of mechanical abuse, the adhesive film can melt due to heat, and the adhesive force provided will decrease. The cover can detach from the side wall or even fall off under the action of the internal pressure of the battery cell, so that the first through hole forms a pressure relief channel connecting the inside and outside of the housing, and the substances inside the housing are released from the inside to the outside along the pressure relief channel formed by the first through hole.

[0010] According to the battery cell housing provided in some embodiments of the present application, the housing further includes an adapter disposed on the outside of the side wall, the through hole further includes a second through hole disposed on the adapter, the second through hole being connected to the first through hole, and the cover sheet being adhered to the side of the adapter away from the side wall via an adhesive film and covering the second through hole. By connecting both sides of the adapter in the thickness direction to the side wall and the cover sheet respectively, the adapter has a larger side surface for connection with the side wall and the cover sheet, which helps to improve the firmness of the connection between the adapter and the side wall and the cover sheet. In this case, A is the bonding area between the cover sheet and the adapter, and B is the cross-sectional area of ​​the second through hole covered by the cover sheet.

[0011] According to the battery cell casing provided in some embodiments of the present application, along the axial direction of the second through hole, the projection of the second through hole is located within the projection range of the first through hole, so that the cross-sectional area of ​​the first through hole is greater than or equal to the cross-sectional area of ​​the second through hole, so that the discharged material in the casing can flow smoothly along the arrangement direction of the first through hole and the second through hole; at the same time, by setting the cross-sectional area of ​​the second through hole to be smaller than the cross-sectional area of ​​the first through hole, the cover sheet can obtain a larger bonding area with the adapter when covering the second through hole, which is beneficial to improving the reliability of the connection between the cover sheet and the adapter.

[0012] According to the battery cell casing provided in some embodiments of the present application, the first direction is perpendicular to the second direction, and the first direction and the second direction are both perpendicular to the axial direction of the first through hole; the length of the first through hole in the first direction is greater than the length of the first through hole in the second direction, and / or the length of the second through hole in the first direction is greater than the length of the second through hole in the second direction, so that part of the pressure relief channel can be expanded in the first direction, thereby improving the pressure relief capacity of the pressure relief channel.

[0013] According to the battery cell casing provided in some embodiments of the present application, the length of the side wall in the first direction is D, and the length of the side wall in the second direction is E, 10mm≤D≤100mm, so that the battery cell can be within a relatively reasonable size range, and at the same time, the length of the first through hole in the first direction is limited; 1mm≤E≤20mm, so that the battery cell can be within a relatively reasonable size range, and at the same time, the length of the first through hole in the second direction is limited.

[0014] According to the battery cell housing provided in some embodiments of the present application, the length of the first through hole in the second direction is L1, 1mm≤L1≤6mm, so that the length of the first through hole in the second direction can match the length of the side wall in the second direction, so that the first through hole is not likely to affect the structural strength of the side wall, which is beneficial to maintaining the structural strength of the battery cell. The length of the second through hole in the second direction is L2, 0.2mm≤L2≤5mm, so that the length of the second through hole in the second direction can match the length of the side wall in the second direction and the length of the first through hole in the second direction, so that the second through hole is not likely to affect the structural strength of the adapter, which is beneficial to maintaining the structural strength of the battery cell. And / or, the length of the first through hole in the first direction is L3, 1mm≤L3≤6mm, so that the length of the first through hole in the first direction will not affect the structural strength of the side wall due to being too long, nor will it reduce the cross-sectional area of ​​the first through hole due to being too short, so that the discharge capacity of the first through hole is not easily affected. The length of the second through hole in the first direction is L4, 0.2mm≤L4≤5mm, so that the length of the second through hole in the first direction will not affect the structural strength of the adapter due to being too long, nor will it reduce the cross-sectional area of ​​the second through hole due to being too short, so that the discharge capacity of the second through hole is not easily affected.

[0015] In the battery cell casing provided in some embodiments of the present application, the first through-hole is configured as a racetrack-shaped hole, allowing the first through-hole to increase its cross-sectional area by increasing its length in the second direction, thereby facilitating improved passage of pressure-relieving material through the first through-hole. Alternatively, the second through-hole is configured as a racetrack-shaped hole, allowing the second through-hole to increase its cross-sectional area by increasing its length in the second direction, thereby facilitating improved passage of pressure-relieving material through the second through-hole.

[0016] According to the battery cell casing provided in some embodiments of the present application, the projection of the bonding area between the cover and the adapter along the axial direction of the first through hole is a first projection, and the width of the first projection in the radial direction of the first through hole is C, 0.6mm≤C≤0.95mm. This not only enables the bonding area between the cover and the adapter to provide sufficient bonding force for the cover, thereby reducing the risk of the cover falling off under normal operating conditions of the battery cell, but also enables the cover to fall off from the adapter in time under thermal runaway conditions, thereby facilitating the timely discharge of leaked substances.

[0017] According to the battery cell housing provided in some embodiments of the present application, By setting the ratio of the bonding area A between the cover and the shell and the cross-sectional area B of the through hole covered by the cover within the above range, the internal pressure of the battery cell can be further released, so that the battery cell can achieve overheating pressure relief while also having good reliability.

[0018] According to the battery cell housing provided in some embodiments of the present application, 0.28mm 2 ≤B≤4.524mm 2 , so that the cover can be smoothly affected by the pressure inside the shell, and is not easily caused to fall off under normal working conditions due to excessive pressure inside the shell, which is beneficial to improving the reliability of the pressure relief mechanism.

[0019] According to some embodiments of the present application, the battery cell housing is 3.581mm 2 ≤A≤8.042mm 2 , which not only enables the cover to fall off smoothly from the adapter under thermal runaway conditions, but also enables the cover to be firmly connected to the adapter under normal conditions.

[0020] According to the battery cell casing provided in some embodiments of the present application, the melting point of the adhesive film is T1, 110°C ≤ T1 ≤ 130°C, so that the adhesive film has good thermal sensitivity under thermal runaway conditions and will not melt under normal conditions.

[0021] According to the battery cell casing provided in some embodiments of the present application, the adhesive film includes a first sub-membrane and a second sub-membrane stacked along the axial direction of the first through hole, the first sub-membrane is located between the second sub-membrane and the cover sheet, and the melting point of the second sub-membrane is lower than the melting point of the first sub-membrane, so that when the adhesive film is heated, the second sub-membrane is more likely to melt, and the cover sheet is more likely to fall off due to the melting of the second sub-membrane, which is beneficial to improving the pressure relief sensitivity of the pressure relief mechanism.

[0022] According to the battery cell casing provided in some embodiments of the present application, the melting point of the second sub-film is T2, 100°C≤T2≤120°C, so that the second sub-film is more likely to melt under thermal runaway conditions, so that the cover sheet can be smoothly detached.

[0023] According to the battery cell casing provided in some embodiments of the present application, the adhesive film also includes a third sub-film located between the first sub-film and the second sub-film. The melting point of the third sub-film is higher than the melting point of the first sub-film and the melting point of the second sub-film, so that the third sub-film can play a good supporting role for the adhesive film as a whole, which is beneficial to improving the overall strength of the adhesive film.

[0024] According to the battery cell casing provided in some embodiments of the present application, the melting point of the third sub-membrane is T3, 130℃≤T3≤150℃, so that the third sub-membrane is not easy to melt compared with the first sub-membrane and the second sub-membrane, and can play a good supporting role for the entire film, reducing the possibility of the film melting under normal working conditions.

[0025] According to the battery cell casing provided in some embodiments of the present application, the adhesive film includes polypropylene.

[0026] According to the battery cell casing provided in some embodiments of the present application, the thickness of the adhesive film in the axial direction of the first through hole is H, 10μm≤H≤48μm, so that the adhesive film has sufficient structural strength without causing material waste due to excessive thickness.

[0027] According to the battery cell casing provided in some embodiments of the present application, the adhesive strength of the adhesive film is P, The film can provide sufficient force for the cover to seal the pressure relief channel, making it difficult for the cover to fall off under normal working conditions. When the pressure inside the shell is too high, the internal pressure of the shell will overcome the adhesive effect of the film and cause the cover to fall off, thereby achieving pressure relief.

[0028] According to some embodiments of the present application, the first through hole of the battery cell housing is a liquid injection hole. By reusing the liquid injection hole as the first through hole for pressure relief, the battery cell manufacturing process can be further simplified, which is conducive to reducing the number of drilling steps and reducing the production cost of the battery cell.

[0029] In a second aspect, some embodiments of the present application provide a pressure relief mechanism for a battery cell, the pressure relief mechanism comprising a cover sheet, an adhesive film, and an adapter, the adapter being provided with a second through hole, the second through hole being used to communicate with the interior of a battery cell housing, the cover sheet being bonded to the adapter via the adhesive film and covering the second through hole, the adhesive film being capable of melting under heat to form a pressure relief channel communicating with the interior and exterior of the housing; the bonding area between the cover sheet and the adapter being F, the cross-sectional area of ​​the second through hole covered by the cover sheet being G,

[0030] Because the bonding force between the cover sheet and the adapter is proportional to the bonding area F between the cover sheet and the adapter, the pressure exerted on the cover sheet by the pressure relief material inside the shell through the second through hole is proportional to the cross-sectional area G of the second through hole covered by the cover sheet. When the pressure exerted on the cover sheet by the pressure relief material inside the shell is greater than the bonding force between the cover sheet and the adapter, the cover sheet falls off from the second through hole. By setting the ratio of the bonding area F between the cover sheet and the adapter to the cross-sectional area G of the second through hole covered by the cover sheet within a reasonable range, when the internal pressure of the battery cell reaches a preset value, the pressure exerted on the cover sheet by the pressure relief material inside the shell is greater than the bonding force between the cover sheet and the adapter, and the cover sheet can fall off in time to form a pressure relief channel, thereby releasing the internal pressure of the battery cell in a timely manner. This allows the pressure relief mechanism of the battery cell to achieve overheating pressure relief while also having good reliability.

[0031] In a third aspect, some embodiments of the present application provide a battery cell, which includes a battery cell casing provided by any of the above technical solutions.

[0032] In a fourth aspect, some embodiments of the present application provide an electrical device, the electrical device including the battery cell provided by any of the above technical solutions, the battery cell being used to provide electrical energy. Since the electrical device includes the battery cell provided by the above technical solution, the electrical device has good reliability.

[0033] The technical solutions provided by the embodiments of the present disclosure bring at least the following beneficial effects:

[0034] The present application provides a battery cell casing, which includes a shell and a pressure relief mechanism, wherein the shell is provided with a through hole; the pressure relief mechanism is provided in the through hole, and the pressure relief mechanism includes an adhesive film and a cover sheet, wherein the cover sheet is bonded to the shell and covers the through hole through the adhesive film, and the adhesive film can be melted by heat to form a pressure relief channel connecting the inside and outside of the shell; the bonding area between the cover sheet and the shell is A, and the cross-sectional area of ​​the through hole covered by the cover sheet is B. In the above structure, by limiting the ratio of the cover sheet's bonding area (A) to the housing's cross-sectional area (B) of the through-hole covered by the cover sheet, the cover sheet can promptly fall off to form a pressure relief channel when the cell's internal pressure reaches a preset value, allowing the cell's internal pressure to be promptly released. This allows the cell to achieve overheating pressure relief while maintaining good reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The features, advantages and technical effects of exemplary embodiments of the present application will be described below with reference to the accompanying drawings.

[0036] FIG1 is a schematic structural diagram of a battery cell provided in one embodiment of the present application;

[0037] FIG2 is a schematic diagram of a disassembled battery cell provided in one embodiment of the present application;

[0038] FIG3 is a schematic diagram of a disassembled battery cell provided in another embodiment of the present application;

[0039] FIG4 is a cross-sectional view of the section AA in FIG1 ;

[0040] FIG5 is a schematic diagram of a disassembled battery cell provided in yet another embodiment of the present application;

[0041] FIG6 is an enlarged view of the adhesive film in one embodiment of the present application;

[0042] FIG7 is an enlarged view of the adhesive film in another embodiment of the present application;

[0043] FIG8 is an enlarged view of the adhesive film in another embodiment of the present application;

[0044] FIG9 is an exploded view of a pressure relief mechanism of a battery cell provided in one embodiment of the present application;

[0045] FIG10 is a cross-sectional view of a pressure relief mechanism of a battery cell provided in one embodiment of the present application.

[0046] In the picture:

[0047] 1. Housing; 11. First through hole; 12. Adapter; 121. Second through hole; 13. Side wall; 2. Pressure relief mechanism; 21. Adhesive film; 211. First sub-membrane; 212. Second sub-membrane; 213. Third sub-membrane; 22. Cover; X, first direction; Y, second direction; 10. Battery cell; 20. Through hole.

[0048] In the accompanying drawings, the drawings are not necessarily drawn to scale. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0050] Currently, judging by market developments, batteries are increasingly being used. They are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace.

[0051] Currently, judging by market developments, batteries are increasingly being used. They are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace.

[0052] The battery cells mentioned in the embodiments of the present application may be secondary batteries or primary batteries. A secondary battery refers to a battery that can be recharged to activate the active material after discharge and continue to be used.

[0053] The battery cell can be a lithium ion battery cell, a sodium ion battery cell, a sodium lithium ion battery cell, a lithium metal battery cell, a sodium metal battery cell, a lithium sulfur battery cell, a magnesium ion battery cell, a nickel metal hydride battery cell, a nickel cadmium battery cell, a lead storage battery cell, etc.

[0054] A battery cell typically includes an electrode assembly. This assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process, active ions (such as lithium ions) are inserted and removed between the positive and negative electrodes. The separator, placed between the positive and negative electrodes, prevents short circuits while allowing the active ions to pass through.

[0055] In some embodiments, the electrode assembly is a wound structure or a laminated structure. Optionally, the electrode assembly is a cylindrical wound structure.

[0056] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing may be a steel housing, an aluminum housing, a plastic housing (e.g., polypropylene), or a composite metal housing (e.g., a copper-aluminum composite housing).

[0057] As an example, the battery cell may be a cylindrical battery cell, a prismatic battery cell or a battery cell of other shapes. The prismatic battery cell includes a square shell battery cell, a blade-shaped battery cell, a polygonal battery cell, and the polygonal battery cell is, for example, a hexagonal battery cell.

[0058] Since the battery cell generates heat when it is working, especially when it is in a state of thermal runaway, a large amount of heat will be generated and a large amount of gas will be released at the same time, causing the pressure inside the battery cell to rise sharply. In order to reduce the risk of explosion and other hazards, a pressure relief mechanism is usually set on the battery cell cover to release the pressure. In the related art, for common steel-shell battery cells, grooves are usually set on the cover so that when the gas pressure inside the battery cell is too high, the grooves will rupture to form a pressure relief channel to release the internal pressure. However, the thermal sensitivity of the grooves in this solution is poor, and it cannot respond to overheating conditions in a timely manner, resulting in poor reliability of pressure relief.

[0059] Based on the above considerations, in order to improve the reliability of pressure relief of the battery cell, the present application provides a battery cell, which includes a shell and a pressure relief mechanism, the shell is provided with a through hole; the pressure relief mechanism is provided in the through hole, the pressure relief mechanism includes a film and a cover sheet, the cover sheet is bonded to the shell and covers the through hole through the film, and the film can be melted by heat to form a pressure relief channel connecting the inside and outside of the shell; the bonding area between the cover sheet and the shell is A, and the cross-sectional area of ​​the through hole covered by the cover sheet is B. Since the bonding force between the cover sheet and the shell is proportional to the bonding area A between the cover sheet and the shell, the pressure exerted on the cover sheet by the pressure relief material inside the shell through the through hole is proportional to the cross-sectional area B of the through hole covered by the cover sheet. When the pressure exerted on the cover sheet by the pressure relief material inside the shell is greater than the bonding force between the cover sheet and the shell, the cover sheet will detach from the through hole or even fall off. By setting the ratio of the bonding area A between the cover sheet and the shell to the cross-sectional area B of the through hole covered by the cover sheet within a reasonable range, when the internal pressure of the battery cell reaches a preset value, the pressure exerted on the cover sheet by the pressure relief material inside the shell is greater than the bonding force between the cover sheet and the shell, and the cover sheet can fall off in time to form a pressure relief channel, thereby releasing the internal pressure of the battery cell in a timely manner. This allows the battery cell to achieve overheating pressure relief while also having good reliability.

[0060] The technical solutions of the battery cell and the electrical device provided in this application are further explained below through specific implementation methods.

[0061] Some embodiments of the present application provide a battery cell casing, as shown in FIG1 , which includes a casing 1 and a pressure relief mechanism 2. As shown in FIG2 , the casing 1 is provided with a through hole 20, and the pressure relief mechanism 2 is provided in the through hole 20. The pressure relief mechanism 2 includes an adhesive film 21 and a cover sheet 22. The cover sheet 22 is bonded to the casing 1 and covers the through hole 20 through the adhesive film 21. The adhesive film 21 can be melted by heat to cause the cover sheet 22 to detach or fall off to form a pressure relief channel connecting the inside and outside of the casing 1. The bonding area between the cover sheet 22 and the casing 1 is A, and the cross-sectional area of ​​the through hole covered by the cover sheet 22 is B.

[0062] The housing 1 may be a peripheral wall structure within the battery cell 10, forming a cavity for accommodating the electrode assembly and other components of the battery cell 10, as well as the electrolyte. The housing 1 may protect the components within the cavity. The through-hole 20 may be a hole-like structure provided on the housing 1, connecting the interior and exterior of the housing 1.

[0063] As shown in Figure 4, the pressure relief mechanism 2 can be a component arranged on the outside of the shell 1 for releasing the internal pressure of the battery cell 10. Its cover is arranged at the through hole 20. The pressure relief mechanism 2 can connect the through hole 20 with the outside in the case of mechanical abuse, so that the pressure inside the battery cell 10 can be released to the outside.

[0064] The cover sheet 22 can be a sheet-like component used to cover the through hole 20 in the pressure relief mechanism 2. It is used to block the through hole 20 and isolate the battery cell 10 from the outside under normal operating conditions. The adhesive film 21 can be a film structure formed by solidifying a hot-melt adhesive material. The cover sheet 22 is bonded to the housing 1 using the adhesive film 21. The adhesive film 21 formed by the hot-melt adhesive material can melt when heated, and the adhesive strength provided will decrease. The cover sheet 22 can fall off from the housing 1 under the action of the internal pressure of the battery cell 10, allowing the through hole 20 to connect the interior and exterior of the housing 1 to form a pressure relief channel, and the internal substances of the housing 1 are released to the outside through the pressure relief channel.

[0065] In some embodiments, the cover 22 can be configured as a metal part with high thermal conductivity, so that the cover 22 has good thermal conductivity, so that the heat generated by the battery cell 10 can be quickly transferred to the side of the film 21 away from the shell 1 through the cover 22, so that the film 21 is heated evenly, which is beneficial to improving the thermal pressure relief sensitivity of the pressure relief mechanism 2.

[0066] Exemplarily, the cover sheet 22 can be a nickel sheet, a stainless steel sheet, or a copper sheet. The nickel sheet, the stainless steel sheet, and the copper sheet all have high thermal conductivity, which is beneficial to further improve the thermal pressure relief sensitivity of the battery cell 10, so that when the temperature of the battery cell 10 is too high, the film 21 can be melted in time, the cover sheet 22 can fall off, and the pressure can be released quickly.

[0067] The bonding area A between the cover sheet 22 and the housing 1 can be the area of ​​the region where the cover sheet 22 is bonded to the housing 1 via the adhesive film 21. The adhesive film 21 is positioned between the cover sheet 22 and the housing 1 to provide adhesive force, thereby bonding the cover sheet 22 to the housing 1. The adhesive force between the cover sheet 22 and the housing 1 is proportional to the bonding area A between the cover sheet 22 and the housing 1. The larger the bonding area A between the cover sheet 22 and the housing 1, the greater the adhesive force between the cover sheet 22 and the housing 1.

[0068] The cross-sectional area B of the through-hole covered by cover sheet 22 can be the area where the internal pressure relief material of housing 1 acts on cover sheet 22. By acting on this area of ​​cover sheet 22, the pressure of the internal pressure relief material of housing 1 is applied to cover sheet 22. The pressure exerted on cover sheet 22 by the internal pressure relief material of housing 1 through the through-hole is proportional to the cross-sectional area B of the through-hole covered by cover sheet 22. The larger the cross-sectional area B of the through-hole covered by cover sheet 22, the greater the pressure exerted on cover sheet 22 by the pressure relief material. When the pressure exerted on cover sheet 22 by the internal pressure relief material of housing 1 exceeds the adhesive force between cover sheet 22 and housing 1, cover sheet 22 will fall off from through-hole 20.

[0069] By limiting the ratio range of the bonding area A between the cover sheet 22 and the housing 1 and the cross-sectional area B of the through hole covered by the cover sheet 22, When the internal pressure of the shell 1 rises, the pressure exerted on the cover 22 by the internal pressure-relieving material of the shell 1 can easily exceed the bonding force between the cover 22 and the shell 1, so that the battery cell 10 can release pressure in a state of minor deformation, so that the internal pressure of the battery cell 10 is released in time.

[0070] In some embodiments, the ratio of the bonding area A between the cover sheet 22 and the housing 1 to the cross-sectional area B of the through hole covered by the cover sheet 22 can be set to For example, It can be 3.34, 4.165 or 5.25, so that the bonding force between the cover sheet 22 and the shell 1 can respond sensitively to the internal pressure of the shell 1, so that the cover sheet 22 can fall off in time to release the pressure after the internal pressure of the shell 1 increases, so that the battery cell 10 can release the pressure in a state of minor deformation.

[0071] In the above structure, by limiting the ratio range of the bonding area A between the cover sheet 22 and the shell 1 and the cross-sectional area B of the through hole covered by the cover sheet 22, when the internal pressure of the battery cell 10 reaches a preset value, the cover sheet 22 can fall off in time to form a pressure relief channel, so that the internal pressure of the battery cell 10 can be released in time, so that the battery cell 10 can achieve overheating pressure relief while also having good reliability.

[0072] In some embodiments, as shown in FIG. 5 and FIG. 6 , the housing 1 includes a side wall 13 , the through hole 20 includes a first through hole 11 provided on the side wall 13 , and the cover 22 is adhered to the side wall 13 via an adhesive film 21 and covers the first through hole 11 .

[0073] The side wall 13 may be a portion of the wall structure of the housing 1, and the pressure relief mechanism 2 is disposed on this portion of the wall structure. The first through hole 11 may be a hole-like structure disposed on the side wall 13, which can connect the interior and exterior of the housing 1. By disposing the first through hole 11 on the side wall 13 and including the through hole 20 in the first through hole 11, the first through hole 11 on the side wall 13 can serve as the through hole 20 in the housing 1 for discharging substances.

[0074] Cover sheet 22 is bonded to side wall 13 via adhesive film 21 and covers first through-hole 11, sealing first through-hole 11 and isolating battery cell 10 from the outside under normal operating conditions. Under mechanical abuse, adhesive film 21 can melt due to heat, reducing the adhesive strength it provides. Cover sheet 22 can detach from side wall 13 or even fall off due to internal pressure in battery cell 10, allowing first through-hole 11 to form a pressure relief channel connecting the interior and exterior of housing 1. Materials within housing 1 are released to the outside along the pressure relief channel formed by first through-hole 11.

[0075] In some embodiments, as shown in Figure 3, the shell 1 also includes an adapter 12 arranged on the outside of the side wall 13, and the through hole 20 also includes a second through hole 121 set on the adapter 12, the second through hole 121 is connected to the first through hole 11, and the cover 22 is adhered to the side of the adapter 12 away from the shell 1 through the adhesive film 21 and covers the second through hole 121.

[0076] The adapter 12 can be a sheet-like component, which is arranged on the outside of the side wall 13 and located between the side wall 13 and the cover plate 22. The two sides of the adapter 12 in the thickness direction are respectively connected to the side wall 13 and the cover plate 22, so that the adapter 12 has a larger side surface to connect with the side wall 13 and the cover plate 22, which helps to improve the firmness of the connection between the adapter 12 and the side wall 13 and the cover plate 22.

[0077] The second through-hole 121 can be a hole-like structure formed on the adapter 12. It communicates with the first through-hole 11 and penetrates the adapter 12 along its thickness, allowing the discharged material to enter the second through-hole 121 from the first through-hole 11 and then be discharged from the battery cell 10. In some embodiments, the axis of the second through-hole 121 is configured to coincide with the axis of the first through-hole 11, so that the second through-hole 121 and the first through-hole 11 are coaxially arranged. This not only facilitates the discharge of the discharged material, but also facilitates the placement of the adapter 12 at the location of the first through-hole 11.

[0078] By adhering the cover sheet 22 to the side of the adapter 12 away from the side wall 13 using the adhesive film 21 and covering the second through hole 121, the cover sheet 22 can be connected to the side wall 13 through the adapter 12, which helps to improve the connection security of the cover sheet 22 to the side wall 13 and the sealing effect of the first through hole 11. The cover sheet 22 is adhered to the adapter 12 and covers the second through hole 121 by the adhesive film 21. When the cover sheet 22 or the adapter 12 is heated, the adhesive film 21 can melt, and the cover sheet 22 can fall off the adapter 12, thereby achieving pressure relief of the battery cell 10.

[0079] For example, the adapter 12 can be made of the same material as the cover 22, so that the adapter 12 and the cover 22 have the same thermal conductivity. This allows both sides of the adhesive film 21 located between the adapter 12 and the cover 22 to be evenly heated, which helps improve the sensitivity and reliability of the thermal pressure relief of the pressure relief mechanism 2. In some embodiments, the adapter 12 and the cover 22 can both be made of nickel sheet, so that both the adapter 12 and the cover 22 have good thermal conductivity.

[0080] In some embodiments, the adapter 12 can be bonded to the outside of the sidewall 13 using adhesive, facilitating the connection between the adapter 12 and the sidewall 13. Alternatively, the adapter 12 can be welded to the outside of the sidewall 13, allowing the materials of the adapter 12 and the sidewall 13 to fuse together, thereby ensuring a secure connection between the adapter 12 and the sidewall 13. For example, the adapter 12 can be laser welded to the outside of the sidewall 13, ensuring high weld quality and enhancing the secure connection between the adapter 12 and the sidewall 13. For example, the adapter 12 can be laser welded to the sidewall 13. Laser penetration welding not only allows for rapid and efficient metal welding, improving production efficiency, but also ensures excellent weld quality at the metal joint, making it less susceptible to surface corrosion and discoloration of the adapter 12, thereby further enhancing the secure and reliable connection between the adapter 12 and the sidewall 13.

[0081] In some embodiments, along the axial direction of the second through hole 121 , the projection of the second through hole 121 is located within the projection range of the first through hole 11 .

[0082] By configuring the second through hole 121 so that the projection of the second through hole 121 in the axial direction is located within the projection range of the first through hole 11 in the axial direction of the second through hole 121, the cross-sectional area of ​​the first through hole 11 is larger than the cross-sectional area of ​​the second through hole 121, so that the discharged material in the shell 1 can flow smoothly along the arrangement direction of the first through hole 11 and the second through hole 121; at the same time, by setting the cross-sectional area of ​​the second through hole 121 to be smaller than the cross-sectional area of ​​the first through hole 11, the cover plate 22 can obtain a larger bonding area with the adapter 12 when covering the second through hole 121, which is beneficial to improve the reliability of the connection between the cover plate 22 and the adapter 12. At this time, the outer diameter of the adapter 12 is larger than the aperture of the first through hole 11, so that the adapter 12 and the shell 1 can be tightly connected. In this solution, the present application does not have any special restrictions on the shape and size of the first through hole 11, as long as the above restrictions are met.

[0083] In some embodiments, the first direction X is perpendicular to the second direction Y, and both the first direction X and the second direction Y are perpendicular to the axial direction of the first through hole 11; the length of the first through hole 11 in the first direction X is greater than the length of the first through hole 11 in the second direction Y, and / or the length of the second through hole 121 in the first direction X is greater than the length of the second through hole 121 in the second direction Y.

[0084] The first direction X and the second direction Y are two perpendicular directions to each other, and both directions are perpendicular to the axial direction of the first through hole 11 , so that the first direction X and the second direction Y are two perpendicular directions on the same plane.

[0085] By setting the length of the first through hole 11 in the first direction X to be greater than the length of the first through hole 11 in the second direction Y, the cross-sectional area of ​​the first through hole 11 in the second direction Y can be increased, which is conducive to improving the drainage capacity of the first through hole 11. By setting the length of the second through hole 121 in the first direction X to be greater than the length of the second through hole 121 in the second direction Y, the cross-sectional area of ​​the second through hole 121 in the second direction Y can be increased, which is conducive to improving the drainage capacity of the second through hole 121.

[0086] In some embodiments, the length of the first through hole 11 in the first direction X may be greater than the length of the first through hole 11 in the second direction Y, or the length of the second through hole 121 in the first direction X may be greater than the length of the second through hole 121 in the second direction Y, so that part of the pressure relief channel can be expanded in the first direction X to improve the pressure relief capacity of the pressure relief channel; or the length of the first through hole 11 in the first direction X may be greater than the length of the first through hole 11 in the second direction Y, and the length of the second through hole 121 in the first direction X may also be greater than the length of the second through hole 121 in the second direction Y, so that the entire pressure relief channel can be expanded in the first direction X, which is beneficial to improving the pressure relief capacity of the pressure relief channel.

[0087] In some embodiments, the length of the side wall 13 in the first direction X is D, the length of the side wall 13 in the second direction Y is E, 10 mm≤D≤100 mm, 1 mm≤E≤20 mm.

[0088] By setting the length E of the side wall 13 in the second direction Y to 1 mm ≤ E ≤ 20 mm, the length of the battery cell 10 in the second direction Y is within a range of 1 mm to 20 mm, thereby allowing the battery cell 10 to be within a relatively reasonable size range. This also limits the length of the first through hole 11 in the second direction Y. In some embodiments, the length E of the side wall 13 in the second direction Y can be set to a range of 2.5 mm to 7 mm. For example, the length of the side wall 13 in the second direction Y can be 3 mm, 4 mm, or 5 mm, allowing the side wall 13 to provide a reasonable size in the second direction Y for the first through hole 11.

[0089] By setting the length D of the side wall 13 in the first direction X to 10mm≤D≤100mm, the length of the battery cell 10 in the first direction X is within the range of 10mm to 100mm, so that the battery cell 10 can be within a more reasonable size range, while also limiting the length of the first through hole 11 in the first direction X.

[0090] In some embodiments, the length D of the side wall 13 in the first direction X can be set to a range of 15 mm to 80 mm. For example, the length of the side wall 13 in the first direction X can be 30 mm, 50 mm or 70 mm, so that the side wall 13 has sufficient size in the first direction X to set the first through hole 11, electrode terminal and other structures or components.

[0091] In some embodiments, the length of the first through hole 11 in the second direction Y is L1, 1mm≤L1≤6mm, and the length of the second through hole 121 in the second direction Y is L2, 0.2mm≤L2≤5mm; the length of the first through hole 11 in the first direction X is L3, 1mm≤L3≤6mm, and the length of the second through hole 121 in the first direction X is L4, 0.2mm≤L4≤5mm.

[0092] By setting the length L1 of the first through hole 11 in the second direction Y to a range of 1 mm to 6 mm, the length of the first through hole 11 in the second direction Y can match the length of the side wall 13 in the second direction Y, so that the first through hole 11 is less likely to affect the structural strength of the side wall 13, which is conducive to maintaining the structural strength of the battery cell 10. Exemplarily, the length L1 of the first through hole 11 in the second direction Y can be set to a range of 1 mm to 3.5 mm. In some embodiments, the length L1 of the first through hole 11 in the second direction Y can be set to 2 mm or 3 mm, so that the length of the first through hole 11 in the second direction Y can better match the length of the side wall 13 in the second direction Y, so that the first through hole 11 set on the side wall 13 is less likely to affect the structural strength of the side wall 13.

[0093] By setting the length L3 of the first through hole 11 in the first direction X to a range of 1 mm to 6 mm, the length of the first through hole 11 in the first direction X does not affect the structural strength of the side wall 13 due to being too long, nor does it reduce the cross-sectional area of ​​the first through hole 11 due to being too short, thereby less likely affecting the drainage capacity of the first through hole 11. In some embodiments, the length of the first through hole 11 in the first direction X can be set to be equal to the length in the second direction Y. For example, the first through hole 11 can be set as a circular hole, which not only makes the first through hole 11 easier to process, but also reduces the impact of the first through hole 11 on the internal stress of the side wall 13, which helps to reduce the impact on the structural strength of the side wall 13.

[0094] By setting the length L2 of the second through hole 121 in the second direction Y to a range of 0.2 mm to 5 mm, the length of the second through hole 121 in the second direction Y can match the length of the side wall 13 in the second direction Y and the length of the first through hole 11 in the second direction Y. This can prevent the second through hole 121 from affecting the structural strength of the adapter 12, thereby facilitating maintaining the structural strength of the battery cell 10. For example, the length L2 of the second through hole 121 in the second direction Y can be set to a range of 0.5 mm to 2 mm. In some embodiments, the length of the second through hole 121 in the second direction Y can be set to 1 mm or 1.5 mm. This allows the length of the second through hole 121 in the second direction Y to better match the length of the first through hole 11 in the second direction Y, thereby enabling the pressure relief material to be released smoothly from the first through hole 11 to the second through hole 121.

[0095] By setting the length L4 of the second through hole 121 in the first direction X to a range of 0.2 mm to 5 mm, the length of the second through hole 121 in the first direction X does not affect the structural strength of the adapter 12 due to being too long, nor does it reduce the cross-sectional area of ​​the second through hole 121 due to being too short, thereby less likely affecting the drainage capacity of the second through hole 121. In some embodiments, the length of the second through hole 121 in the first direction X can be set to be equal to the length in the second direction Y. For example, the second through hole 121 can be set as a circular hole, which not only makes the second through hole 121 easier to process, but also reduces the impact of the second through hole 121 on the internal stress of the adapter 12, which helps to reduce the impact on the structural strength of the adapter 12.

[0096] In some embodiments, the first through hole 11 is configured as a racetrack-shaped hole, and / or the second through hole 121 is configured as a racetrack-shaped hole.

[0097] A racetrack-shaped hole may refer to a hole having a racetrack-shaped shape in a cross-section perpendicular to the hole axis. The first through hole 11 is configured as a racetrack-shaped hole, with its major axis arranged along the first direction X and its minor axis arranged along the second direction Y. This allows the first through hole 11 to increase its cross-sectional area by increasing its length in the second direction Y, which helps improve the ability of the first through hole 11 to pass pressure relief material. The second through hole 121 is configured as a racetrack-shaped hole, with its major axis arranged along the first direction X and its minor axis arranged along the second direction Y. This allows the second through hole 121 to increase its cross-sectional area by increasing its length in the second direction Y, which helps improve the ability of the second through hole 121 to pass pressure relief material.

[0098] In some embodiments, a projection of the bonding area between the cover sheet 22 and the adapter 12 along the axial direction of the first through hole 11 is a first projection. The width of the first projection in the radial direction of the first through hole 11 is C, and 0.6 mm ≤ C ≤ 0.95 mm.

[0099] The first projection can be the projection of the bonding area between the cover sheet 22 and the adapter 12 in the axial direction of the first through hole 11. Due to the provision of the second through hole 121 in the adapter 12, the bonding area between the cover sheet 22 and the adapter 12 is annular. The width C of the first projection in the radial direction of the first through hole 11 is set to a range of 0.6mm to 0.95mm. This not only ensures that the bonding area between the cover sheet 22 and the adapter 12 can provide sufficient bonding force for the cover sheet 22, thereby reducing the risk of the cover sheet 22 falling off under normal operating conditions of the battery cell 10, but also enables the cover sheet 22 to fall off from the adapter 12 in a timely manner under thermal runaway conditions, thereby facilitating the timely discharge of the leaked material. In some embodiments, the width C of the first projection in the radial direction of the first through hole 11 can range from 0.65 mm to 0.9 mm. For example, the width C of the first projection in the radial direction of the first through hole 11 can be set to 0.65 mm, 0.7 mm or 0.8 mm, so that the bonding force provided by the adhesive film 21 in the bonding area can not only reduce the risk of the cover sheet 22 falling off under normal operating conditions, but also enable the cover sheet 22 to fall off in time under thermal runaway conditions to discharge the leaked substances in time.

[0100] In some embodiments, 0.2 mm 2 ≤B≤4.8mm 2 .

[0101] By setting the range of the cross-sectional area B of the through hole covered by the cover sheet 22 to 0.28 mm 2 ≤B≤4.524mm 2 , so that the cover 22 can be smoothly affected by the pressure inside the shell 1, and is not easily caused to fall off under normal working conditions due to excessive pressure inside the shell 1, which is beneficial to improving the reliability of the pressure relief mechanism 2.

[0102] In some embodiments, the cross-sectional area B of the through hole covered by the cover sheet 22 may be in the range of 0.785 mm 2 Up to 4.524mm 2 , which makes the pressure relief mechanism 2 have higher reliability.

[0103] In some embodiments, 3.581 mm 2 ≤A≤8.042mm 2 .

[0104] By setting the bonding area A between the cover sheet 22 and the housing 1 to 3.581 mm 2 to 8.042mm 2 , which not only enables the cover 22 to fall off smoothly from the adapter 12 under thermal runaway conditions, but also enables the cover 22 to be firmly connected to the adapter 12 under normal conditions. In some embodiments, the bonding area A between the cover 22 and the housing 1 can be in the range of 4.406mm2 to 8.042mm 2 , so that the cover piece 22 can be firmly connected to the adapter 12 under normal working conditions and is not easily removed due to factors such as collision with external components, thereby making the pressure relief mechanism 2 more reliable.

[0105] In some embodiments, the melting point of the adhesive film 21 is T1, 110°C≤T1≤130°C.

[0106] By setting the melting point T1 of the adhesive film 21 to 110° C. ≤ T1 ≤ 130° C., the adhesive film 21 has good thermal sensitivity under thermal runaway conditions and will not melt under normal conditions.

[0107] In some embodiments, 118° C. ≤ T1 ≤ 128° C., the melting point range of the adhesive film 21 can not only make the pressure relief mechanism 2 have good thermal sensitivity, but also reduce the possibility of melting under normal working conditions.

[0108] For example, the melting point T1 of the adhesive film 21 may be 120° C. or 125° C., so that the adhesive film 21 has good thermal sensitivity and good reliability.

[0109] In some embodiments, as shown in Figure 7, the adhesive film 21 includes a first sub-film 211 and a second sub-film 212 stacked along the axial direction of the first through hole 11, the first sub-film 211 is located between the second sub-film 212 and the cover sheet 22, and the melting point of the second sub-film 212 is lower than the melting point of the first sub-film 211.

[0110] The first sub-film 211 and the second sub-film 212 are both partial film layers of the adhesive film 21, and are stacked along the axial direction of the first through-hole 11. By disposing the first sub-film 211 between the second sub-film 212 and the cover sheet 22, and setting the melting point of the second sub-film 212 to be lower than that of the first sub-film 211, the second sub-film 212 is more likely to melt when the adhesive film 21 is heated, making it easier for the cover sheet 22 to fall off due to the melting of the second sub-film 212, thereby improving the pressure relief sensitivity of the pressure relief mechanism 2.

[0111] Illustratively, the melting point of the second sub-film 212 is T2, 100°C≤T2≤120°C.

[0112] By setting the melting point T2 of the second sub-film 212 to 100° C. ≤ T2 ≤ 120° C., the second sub-film 212 is more likely to melt under thermal runaway conditions.

[0113] In some embodiments, 105° C. ≤ T2 ≤ 115° C. For example, the melting point T2 of the second sub-film 212 may be 110° C., so that the second sub-film 212 is more likely to melt under thermal runaway conditions, so that the cover sheet 22 can be smoothly detached.

[0114] In some embodiments, as shown in FIG8 , the adhesive film 21 further includes a third sub-film 213 located between the first sub-film 211 and the second sub-film 212 , and the melting point of the third sub-film 213 is higher than that of the first sub-film 211 and the second sub-film 212 .

[0115] The third sub-film 213 is a partial film layer in the adhesive film 21. By setting the third sub-film 213 between the first sub-film 211 and the second sub-film 212, and setting the melting point of the third sub-film 213 to be higher than the melting point of the first sub-film 211 and the melting point of the second sub-film 212, the third sub-film 213 can play a good supporting role for the adhesive film 21 as a whole, which is beneficial to improving the overall strength of the adhesive film 21.

[0116] In some embodiments, the melting point of the third sub-film 213 is T3, 130°C≤T3≤150°C.

[0117] By setting the melting point T3 of the third sub-film 213 to 130°C ≤ T3 ≤ 150°C, the melting point of the third sub-film 213 is higher than that of the first sub-film 211 and the second sub-film 212 on either side of it. This makes the third sub-film 213 less likely to melt relative to the first sub-film 211 and the second sub-film 212, thereby providing good support for the entire adhesive film 21 and reducing the possibility of the adhesive film 21 melting under normal operating conditions. For example, the melting point of the third sub-film 213 can be set to 135°C, 140°C, or 145°C, making it less likely to melt, thereby better maintaining the structural strength of the adhesive film 21 and making it less susceptible to damage.

[0118] In some embodiments, the adhesive film 21 includes polypropylene.

[0119] By making the adhesive film 21 comprise polypropylene, the adhesive film 21 not only has excellent adhesive properties, enabling the cover sheet 22 to be firmly bonded to the housing 1, but also has the property of melting when heated. For example, the adhesive film 21 may also comprise at least one thermoplastic material such as polyethylene, polyvinyl chloride, polystyrene, polyamide, polyoxymethylene, polycarbonate, polyphenylene ether, polysulfone, or rubber, enabling the adhesive film 21 to melt when heated, allowing the cover sheet 22 to be removed from the housing 1.

[0120] In some embodiments, the thickness of the adhesive film 21 in the axial direction of the first through hole 11 is H, and 10 μm≤H≤48 μm.

[0121] By setting the thickness H of the adhesive film 21 in the axial direction of the first through hole 11 to be in the range of 8 μm to 49 μm, the adhesive film 21 has sufficient structural strength while avoiding material waste due to excessive thickness. In some embodiments, the thickness H of the adhesive film 21 in the axial direction of the first through hole 11 can be set in the range of 40 μm ≤ H ≤ 45 μm. For example, H can be 42 μm or 44 μm. This keeps the thickness of the adhesive film 21 within a reasonable range, ensuring sufficient structural strength while avoiding material waste.

[0122] In some embodiments, the adhesive strength of the adhesive film 21 is P,

[0123] The adhesive strength P of the adhesive film 21 refers to the adhesive force that the adhesive film 21 can provide per unit adhesive surface. The range is limited to 0.08Mpa to 2Mpa, so that the film 21 can provide sufficient force for the cover piece 22 to block the pressure relief channel, so that the cover piece 22 is not easy to fall off under normal working conditions, and when the internal pressure of the shell 1 is too high, the internal pressure of the shell 1 will overcome the adhesive effect of the film 21 and cause the cover piece 22 to fall off, thereby achieving pressure relief.

[0124] For example, The range can be limited to 0.1 MPa to 1.5 MPa, so that the adhesive film 21 can provide sufficient bonding strength while also being able to release the pressure inside the housing 1 in a timely manner.

[0125] In some embodiments, It can be adjusted according to the size of the battery cell 10. As the size of the battery cell 10 increases, It can be reduced accordingly so that the bonding strength of the adhesive film 21 can match the pressure resistance that decreases as the size of the battery cell 10 increases.

[0126] In some embodiments, the first through hole 11 is a liquid injection hole.

[0127] By reusing the injection hole as the first through hole 11 for pressure relief, the preparation process of the battery cell 10 can be further simplified, which is beneficial to reducing the drilling steps and lowering the preparation cost of the battery cell 10.

[0128] In other embodiments, the first through hole 11 may also be another through hole formed on the side wall 13 and communicating with the inside and outside of the housing 1 .

[0129] The beneficial effects of the battery cell casing provided by the specific embodiments of the present application are further illustrated below through comparative experiments.

[0130] In this comparative experiment, the battery cell 10 is used as the experimental object. The battery cell shell in the battery cell 10 includes a shell 1 and a pressure relief mechanism 2. The pressure relief mechanism 2 includes a film 21 and a cover 22. The shell 1 includes a side wall 13 and an adapter 12. The side wall 13 is provided with a first through hole 11. The adapter 12 is provided with a second through hole 121 connected to the first through hole 11. The cover 22 is adhered to the side of the adapter 12 away from the side wall 13 through the film 21 and covers the second through hole 121.

[0131] The ratio of the bonding area A between the cover sheet 22 and the housing 1 and the cross-sectional area B of the second through hole 121 covered by the cover sheet 22 is set to The battery cell 10 in the range of is used as the experimental object in the embodiment of the comparative experiment; the ratio of the bonding area A of the cover sheet 22 and the housing 1 to the cross-sectional area B of the second through hole 121 covered by the cover sheet 22 exceeds The battery cells 10 in the range of are used as experimental objects in the comparative example of the comparative experiment.

[0132] The pressure relief pass rate of the battery cell 10 is tested by first charging the battery cell 10 at 37° C. until the voltage of the battery cell 10 reaches 4.505 V, then heating the battery cell 10 to 130° C. and maintaining it for 30 minutes, and calculating the pressure relief pass rate of multiple battery cells 10 within 30 minutes.

[0133] The differences in various parameters of the battery cells 10 in the comparative examples and the embodiments are as follows:

[0134] Example 1

[0135] The aperture of the second through hole 121 is 0.9 mm, the diameter of the cover sheet 22 is 2.5 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.8 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 0.636 mm. 2 The bonding area A between the cover 22 and the housing 1 is 4.273 mm 2 ,

[0136] Example 2

[0137] The aperture of the second through hole 121 is 1 mm, the diameter of the cover sheet 22 is 2.5 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.75 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 0.785 mm. 2 The bonding area A between the cover 22 and the housing 1 is 4.123 mm 2 ,

[0138] Example 3

[0139] The aperture of the second through hole 121 is 1.1 mm, the diameter of the cover sheet 22 is 2.5 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.7 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 0.95 mm. 2 The bonding area A between the cover 22 and the housing 1 is 3.958 mm 2 ,

[0140] Example 4

[0141] The aperture of the second through hole 121 is 1.2 mm, the diameter of the cover sheet 22 is 2.5 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.65 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 1.131 mm. 2 The bonding area A between the cover 22 and the housing 1 is 3.778 mm 2 ,

[0142] Example 5

[0143] The aperture of the second through hole 121 is 1.3 mm, the diameter of the cover sheet 22 is 2.5 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.6 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 1.327 mm. 2 The bonding area A between the cover 22 and the housing 1 is 3.581 mm 2 ,

[0144] Example 6

[0145] The aperture of the second through hole 121 is 0.8 mm, the diameter of the cover sheet 22 is 2.5 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.85 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 0.503 mm. 2 The bonding area A between the cover 22 and the housing 1 is 4.406 mm 2 ,

[0146] Example 7

[0147] The aperture of the second through hole 121 is 0.7 mm, the diameter of the cover sheet 22 is 2.5 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.9 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 0.385 mm. 2 The bonding area A between the cover 22 and the housing 1 is 4.524 mm 2 ,

[0148] Example 8

[0149] The aperture of the second through hole 121 is 0.6 mm, the diameter of the cover sheet 22 is 2.5 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.95 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 0.283 mm. 2 The bonding area A between the cover 22 and the housing 1 is 4.626 mm 2 ,

[0150] Example 9

[0151] The aperture of the second through hole 121 is 1 mm, the diameter of the cover sheet 22 is 2.6 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.8 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 0.785 mm. 2 The bonding area A between the cover 22 and the housing 1 is 4.524 mm 2 ,

[0152] Example 10

[0153] The aperture of the second through hole 121 is 1.1 mm, the diameter of the cover sheet 22 is 2.7 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.8 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 0.95 mm. 2 The bonding area A between the cover 22 and the housing 1 is 4.775 mm 2 ,

[0154] Example 11

[0155] The aperture of the second through hole 121 is 1.2 mm, the diameter of the cover sheet 22 is 2.8 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.8 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 1.131 mm. 2 The bonding area A between the cover 22 and the housing 1 is 5.027 mm 2 ,

[0156] Example 12

[0157] The aperture of the second through hole 121 is 1.3 mm, the diameter of the cover sheet 22 is 2.9 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.8 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 1.327 mm. 2 The bonding area A between the cover 22 and the housing 1 is 5.278 mm 2 ,

[0158] Example 13

[0159] The aperture of the second through hole 121 is 1.4 mm, the diameter of the cover sheet 22 is 3 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.8 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 1.539 mm. 2 The bonding area A between the cover 22 and the housing 1 is 5.529 mm 2 ,

[0160] Example 14

[0161] The aperture of the second through hole 121 is 1.5 mm, the diameter of the cover sheet 22 is 3.1 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.8 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 1.767 mm. 2 The bonding area A between the cover 22 and the housing 1 is 5.781 mm 2 ,

[0162] Example 15

[0163] The aperture of the second through hole 121 is 1.6 mm, the diameter of the cover sheet 22 is 3.2 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.8 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 2.011 mm. 2 The bonding area A between the cover 22 and the housing 1 is 6.032 mm 2 ,

[0164] Example 16

[0165] The aperture of the second through hole 121 is 1.7 mm, the diameter of the cover sheet 22 is 3.3 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.8 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 2.27 mm. 2 The bonding area A between the cover 22 and the housing 1 is 6.283 mm 2 ,

[0166] Example 17

[0167] The aperture of the second through hole 121 is 1.8 mm, the diameter of the cover sheet 22 is 3.4 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.8 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 2.545 mm. 2 The bonding area A between the cover 22 and the housing 1 is 6.535 mm 2 ,

[0168] Example 18

[0169] The aperture of the second through hole 121 is 1.9 mm, the diameter of the cover sheet 22 is 3.5 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.8 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 2.835 mm. 2 The bonding area A between the cover 22 and the housing 1 is 6.786 mm 2 ,

[0170] Example 19

[0171] The aperture of the second through hole 121 is 2 mm, the diameter of the cover sheet 22 is 3.6 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.8 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 3.142 mm. 2 The bonding area A between the cover 22 and the housing 1 is 7.037 mm 2 ,

[0172] Example 20

[0173] The aperture of the second through hole 121 is 2.1 mm, the diameter of the cover sheet 22 is 3.7 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.8 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 3.464 mm. 2 The bonding area A between the cover 22 and the housing 1 is 7.288 mm 2 ,

[0174] Example 21

[0175] The aperture of the second through hole 121 is 2.2 mm, the diameter of the cover sheet 22 is 3.8 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.8 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 3.801 mm. 2 The bonding area A between the cover 22 and the housing 1 is 7.54 mm 2 ,

[0176] Example 22

[0177] The aperture of the second through hole 121 is 2.3 mm, the diameter of the cover sheet 22 is 3.9 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.8 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 4.155 mm. 2The bonding area A between the cover 22 and the housing 1 is 7.791 mm 2 ,

[0178] Example 23

[0179] The aperture of the second through hole 121 is 2.4 mm, the diameter of the cover sheet 22 is 4 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.8 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 4.524 mm. 2 The bonding area A between the cover 22 and the housing 1 is 8.042 mm 2 ,

[0180] Example 24

[0181] The diameter of the first through hole 11 is 0.9 mm, and the diameter of the cover sheet 22 is 2.5 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 0.636 mm. 2 The bonding area A between the cover 22 and the housing 1 is 4.273 mm 2 ,

[0182] Example 25

[0183] The diameter of the first through hole 11 is 1.5 mm, and the diameter of the cover sheet 22 is 2.5 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 1.76 mm. 2 The bonding area A between the cover 22 and the housing 1 is 3.14 mm 2 ,

[0184] Example 26

[0185] The aperture of the first through hole 11 is 0.6 mm, and the diameter of the cover sheet 22 is 2.5 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 0.283 mm. 2 The bonding area A between the cover 22 and the housing 1 is 4.626 mm 2 ,

[0186] Comparative Example 1

[0187] The aperture of the second through hole 121 is 0.55 mm, the diameter of the cover sheet 22 is 2.5 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.98 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 0.238 mm. 2 The bonding area A between the cover 22 and the housing 1 is 4.671 mm 2 ,

[0188] Comparative Example 2

[0189] The aperture of the second through hole 121 is 0.5 mm, the diameter of the cover sheet 22 is 2.5 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 1 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 0.196 mm. 2 The bonding area A between the cover 22 and the housing 1 is 4.712 mm 2 ,

[0190] Comparative Example 3

[0191] The aperture of the second through hole 121 is 2.4 mm, the diameter of the cover sheet 22 is 2.5 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.05 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 4.524 mm. 2 The bonding area A between the cover 22 and the housing 1 is 0.385 mm 2 ,

[0192] Comparative Example 4

[0193] The aperture of the second through hole 121 is 2.4 mm, the diameter of the cover sheet 22 is 2.5 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 0.05 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 4.524 mm. 2 The bonding area A between the cover 22 and the housing 1 is 2.545 mm 2 ,

[0194] Comparative Example 5

[0195] The aperture of the second through hole 121 is 2.4 mm, the diameter of the cover sheet 22 is 3.8 mm, and the width C of the first projection in the radial direction of the first through hole 11 is 1.7 mm. At this time, the cross-sectional area B of the through hole 20 covered by the cover sheet 22 is 4.524 mm. 2 The bonding area A between the cover 22 and the housing 1 is 6.817 mm 2 ,

[0196] Table 1 shows the pass rates of pressure relief of the battery cells in the comparative example and the embodiment in the comparative experiment of this application.

[0197] It can be seen from Examples 1 to 26 in Table 1 that when the ratio of the bonding area A between the cover sheet 22 and the housing 1 and the cross-sectional area B of the through hole covered by the cover sheet 22 is configured to be When the pressure inside the battery cell 10 reaches a preset value, the cover 22 can fall off in time to form a pressure relief channel, so that the internal pressure of the battery cell 10 can be released in time, which is beneficial to improving the reliability of the pressure relief of the battery cell 10.

[0198] It can be seen from Examples 1, 6, 7, 8 and 9 that as the ratio of the bonding area A between the cover sheet 22 and the housing 1 and the cross-sectional area B of the through hole covered by the cover sheet 22 increases, As the pressure increases, the pressure relief rate of the battery cell 10 decreases. This is because the ratio of the bonding area A of the cover sheet 22 and the shell 1 to the cross-sectional area B of the through hole covered by the cover sheet 22 increases. As the cover sheet 22 and the shell 1 increase, the bonding area A between the cover sheet 22 and the shell 1 increases, the bonding force between the cover sheet 22 and the shell 1 increases, and the force exerted by the internal pressure relief material of the shell 1 on the cover sheet 22 becomes more difficult to push the cover sheet 22 off the shell 1.

[0199] Table 1 Note: “ / ” in Table 1 indicates that there is no corresponding preparation parameter, substance or performance parameter.

[0200] From Comparative Examples 1 to 2, it can be seen that when the ratio of the bonding area A between the cover sheet 22 and the housing 1 and the cross-sectional area B of the through hole covered by the cover sheet 22 is When the pressure relief rate of the battery cell 10 is less than 60%, when the internal pressure of the battery cell 10 reaches the preset value, the cover sheet 22 cannot fall off in time to form a pressure relief channel, which is not conducive to the release of the internal pressure of the battery cell 10 and the pressure relief of the battery cell 10 is unreliable. When the battery cell 10 is under pressure relief condition, the battery cell 10 cannot be decompressed. This is because when the ratio of the bonding area A of the cover sheet 22 and the shell 1 to the cross-sectional area B of the through hole covered by the cover sheet 22 is When the temperature of the battery cell 10 does not reach 130° C., the cover sheet 22 falls off, and the battery cell 10 cannot be thermally decompressed under the preset decompression condition (temperature 130° C.).

[0201] As shown in Figures 9 and 10, some embodiments of the present application further provide a pressure relief mechanism 2 for a battery cell 10. The pressure relief mechanism 2 includes a cover sheet 22, an adhesive film 21, and an adapter 12. The adapter 12 is provided with a second through hole 121. The second through hole 121 is used to communicate with the interior of the housing 1 of the battery cell 10. The cover sheet 22 is bonded to the adapter 12 through the adhesive film 21 and covers the second through hole 121. The adhesive film 21 can be melted by heat to cause the cover sheet 22 to fall off to form a pressure relief channel connecting the interior and exterior of the housing 1. The bonding area between the cover sheet 22 and the adapter 12 is F, and the cross-sectional area of ​​the second through hole covered by the cover sheet 22 is G.

[0202] Because the adhesive force between the cover sheet 22 and the adapter 12 is proportional to the bonding area F between the cover sheet 22 and the adapter 12, the pressure exerted on the cover sheet 22 by the pressure relief material inside the housing 1 through the second through hole is proportional to the cross-sectional area G of the second through hole covered by the cover sheet 22. When the pressure exerted on the cover sheet 22 by the pressure relief material inside the housing 1 is greater than the adhesive force between the cover sheet 22 and the adapter 12, the cover sheet 22 falls off from the second through hole 121. By setting the ratio of the bonding area F between the cover sheet 22 and the adapter 12 to the cross-sectional area G of the second through hole covered by the cover sheet 22 within a reasonable range, when the internal pressure of the battery cell 10 reaches a preset value, the pressure exerted on the cover sheet 22 by the pressure relief material inside the housing 1 is greater than the adhesive force between the cover sheet 22 and the adapter 12, allowing the cover sheet 22 to fall off in a timely manner to form a pressure relief channel, thereby promptly releasing the internal pressure of the battery cell 10. This allows the pressure relief mechanism 2 of the battery cell 10 to achieve overheating pressure relief while also maintaining good reliability.

[0203] Some embodiments of the present application further provide a battery cell 10, which includes the battery cell housing provided by the above technical solution. Since the battery cell includes the battery cell housing provided by the above technical solution, the pressure relief of the battery cell has good reliability.

[0204] Some embodiments of the present application further provide an electrical device, comprising the battery cell 10 provided by the above technical solution, for providing electrical energy. Because the electrical device comprises the battery cell 10 provided by the above technical solution, the battery of the electrical device is less susceptible to thermal runaway and has good reliability.

[0205] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and components may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions within the scope of the claims.

Claims

1. A battery cell casing, characterized in that: include: A housing having a through hole; A pressure relief mechanism is provided at the through hole, the pressure relief mechanism comprises a glue film and a cover sheet, the cover sheet is bonded to the shell body and covers the through hole through the glue film, and the glue film can be melted by heat to form a pressure relief channel connecting the inside and outside of the shell body; The bonding area between the cover sheet and the housing is A, and the cross-sectional area of ​​the through hole covered by the cover sheet is B.

2. The battery cell casing according to claim 1, characterized in that: The shell includes a side wall, the through hole includes a first through hole arranged on the side wall, and the cover sheet is adhered to the side wall through the adhesive film and covers the first through hole.

3. The battery cell casing according to claim 2, characterized in that: The shell also includes an adapter arranged on the outside of the side wall, and the through hole also includes a second through hole arranged on the adapter, the second through hole is connected to the first through hole, and the cover sheet is bonded to the side of the adapter away from the side wall through the adhesive film and covers the second through hole.

4. The battery cell casing according to claim 3, characterized in that: Along the axial direction of the second through hole, the projection of the second through hole is located within the projection range of the first through hole.

5. The battery cell casing according to claim 3, characterized in that: The first direction is perpendicular to the second direction, and both the first direction and the second direction are perpendicular to the axial direction of the first through hole; the length of the first through hole in the first direction is greater than the length of the first through hole in the second direction, and / or the length of the second through hole in the first direction is greater than the length of the second through hole in the second direction.

6. The battery cell casing according to claim 5, characterized in that: The length of the side wall in the first direction is D, the length of the side wall in the second direction is E, 10 mm ≤ D ≤ 100 mm, 1 mm ≤ E ≤ 20 mm.

7. The battery cell casing according to claim 5, characterized in that: The length of the first through hole in the second direction is L1, 1mm≤L1≤6mm, and the length of the second through hole in the second direction is L2, 0.2mm≤L2≤5mm; and / or the length of the first through hole in the first direction is L3, 1mm≤L3≤6mm, and the length of the second through hole in the first direction is L4, 0.2mm≤L4≤5mm.

8. The battery cell casing according to claim 5, characterized in that: The first through hole is configured as a racetrack-shaped hole, and / or the second through hole is configured as a racetrack-shaped hole.

9. The battery cell casing according to claim 5, characterized in that: The projection of the bonding area between the cover sheet and the adapter along the axial direction of the first through hole is a first projection, and the width of the first projection in the radial direction of the first through hole is C, 0.6mm≤C≤0.95mm.

10. The battery cell casing according to any one of claims 1 to 9, characterized in that:

11. The battery cell casing according to any one of claims 1 to 9, characterized in that: 0.28mm 2 ≤B≤4.524mm 2 。 12. The battery cell casing according to any one of claims 1 to 9, characterized in that: 3.581mm 2 ≤A≤8.042mm 2 。 13. The battery cell casing according to claim 1, characterized in that: The melting point of the adhesive film is T1, 110°C≤T1≤130°C.

14. The battery cell casing according to claim 1, characterized in that: The adhesive film includes a first sub-film and a second sub-film stacked along the axial direction of the through hole, the first sub-film is located between the second sub-film and the cover sheet, and the melting point of the second sub-film is lower than the melting point of the first sub-film.

15. The battery cell casing according to claim 14, characterized in that: The melting point of the second sub-film is T2, 100°C≤T2≤120°C.

16. The battery cell casing according to claim 14, characterized in that: The adhesive film further includes a third sub-film located between the first sub-film and the second sub-film, and the melting point of the third sub-film is higher than the melting points of the first sub-film and the second sub-film.

17. The battery cell casing according to claim 16, characterized in that: The melting point of the third sub-film is T3, 130°C≤T3≤150°C.

18. The battery cell casing according to any one of claims 1 to 9, characterized in that: The adhesive film comprises polypropylene.

19. The battery cell casing according to any one of claims 1 to 9, characterized in that: The thickness of the adhesive film in the axial direction of the through hole is H, and 10 μm≤H≤48 μm.

20. The battery cell casing according to any one of claims 1 to 9, characterized in that: The adhesive strength of the adhesive film is P, 21. The battery cell casing according to any one of claims 1 to 9, characterized in that: The through hole is a liquid injection hole.

22. A pressure relief mechanism for a battery cell, characterized in that: The pressure relief mechanism comprises a cover sheet, an adhesive film and an adapter, wherein the adapter is provided with a second through hole, wherein the second through hole is used to communicate with the interior of the shell of the battery cell, wherein the cover sheet is bonded to the adapter through the adhesive film and covers the second through hole, wherein the adhesive film can be melted by heat to form a pressure relief channel communicating with the interior and exterior of the shell; wherein the bonding area between the cover sheet and the adapter is F, and the cross-sectional area of ​​the second through hole covered by the cover sheet is G, 23. A battery cell, characterized in that: Comprising a battery cell casing as claimed in any one of claims 1 to 21.

24. An electrical device, characterized in that: The battery cell comprises the battery cell as claimed in claim 23, wherein the battery cell is used to provide electrical energy.

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