Casing, cell, and electric device

Abstract

A casing (20), a cell (100), and an electric device. The casing (20) comprises a housing (21) and a pressure relief assembly (23); the housing (21) is provided with a pressure relief hole (211); the pressure relief assembly (23) blocks the pressure relief hole (211); the pressure relief assembly (23) comprises a bonding layer (231); the bonding layer (231) is bonded to the housing (21); and the bonding layer (231) is configured to lose adhesiveness when the temperature inside the housing (21) reaches a threshold temperature, thereby opening the pressure relief hole to relieve pressure inside the housing (21). The bonding area of the bonding layer (231) is S, wherein 2mm2≤S≤10mm2. By opening the pressure relief hole (211) when the bonding layer (231) of the pressure relief assembly (23) lose adhesiveness when receiving heat, the pressure relief assembly (23) has good thermal sensitivity and high pressure relief reliability, so that the safety of the cell having the casing (20) can be improved, there is no need to reserve a large space for the pressure relief assembly (23), and the space of the electric device is fully utilized. Since 2mm2≤S≤10mm2, when the casing (20) is in a normal working state, the bonding layer (231) can ensure that the pressure relief assembly (23) effectively blocks the pressure relief hole (211), and can also lose adhesiveness in time when the pressure and temperature inside the casing (20) are abnormal, thereby relieving pressure in time.

Description

Casing, battery cells and electrical equipment

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application 2023115786158, filed on November 24, 2023, entitled “Casing, battery cell and electrical equipment,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to a housing, a battery cell and an electrical device. Background Art

[0004] With the rapid development of new energy technologies, battery cells have been widely used in electronic equipment, electric vehicles, electric two-wheeled vehicles, power tools and other fields. The safety performance requirements for battery cells are also becoming increasingly stringent.

[0005] Summary of the Invention

[0006] The embodiments of the present application provide a housing, a battery cell, and an electrical device to improve the safety performance of the battery cell.

[0007] In a first aspect, an embodiment of the present application provides a housing, comprising a shell and a pressure relief assembly; the shell having a pressure relief hole; the pressure relief assembly sealing the pressure relief hole, the pressure relief assembly comprising an adhesive layer, the adhesive layer being bonded to the shell, the pressure relief assembly being configured to lose viscosity when heated when the temperature inside the shell reaches a threshold temperature, thereby opening the pressure relief hole to release the pressure inside the shell, wherein the threshold temperature is between 110° and 130°; wherein the bonding area of ​​the adhesive layer is S, 2mm 2 ≤S≤10mm 2 .

[0008] In the above technical solution, the pressure relief hole is opened when the adhesive layer of the pressure relief component loses its viscosity due to heat, thereby releasing the pressure within the housing, reducing the risk of safety issues such as explosion and fire in the housing, thereby improving the safety performance of the battery cell with this housing. Since the adhesive layer of the pressure relief component opens the pressure relief hole when it loses its viscosity due to heat, the pressure relief component has good thermal sensitivity, making the pressure relief reliability higher, which can improve the safety of the battery cell with this housing. Compared with the pressure relief method of scoring grooves, this solution does not require a large space to be reserved for the pressure relief component, fully utilizing the space of the electrical equipment, improving the space utilization rate of the electrical equipment, making the structure of the electrical equipment more compact, and reducing the cost of preparing the pressure relief component. Since the adhesive layer of the pressure relief component opens the pressure relief hole when it loses its viscosity due to heat, the pressure within the housing is released, which is also beneficial to improving the pass rate of the hot box of the battery cell with this housing. The threshold temperature is the set pressure relief temperature. When the threshold temperature range meets the range of 110-130℃, pressure relief can be performed within the appropriate temperature range. When the temperature is above the threshold temperature of 130℃, pressure relief failure is likely to occur. When the temperature is below the threshold temperature of 110℃, leakage may occur. Both of these cannot achieve the ideal pressure relief effect, which will lead to poor cycle performance and hot box pass rate of the battery cell. The bonding area S of the bonding layer meets 2mm 2 ≤S≤10mm 2 , so that the shell has good adhesion when it is in normal working state, so that the adhesive layer can ensure that the pressure relief component effectively blocks the pressure relief hole, thereby ensuring the normal operation of the battery cell with the shell. It can also lose viscosity in time when the pressure and temperature inside the shell are abnormal, so that the pressure relief component can open the pressure relief hole and relieve pressure in time, thereby improving the safety performance of the battery cell with the shell.

[0009] In some embodiments of the first aspect of the present application, 3mm 2 ≤S≤8mm 2 .

[0010] In the above technical solution, the bonding area S of the bonding layer satisfies 3mm 2 ≤S≤8mm 2 , so that the shell has better bonding ability when it is in normal working state, so that the bonding layer can ensure that the pressure relief component effectively blocks the pressure relief hole, thereby ensuring the normal operation of the battery cell with the shell. It can also lose viscosity in time when the pressure and temperature inside the shell are abnormal, so that the pressure relief component can open the pressure relief hole and relieve pressure in time, thereby improving the safety performance of the battery cell with the shell.

[0011] In some embodiments of the first aspect of the present application, the adhesive layer comprises a polymer.

[0012] In the above technical solution, the adhesive layer includes a polymer, which can play a role of high bonding performance under normal working conditions, so that the pressure relief component can achieve a sealing function; under high temperature conditions, the adhesive layer can quickly lose its viscosity, causing the pressure relief component to open the pressure relief hole, exposing the pressure relief hole, forming a pressure relief channel, and realizing a timely pressure relief function.

[0013] In some embodiments of the first aspect of the present application, the material of the polymer includes at least one of ethylene, propylene, vinylidene fluoride, acrylic acid, acrylic ester, styrene, acrylonitrile, maleic anhydride, vinyl chloride and allyl chloride.

[0014] In the above technical solution, the above material can not only help the adhesive layer to have high bonding performance under normal working conditions, so that the pressure relief component can achieve the sealing function; it is also beneficial for the adhesive layer to quickly lose its viscosity under high temperature conditions, causing the pressure relief component to open the pressure relief hole, expose the pressure relief hole, form a pressure relief channel, and achieve timely pressure relief function.

[0015] In some embodiments of the first aspect of the present application, the mass proportion of the polymer is 70% to 95%.

[0016] In the above technical solution, the mass proportion of the polymer is 70% to 95%, which is beneficial for the adhesive layer to have high bonding performance under normal working conditions, thereby enabling the pressure relief component to achieve a sealing function; it is also beneficial for the adhesive layer to quickly lose its viscosity under high temperature conditions, causing the pressure relief component to open the pressure relief hole, exposing the pressure relief hole, forming a pressure relief channel, and achieving a timely pressure relief function.

[0017] In some embodiments of the first aspect of the present application, the melting point of the polymer is A, 70°C≤A≤100°C.

[0018] In the above technical solution, the melting point of the polymer is A, 70℃≤A≤100℃, so that the adhesive layer can lose its viscosity before the shell explodes, catches fire, etc., so that the pressure relief component opens the pressure relief hole to release the pressure inside the shell, reducing the explosion, fire and other problems of the battery cell with the shell, which is beneficial to improve the safety performance of the battery cell.

[0019] In some embodiments of the first aspect of the present application, the volume distribution particle size Dv90 of the polymer is 2.5 μm to 4.5 μm, and / or the weight average molecular weight of the polymer is K, 15w≤K≤25w.

[0020] In the above technical solution, the volume distribution particle size Dv90 of the polymer is 2.5 μm to 4.5 μm, which facilitates the adhesive layer to have good adhesive properties. The weight-average molecular weight K of the polymer is 15w≤K≤25w, which facilitates good adhesive and mechanical properties of the adhesive layer and reduces the difficulty of manufacturing the adhesive layer. W represents ten thousand, and 15w represents 150,000.

[0021] In some embodiments of the first aspect of the present application, the adhesive force of the adhesive layer is F, 10 N / m≤F≤40 N / m.

[0022] In the above technical solution, 10N / m≤F≤40N / m, which is beneficial for the adhesive layer to have high bonding performance under normal working conditions, so that the pressure relief component can achieve the sealing function; it is also beneficial for the adhesive layer to quickly lose its viscosity under high temperature conditions, causing the pressure relief component to open the pressure relief hole, expose the pressure relief hole, form a pressure relief channel, and achieve timely pressure relief function.

[0023] In some embodiments of the first aspect of the present application, the pressure relief assembly further includes a diaphragm, the diaphragm covers the pressure relief hole, and the surface of the diaphragm facing the shell is provided with the adhesive layer connected to the shell.

[0024] In the above technical solution, the diaphragm covers the pressure relief hole, providing a seal. The surface of the diaphragm facing the housing is provided with an adhesive layer, which bonds the diaphragm to the housing via the adhesive layer, making the connection method simple and convenient. When the adhesive layer loses its viscosity due to heat, the diaphragm easily separates from the housing, allowing the diaphragm to open the pressure relief hole to release pressure, achieving timely pressure relief and improving the safety performance of the battery cell equipped with this housing. Covering the pressure relief hole with the diaphragm simplifies the structure of the pressure relief assembly and reduces manufacturing costs.

[0025] In some embodiments of the first aspect of the present application, the pressure relief assembly further includes a first metal sheet and a diaphragm; the diaphragm is arranged between the first metal sheet and the shell, the diaphragm is connected to the shell through an adhesive layer, and the surface of the diaphragm facing away from the shell is provided with the adhesive layer connected to the first metal sheet, and the first metal sheet covers the pressure relief hole.

[0026] In the above technical solution, the first metal sheet covers the pressure relief hole, which helps improve the sealing performance of the pressure relief assembly under normal operating conditions. The surface of the diaphragm facing the first metal sheet is provided with an adhesive layer, which bonds the diaphragm to the first metal sheet via the adhesive layer. This simple connection method, when the adhesive layer loses its viscosity due to heat, easily separates the first metal sheet from the diaphragm, allowing the first metal sheet to open the pressure relief hole and release pressure, achieving timely pressure relief and improving the safety performance of the battery cell equipped with this housing.

[0027] In some embodiments of the first aspect of the present application, the thickness of the first metal sheet is h1, 0.03 mm ≤ h1 ≤ 1.00 mm.

[0028] In the above technical solution, 0.03mm≤h1≤1.00mm, so that the first metal sheet has better strength, which is conducive to improving the sealing performance. It can also minimize the space occupied by the first metal sheet, making the structure of the battery cell with the shell smaller.

[0029] In some embodiments of the first aspect of the present application, 0.03 mm ≤ h1 ≤ 0.15 mm.

[0030] In the above technical solution, 0.03mm≤h1≤0.15mm, so that the first metal sheet has better strength, which is beneficial to improving the sealing performance, and can also make the space occupied by the first metal sheet smaller, making the structure of the battery cell with the shell smaller.

[0031] In some embodiments of the first aspect of the present application, the thermal conductivity of the first metal sheet is P1, 10W / (m*K)≤P1≤500W / (m*K).

[0032] In the above technical solution, the thermal conductivity of the first metal sheet is P1, 10W / (m*K)≤P1≤500W / (m*K), which is conducive to the transfer of heat to the adhesive layer through the first metal sheet, so that the adhesive layer between the first metal sheet and the diaphragm can lose its viscosity in time, reducing the risk of safety problems such as explosion and fire in the casing, thereby improving the safety performance of the battery cell with the casing.

[0033] In some embodiments of the first aspect of the present application, 80 W / (m*K)≤P1≤420 W / (m*K).

[0034] In the above technical solution, 80W / (m*K)≤P1≤420W / (m*K), which makes the first metal sheet more sensitive to temperature and can transfer heat to the bonding layer between the diaphragm and the first metal sheet more promptly, so that the bonding layer between the first metal sheet and the diaphragm can lose its stickiness in time, reducing the risk of safety problems such as explosion and fire in the casing, thereby improving the safety performance of the battery cell with the casing.

[0035] In some embodiments of the first aspect of the present application, the pressure relief assembly further includes a second metal sheet, which is provided with a second through hole; the second metal sheet is connected between the diaphragm and the shell, the second through hole is connected to the pressure relief hole, the surface of the diaphragm facing away from the first metal sheet is provided with the adhesive layer for bonding the second metal sheet, and the second metal sheet is connected to the outer surface of the shell.

[0036] In the above technical solution, the second metal sheet is bonded through an adhesive layer arranged on the side of the diaphragm facing away from the first metal sheet, making the connection simpler and more convenient. The metal sheet has good thermal conductivity. The setting of the second metal sheet is conducive to the rapid transfer of heat inside the shell to the adhesive layer between the diaphragm and the second metal sheet, so that the adhesive layer can lose its stickiness in time, thereby making the pressure relief sensitivity of the pressure relief component better, reducing the risk of safety problems such as explosion and fire in the shell, thereby improving the safety performance of the battery cell with the shell.

[0037] In some embodiments of the first aspect of the present application, the diaphragm is provided with a first through hole, and the first through hole is connected to the pressure relief hole.

[0038] In the above technical solution, the diaphragm is provided with a first through hole connected to the pressure relief hole, which reduces the risk of the diaphragm blocking the discharge of air pressure inside the shell and improves the pressure relief efficiency of the pressure relief assembly.

[0039] In some embodiments of the first aspect of the present application, the pressure relief assembly further includes a second metal sheet and a diaphragm, the second metal sheet is provided with the second through hole; the second metal sheet is arranged between the diaphragm and the shell, the second metal sheet is connected to the shell, the second through hole is connected to the pressure relief hole, the surface of the diaphragm facing the shell is provided with the adhesive layer connected to the second metal sheet, and the diaphragm covers the second through hole.

[0040] In the above technical solution, the second metal sheet is connected to the shell, and the side of the second metal sheet facing away from the shell is connected to the diaphragm through an adhesive layer, making the connection simpler and more convenient. The metal sheet has good thermal conductivity. The provision of the second metal sheet facilitates the rapid transfer of heat from the inside of the shell to the adhesive layer between the diaphragm and the second metal sheet, so that the adhesive layer can lose its viscosity in time, thereby making the pressure relief sensitivity of the pressure relief assembly better, reducing the risk of safety problems such as explosion and fire in the shell, thereby improving the safety performance of the battery cell with the shell. The diaphragm covers the second through hole, which can play a sealing role under normal operating conditions. The surface of the diaphragm facing the shell is provided with an adhesive layer, and the diaphragm is bonded to the second metal sheet through the adhesive layer, making the connection simpler and more convenient. When the good thermal conductivity of the second metal sheet can make the adhesive layer lose its viscosity due to heat, the diaphragm can be easily separated from the second metal sheet, thereby allowing the diaphragm to open the second through hole, and then open the pressure relief hole to release pressure, achieving timely pressure relief and improving the safety performance of the battery cell with the shell.

[0041] In some embodiments of the first aspect of the present application, the thermal conductivity of the second metal sheet is P2, 10W / (m*K)≤P2≤500W / (m*K).

[0042] In the above technical solution, the thermal conductivity of the second metal sheet is P2, 10W / (m*K)≤P2≤500W / (m*K), which is conducive to the heat in the shell being transferred to the adhesive layer through the second metal sheet, so that the adhesive layer between the second metal sheet and the diaphragm can lose its viscosity in time, reducing the risk of safety problems such as explosion and fire in the shell, thereby improving the safety performance of the battery cell with the shell.

[0043] In some embodiments of the first aspect of the present application, 80 W / (m*K)≤P2≤420 W / (m*K).

[0044] In the above technical solution, 80W / (m*K)≤P2≤420W / (m*K), which makes the second metal sheet more sensitive to temperature and can transfer heat to the bonding layer between the diaphragm and the second metal sheet more promptly, so that the bonding layer between the second metal sheet and the diaphragm can lose its stickiness in time, reducing the risk of safety problems such as explosion and fire in the casing, thereby improving the safety performance of the battery cell with the casing.

[0045] In some embodiments of the first aspect of the present application, the shell satisfies at least one of the following conditions: Condition A: the thickness of the second metal sheet is h2, 0.03mm≤h2≤1mm; Condition B: the diameter of the second through hole is D1, 0.1mm≤D1≤4mm.

[0046] In the above technical solution, 0.03mm≤h2≤1mm ensures that the second metal sheet has good strength, which is beneficial for improving sealing performance. It also minimizes the space occupied by the second metal sheet, making the structure of the battery cell with this housing smaller. The diameter of the second through hole is D1, and 0.1mm≤D1≤4mm. This not only provides a larger connection area between the second metal sheet and the diaphragm, and the second metal sheet and the housing, improving connection stability, but also reduces the risk of the second metal sheet blocking the pressure relief hole. After the adhesive layer loses its viscosity, the pressure relief hole can release pressure in a timely and efficient manner, thereby improving the safety performance of the battery cell with this housing.

[0047] In some embodiments of the first aspect of the present application, the pressure relief hole is a liquid injection hole.

[0048] In the above technical solution, the pressure relief hole can not only relieve pressure after the adhesive layer loses its viscosity due to heat, but also be used to inject liquid into the shell during the battery cell assembly process. One hole has multiple uses, which can simplify the structure of the shell, thereby simplifying the preparation process of the battery cell with the shell and reducing the preparation cost of the battery cell.

[0049] In some embodiments of the first aspect of the present application, the material of the first metal sheet is one or more of nickel, aluminum or stainless steel.

[0050] In some embodiments of the first aspect of the present application, the material of the second metal sheet is one or more of nickel, aluminum or stainless steel.

[0051] The selection of the above-mentioned materials is conducive to the heat in the shell being transferred to the adhesive layer through the second metal sheet, so that the adhesive layer between the second metal sheet and the diaphragm can lose its viscosity in time, reducing the risk of safety problems such as explosion and fire in the shell, thereby improving the safety performance of the battery cell with the shell.

[0052]

[0053] In a second aspect, an embodiment of the present application provides a battery cell, comprising an electrode assembly and a casing provided in any of the above embodiments.

[0054] In the above technical solution, the above-mentioned shell opens the pressure relief hole when the adhesive layer of the pressure relief component loses its viscosity due to heat, thereby being able to release the pressure inside the shell, reducing the risk of safety problems such as explosion and fire in the shell, and thus improving the safety performance of the battery cell with the shell. The pressure relief hole is opened when the adhesive layer of the pressure relief component loses its viscosity due to heat. The thermal sensitivity of the pressure relief component is good, so that the reliability of the pressure relief is high, which can improve the safety of the battery cell with the shell. Compared with the pressure relief method of the notched groove, this solution does not need to reserve a large space for the pressure relief component, and fully utilizes the space of the electrical equipment powered by the battery cell, improves the space utilization rate of the electrical equipment, and also makes the structure of the electrical equipment more compact, and the cost of preparing the pressure relief component is lower.

[0055] In a third aspect, an embodiment of the present application provides an electrical device, which includes the battery cell provided in the above embodiment.

[0056] In the above technical solution, the battery cell has good safety performance and can improve the power safety and stability of the electrical equipment powered by the battery cell. The battery cell in the above embodiment does not require a large space to be reserved for the pressure relief component, which can fully utilize the space of the electrical equipment, improve the space utilization rate of the electrical equipment, and also make the structure of the electrical equipment more compact. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0058] FIG1 is a schematic diagram of the structure of a battery cell provided in some embodiments of the present application;

[0059] FIG2 is an exploded view of the battery cell in FIG1 ;

[0060] FIG3 is a schematic diagram of the structure of a battery cell provided in some embodiments of the present application from another perspective;

[0061] FIG4 is a cross-sectional view taken along the line Q1-Q1 in FIG3 ;

[0062] FIG5 is an enlarged view of point E1 in FIG4 ;

[0063] FIG6 is a schematic structural diagram of a battery cell provided in some other embodiments of the present application;

[0064] FIG7 is an exploded view of the battery cell in FIG6 ;

[0065] FIG8 is a schematic diagram of the structure of a battery cell provided in some other embodiments of the present application from another perspective;

[0066] FIG9 is a cross-sectional view taken along the line Q2-Q2 in FIG8 ;

[0067] FIG10 is an enlarged view of point E2 in FIG9 ;

[0068] FIG11 is a schematic structural diagram of a battery cell provided in some further embodiments of the present application;

[0069] FIG12 is an exploded view of the battery cell in FIG11 ;

[0070] FIG13 is a schematic diagram of the structure of a battery cell provided in some other embodiments of the present application from another perspective;

[0071] FIG14 is a cross-sectional view taken along line Q3-Q3 in FIG13;

[0072] FIG15 is an enlarged view of point E3 in FIG14 ;

[0073] FIG16 is a schematic structural diagram of a battery cell provided in some other embodiments of the present application;

[0074] FIG17 is a cross-sectional view taken along line Q4-Q4 in FIG16 ;

[0075] FIG18 is an enlarged view of point E4 in FIG17 .

[0076] Icon: 100-battery cell; 10-electrode assembly; 20-housing; 20a-accommodation space; 21-shell; 211-pressure relief hole; 22-pole; 23-pressure relief assembly; 231-adhesive layer; 232-diaphragm; 2321-first through hole; 233-first metal sheet; 234-second metal sheet; 2341-second through hole. DETAILED DESCRIPTION

[0077] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of 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. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0078] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0079] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0080] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0081] In the description of the embodiments of the present application, it should be noted that the indicated orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the product of the application is conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. These are merely for the convenience of describing the present application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present application. In addition, the terms "first," "second," "third," etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0082] Currently, market developments indicate that batteries are becoming increasingly widespread. They are used in a wide range of electric vehicles, including electric bicycles, electric motorcycles, and electric vehicles, as well as in power tools, drones, and energy storage devices. As battery applications continue to expand, market demand is also growing.

[0083] Currently, to improve safety, rigid-cased battery cells are laser-grooved in the casing to relieve pressure when excessive internal pressure builds up. Electrical devices equipped with rigid-cased cells require a larger valve opening corresponding to the grooves, resulting in a larger overall footprint for the device. Furthermore, the grooves have poor thermal sensitivity, resulting in less reliable pressure relief and impacting cell safety. Laser grooving also increases cell production costs and reduces the cell's hot box pass rate.

[0084] Based on the above considerations, in order to improve the safety performance and pressure relief reliability of the battery cell, an embodiment of the present application provides a shell including a shell and a pressure relief assembly; the shell has a pressure relief hole; the pressure relief assembly blocks the pressure relief hole, the pressure relief assembly includes an adhesive layer, the adhesive layer is adhered to the shell, and the pressure relief assembly is configured to lose viscosity when the adhesive layer is configured to be heated when the temperature inside the shell reaches a threshold temperature, thereby opening the pressure relief hole to release the pressure inside the shell; the threshold temperature is between 110° and 130°; wherein the bonding area of ​​the adhesive layer is S, 2mm 2 ≤S≤10mm 2 .

[0085] The pressure relief hole is opened when the adhesive layer of the pressure relief component loses its viscosity due to heat, thereby releasing the pressure inside the shell, reducing the risk of safety problems such as explosion and fire in the shell, thereby improving the safety performance of the battery cell with the shell.

[0086] The pressure relief hole is opened when the adhesive layer of the pressure relief component loses its viscosity due to heat. The pressure relief component has good thermal sensitivity, which makes the pressure relief more reliable and can improve the safety of the battery cell with this casing. Compared with the pressure relief method of the scored groove, this solution does not need to reserve a large space for the pressure relief component, fully utilizes the space of the electrical equipment, improves the space utilization rate of the electrical equipment, makes the structure of the electrical equipment more compact, and reduces the cost of preparing the pressure relief component.

[0087] The pressure relief hole is opened when the adhesive layer of the pressure relief component loses its viscosity due to heat, thereby releasing the pressure inside the shell, which is also beneficial to improving the pass rate of the hot box of the battery cell with the shell.

[0088] The bonding area S of the bonding layer meets 2mm 2 ≤S≤10mm 2 , so that the shell has good adhesion when it is in normal working state, so that the adhesive layer can ensure that the pressure relief component effectively blocks the pressure relief hole, thereby ensuring the normal operation of the battery cell with the shell. It can also lose viscosity in time when the pressure and temperature inside the shell are abnormal, so that the pressure relief component can open the pressure relief hole and relieve pressure in time, thereby improving the safety performance of the battery cell with the shell.

[0089] The battery cells disclosed in the embodiments of this application can be used in, but are not limited to, electric two-wheeled vehicles, power tools, drones, energy storage devices, and other electrical equipment. Battery cells meeting the working conditions of this application can also be used as power supply systems for electrical equipment, which helps improve the safety performance of the battery cells.

[0090] The present invention provides an electrical device that uses a battery cell as a power source. The electrical device may include, but is not limited to, electronic devices, power tools, electric vehicles, drones, and energy storage devices. Electronic devices may include mobile phones, tablets, and laptops, power tools may include electric drills and electric saws, and electric vehicles may include electric cars, electric motorcycles, and electric bicycles.

[0091] As shown in Figures 1 and 2, an embodiment of the present application provides a battery cell 100, which includes an electrode assembly 10 and a housing 20. The housing 20 defines a receiving space 20a, in which the electrode assembly 10 is received. The receiving space 20a may also contain an electrolyte, such as an electrolyte solution.

[0092] The electrode assembly 10 includes a positive electrode sheet, a negative electrode sheet and a separator. The separator is disposed between the positive electrode sheet and the negative electrode sheet. The separator is used to insulate and separate the positive electrode sheet and the negative electrode sheet.

[0093] The positive electrode sheet consists of a positive current collector and a positive active material layer, which is deposited on the positive current collector. For lithium-ion batteries, for example, the positive current collector can be made of aluminum, while the positive active material layer can be made of lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide.

[0094] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, which is disposed on the negative electrode current collector. The negative electrode current collector can be made of copper, and the negative electrode active material can be carbon, silicon, or a silicon-carbon composite.

[0095] The material of the isolation film may include PP (polypropylene) or PE (polyethylene).

[0096] The battery cell 100 also includes a positive tab and a negative tab. The positive tab is connected to the positive electrode sheet of the electrode assembly 10, and the negative tab is connected to the negative electrode sheet of the electrode assembly 10. Specifically, the positive tab is connected to the positive electrode current collector of the positive electrode sheet, and the negative tab is connected to the negative electrode current collector of the negative electrode sheet. The positive tab and the positive electrode current collector can be integrally formed, for example, by die-cutting the positive electrode current collector and the positive tab, thereby achieving an integral formation of the positive tab and the positive electrode current collector. The positive tab and the positive electrode current collector can also be provided as separate bodies and then connected as one, for example, by welding, conductive adhesive, or the like. The negative tab and the negative electrode current collector can be integrally formed, for example, by die-cutting the negative electrode current collector and the negative tab, thereby achieving an integral formation of the negative tab and the negative electrode current collector. The negative tab and the negative electrode current collector can also be provided as separate bodies and then connected as one, for example, by welding, conductive adhesive, or the like.

[0097] The electrode assembly 10 can be a laminated electrode assembly 10, in which at least one positive electrode sheet, at least one negative electrode sheet and at least one isolation membrane are stacked in a certain order. The isolation membrane is arranged between the positive electrode sheet and the negative electrode sheet to insulate and separate the positive electrode sheet and the negative electrode sheet, thereby reducing the risk of short circuit of the battery cell 100.

[0098] The electrode assembly 10 may also be a wound electrode assembly 10. A positive electrode sheet, a negative electrode sheet, and a separator are stacked in a certain order and wound around a central axis to form the wound electrode assembly 10. The separator is disposed between the positive electrode sheet and the negative electrode sheet to insulate and separate the positive and negative electrode sheets.

[0099] The shell 20 may be a hard shell 21 , for example, the shell 20 may be a steel shell or an aluminum shell, forming a steel shell battery core or an aluminum shell battery core respectively.

[0100] The outer shell 20 includes a shell 21 and a pole 22, and a receiving space 20a is formed in the shell 21. The pole 22 is used to connect to the tab of the battery cell 100. As shown in Figures 1 and 2, in some embodiments, only one pole 22 may be provided on the shell 21, and the pole 22 is insulated and provided on the shell 21. One of the positive tab and the negative tab is electrically connected to the pole 22, and the other of the positive tab and the negative tab is electrically connected to the shell 21. Then, the pole 22 and the shell 21 respectively form the positive output terminal and the negative output terminal of the battery cell 100 for connecting to an external device. The pole 22 can be provided on a side wall of the shell 20 and protrude from the outer surface of the side wall to facilitate electrical connection between the pole 22 and the external device. The pole 22 can be connected to the shell 21 by bonding, riveting, etc.

[0101] In other embodiments, the housing 20 may include two poles 22, both of which are insulated and disposed within the housing 21, with the positive and negative tabs electrically connected to the two poles 22, respectively. The two poles 22 respectively form the positive and negative output terminals of the battery cell 100, and the positive and negative output terminals are respectively used to electrically connect to external devices. The two poles 22 may be located on the same sidewall of the housing 20 and protrude therefrom, or they may be located on different sidewalls of the housing 20.

[0102] As shown in Figures 1 and 2, in some embodiments, the housing 21 is further provided with a pressure relief hole 211, and the outer shell 20 further includes a pressure relief assembly 23. The pressure relief assembly 23 blocks the pressure relief hole 211 to form an independent space inside the housing 21. When the pressure relief assembly 23 opens the pressure relief hole 211, a pressure relief channel is formed, thereby relieving the pressure inside the housing 21, reducing the pressure inside the housing 21 and reducing the risk of explosion, fire, and other safety issues in the battery cell 100.

[0103] The pressure relief hole 211 and the pressure relief assembly 23 can be arranged on the same side wall of the shell 21 as the pole 22. In this way, the pressure relief assembly 23 can utilize the space on the side wall where the pole 22 is arranged that is not occupied by the pole 22. When the battery cell 100 is installed in the electrical equipment, since the pole 22 protrudes from the outer surface of the side wall, there is a certain space between the outer surface of the side wall and the electrical equipment. The pressure relief assembly 23 can be located in the space formed between the outer surface of the side wall where the pole 22 is arranged and the electrical equipment, making full use of the space. In addition, since when the battery cell 100 is installed in the electrical equipment, space needs to be reserved to facilitate the electrical connection of the pole 22 with other components of the electrical equipment, the pole 22 and the pressure relief assembly 23 are arranged on the same side wall. There is no need to reserve space for the pressure relief assembly 23 to achieve pressure relief. This can further save space in the electrical equipment and make the structure of the electrical equipment more compact.

[0104] In some embodiments, the housing 20 may be provided with an independent injection hole and the pressure relief hole 211 , through which electrolyte may be injected into the housing 21 , so that the injection hole and the pressure relief hole 211 can respectively play the role of injection and pressure relief.

[0105] In other embodiments, the pressure relief hole 211 is a liquid injection hole, that is, the battery cell 100 can inject electrolyte into the interior of the housing 21 through the pressure relief hole 211. Therefore, the pressure relief hole 211 can not only relieve pressure after the adhesive layer 231 loses its viscosity due to heat, but can also be used to inject liquid into the interior of the housing 21 during the assembly process of the battery cell 100. This hole has multiple uses, can simplify the structure of the housing 20, and thus simplify the preparation process of the battery cell 100 with the housing 20, reducing the preparation cost of the battery cell 100.

[0106] As shown in FIG. 5 , in some embodiments, the pressure relief assembly 23 includes an adhesive layer 231 . The pressure relief assembly 23 is configured to open the pressure relief hole 211 to release the pressure inside the housing 21 when the adhesive layer 231 loses its adhesiveness due to heat.

[0107] By opening the pressure relief hole 211 when the adhesive layer 231 of the pressure relief component 23 loses its viscosity due to heat, the pressure inside the housing 20 can be released, reducing the risk of safety issues such as explosion and fire in the housing 21, thereby improving the safety performance of the battery cell 100 with the housing 20. By opening the pressure relief hole 211 when the adhesive layer 231 of the pressure relief component 23 loses its viscosity due to heat, the pressure relief component 23 has good thermal sensitivity, making the pressure relief more reliable, and can improve the safety of the battery cell 100 with the housing 20. Compared with the pressure relief method of the scored groove, this solution does not require a large space to be reserved for the pressure relief component 23, making full use of the space of the electrical equipment, improving the space utilization rate of the electrical equipment, and also making the structure of the electrical equipment more compact, and the cost of preparing the pressure relief component 23 is lower. When the temperature inside the shell reaches a threshold temperature, the adhesive layer 231 of the pressure relief component 23 loses its viscosity, thereby opening the pressure relief hole 211 to release the pressure inside the shell 20, which is also beneficial to improving the pass rate of the hot box of the battery cell 100 with the shell 20.

[0108] The pressure relief hole 211 can have various shapes, such as a circular hole, a rectangular hole, an elliptical hole, etc. In the embodiment where the pressure relief hole 211 is a circular hole, the diameter of the pressure relief hole 211 is d1, and 0.5mm≤d1≤5.5mm. This ensures that the pressure relief hole 211 has a good pressure relief capacity and pressure relief rate, and also alleviates the problem of reduced strength of the housing 21 due to the provision of the pressure relief hole 211. For example, d1 can be 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, etc.

[0109] As shown in FIG. 1 to FIG. 5 , the pressure relief assembly 23 further includes a diaphragm 232 . The diaphragm 232 covers the pressure relief hole 211 . An adhesive layer 231 connected to the housing 21 is provided on the surface of the diaphragm 232 facing the housing 21 .

[0110] It is understandable that the diaphragm 232 is bonded to the surface of the housing 21 via the adhesive layer 231. The adhesive layer 231 can be disposed on the periphery of the pressure relief hole 211, for example, the adhesive layer 231 is a circular ring structure disposed on the periphery of the pressure relief hole 211.

[0111] Observed along the axial direction of the pressure relief hole 211 , the area of ​​the surface of the diaphragm 232 facing the housing 21 and the area of ​​the adhesive layer 231 provided on the side of the diaphragm 232 facing the housing 21 may be equal to or unequal to each other.

[0112] Diaphragm 232 covers pressure relief hole 211. Under normal operating conditions, gas inside housing 21 is less likely to be blocked by diaphragm 232 and escape from housing 21 after passing through pressure relief hole 211. In this case, pressure relief assembly 23 can consist solely of diaphragm 232 and adhesive layer 231 disposed on the surface of diaphragm 232 facing housing 21. This simplifies the structure of pressure relief assembly 23, occupies less space, and reduces manufacturing costs.

[0113] Therefore, by covering the pressure relief hole 211 with the diaphragm 232, a seal can be achieved. The surface of the diaphragm 232 facing the housing 21 is provided with an adhesive layer 231. The diaphragm 232 is bonded to the housing 21 via the adhesive layer 231, making the connection method simple and convenient. When the internal temperature of the housing reaches a threshold temperature, the adhesive layer 231 loses its viscosity, and the diaphragm 232 easily separates from the housing 21, thereby opening the pressure relief hole 211 to release pressure, achieving timely pressure relief and improving the safety performance of the battery cell 100 equipped with the housing 20. By covering the pressure relief hole 211 with the diaphragm 232, the structure of the pressure relief assembly 23 is simple and the manufacturing cost is low.

[0114] As shown in Figures 6 to 10, in some embodiments, the pressure relief assembly 23 also includes a first metal sheet 233 and a diaphragm 232; the diaphragm 232 is arranged between the first metal sheet 233 and the shell 21, the diaphragm 232 is connected to the shell 21, and the surface of the diaphragm 232 facing away from the shell 21 is provided with an adhesive layer 231 connected to the first metal sheet 233, and the first metal sheet 233 covers the pressure relief hole 211.

[0115] The surface of the diaphragm 232 facing the housing 21 is connected to the housing 21. In some embodiments, the surface of the diaphragm 232 facing the housing 21 is provided with an adhesive layer 231, and the diaphragm 232 is connected to the housing 21 through the adhesive layer 231, making the connection simpler and more convenient.

[0116] The surface of the diaphragm 232 facing away from the housing 21 is also provided with an adhesive layer 231. The first metal sheet 233 is bonded to the diaphragm 232 via the adhesive layer 231 on the surface of the diaphragm 232 facing away from the housing 21. That is, adhesive layers 231 are provided on both sides of the diaphragm 232. One adhesive layer 231 is used to bond the diaphragm 232 to the housing 21, and the other adhesive layer 231 is used to bond the diaphragm 232 to the first metal sheet 233. During the manufacturing process of the battery cell 100, the first metal sheet 233, adhesive layer 231, diaphragm 232, and adhesive layer 231 can be stacked and arranged in sequence. Then, by applying pressure and activating the adhesive layer 231, the diaphragm 232 and the first metal sheet 233 are bonded together to form a single unit. Under abuse conditions, such as when the temperature of the battery cell 100 reaches 110-130°C, the adhesive layer 231 in the pressure relief assembly 23 loses its viscosity, causing the diaphragm 232 and the first metal sheet 233 to fall off, exposing the pressure relief hole 211 and forming a pressure relief channel; under normal working conditions (such as temperature less than or equal to 85°C), the sealing function can be achieved.

[0117] The first metal sheet 233 covers the pressure relief hole 211. Under normal operating conditions, the gas inside the housing 21 is less likely to be blocked by the first metal sheet 233 after passing through the pressure relief hole 211 and discharged from the housing 21. External impurities are less likely to be blocked by the first metal sheet 233 and enter the housing 21. For example, the first metal sheet 233 can reduce the penetration of polymer water into the diaphragm 232.

[0118] Therefore, the first metal sheet 233 covers the pressure relief hole 211, which helps improve the sealing performance of the pressure relief assembly 23 under normal operating conditions. The surface of the diaphragm 232 facing the first metal sheet 233 is provided with an adhesive layer 231. The diaphragm 232 is bonded to the first metal sheet 233 via the adhesive layer 231. The connection method is simple. When the adhesive layer 231 loses its viscosity due to heat, the first metal sheet 233 can be easily separated from the diaphragm 232, thereby opening the pressure relief hole 211 to release pressure, achieving timely pressure relief and improving the safety performance of the battery cell 100 equipped with the housing 20.

[0119] In the embodiment where the pressure relief assembly 23 includes a first metal sheet 233 and a diaphragm 232, a first through hole 2321 may be provided on the diaphragm 232, and the first through hole 2321 communicates with the pressure relief hole 211. The cross-sectional area of ​​the first through hole 2321 may be greater than, less than, or equal to the cross-sectional area of ​​the pressure relief hole 211. The first through hole 2321 may have various shapes, such as a circular hole, a rectangular hole, an elliptical hole, etc. FIG7 illustrates a case where the first through hole 2321 is circular. The first through hole 2321 and the pressure relief hole 211 may be coaxially arranged.

[0120] The material of the first metal sheet 233 can be aluminum, nickel, stainless steel, etc. The material of the first metal sheet 233 is one or more of nickel, aluminum, or stainless steel. Among them, the first metal sheet 233 can be composed of any one of nickel, aluminum, and stainless steel, for example, the material of the first metal sheet 233 is aluminum, or the material of the first metal sheet 233 is nickel, or the material of the first metal sheet 233 is stainless steel. Of course, the material of the second metal sheet 234 can also be composed of two materials among aluminum, nickel, and stainless steel, for example, the first metal sheet 233 is composed of aluminum and nickel, or the first metal sheet 233 is composed of aluminum and stainless steel, or the first metal sheet 233 is composed of stainless steel and nickel. The first metal sheet 233 can also be composed of three materials: nickel, aluminum, and stainless steel.

[0121] The first metal sheet 233 may have various shapes, for example, the first metal sheet 233 may be circular, rectangular, oval, etc.

[0122] In some embodiments, the thickness of the first metal sheet 233 is h1, where 0.03 mm ≤ h1 ≤ 1.00 mm.

[0123] Illustratively, h1 may be 0.03 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.00 mm, etc.

[0124] 0.03mm≤h1≤1.00mm, so that the first metal sheet 233 has better strength, which is beneficial to improving the sealing performance, and can also minimize the space occupied by the first metal sheet 233, so that the structure of the battery cell 100 with the shell 20 is smaller.

[0125] Furthermore, 0.03mm≤h1≤0.15mm. For example, h1 can be 0.035mm, 0.04mm, 0.045mm, 0.05mm, 0.055mm, 0.065mm, 0.065mm, 0.07mm, 0.075mm, 0.08mm, 0.085mm, 0.09mm, 0.095mm, 0.15mm, etc.

[0126] 0.03mm≤h1≤0.15mm, so that the first metal sheet 233 has better strength, which is beneficial to improving the sealing performance, and can also make the space occupied by the first metal sheet 233 smaller, so that the structure of the battery cell 100 with the shell 20 is smaller.

[0127] In some embodiments, the thermal conductivity of the first metal sheet 233 is P1, 10 W / (m*K)≤P1≤500 W / (m*K).

[0128] Exemplarily, P1 can be 10W / (m*K), 100W / (m*K), 150W / (m*K), 200W / (m*K), 250W / (m*K), 300W / (m*K), 350W / (m*K), 400W / (m*K), 450W / (m*K), 500W / (m*K), etc.

[0129] The thermal conductivity of the first metal sheet 233 is P1, 10W / (m*K)≤P1≤500W / (m*K), which is conducive to the transfer of heat to the adhesive layer 231 through the first metal sheet 233, so that the adhesive layer 231 between the first metal sheet 233 and the diaphragm 232 can lose its viscosity in time, reducing the risk of safety problems such as explosion and fire in the shell 20, thereby improving the safety performance of the battery cell 100 with the shell 20.

[0130] Furthermore, 80 W / (m*K)≤P1≤420 W / (m*K). For example, P1 can be 80 W / (m*K), 120 W / (m*K), 180 W / (m*K), 220 W / (m*K), 280 W / (m*K), 320 W / (m*K), 380 W / (m*K), 420 W / (m*K), etc.

[0131] 80W / (m*K)≤P1≤420W / (m*K), making the first metal sheet 233 more sensitive to temperature and able to transfer heat to the diaphragm 232 and the adhesive layer 231 of the first metal sheet 233 more promptly, so that the adhesive layer 231 between the first metal sheet 233 and the diaphragm 232 can lose its viscosity in time, reducing the risk of safety problems such as explosion and fire in the casing 20, thereby improving the safety performance of the battery cell 100 with the casing 20.

[0132] As shown in Figures 11 to 15, in some embodiments, the pressure relief assembly 23 also includes a second metal sheet 234, which is provided with a second through hole 2341; the second metal sheet 234 is connected between the diaphragm 232 and the shell 21, and the second through hole 2341 is connected to the pressure relief hole 211. The surface of the diaphragm 232 facing away from the first metal sheet 233 is provided with an adhesive layer 231 for bonding the second metal sheet 234, and the second metal sheet 234 is connected to the outer surface of the shell 20.

[0133] The second metal sheet 234 is bonded by the adhesive layer 231 arranged on the side of the diaphragm 232 away from the first metal sheet 233, making the connection simpler and more convenient. The metal sheet has good thermal conductivity. The setting of the second metal sheet 234 is conducive to the rapid transfer of heat inside the shell 20 to the adhesive layer 231 between the diaphragm 232 and the second metal sheet 234, so that the adhesive layer 231 can lose its viscosity in time, thereby making the pressure relief sensitivity of the pressure relief component 23 better, reducing the risk of safety problems such as explosion and fire in the shell 20, thereby improving the safety performance of the battery cell 100 with the shell 20.

[0134] Adhesive layers 231 are provided on both sides of the diaphragm 232. One adhesive layer 231 connects the second metal sheet 234 and the diaphragm 232, and the other adhesive layer 231 connects the first metal sheet 233 and the diaphragm 232. During the assembly of the battery cell 100, the first metal sheet 233, the adhesive layer 231, the diaphragm 232, the adhesive layer 231 and the second metal sheet 234 are stacked in sequence. By pressurizing and activating, the diaphragm 232 is bonded to the first metal sheet 233 through the adhesive layer 231, and the diaphragm 232 is bonded to the second metal through the adhesive layer 231 to form a whole. Subsequently, the second metal sheet 234 can be connected to the housing 21 through a laser welding process so that the pressure relief assembly 23 forms a sealing effect on the pressure relief hole 211. Under abuse conditions, such as when the temperature of the battery cell 100 reaches 110°C to 150°C, the adhesive layer 231 in the pressure relief component 23 loses its viscosity, causing the diaphragm 232 and the first metal sheet 233, and the diaphragm 232 and the second metal sheet 234 to fall off, exposing the through hole of the annular sheet and forming a pressure relief channel; under normal working conditions (such as temperature less than or equal to 85°C), the pressure relief component 23 can realize the sealing function.

[0135] The second through hole 2341 can have various shapes, such as a circular hole, a rectangular hole, an elliptical hole, etc.

[0136] The second metal sheet 234 can have various shapes, such as circular, rectangular, oval, etc.

[0137] The material of the second metal sheet 234 includes but is not limited to aluminum, nickel, stainless steel, etc. The material of the second metal sheet 234 is one or more of nickel, aluminum or stainless steel. Among them, the second metal sheet 234 can be composed of any one of nickel, aluminum and stainless steel, such as the material of the second metal sheet 234 is aluminum, or the material of the second metal sheet 234 is nickel, or the material of the second metal sheet 234 is stainless steel. Of course, the material of the second metal sheet 234 can also be composed of two materials among aluminum, nickel and stainless steel, such as the second metal sheet 234 is composed of aluminum and nickel, or the second metal sheet 234 is composed of aluminum and stainless steel, or the second metal sheet 234 is composed of stainless steel and nickel. The second metal sheet 234 can also be composed of three materials: nickel, aluminum and stainless steel.

[0138] In the embodiment where the pressure relief assembly 23 includes a first metal sheet 233, a diaphragm 232, and a second metal sheet 234, the diaphragm 232 may or may not be provided with a first through hole 2321. When the diaphragm 232 is provided with the first through hole 2321, the cross-sectional area of ​​the second through hole 2341 may be greater than, less than, or equal to the cross-sectional area of ​​the first through hole 2321. When both the first through hole 2321 and the second through hole 2341 are circular holes, the first through hole 2321 and the second through hole 2341 may be coaxially arranged.

[0139] In some embodiments, the diameter of the second through hole 2341 is D1, 0.1 mm ≤ D1 ≤ 4 mm.

[0140] Illustratively, D1 may be 0.1 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, etc.

[0141] 0.1mm≤D1≤4mm, which not only ensures a larger connection area between the second metal sheet 234 and the diaphragm 232, and between the second metal sheet 234 and the shell 21, thereby improving the connection stability, but also reduces the risk of the second metal sheet 234 blocking the pressure relief hole 211. After the adhesive layer 231 loses its viscosity, the pressure relief hole 211 can release pressure in a timely and efficient manner, thereby improving the safety performance of the battery cell 100 with the shell 20.

[0142] Furthermore, 0.3 mm ≤ D1 ≤ 3 mm. For example, D1 can be 0.3 mm, 0.38 mm, 1.2 mm, 1.8 mm, 2.2 mm, 2.8 mm, 3 mm, etc.

[0143] In some embodiments, the outer diameter of the second metal sheet 234 is D2, and 1 mm ≤ D2 ≤ 6 mm. This helps the second metal sheet 234 have a larger coverage area, facilitates the connection between the second metal sheet 234 and the housing 21, and makes the space occupied by the second metal sheet 234 more reasonable, which helps reduce the volume of the battery cell 100. For example, D2 can be 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, etc.

[0144] Furthermore, 2mm≤D2≤5mm. For example, D2 can be 2mm, 2.3mm, 2.8mm, 3.3mm, 3.8mm, 4.3mm, 4.8mm, 5mm, etc.

[0145] In some embodiments, the outer diameter of the second metal sheet 234 is greater than or equal to the diameter of the pressure relief hole 211 , ie, D2 ≥ d1 .

[0146] In some embodiments, the outer diameter of the first metal sheet 233 is smaller than the outer diameter of the second metal sheet 234 , and the outer diameter of the first metal sheet 233 is larger than the diameter of the second through hole 2341 .

[0147] In some embodiments, the thickness of the second metal sheet 234 is h2, where 0.03 mm ≤ h2 ≤ 1 mm.

[0148] Illustratively, h2 may be 0.03 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, etc.

[0149] 0.03mm≤h2≤1mm, so that the second metal sheet 234 has better strength, which is beneficial to improving the sealing performance, and can also minimize the space occupied by the second metal sheet 234, so that the structure of the battery cell 100 with the shell 20 is smaller.

[0150] Furthermore, 0.05 mm ≤ h2 ≤ 0.15 mm. For example, h2 can be 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, 0.095 mm, 0.15 mm, etc.

[0151] In some embodiments, the thermal conductivity of the second metal sheet 234 is P2, 10 W / (m*K)≤P2≤500 W / (m*K).

[0152] Exemplarily, P2 can be 10W / (m*K), 100W / (m*K), 150W / (m*K), 200W / (m*K), 250W / (m*K), 300W / (m*K), 350W / (m*K), 400W / (m*K), 450W / (m*K), 500W / (m*K), etc.

[0153] 10W / (m*K)≤P2≤500W / (m*K), which is conducive to the heat in the shell 21 being transferred to the adhesive layer 231 through the second metal sheet 234, so that the adhesive layer 231 between the second metal sheet 234 and the diaphragm 232 can lose its viscosity in time, reducing the risk of safety problems such as explosion and fire in the shell 20, thereby improving the safety performance of the battery cell 100 with the shell 20.

[0154] Furthermore, 80 W / (m*K) ≤ P2 ≤ 420 W / (m*K). For example, P2 can be 80 W / (m*K), 120 W / (m*K), 180 W / (m*K), 220 W / (m*K), 280 W / (m*K), 320 W / (m*K), 380 W / (m*K), 420 W / (m*K), etc.

[0155] 80W / (m*K)≤P2≤420W / (m*K), making the second metal sheet 234 more sensitive to temperature and able to transfer heat to the diaphragm 232 and the adhesive layer 231 of the second metal sheet 234 more promptly, so that the adhesive layer 231 between the second metal sheet 234 and the diaphragm 232 can lose its viscosity in time, reducing the risk of safety problems such as explosion and fire in the outer shell 20, thereby improving the safety performance of the battery cell 100 with the outer shell 20.

[0156] As shown in Figures 16, 17, and 18, in some embodiments, the pressure relief assembly 23 also includes a second metal sheet 234 and a diaphragm 232, and the second metal sheet 234 is provided with a second through hole 2341; the second metal sheet 234 is arranged between the diaphragm 232 and the shell 21, the second metal sheet 234 is connected to the shell 21, the second through hole 2341 is connected to the pressure relief hole 211, and the surface of the diaphragm 232 facing the shell 21 is provided with an adhesive layer 231 connected to the second metal sheet 234, and the diaphragm 232 covers the second through hole 2341.

[0157] An adhesive layer 231 is provided on the surface of the diaphragm 232 facing the housing 21 , and the diaphragm 232 and the second metal sheet 234 are bonded together by the adhesive layer 231 .

[0158] The diaphragm 232 is not provided with the first through hole 2321. The diaphragm 232 indirectly covers the pressure relief hole 211 by covering the second through hole 2341.

[0159] The second metal sheet 234 is connected to the shell 21. The side of the second metal sheet 234 facing away from the shell 21 is connected to the diaphragm 232 through the adhesive layer 231, making the connection simpler and more convenient. The metal sheet has good thermal conductivity. The setting of the second metal sheet 234 is conducive to the rapid transfer of heat inside the shell 20 to the adhesive layer 231 between the diaphragm 232 and the second metal sheet 234, so that the adhesive layer 231 can lose its viscosity in time, thereby making the pressure relief sensitivity of the pressure relief component 23 better, reducing the risk of safety problems such as explosion and fire in the shell 20, thereby improving the safety performance of the battery cell 100 with the shell 20. The second through hole 2341 is covered by the diaphragm 232, which can play a sealing role under normal working conditions. The surface of the diaphragm 232 facing the shell 21 is provided with an adhesive layer 231. The diaphragm 232 is bonded to the second metal sheet 234 through the adhesive layer 231, making the connection simpler and more convenient. When the good thermal conductivity of the second metal sheet 234 can make the adhesive layer 231 lose its viscosity due to heat, the diaphragm 232 can be easily separated from the second metal sheet 234, so that the diaphragm 232 opens the second through hole 2341, and then opens the pressure relief hole 211 to release the pressure, thereby achieving timely pressure relief and improving the safety performance of the battery cell 100 with the shell 20.

[0160] In some embodiments, the total thickness of the diaphragm 232 and the adhesive layer 231 disposed on the diaphragm 232 is h3. In embodiments where the adhesive layer 231 is disposed on one side of the diaphragm 232, h3 is the sum of the thickness of the diaphragm 232 and the thickness of the adhesive layer 231 disposed on one side of the diaphragm 232. In embodiments where the adhesive layer 231 is disposed on both sides of the diaphragm 232, h3 is the sum of the thickness of the diaphragm 232 and the thickness of the adhesive layer 231 disposed on both sides of the diaphragm 232. In some embodiments, 0.02mm≤h3≤1mm, so that the entire structure formed by the diaphragm 232 and the adhesive layer 231 occupies a smaller space, thereby reducing the volume of the pressure relief assembly 23 and facilitating the miniaturization of the battery cell 100. For example, h3 can be 0.02mm, 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 1mm, etc.

[0161] Furthermore, 0.1 mm ≤ h3 ≤ 0.3 mm allows the diaphragm 232 and adhesive layer 231 to occupy a smaller space, thereby reducing the volume of the pressure relief assembly 23 and facilitating the miniaturization of the battery cell 100. For example, h3 can be 0.1 mm, 0.13 mm, 0.15 mm, 0.17 mm, 0.25 mm, 0.27 mm, 0.3 mm, etc.

[0162] In some embodiments, the bonding area of ​​the bonding layer 231 is S, 2mm 2 ≤S≤10mm 2 The bonding surface S of the bonding layer 231 refers to the bonding area of ​​the bonding layer 231 on either side of the film 232 .

[0163] For example, S can be 2 mm 2 , 3mm 2 , 4mm 2 , 5mm 2 , 6mm 2 , 7mm 2 , 8mm 2 , 9mm 2 , 10mm 2 wait.

[0164] The bonding area S of the bonding layer 231 satisfies 2 mm 2 ≤S≤10mm 2 , so that the shell 20 has good adhesion when it is in normal working state, so that the adhesive layer 231 can ensure that the pressure relief component 23 effectively blocks the pressure relief hole 211, thereby ensuring the normal operation of the battery cell 100 with the shell 20, and can also lose viscosity in time when the pressure and temperature inside the shell 20 are abnormal, so that the pressure relief component 23 can open the pressure relief hole 211 and relieve pressure in time, thereby improving the safety performance of the battery cell 100 with the shell 20.

[0165] Furthermore, 3mm 2 ≤S≤8mm 2 For example, S can be 3mm 2 , 3.5mm 2 , 4.5mm 2 , 5.5mm 2 , 6.5mm 2 , 7.5mm 2 , 8mm 2 wait.

[0166] The bonding area S of the bonding layer 231 satisfies 3 mm 2 ≤S≤8mm 2 , so that the shell 20 has better adhesion when it is in normal working state, so that the adhesive layer 231 can ensure that the pressure relief component 23 effectively blocks the pressure relief hole 211, thereby ensuring the normal operation of the battery cell 100 with the shell 20, and can also lose viscosity in time when the pressure and temperature inside the shell 20 are abnormal, so that the pressure relief component 23 can open the pressure relief hole 211 and relieve pressure in time, thereby improving the safety performance of the battery cell 100 with the shell 20.

[0167] The adhesive layer 231 can be positioned away from the pressure relief hole 211. Specifically, when viewed along the axial direction of the pressure relief hole 211, the adhesive layer 231 is positioned on the periphery of the pressure relief hole 211. The adhesive layer 231 does not cover the portion of the diaphragm 232 corresponding to the pressure relief hole 211, which reduces the amount of material required for the adhesive layer 231 and saves costs. In some embodiments, the bonding area S of an adhesive layer 231 can be calculated as the difference between the surface area of ​​the diaphragm 232 along the axial direction of the pressure relief hole 211 and the cross-sectional area of ​​the pressure relief hole 211.

[0168] In some embodiments, the adhesive layer 231 includes a polymer, which can play a role of high bonding performance under normal working conditions, so that the pressure relief component 23 can achieve a sealing function; under high temperature conditions, the adhesive layer 231 can quickly lose its viscosity, causing the pressure relief component 23 to open the pressure relief hole 211, exposing the pressure relief hole 211, forming a pressure relief channel, and achieving a timely pressure relief function.

[0169] The polymer may be made of a variety of materials. For example, in some embodiments, the polymer includes at least one of ethylene, propylene, vinylidene fluoride, acrylic acid, acrylic ester, styrene, acrylonitrile, maleic anhydride, vinyl chloride, and allyl chloride.

[0170] The above-mentioned material can not only help the adhesive layer 231 to have high bonding performance under normal working conditions, so that the pressure relief component 23 can achieve a sealing function; it can also help the adhesive layer 231 to quickly lose its viscosity under high-temperature working conditions, causing the pressure relief component 23 to open the pressure relief hole 211, exposing the pressure relief hole 211, forming a pressure relief channel, and achieving a timely pressure relief function.

[0171] The polymer may be made of any one of the above materials, or may be made of two or more of the above materials.

[0172] Of course, the polymer can also be replaced by other materials that can replace the above materials.

[0173] The mass proportion of the polymer in the adhesive layer 231 can be designed according to actual needs. For example, the mass proportion of the polymer in the adhesive layer 231 is 70% to 95%, which is beneficial for the adhesive layer 231 to have high bonding performance under normal working conditions, thereby enabling the pressure relief component 23 to achieve a sealing function; it is also beneficial for the adhesive layer 231 to quickly lose its viscosity under high temperature conditions, causing the pressure relief component 23 to open the pressure relief hole 211, exposing the pressure relief hole 211, forming a pressure relief channel, and achieving a timely pressure relief function.

[0174] The adhesive layer 231 may also include some auxiliary components. For example, the adhesive layer 231 may include 90% by weight of the polymer and 10% by weight of auxiliary components. The auxiliary components mainly include CMC (Carboxymethyl Cellulose) and polyoxyethylene ether.

[0175] The following is an exemplary method for forming the membrane 232 and the adhesive layer 231 into a whole:

[0176] 10 parts ethylene, 90 parts propylene, and a methylcyclohexane solution were added to a reaction kettle and stirred at 130°C until uniform. N-dodecyldimethylamine, hexadecyltrimethylammonium bromide, and deionized water were then added and stirred at room temperature. The above polymer, CMC-Na, polyoxyethylene ether, and deionized water were added to a blender to form a slurry with a viscosity of 40 mPa·s and a solids content of 5%. This slurry was evenly coated on one side of a porous polyethylene membrane 232. After oven drying, an adhesive layer 231 was formed on one side of the substrate. The same preparation process was repeated on the other side, and a second adhesive layer 231 was applied. After oven drying, an adhesive layer 231 was formed on the other side of the substrate, thereby forming adhesive layers 231 on both sides of the membrane 232.

[0177] In some embodiments, the polymer has a melting point A, 70°C ≤ A ≤ 100°C.

[0178] Illustratively, A may be 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, etc.

[0179] 70℃≤A≤100℃, so that the adhesive layer 231 can lose its viscosity before the shell 20 has problems such as explosion and fire, so that the pressure relief component 23 opens the pressure relief hole 211 to release the pressure in the shell 21, reducing the risk of explosion, fire and other problems in the battery cell 100 with the shell 20, which is beneficial to improving the safety performance of the battery cell 100.

[0180] In some embodiments, the volume distribution particle size Dv90 of the polymer is 2.5 μm to 4.5 μm.

[0181] Dv90 is the particle size at which 90% of the volume distribution of particles in the polymer is obtained. For example, Dv90 can be 2.5 μm, 2.8 μm, 3 μm, 3.2 μm, 3.5 μm, 3.8 μm, 4 μm, 4.2 μm, 4.5 μm, etc.

[0182] The volume distribution particle size Dv90 of the polymer is 2.5 μm to 4.5 μm, which is beneficial for the adhesive layer 231 to have better adhesive properties.

[0183] In some embodiments, the volume distribution particle size Dv50 of the polymer is 0.8 μm to 1.8 μm.

[0184] Dv50 is the particle size at which 50% of the volume distribution of particles in the polymer occurs. For example, Dv50 can be 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, etc.

[0185] In some embodiments, the weight average molecular weight of the polymer is K, 15w≤K≤25w.

[0186] Weight-average molecular weight is one of the fundamental parameters of polymers, measuring their relative mass and distribution. It is closely related to the performance and processing properties of polymer materials. If the relative mass is too low, the material's mechanical strength and toughness are poor, making it ineffective for practical applications. If the relative mass is too high, the melt viscosity increases, making processing and molding difficult. A polymer weight-average molecular weight K of 15w ≤ K ≤ 25w promotes good bonding and mechanical properties for the adhesive layer 231 and reduces the manufacturing complexity of the adhesive layer 231.

[0187] For example, K can be 15w, 16w, 17w, 18w, 19w, 20w, 21w, 22w, 23w, 24w, 25w, etc.

[0188] In some embodiments, the adhesive force of the adhesive layer 231 is F, 10 N / m≤F≤40 N / m.

[0189] The method for testing the adhesive force of the adhesive layer 231 can be referred to related technologies and will not be described in detail in this application.

[0190] 10N / m≤F≤40N / m, which is beneficial for the adhesive layer 231 to have high bonding performance under normal working conditions, thereby enabling the pressure relief component 23 to achieve a sealing function; it is also beneficial for the adhesive layer 231 to quickly lose its viscosity under high temperature conditions, causing the pressure relief component 23 to open the pressure relief hole 211, exposing the pressure relief hole 211, forming a pressure relief channel, and achieving a timely pressure relief function.

[0191] Illustratively, F may be 10 N / m, 15 N / m, 20 N / m, 25 N / m, 30 N / m, 35 N / m, 40 N / m, etc.

[0192] It should be noted that, when an adhesive layer 231 for bonding to the housing 21 is provided on the side of the diaphragm 232 facing the housing 21 , the adhesive force F of the adhesive layer 231 may be the adhesive force between the diaphragm 232 and the housing 21 .

[0193] In the case where an adhesive layer 231 for bonding to the first metal sheet 233 is provided on the side of the diaphragm 232 facing away from the housing 21 , the adhesive force F of the adhesive layer 231 may be the adhesive force between the diaphragm 232 and the first metal sheet 233 .

[0194] When an adhesive layer 231 for bonding to the second metal sheet 234 is provided on the side of the diaphragm 232 facing away from the first metal sheet 233 , the adhesive force F of the adhesive layer 231 may be the adhesive force between the diaphragm 232 and the second metal sheet 234 .

[0195] To verify the safety performance of the battery cell 100 provided in the embodiment of the present application, the following tests were conducted on the battery cell 100, in which the pressure relief assembly 23 includes a first metal sheet 233, a diaphragm 232, and a second metal sheet 234, and an adhesive layer 231 is provided on both sides of the diaphragm 232.

[0196] 1. Overcharge test: Test discharge the battery cell 100 and then place it in an explosion-proof box. Connect the thermocouple (fix the thermocouple contact to the center of the surface of the battery cell 100) and connect the power supply to charge. Charge at a constant current of 3C to 4.6V until the voltage reaches the maximum value. Stop the test if any of the following conditions are met:

[0197] a) Continuous charging time reaches 7h;

[0198] b) The temperature of the battery cell 100 drops to 20% below the peak value.

[0199] If the battery cell 100 does not catch fire or explode, it is determined that the battery cell 100 is safe.

[0200] 2. Overdischarge Test: After performing a standard discharge, place battery cell 100 in an explosion-proof box. Connect an external resistor of 30 ohms and continue discharging for 7 hours, or until the voltage is less than 0.2V. If battery cell 100 does not leak, ignite, or explode, it is considered safe.

[0201] III. 130°C Thermal Shock Test 1: After fully charging battery cell 100 using the standard charging profile, perform the test within 12-24 hours. Heat using convection or a circulating hot air oven, starting at 25±3°C at a rate of 5±2°C / min, to 130±2°C. Hold the temperature for 30 minutes before the test is complete. If battery cell 100 does not catch fire or explode, it is deemed safe.

[0202] IV. 130°C Thermal Shock Test II: After fully charging battery cell 100 using the standard charging profile, conduct the test within 12-24 hours. Heat using convection or a circulating hot air oven, starting at 25±3°C at a rate of 5±2°C / min, to 130±2°C. Hold the temperature for 30 minutes before the test is complete. If battery cell 100 does not catch fire or explode, the battery is deemed safe.

[0203] 5. 150°C Thermal Shock Test: After fully charging battery cell 100 using the standard charging profile, perform the test within 12-24 hours. Heat the battery cell 100 using convection or a circulating hot air oven, starting at 25±3°C at a rate of 5±2°C / min, and then raise the temperature to 150±2°C. Hold the temperature for 30 minutes before the test is complete. If the battery cell 100 does not catch fire or explode, the battery cell 100 is deemed to be safe.

[0204] According to the above-mentioned overcharge test method, over-discharge test method, 130°C thermal shock test method 1, 130°C thermal shock test method 2, and 150°C thermal shock test method, while maintaining the same shape, size, material, and other conditions of the diaphragm 232 of the pressure relief assembly 23 of the battery cell 100, as well as the shape, material, and bonding area of ​​the adhesive layer 231 in each embodiment, by changing the thickness h1 of the first metal sheet 233, the thickness h2 of the second metal sheet 234, the thermal conductivity P1 of the first metal sheet 233, and the thermal conductivity P2 of the second metal sheet 234, the effects of the thickness h1 of the first metal sheet 233, the thickness h2 of the second metal sheet 234, the thermal conductivity P1 of the first metal sheet 233, and the thermal conductivity P2 of the second metal sheet 234 on the overcharge pass rate, over-discharge pass rate, and hot box pass rate of the battery cell 100 were respectively determined. The data shown in Table 1 were obtained.

[0205] In Table 1, the battery cells 100 in Examples 1-7, 26, and 27 differ in the thickness h1 of the first metal sheet 233, to determine the effect of the thickness h1 of the first metal sheet 233 on the overcharge, over-discharge, and hot box pass rates of the battery cells 100. In Examples 28, 29, 2, and 8-11, the battery cells 100 differ in the thickness h2 of the second metal sheet 234, to determine the effect of the thickness h2 of the second metal sheet 234 on the overcharge, over-discharge, and hot box pass rates of the battery cells 100. In Examples 30, 31, 2, and 12-16, the battery cells 100 differ in the thermal conductivity P1 of the first metal sheet 233, to determine the effect of the thermal conductivity P1 of the first metal sheet 233 on the overcharge, over-discharge, and hot box pass rates of the battery cells 100. In Examples 32, 33, and 17 to 21, the difference between the battery cells 100 in each embodiment is the different thermal conductivity coefficients P2 of the second metal sheet 234, so as to obtain the influence of the thermal conductivity coefficient P2 of the second metal sheet 234 on the overcharge pass rate, over-discharge pass rate, and hot box pass rate of the battery cell 100. In Examples 34, 22 to 25, the difference between the battery cells 100 in each embodiment is the diameter D of the second through hole 2341. 1 The influence of the diameter D1 of the second through hole 2341 on the overcharge pass rate, over-discharge pass rate, and hot box pass rate of the battery cell 100 is obtained.

[0206] Table 1:

[0207] From Table 1 we can see that:

[0208] 1. It can be seen from Examples 26, 27, and 1 to 7 that when the thickness h2 of the second metal sheet 234, the thermal conductivity P1 of the first metal sheet 233, the thermal conductivity P2 of the second metal sheet 234, and the diameter D1 of the second through hole 2341 are constant, when the thickness h1 of the first metal sheet 233 is 0.02 mm, the overcharge pass rate of the battery cell 100 is 55%, the over-discharge pass rate is 40%, and the hot box pass rate is 55%, all of which are relatively low; when the thickness h1 of the first metal sheet 233 is 1.2 mm, the overcharge pass rate of the battery cell 100 is 65%, the over-discharge pass rate is 62%, and the hot box pass rate is 45%, all of which are relatively low. When the thickness h1 of the first metal sheet 233 is 0.03 mm ≤ h1 ≤ 1 mm, the overcharge pass rate, over-discharge pass rate, and hot box pass rate all increase first and then decrease as the thickness h1 of the first metal sheet 233 gradually increases. The battery cell 100 has high overcharge pass rate, over-discharge pass rate, and hot box pass rate, with the overcharge test rate, over-discharge test rate, and hot box test rate all being greater than or equal to 80%. Therefore, when the thickness h1 of the first metal sheet 233 is 0.03 mm ≤ h1 ≤ 1 mm, the battery cell 100 still has good overcharge pass rate, over-discharge pass rate, and hot box pass rate, and the battery cell 100 has good safety and reliability.

[0209] 2. It can be seen from Examples 28, 29, 2, and 8 to 11 that when the thickness h1 of the first metal sheet 233, the thermal conductivity P1 of the first metal sheet 233, the thermal conductivity P2 of the second metal sheet 234, and the diameter D1 of the second through hole 2341 are constant, when the thickness h2 of the second metal sheet 234 is 0.02 mm, the overcharge pass rate of the battery cell 100 is 67%, the over-discharge pass rate is 63%, and the hot box pass rate is 65%, all of which are relatively low; when the thickness h2 of the second metal sheet 234 is 1.1 mm, the overcharge pass rate of the battery cell 100 is 57%, the over-discharge pass rate is 60%, and the hot box pass rate is 35%, all of which are relatively low. When the thickness h2 of the second metal sheet 234 increases within the range of 0.03 mm ≤ h2 ≤ 1 mm, the overcharge pass rate decreases, while the over-discharge pass rate and hot box pass rate decrease overall. Battery cell 100 exhibits high overcharge, over-discharge, and hot box pass rates, with the overcharge, over-discharge, and hot box test rates all exceeding 80%. In particular, the hot box pass rate may exceed 90%. Therefore, when the thickness h2 of the second metal sheet 234 increases within the range of 0.03 mm ≤ h2 ≤ 1 mm, battery cell 100 exhibits good overcharge, over-discharge, and hot box pass rates, demonstrating excellent safety and reliability.

[0210] 3. It can be seen from Examples 30, 31, 2, and 12 to 16 that, when the thickness h1 of the first metal sheet 233, the thickness h2 of the second metal sheet 234, the thermal conductivity P2 of the second metal sheet 234, and the diameter D1 of the second through hole 2341 are constant, when the thermal conductivity P1 of the first metal sheet 233 is 8 W / (m*K), the overcharge pass rate of the battery cell 100 is 75%, the over-discharge pass rate is 78%, and the hot box pass rate is 55%, all of which are relatively low; when the thermal conductivity P1 of the first metal sheet 233 is 510 W / (m*K), the overcharge pass rate of the battery cell 100 is 70%, the over-discharge pass rate is 72%, and the hot box pass rate is 70%, all of which are relatively low. When 10W / (m*K)≤P1≤500W / (m*K), as the thermal conductivity of the first metal sheet 233 gradually increases, the overcharge pass rate, over-discharge pass rate, and hot box pass rate show a trend of first increasing and then decreasing. The battery cell 100 has a relatively high overcharge pass rate, over-discharge pass rate, and hot box pass rate. The overcharge test rate, over-discharge test rate, and hot box test rate exceed 75%, especially the overcharge pass rate and over-discharge pass rate are both greater than or equal to 80%. Among them, when 80W / (m*K)≤P1≤420W / (m*K), the overcharge pass rate, over-discharge pass rate, and hot box pass rate are all better, all greater than or equal to 80%. Therefore, when 10W / (m*K)≤P1≤500W / (m*K), the battery cell 100 also has a relatively good overcharge pass rate, over-discharge pass rate, and hot box pass rate, and the battery cell 100 has good safety and reliability. When 80W / (m*K)≤P1≤420W / (m*K), the overcharge pass rate, over-discharge pass rate and hot box pass rate are all better.

[0211] 4. It can be seen from Examples 32, 33, and 17 to 21 that, when the thickness h1 of the first metal sheet 233, the thickness h2 of the second metal sheet 234, the thermal conductivity P1 of the first metal sheet 233, and the diameter D1 of the second through hole 2341 are constant, when the thermal conductivity P2 of the second metal sheet 234 is 9 W / (m*K), the overcharge pass rate of the battery cell 100 is 46%, the over-discharge pass rate is 50%, and the hot box pass rate is 45%, all of which are relatively low; when the thermal conductivity P2 of the second metal sheet 234 is 505 W / (m*K), the overcharge pass rate of the battery cell 100 is 73%, the over-discharge pass rate is 72%, and the hot box pass rate is 70%, all of which are relatively low. When 10W / (m*K)≤P2≤500W / (m*K), as the thermal conductivity of the second metal sheet 234 gradually increases, the overcharge pass rate, over-discharge pass rate, and hot box pass rate show a trend of first increasing and then decreasing. The battery cell 100 has a relatively high overcharge pass rate, over-discharge pass rate, and hot box pass rate. The overcharge test rate, over-discharge test rate, and hot box test rate are all greater than or equal to 79%, especially the overcharge pass rate and hot box pass rate are both greater than or equal to 80%. Among them, when 70W / (m*K)≤P2≤420W / (m*K), the overcharge pass rate, over-discharge pass rate, and hot box pass rate are all better, all greater than or equal to 79%. Therefore, when 10W / (m*K)≤P2≤500W / (m*K), the battery cell 100 also has a relatively good overcharge pass rate, over-discharge pass rate, and hot box pass rate, and the battery cell 100 has good safety and reliability.

[0212] 5. It can be seen from Examples 34 and 22 to 25 that when the thickness h1 of the first metal sheet 233, the thickness h2 of the second metal sheet 234, the thermal conductivity P1 of the first metal sheet 233, and the thermal conductivity P2 of the second metal sheet 234 are constant, when the diameter D1 of the second through hole 2341 is 5 mm, the overcharge pass rate, over-discharge pass rate, and hot box pass rate of the battery cell 100 are 71%, 73%, and 65%, which are all relatively low; when 0.1 mm ≤ D1 ≤ 4 mm, as the diameter of the second through hole 2341 gradually increases, the overcharge pass rate and the over-discharge pass rate show a trend of gradually increasing, and the hot box pass rate generally shows a trend of first increasing and then decreasing. The battery cell 100 has a high overcharge pass rate, over-discharge pass rate, and hot box pass rate. The overcharge test rate, over-discharge test rate, and hot box test rate are all greater than or equal to 78%, especially the over-discharge pass rate and the hot box pass rate are both greater than or equal to 80%. Therefore, when 0.1 mm ≤ D1 ≤ 4 mm, the battery cell 100 still has good overcharge pass rate, over-discharge pass rate and hot box pass rate, and the battery cell 100 has good safety and reliability.

[0213] According to the above-mentioned overcharge test method, overdischarge test method, 130°C thermal shock test method 1, 130°C thermal shock test method 2, and 150°C thermal shock test method, while maintaining the other conditions of the battery cell 100 in each embodiment the same, by changing the adhesive layer polymer type, polymer mass ratio, polymer melting point, polymer Dv90, polymer weight-average molecular weight, adhesive layer area, and threshold temperature, the effects of the adhesive layer polymer type, polymer mass ratio, polymer melting point, polymer weight-average molecular weight, adhesive layer area, and threshold temperature on the hot box pass rate and 45°C cycle 500-cycle capacity retention rate of the battery cell 100 were respectively determined. The data in Table 2 were obtained.

[0214] In Table 2, the difference between the battery cells 100 in Examples 2-1 to 2-3 is the different mass ratios of the polymers, so as to obtain the effect of the mass ratio of the polymer on the hot box pass rate and the capacity retention rate after 500 cycles at 45°C of the battery cells 100. In Examples 2-21, 2-4, 2-5, 2-6, and 2-20, the difference between the battery cells 100 in Examples 2-23, 2-7, 2-8, 2-9, and 2-22 is the different polymer Dv90, so as to obtain the effect of the polymer Dv90 on the hot box pass rate and the capacity retention rate after 500 cycles at 45°C of the battery cells 100. In Example 2-10, Example 2-2, and Example 2-11, the difference between the battery cells 100 in each embodiment is the different weight-average molecular weight of the polymer, so as to obtain the effect of the weight-average molecular weight of the polymer on the hot box pass rate and the capacity retention rate after 500 cycles at 45°C of the battery cells 100. In Comparative Example 2-1, Comparative Example 2-2, Example 2-2, Example 2-12 to Example 2-17, the difference between the battery cells 100 in each embodiment is the different bonding area, so as to obtain the effect of the bonding area on the hot box pass rate and the capacity retention rate after 500 cycles at 45°C of the battery cells 100. In Example 2-14, Example 2-24, Example 2-25, and Example 2-26, the difference between the battery cells 100 in each embodiment is the different type of polymer, so as to obtain the effect of the type of polymer on the hot box pass rate and the capacity retention rate after 500 cycles at 45°C of the battery cells 100. In Example 2-2, Example 2-27 to Example 2-28 and Comparative Examples 2-3 to 2-6, the difference between the battery cells 100 in each embodiment is the different threshold temperatures, so as to obtain the influence of the threshold temperature on the hot box pass rate and the capacity retention rate of the battery cell 100 after 500 cycles at 45°C.

[0215] Table 2:

[0216]

[0217] From Table 2 we can see that:

[0218] 1. From Examples 2-1 to 2-3, it can be seen that when the polymer type, melting point, Dv90, weight average molecular weight, and bonding area of ​​the adhesive layer 231 are the same, when the mass ratio of the polymer is 70%, the hot box pass rate of the battery cell 100 is 10 / 12, and the capacity retention rate after 500 cycles at 45°C is 80%; when the mass ratio of the polymer is 80%, the hot box pass rate of the battery cell 100 is 11 / 12, and the capacity retention rate after 500 cycles at 45°C is 82%; when the mass ratio of the polymer is 80%, the hot box pass rate of the battery cell 100 is 11 / 12, and the capacity retention rate after 500 cycles at 45°C is 82%; When it is 95%, the hot box pass rate of the battery cell 100 is 10 / 12, and the capacity retention rate after 500 cycles at 45°C is 81%. With the increase of the polymer mass ratio, the hot box pass rate and the capacity retention rate after 500 cycles at 45°C of the battery cell both show a trend of first increasing and then decreasing. The hot box pass rates are greater than or equal to 10 / 12, and the capacity retention rates after 500 cycles at 45°C are both greater than 80%. Therefore, when the mass proportion of the polymer in the adhesive layer 231 is 70% to 95%, the battery cell 100 has a higher hot box pass rate and capacity retention rate.

[0219] 2. It can be seen from Examples 2-21, 2-4, 2-5, 2-6, and 2-20 that when the polymer type of the bonding layer 231 is the same, the mass ratio of the polymer is the same, the polymer Dv90 is the same, the weight average molecular weight of the polymer is the same, and the bonding area is the same, when the melting point of the polymer is 60°C, the hot box pass rate of the battery cell 100 is 9 / 12, and the capacity retention rate after 500 cycles at 45°C is 77.85%; when the melting point of the polymer is 70°C, the hot box pass rate of the battery cell 100 is 11 / 12, and the capacity retention rate after 500 cycles at 45°C is 81.5%; when the melting point of the polymer is 90°C, the hot box pass rate of the battery cell 100 is 12 / 12, and the capacity retention rate after 500 cycles at 45°C is 81.6%; when the melting point of the polymer is 100°C, the hot box pass rate of the battery cell 100 is 11 / 12 , the capacity retention rate after 500 cycles at 45°C is 81.8%; when the melting point of the polymer is 110°C, the hot box pass rate of the battery cell 100 is 8 / 12, and the capacity retention rate after 500 cycles at 45°C is 77.5%; with the increase of the melting point of the polymer, the hot box pass rate of the battery cell tends to first increase and then decrease, and the hot box pass rate is relatively high, the hot box pass rate is greater than or equal to 8 / 12, and the capacity retention rate after 500 cycles at 45°C gradually increases, and the capacity retention rate after 500 cycles at 45°C is relatively high, both exceeding 77%, especially when the melting point of the polymer is 70°C, 90°C, and 100°C, the hot box pass rate is greater than or equal to 11 / 12, and the capacity retention rate after 500 cycles at 45°C exceeds 81%. Therefore, when the melting point of the polymer in the adhesive layer 231 is 70°C~100°C, the hot box pass rate and capacity retention rate of the battery cell 100 are relatively high.

[0220] 3. It can be seen from Examples 2-23, 2-7, 2-8, 2-9 and 2-22 that when the polymer type of the bonding layer 231 is the same, the mass ratio of the polymer is the same, the melting point of the polymer is the same, the weight average molecular weight of the polymer is the same, and the bonding area is the same, when the polymer Dv90 is 2 μm, the hot box pass rate of the battery cell 100 is 8 / 12, and the capacity retention rate after 500 cycles at 45°C is 77.1%; when the polymer Dv90 is 2.5 μm, the hot box pass rate of the battery cell 100 is 11 / 12, and the capacity retention rate after 500 cycles at 45°C is 81.5%; when the polymer Dv90 is 4 μm, the hot box pass rate of the battery cell 100 is 11 / 12, and the capacity retention rate after 500 cycles at 45°C is 81.6%; when the polymer Dv90 is 4.5 μm, the hot box pass rate of the battery cell 100 is 10 / 12, and the capacity retention rate after 500 cycles at 45°C is 77.1%. The capacity retention rate after 500 cycles is 81.7%; when the polymer Dv90 is 5μm, the hot box pass rate of the battery cell 100 is 9 / 12, and the capacity retention rate after 500 cycles at 45℃ is 78.5%. As the polymer Dv90 increases, the hot box pass rate of the battery cell generally tends to first increase and then decrease. The hot box pass rates are all high and are all greater than or equal to 8 / 12. The capacity retention rate after 500 cycles at 45℃ tends to first increase and then decrease. The capacity retention rate after 500 cycles at 45℃ is all high, exceeding 77%. Especially when the polymer Dv90 is 2.5μm, 4μm, and 4.5μm, the hot box pass rate exceeds 10 / 12, and the capacity retention rate after 500 cycles at 45℃ exceeds 81%. Therefore, when the polymer Dv90 of the bonding layer 231 is 2.5μm~4.5μm, the battery cell 100 has a better hot box pass rate and capacity retention rate.

[0221] 4. From Examples 2-10, 2-2, and 2-11, it can be seen that when the polymer type of the bonding layer 231 is the same, the mass ratio of the polymer is the same, the melting point of the polymer is the same, the Dv90 of the polymer is the same, and the bonding area is the same, when the weight average molecular weight of the polymer is 15w, the hot box pass rate of the battery cell 100 is 10 / 12, and the capacity retention rate after 500 cycles at 45°C is 80.3%; the weight average molecular weight of the polymer is

[0222] When the weight average molecular weight of the polymer is 20w, the hot box pass rate of the battery cell 100 is 11 / 12, and the capacity retention rate after 500 cycles at 45°C is 82%; when the weight average molecular weight of the polymer is 25w, the hot box pass rate of the battery cell 100 is 11 / 12, and the capacity retention rate after 500 cycles at 45°C is 81.8%. As the weight average molecular weight of the polymer increases, the hot box pass rate of the battery cell tends to increase as a whole, and the hot box pass rate is greater than or equal to 10 / 12. The capacity retention rate after 500 cycles at 45°C first increases and then decreases, and the capacity retention rate after 500 cycles at 45°C exceeds 80%. Therefore, when the weight average molecular weight of the polymer in the adhesive layer 231 is 15w~25w, the hot box pass rate and capacity retention rate of the battery cell 100 are both high.

[0223] 5. From Comparative Example 2-1, Comparative Example 2-2, Example 2-2, Example 2-12 to Example 2-17, it can be seen that when the polymer type of the adhesive layer 231 is the same, the mass ratio of the polymer is the same, the melting point of the polymer is the same, the Dv90 of the polymer is the same, and the weight average molecular weight of the polymer is the same, the bonding area is 1mm 2 The hot box pass rate of the battery cell 100 is 5 / 12, and the capacity retention rate after 500 cycles at 45°C is 71%; the bonding area is 2mm 2 The hot box pass rate of the battery cell 100 is 10 / 12, and the capacity retention rate after 500 cycles at 45°C is 80.5%; the bonding area is 2.5mm 2 The hot box pass rate of the battery cell 100 is 11 / 12, and the capacity retention rate after 500 cycles at 45°C is 80.8%; the bonding area is 3mm 2 The hot box pass rate of the battery cell 100 is 11 / 12, and the capacity retention rate after 500 cycles at 45°C is 82%; the bonding area is 6mm 2 The hot box pass rate of the battery cell 100 is 11 / 12, and the capacity retention rate after 500 cycles at 45°C is 82.5%; the bonding area is 8mm 2 The hot box pass rate of the battery cell 100 is 12 / 12, and the capacity retention rate after 500 cycles at 45°C is 82.3%; the bonding area is 9mm 2 The hot box pass rate of the battery cell 100 is 11 / 12, and the capacity retention rate after 500 cycles at 45°C is 81.4%; the bonding area is 10mm 2 The hot box pass rate of the battery cell 100 is 10 / 12, and the capacity retention rate after 500 cycles at 45°C is 81.6%; the bonding area is 11mm 2 When the bonding area is 2mm, the hot box pass rate of the battery cell is 7 / 12, and the capacity retention rate after 500 cycles at 45℃ is 74.3%; with the increase of the bonding area, the hot box pass rate of the battery cell generally increases first and then decreases, and the capacity retention rate after 500 cycles at 45℃ generally increases first and then decreases.2 , 2.5mm 2 , 3mm 2 , 6mm 2 , 8mm 2 , 9mm 2 , 10mm 2 When the hot box pass rate is greater than or equal to 10 / 12, the capacity retention rate after 500 cycles at 45℃ is more than 80%. Therefore, when the bonding area is 2mm 2 ~10mm 2 When the bonding area is 3mm, the hot box pass rate and capacity retention rate of the battery cell 100 are both high. 2 , 6mm 2 , 8mm 2 When the hot box pass rate of the battery cell 100 was 11 / 12, 11 / 12, and 12 / 12 respectively, the capacity retention rate of the battery cell 100 after 500 cycles at 45°C was 82%, 82.5%, and 82.3% respectively, all exceeding 82%. Therefore, when the bonding area is 3mm 2 ~8mm 2 When , the battery cell 100 has a better hot box pass rate and capacity retention rate.

[0224] 6. It can be seen from Examples 2-14, 2-24, 2-25, and 2-26 that when the mass ratio of the polymers is the same, the melting point of the polymers is the same, the Dv90 of the polymers is the same, the weight average molecular weight of the polymers, and the area of ​​the bonding layer is the same, and the types of polymers are polyacrylic acid, polypropylene, polyethylene, and polyvinylidene fluoride, respectively, the battery cell 100 has a hot box pass rate greater than or equal to 10 / 12 and a capacity retention rate of more than 80%. Both the hot box pass rate and the capacity retention rate are high, especially when the type of polymer is polyacrylic acid, the hot box pass rate of the battery cell 100 is 11 / 12, and the capacity retention rate is 82.5%. Therefore, when the mass ratio of the polymers is the same, the melting point of the polymers is the same, the Dv90 of the polymers is the same, the weight average molecular weight of the polymers, and the area of ​​the bonding layer is the same, when the polymer is polyacrylic acid, the battery cell 100 has a better capacity retention rate and hot box pass rate.

[0225] 7. It can be seen from Example 2-2, Example 2-27 to Example 2-28, and Comparative Examples 2-3 to 2-6 that when the set threshold temperature meets the protection range of this application, the pressure will not be released at too low or too high a temperature, which will enable the battery cell 100 to have a better capacity retention rate and hot box pass rate.

[0226] The application embodiment further provides an electrical device, which includes the battery cell 100 provided in any of the above embodiments.

[0227] The battery cell 100 has good safety performance and can improve the safety and stability of the electrical equipment powered by the battery cell 100. The battery cell 100 in the above embodiment does not require a large space to be reserved for the pressure relief assembly 23, which can fully utilize the space of the electrical equipment, improve the space utilization rate of the electrical equipment, and also make the structure of the electrical equipment more compact.

[0228] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A housing, wherein: include: A housing having a pressure relief hole; A pressure relief assembly, blocking the pressure relief hole, the pressure relief assembly comprising an adhesive layer, the adhesive layer being bonded to the shell, the adhesive layer being configured to lose viscosity when the temperature inside the shell reaches a threshold temperature, thereby opening the pressure relief hole to release the pressure inside the shell; the threshold temperature is between 110° and 130°; Wherein, the bonding area of ​​the bonding layer is S, 2mm 2 ≤S≤10mm 2 .

2. The housing according to claim 1, wherein: 3mm 2 ≤S≤8mm 2 。 3. The housing according to claim 1, wherein: The adhesive layer includes a polymer.

4. The housing according to claim 3, wherein: The material of the polymer includes at least one of ethylene, propylene, vinylidene fluoride, acrylic acid, acrylic ester, styrene, acrylonitrile, maleic anhydride, vinyl chloride and allyl chloride.

5. The housing according to claim 3, wherein: Based on the total mass of the adhesive layer, the mass proportion of the polymer is 70% to 95%.

6. The housing according to claim 3, wherein: The melting point of the polymer is A, 70°C≤A≤100°C.

7. The housing according to claim 3, wherein: The volume distribution particle size Dv90 of the polymer is 2.5 μm to 4.5 μm; and / or the weight average molecular weight of the polymer is K, 150000≤K≤250000.

8. The housing according to claim 1, wherein: The adhesive force of the adhesive layer is F, 10N / m≤F≤40N / m.

9. The housing according to claim 1, wherein: The pressure relief assembly further includes a diaphragm, the diaphragm covers the pressure relief hole, and the adhesive layer is arranged on a surface of the diaphragm facing the housing.

10. The housing according to claim 1, wherein The pressure relief assembly also includes a first metal sheet and a diaphragm; The diaphragm is arranged between the first metal sheet and the shell, the diaphragm is connected to the shell through the adhesive layer, the surface of the diaphragm facing away from the shell is provided with the adhesive layer connected to the first metal sheet, and the first metal sheet covers the pressure relief hole.

11. The housing according to claim 10, wherein The thickness of the first metal sheet is h1, 0.03 mm ≤ h1 ≤ 1.00 mm.

12. The housing according to claim 11, wherein 0.03mm≤h1≤0.15mm.

13. The housing according to claim 11, wherein The thermal conductivity of the first metal sheet is P1, 10W / (m*K)≤P1≤500W / (m*K).

14. The housing according to claim 13, wherein 80W / (m*K)≤P1≤420W / (m*K).

15. The housing according to claim 10, wherein: The pressure relief assembly further includes a second metal sheet, wherein the second metal sheet is provided with a second through hole; The second metal sheet is connected between the diaphragm and the shell, the second through hole is connected to the pressure relief hole, the surface of the diaphragm facing away from the first metal sheet is provided with the bonding layer for bonding the second metal sheet, and the second metal sheet is connected to the outer surface of the shell.

16. The housing according to claim 15, wherein The diaphragm is provided with a first through hole, and the first through hole is communicated with the pressure relief hole.

17. The housing according to claim 1, wherein The pressure relief assembly further includes a second metal sheet and a diaphragm, wherein the second metal sheet is provided with a second through hole; The second metal sheet is arranged between the diaphragm and the shell, the second metal sheet is connected to the shell, the second through hole is connected to the pressure relief hole, the surface of the diaphragm facing the shell is provided with the adhesive layer connected to the second metal sheet, and the diaphragm covers the second through hole.

18. The housing according to claim 15 or 17, wherein: The thermal conductivity of the second metal sheet is P2, 10W / (m*K)≤P2≤500W / (m*K).

19. The housing according to claim 18, wherein 80W / (m*K)≤P2≤420W / (m*K).

20. The housing according to claim 15 or 17, wherein: The housing satisfies at least one of the following conditions: Condition A: the thickness of the second metal sheet is h2, 0.03 mm ≤ h2 ≤ 1 mm; Condition B: The diameter of the second through hole is D1, 0.1 mm ≤ D1 ≤ 4 mm.

21. The housing of claim 1, wherein: The pressure relief hole is a liquid injection hole.

22. The housing according to claim 10, wherein The material of the first metal sheet is one or more of nickel, aluminum or stainless steel.

23. The housing of claim 17, wherein: The material of the second metal sheet is one or more of nickel, aluminum or stainless steel.

24. A battery cell, wherein: include: The housing according to any one of claims 1 to 23; The electrode assembly is located in the shell.

25. An electrical device, wherein: Comprising the battery cell according to claim 24.

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