Secondary battery and electronic device

Abstract

The invention relates to the technical field of batteries, and discloses a secondary battery and electronic equipment, and a first side wall of a shell in the secondary battery is provided with a first through hole. The first through hole is covered with the pressure relief assembly, the pressure relief assembly comprises a metal deformation piece and a sealing piece, the metal deformation piece comprises an active deformation layer and a passive deformation layer, a protection layer is arranged on the outer surface of the metal deformation piece, and the sealing piece is connected with the protection layer and the first side wall; the active deformation layer is closer to the first side wall, or the passive deformation layer is closer to the first side wall; the thermal expansion coefficient of the active deformation layer is larger than that of the passive deformation layer. According to the secondary battery provided by the embodiment of the invention, the outer surfaces of the active deformation layer and the passive deformation layer are coated with the protective layers, and the active deformation layer and the passive deformation layer are isolated from the outside by the protective layers, so that the probability of electrochemical corrosion caused by contact between the active deformation layer and the passive deformation layer and external water vapor, oxygen and the like is reduced, and the service lives of the active deformation layer and the passive deformation layer are prolonged.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of batteries, and in particular, to a secondary battery and an electronic device. Background Art

[0002] With the rapid development of new energy technologies, batteries have been widely used in fields such as mobile phones, laptop computers, and electric vehicles, and the quality and safety requirements for batteries are also getting higher and higher. However, when the battery is in a high-temperature environment or short-circuited, it is likely to cause thermal runaway of the battery, and the internal air pressure of the battery gradually increases, which is likely to cause the battery to catch fire or even explode, posing a safety risk. Existing pressure relief structures have problems such as pressure relief lag or premature pressure relief. Summary of the Invention

[0003] The embodiments of the present application provide a secondary battery and an electronic device, which can effectively improve the pressure relief effect of the pressure relief component in the secondary battery.

[0004] One technical solution adopted in the embodiments of the present application is: to provide a secondary battery, including a housing and a pressure relief component. The housing is provided with a receiving cavity. The housing includes a first side wall, and the first side wall is provided with a through first through hole along its thickness direction X. The pressure relief component is disposed on the first side wall and covers the first through hole. The pressure relief component includes a metal deformation member and a sealing member. The metal deformation member includes an active deformation layer and a passive deformation layer. A protective layer is provided on the outer surface of the metal deformation member. The sealing member connects the protective layer and the first side wall; the active deformation layer is closer to the first side wall, or the passive deformation layer is closer to the first side wall. The coefficient of thermal expansion G1 of the active deformation layer is greater than the coefficient of thermal expansion G2 of the passive deformation layer.

[0005] In the secondary battery of the embodiments of the present application, by setting the metal deformation member as the pressure relief structure, the characteristic of metal expanding when heated is effectively utilized, which can increase the action response speed of the metal deformation member to improve the pressure relief efficiency. And by covering the outer surfaces of the active deformation layer and the passive deformation layer with a protective layer, on the one hand, the protective layer separates the active deformation layer and the passive deformation layer from the outside world, thereby reducing the probability of electrochemical corrosion caused by the direct contact of the active deformation layer and the passive deformation layer with water vapor, oxygen, etc. in the outside world. On the other hand, the protective layer covers the active deformation layer and the passive deformation layer, which helps to eliminate the stress concentration during the bending deformation of the two, ensuring the stable deformation performance and reset performance of the active deformation layer and the passive deformation layer, and extending the service life of the active deformation layer and the passive deformation layer.

[0006] In some embodiments, along the stacking direction of the active deformation layer and the passive deformation layer, the thickness H1 of the protective layer satisfies: 0.01 mm ≤ H1 ≤ 0.1 mm. By setting the thickness of the protective layer within the above range, while ensuring that the protective layer has an insulating effect, it also has better flexibility, thereby reducing the influence of the protective layer on the thermal bending of the active deformation layer and the passive deformation layer. In some embodiments, the thickness of the protective layer satisfies: 0.03 mm ≤ H1 ≤ 0.06 mm.

[0007] In some embodiments, the protective layer includes a first layer and a second layer. The first layer is disposed on the outer surface after the active deformation layer and the passive deformation layer are stacked. Along the thickness direction of the active deformation layer, the second layer is located between the active deformation layer and the passive deformation layer, and the second layer is connected to the first layer. The main function of the first layer is to isolate the active deformation layer and the passive deformation layer from the external environment, reducing the probability of electrochemical corrosion caused by the contact of the active deformation layer and the passive deformation layer with oxygen, water vapor, etc. in the external environment. The main function of the second layer is to isolate the active deformation layer from the passive deformation layer, reducing the probability of electrochemical corrosion caused by their direct contact.

[0008] In some embodiments, the protective layer and the seal are integrally formed. The protective layer and the seal are made of the same material. The integrally formed structure is beneficial to reducing the difficulty of manufacturing the metal deformation part, reducing the thickness of one protective layer, and improving the overall energy density of the secondary battery.

[0009] In some embodiments, the protective layer includes at least one of a galvanized layer, a nickel-plated layer, a chromium-plated layer, a copper-plated layer, an epoxy resin or a polyurethane or a polyester organic layer, a ceramic layer, a polytetrafluoroethylene layer, an anodized layer, and a phosphating layer. The above materials all have better chemical stability and antioxidant properties, reducing the probability of their corrosion and being beneficial to extending their service life.

[0010] In some embodiments, the melting point T1 of the protective layer and the melting point T2 of the seal satisfy: T1 - T2 ≥ 15 °C. Controlling the difference between the melting point T1 of the protective layer and the melting point T2 of the seal at 15 °C or more can effectively ensure that when the seal is heated and melted, the protective layer can still maintain its shape, effectively covering the active deformation layer and the passive deformation layer without affecting the normal operation of the active deformation layer and the passive deformation layer.

[0011] In some embodiments, the melting point T1 of the protective layer and the operating temperature T3 of the active deformation layer satisfy: T1 - T3 ≥ 10 °C, and / or, the melting point T1 of the protective layer and the operating temperature T4 of the passive deformation layer satisfy: T1 - T4 ≥ 10 °C. Controlling the difference between the melting point T1 of the protective layer and the operating temperature T3 of the active deformation layer and / or the operating temperature T4 of the passive deformation layer at 10 °C or more can reduce the probability of the protective layer melting and failing when the active deformation layer and the passive deformation layer are deformed.

[0012] In some embodiments, along the thickness direction of the first side wall, the first side wall has a first surface and a second surface, the first surface defines a local boundary of the receiving cavity, the second surface is away from the receiving cavity, and the first through hole passes through the first surface and the second surface. The metal deformable member is located in the receiving cavity, and the seal is respectively connected to the first surface and the protective layer on the surface of the active deformation layer, or the seal is respectively connected to the first surface and the protective layer on the surface of the passive deformation layer. Alternatively, the metal deformable member is located outside the receiving cavity, and the seal is respectively connected to the second surface and the protective layer on the surface of the active deformation layer, or the seal is respectively connected to the second surface and the protective layer on the surface of the passive deformation layer. The pressure relief component is arranged in the receiving cavity. Under the premise of not affecting the pressure relief effect, the space between the head of the battery cell component and the first side wall can be effectively utilized, the probability of the pressure relief component located in the receiving cavity being damaged by the outside is reduced, and the pressure relief component located in the receiving cavity can sense the temperature changes inside the secondary battery more timely. The pressure relief component is arranged outside the receiving cavity, and it is easier to connect the pressure relief component to the housing on the outside of the housing. When the secondary battery is in thermal runaway, the metal deformation part bends away from the receiving cavity, which is consistent with the direction in which the gas in the receiving cavity is discharged outward, reducing the obstruction of the metal deformation part to the gas flow and increasing the pressure relief speed. Specifically, when the passive deformation layer is closer to the receiving cavity, the middle of the metal deformation part bulges outward to open the first through hole, and when the active deformation layer is closer to the receiving cavity, the edge of the metal deformation part is tilted outward to open the first through hole.

[0013] In some embodiments, the pressure relief assembly includes a connector, the connector is fixed to the first side wall, the connector is provided with a second through hole, the second through hole is connected to the first through hole, the sealing member is connected to the connector, the connector is connected to the protective layer on the surface of the active deformation layer, or the connector is connected to the protective layer on the surface of the passive deformation layer, and the metal deformation member covers the second through hole. Adding a connector to connect the sealing member and the first side wall can facilitate the connection and fixation of the sealing member and the shell, and also help to improve the sealing between the sealing member and the shell.

[0014] In some embodiments, the connector is a metal ring, and the metal ring is welded to the first side wall. The connector is set in a circular ring shape, on the one hand, to facilitate welding of the connector and the shell, on the other hand, to make the force of the connector in the circumferential direction uniform, reduce stress concentration, and on the other hand, the pressure relief hole can be made smaller by controlling the inner diameter of the circular ring, so as to improve the sealing of the secondary battery under normal working conditions.

[0015] In some embodiments, the outer diameter D2 of the connecting member and the diameter D1 of the first through hole satisfy: D2 > D1. And / or, the outer diameter D3 of the active deformation layer and the outer diameter D2 of the connecting member satisfy: D3 ≤ D2, and the outer diameter D3 of the active deformation layer and the diameter D4 of the second through hole of the connecting member satisfy: D3 > D4. Setting the outer diameter of the connecting member to be greater than the diameter of the first through hole enables the connecting member to be fixedly connected to the first side wall. Setting the outer diameter of the active deformation layer to be less than or equal to the outer diameter of the connecting member can reduce the difficulty of laser welding the connecting member to the housing. Setting the outer diameter of the active deformation layer to be greater than the diameter of the second through hole can ensure that the active deformation layer completely covers the second through hole to seal the second through hole under normal working conditions.

[0016] In some embodiments, the diameter D1 of the first through hole satisfies: 0.5 mm ≤ D1 ≤ 5.5 mm; and / or, the outer diameter D2 of the connecting member satisfies: 1 mm ≤ D2 ≤ 6 mm; and / or, the outer diameter D3 of the active deformation layer satisfies: 0.1 mm ≤ D3 ≤ 6 mm; and / or, the diameter D4 of the second through hole satisfies: 0.1 mm ≤ D4 ≤ 4 mm. On the basis that the exhaust rate of the first through hole is greater than or equal to the gas generation rate during thermal runaway of the battery cell assembly, the smaller the diameter of the first through hole, the less water vapor, oxygen, etc. outside the secondary battery enter the accommodation cavity through the first through hole, thereby reducing the side reaction rate of the battery cell assembly caused by water vapor and oxygen, and reducing the risk of explosion and fire of the battery cell assembly.

[0017] In some embodiments, the material of the active deformation layer includes at least one of nickel-chromium-iron alloy, nickel, copper, copper-tin-zinc alloy, copper-zinc alloy or alloy steel; the material of the passive deformation layer includes at least one of nickel-iron alloy, invar alloy, nickel-chromium-iron or manganese-copper-nickel; the above materials are more sensitive to temperature, which is beneficial to the thermal deformation of the active deformation layer and the passive deformation layer. The material of the connecting member includes at least one of aluminum, nickel, and stainless steel, which is beneficial to the welding of the connecting member to the housing and reduces the probability of corrosion and rust of the connecting member.

[0018] In some embodiments, the secondary battery includes a battery cell assembly and a terminal assembly. The battery cell assembly is disposed in the accommodation cavity. The battery cell assembly has a head, and the head is opposite to and spaced from the first side wall; the terminal assembly is disposed through the first side wall, and the terminal assembly is electrically connected to the head of the battery cell assembly. Setting the pressure relief component and the terminal component on the same side wall of the housing can effectively utilize the space between the battery cell assembly and the first side wall, and when thermal runaway occurs, the gas accumulated between the battery cell assembly and the first side wall is more likely to push open the pressure relief component for pressure relief.

[0019] Another technical solution adopted in the embodiments of the present application is: to provide an electronic device including the secondary battery, and the secondary battery is used to provide electrical energy.

[0020] The beneficial effects of the embodiments of the present application are as follows: In the embodiments of the present application, the secondary battery is provided with a metal deformation member as a pressure relief structure, effectively utilizing the characteristic of the metal expanding when heated, which can increase the action response speed of the metal deformation member to improve the pressure relief efficiency. And by coating a protective layer on the outer surfaces of the active deformation layer and the passive deformation layer, on the one hand, it can reduce the probability of electrochemical corrosion caused by the direct contact between the active deformation layer and the passive deformation layer and external water vapor, oxygen, etc.; on the other hand, the protective layer coated on the active deformation layer and the passive deformation layer helps to eliminate the stress concentration during the bending deformation of the two, ensuring the stable deformation performance and reset performance of the active deformation layer and the passive deformation layer, and prolonging the service life of the active deformation layer and the passive deformation layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application, the following will briefly introduce the drawings required for use in the description of the specific embodiments. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0022] Figure 1 It is a schematic diagram of the secondary battery according to the embodiment of the present application.

[0023] Figure 2 It is an exploded view of the secondary battery according to the embodiment of the present application.

[0024] Figure 3 It is a cross-sectional view of the pressure relief assembly of the secondary battery according to the embodiment of the present application.

[0025] Figure 4 It is a cross-sectional view of the pressure relief assembly of the secondary battery according to another embodiment of the present application.

[0026] Figure 5 It is a partial cross-sectional view of the pressure relief assembly of the secondary battery according to the embodiment of the present application when it is located in the receiving cavity and in a sealed state.

[0027] Figure 6 It is a partial cross-sectional view of the integrated molding of the protective layer and the seal of the secondary battery according to the embodiment of the present application.

[0028] Figure 7 It is a partial cross-sectional view of the pressure relief assembly of the secondary battery according to the embodiment of the present application when it is located in the receiving cavity and in a pressure relief state.

[0029] Figure 8 It is a partial cross-sectional view of the pressure relief assembly of the secondary battery according to another embodiment of the present application when it is located in the receiving cavity and in a pressure relief state.

[0030] Figure 9 It is a partial cross-sectional view of the pressure relief assembly of the secondary battery according to the embodiment of the present application when it is located outside the housing and in a sealed state.

[0031] Figure 10 It is a partial cross-sectional view of the pressure relief component of the secondary battery in the embodiment of the present application when it is located outside the housing and in a pressure relief state.

[0032] Figure 11 It is a partial cross-sectional view of the pressure relief component of the secondary battery in another embodiment of the present application when it is located outside the housing and in a pressure relief state.

[0033] Figure 12 It is an explosion diagram of the secondary battery in another embodiment of the present application.

[0034] Figure 13 It is a partial cross-sectional view of the pressure relief component of the secondary battery in another embodiment of the present application when it is located outside the housing and in a sealed state.

[0035] Figure 14 It is a dimension marking diagram of the pressure relief component of the secondary battery in another embodiment of the present application.

[0036] The reference numerals in the specific embodiments are as follows:

[0037] 100, secondary battery; 10, housing; 11, receiving cavity; 12, first side wall; 121, first through hole; 122, first surface; 123, second surface; 20, pressure relief component; 21, metal deformation member; 211, active deformation layer; 212, passive deformation layer; 213, protective layer; 2131, first layer; 2132, second layer; 22, seal; 23, connecting member; 231, second through hole; 30, cell assembly; 31, head; 30a, spacing; 40, terminal assembly; X, thickness direction. Specific embodiments

[0038] For ease of understanding the present application, the following provides a more detailed description of the present application in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on the other element, or there can be one or more intermediate elements therebetween. When an element is described as "connected to" another element, it can be directly connected to the other element, or there can be one or more intermediate elements therebetween. The terms "upper", "lower", "inner", "outer", "vertical", "horizontal", etc. used in this specification indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for facilitating the description of the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation of the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0039] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0040] In addition, the technical features involved in different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0041] Please refer to Figure 1 and Figure 2 As shown in [figures not provided], this application provides a secondary battery 100, which includes a housing 10, a pressure relief component 20, a battery cell component 30, and a terminal component 40. The pressure relief component 20 is disposed on the housing 10 to achieve pressure relief when the secondary battery 100 undergoes thermal runaway. The battery cell component 30 is disposed inside the housing 10, and the terminal component 40 is disposed on the housing 10. The terminal component 40 is electrically connected to the battery cell component 30 to form the positive or negative terminal of the secondary battery 100. Of course, the inside of the housing 10 also has an electrolyte, and the electrolyte infiltrates the battery cell component 30 so that the battery cell component 30 can undergo normal electrochemical reactions.

[0042] In some embodiments, the housing 10 is a square rigid steel shell. The housing 10 is provided with a receiving cavity 11 for accommodating the battery cell component 30. The housing 10 includes a first side wall 12, and a through first through hole 121 is provided along the thickness direction X of the first side wall 12. The first through hole 121 communicates with the outside and the receiving cavity 11. The pressure relief component 20 is disposed on the first side wall 12 of the housing 10 and covers the first through hole 121. Under normal operating conditions, the pressure relief component 20 covers and seals the first through hole 121 to keep the receiving cavity 11 in a sealed state. When the battery cell component 30 undergoes thermal runaway, the pressure relief component 20 can open at least part of the first through hole 121 to quickly discharge the high-pressure gas inside the receiving cavity 11, achieve pressure relief of the secondary battery 100, and reduce the probability of its explosion and fire.

[0043] Please refer to Figure 2 and Figure 3, the pressure relief component 20 includes a metal deformation member 21 and a seal member 22. The metal deformation member 21 includes an active deformation layer 211 and a passive deformation layer 212. The active deformation layer 211 and the passive deformation layer 212 are stacked in their own thickness direction X, and when heated to the operating temperature, both deform. Among them, the coefficient of thermal expansion G1 of the active deformation layer 211 is greater than the coefficient of thermal expansion G2 of the passive deformation layer 212. A protective layer 213 is provided on the outer surface of the metal deformation member 21. The protective layer 213 separates the active deformation layer 211 and the passive deformation layer 212 from the outside, that is, the protective layer 213 covers the outer surfaces of the active deformation layer 211 and the passive deformation layer 212. The seal member 22 connects the protective layer 213 and the first side wall 12, so that the metal deformation member 21 is fixed on the first side wall 12. The active deformation layer is closer to the first side wall, or, the passive deformation layer is closer to the first side wall.

[0044] When the battery cell assembly 30 undergoes thermal runaway, the heat inside the accommodation cavity 11 is transferred to the metal deformation member 21. Since the coefficient of thermal expansion G1 of the active deformation layer 211 is greater than the coefficient of thermal expansion G2 of the passive deformation layer 212, the amount of deformation of the active deformation layer 211 is greater than the amount of deformation of the passive deformation layer 212. The active deformation layer 211 bends towards the passive deformation layer 212, and the first through hole 121 is opened. The gas inside the accommodation cavity 11 can be discharged to the outside through the first through hole 121 to achieve pressure relief. When the temperature inside the accommodation cavity 11 drops, the active deformation layer 211 and the passive deformation layer 212 gradually return to their initial states to cover the first through hole 121, thereby sealing the accommodation cavity 11.

[0045] Among them, for the measurement of the coefficients of thermal expansion of the active deformation layer 211 and the passive deformation layer 212, a dilatometer can be used for measurement. Specifically: First, prepare a rectangular sample to ensure that the surface of the sample is smooth and defect-free. Use a dilatometer, calibrate the equipment to ensure the accuracy of the measurement. Place the sample in the dilatometer and conduct tests in a controlled temperature environment. Slowly and evenly change the temperature, and measure the dimensional changes of the sample. During the temperature change process, the dilatometer will record the length changes of the sample, and record the length change data at different temperatures. Use the formula to calculate the linear coefficient of thermal expansion G = ΔL / (L0×ΔT), where ΔL is the length change, L0 is the initial length, and ΔT is the temperature change.

[0046] Compared with the prior art in which a pressure relief valve body is used as the pressure relief structure of the secondary battery 100, the pressure relief principle of the pressure relief valve body is that the high-temperature and high-pressure gas in the accommodation cavity 11 directly breaks through the pressure relief valve for pressure relief. In the embodiment of the present application, the secondary battery 100 is provided with a metal deformation member 21 as the pressure relief structure. On the one hand, the characteristic of metal thermal expansion is effectively utilized, which can increase the action response speed of the metal deformation member 21 to improve the pressure relief efficiency. On the other hand, the metal deformation member 21 can return to its initial state after the temperature drops, can be reused, and reduces costs.

[0047] In the secondary battery 100 of the embodiment of the present application, the metal deformation member 21 is provided with a protective layer 213 on the outer surfaces of the active deformation layer 211 and the passive deformation layer 212. On the first hand, it can reduce the probability of electrochemical corrosion caused by the direct exposure of the active deformation layer 211 and the passive deformation layer 212 to the air and contact with oxygen, water vapor, etc. in the air. On the second hand, the protective layer 213 adheres to the outer surfaces of the active deformation layer 211 and the passive deformation layer 212, which helps to reduce the stress concentration during the deformation of the active deformation layer 211 and the passive deformation layer 212, ensures the stable deformation performance and reset performance of the active deformation layer 211 and the passive deformation layer 212, and prolongs the service life of the active deformation layer 211 and the passive deformation layer 212.

[0048] In some embodiments, the material of the active deformation layer 211 includes at least one of nickel-chromium-iron alloy, nickel, copper, copper-tin-zinc alloy, copper-zinc alloy or alloy steel. The material of the passive deformation layer 212 includes at least one of nickel-iron alloy, invar alloy, nickel-chromium-iron or manganese-copper-nickel. The above materials are more sensitive to temperature, which is beneficial to the thermal deformation of the active deformation layer 211 and the passive deformation layer 212.

[0049] The material of the protective layer 213 includes at least one of galvanized layer, nickel-plated layer, chromium-plated layer, copper-plated layer, epoxy resin or polyurethane or polyester organic layer, ceramic layer, polytetrafluoroethylene layer, anodic oxidation layer, phosphating layer. The above materials all have good chemical stability and oxidation resistance, so that the protective layer 213 can effectively cover the active deformation layer 211 and the passive deformation layer 212, effectively isolate from the outside world, reduce the probability of corrosion of the two, and is beneficial to prolong the service life of the two.

[0050] In some embodiments, please refer to Figure 3, along the stacking direction X of the active deformation layer 211 and the passive deformation layer 212, the thickness of the protective layer 213 satisfies: 0.01 mm ≤ H1 ≤ 0.1 mm. By setting the thickness of the protective layer 213 within the above range, while ensuring that the protective layer 213 has an insulating effect, it also has better flexibility, thereby reducing the influence of the protective layer 213 on the thermal bending of the active deformation layer 211 and the passive deformation layer 212. In some embodiments, the thickness of the protective layer 213 satisfies: 0.03 mm ≤ H1 ≤ 0.06 mm.

[0051] In some embodiments, please refer to Figure 4 , the protective layer 213 includes a first layer 2131 and a second layer 2132. The first layer 2131 is disposed on the outer surfaces of the active deformation layer 211 and the passive deformation layer 212. Along the thickness direction X of the active deformation layer 211, the second layer 2132 is located between the active deformation layer 211 and the passive deformation layer 212, and the second layer 2132 is connected to the first layer 2131. The main function of the first layer 2131 is to isolate the active deformation layer 211 and the passive deformation layer 212 from the external environment, reducing the probability of electrochemical corrosion caused by the contact of the active deformation layer 211 and the passive deformation layer 212 with oxygen, water vapor, etc. in the external environment. The main function of the second layer 2132 is to isolate the active deformation layer 211 from the passive deformation layer 212, reducing the probability of electrochemical corrosion caused by their direct contact.

[0052] In some embodiments, please refer to Figure 6 , the protective layer 213 and the seal 22 are integrally formed. The protective layer 213 and the seal 22 are made of the same material. The integrally formed structure is beneficial to reducing the manufacturing difficulty of the metal deformable part 21 and improving the sealing performance between the metal deformable part 21 and the housing 10. As an example, the protective layer 213 is disposed on the outer surfaces of the active deformation layer 211 and the passive deformation layer 212, and the thickness of the protective layer 213 on the side close to the active deformation layer 211 is larger. This thicker side forms the seal 22 to connect the active deformation layer 211 to the first side wall 12 or, as described below, to connect the active deformation layer 211 to the connector 23. In other embodiments, the thickness of the protective layer 213 on the side close to the passive deformation layer 212 can be set to be larger to connect the passive deformation layer 212 to the first side wall 12 or the connector 23.

[0053] In some embodiments, the melting point T1 of the protective layer 213 is greater than the melting point T2 of the seal 22. Under normal operating conditions of the secondary battery 100, the seal 22 fixedly connects the protective layer 213 on the surface of the active deformation layer 211 to the first side wall 12 of the housing 10, and the seal 22 is in a solid state to ensure the sealing effect. When the battery cell assembly 30 undergoes thermal runaway, the seal 22 is heated and at least partially becomes in a molten state, and the bonding effect of the seal 22 on the protective layer 213 on the surface of the active deformation layer 211 is reduced, enabling the active deformation layer 211 to bend smoothly towards the passive deformation layer 212 to open the first through hole 121 for pressure relief. Setting the melting point T1 of the protective layer 213 to be greater than the melting point T2 of the seal 22 allows the protective layer 213 to maintain its shape to cover the outer surfaces of the active deformation layer 211 and the passive deformation layer 212 when the seal 22 is heated and melted, achieving effective isolation and protection for the two. In some embodiments, the melting point T1 of the protective layer 213 and the melting point T2 of the seal 22 satisfy: T1 - T2 ≥ 15°C. Controlling the difference between the melting point T1 of the protective layer 213 and the melting point T2 of the seal 22 at 15°C or more can effectively ensure that when the seal 22 is heated and melted, the protective layer 213 can still maintain its shape, effectively cover the active deformation layer 211 and the passive deformation layer 212, and does not affect the normal operation of the active deformation layer 211 and the passive deformation layer 212.

[0054] In some embodiments, the melting point T1 of the protective layer 213 is greater than the operating temperature T3 of the active deformation layer 211, and / or the melting point T1 of the protective layer 213 is greater than the operating temperature T4 of the passive deformation layer 212. Setting the melting point of the protective layer 213 to be greater than the operating temperature of the active deformation layer 211 and / or the passive deformation layer 212 enables the protective layer 213 to remain attached to the outer surfaces and interiors of the active deformation layer 211 and the passive deformation layer 212 during the process of thermal expansion and deformation of the active deformation layer 211 and the passive deformation layer 212, effectively covering and spacing the two, preventing the two from being directly exposed to the outside air, and reducing the stress concentration during deformation of the two. In some embodiments, the melting point T1 of the protective layer 213 and the operating temperature T3 of the active deformation layer 211 satisfy: T1 - T3 ≥ 10°C, and / or the melting point T1 of the protective layer 213 and the operating temperature T4 of the passive deformation layer 212 satisfy: T1 - T4 ≥ 10°C. Controlling the difference between the melting point T1 of the protective layer 213 and the operating temperature T3 of the active deformation layer 211 and / or the operating temperature T4 of the passive deformation layer 212 at 10°C or more can reduce the probability of the protective layer 213 melting and failing during the deformation of the active deformation layer 211 and the passive deformation layer 212.

[0055] The principles and methods for measuring the operating temperature T3 of the active deformation layer 211 or the operating temperature T4 of the passive deformation layer 212 are as follows:

[0056] [Measurement Principle] A bimetallic strip is composed of two metal layers with different coefficients of thermal expansion (a1 and a2, where a1 > a2) laminated together. When the temperature changes, the two metal layers expand to different extents, causing the bimetallic strip to bend towards the side with the lower coefficient of expansion. When the bimetallic strip is heated, the temperature at which the bimetallic strip begins to deform is the operating temperature.

[0057] [Measurement Method]

[0058] 1. Sample Fixation: Fix one end of the bimetallic strip, and leave the other end free or connect it to a contact / displacement sensor to ensure that the deformation is not hindered.

[0059] 2. Temperature Control Device: Use a thermostatic bath, temperature control box, or heating platform, equipped with a high-precision temperature sensor (such as PT100, thermocouple), and place it near the bimetallic strip after calibration.

[0060] 3. Action Detection System: (a) Electrical Contact Method: Connect a circuit (such as an LED or ammeter), and record the temperature when the bimetallic strip triggers the contact to open / close. (b) Displacement Measurement Method: Use a laser displacement meter or micrometer to monitor the deformation in real-time, and record the temperature when the preset value is reached.

[0061] 4. Heating and Recording: Heat at a slow and constant rate (such as 0.5 °C / min) to avoid thermal hysteresis; synchronously record the temperature and the change in deformation / electrical signal to capture the temperature at the moment of action.

[0062] 5. Repeatability Test: Conduct multiple heating and cooling cycles (3 - 5 times), calculate the average value and deviation of the operating temperature, and evaluate the stability.

[0063] 6. Error Control: Ensure uniform heating (such as oil bath or forced convection), calibrate the temperature sensor, control the ambient temperature fluctuation, and use a low heating rate to reduce the influence of hysteresis.

[0064] In some embodiments, please refer to Figure 5 and Figure 9 , along the thickness direction X of the first sidewall 12, the first sidewall 12 has a first surface 122 and a second surface 123. The first surface 122 defines a partial boundary of the receiving cavity 11, the second surface 123 faces away from the receiving cavity 11, and the first through hole 121 penetrates through the first surface 122 and the second surface 123. The pressure relief assembly 20 can be disposed on the first surface 122, that is, the pressure relief assembly 20 is located inside the receiving cavity 11, or the pressure relief assembly 20 can also be disposed on the second surface 123, that is, the pressure relief assembly 20 is located outside the receiving cavity 11.

[0065] As an example, such as Figure 5 and Figure 7As shown, the pressure relief component 20 is disposed within the receiving cavity 11. The seal 22 is respectively connected to the first surface 122 and the protective layer 213 on the surface of the active deformation layer 211. The active deformation layer 211 is closer to the first sidewall 12 than the passive deformation layer 212. The metal deformation member 21 is located within the receiving cavity 11. When the battery cell assembly 30 undergoes a thermal runaway, the edge regions of the active deformation layer 211 and the passive deformation layer 212 bend towards the battery cell assembly 30, and the region farther away from the center of the metal deformation member 21 has a greater amount of deformation, so that at least a part of the first through hole 121 is opened, and the gas within the receiving cavity 11 is discharged to the outside through the first through hole 121 to achieve pressure relief.

[0066] Or as Figure 8 As shown, the seal 22 is respectively connected to the first surface 122 and the protective layer 213 on the surface of the passive deformation layer 212. The passive deformation layer 212 is closer to the first sidewall 12 than the active deformation layer 211. The metal deformation member 21 is located within the receiving cavity 11. When the battery cell assembly 30 undergoes a thermal runaway, the central regions of the active deformation layer 211 and the passive deformation layer 212 bend towards the battery cell assembly 30, and the region closer to the center of the metal deformation member 21 has a greater amount of deformation, so that at least a part of the first through hole 121 is opened.

[0067] By disposing the pressure relief component 20 within the receiving cavity 11, during the normal use of the secondary battery 100, the probability of the pressure relief component 20 being damaged can be reduced. And when the secondary battery 100 undergoes a thermal runaway, since there is a spaced arrangement between the battery cell assembly 30 and the first sidewall 12 of the housing 10, the space of this part of the interval can be fully utilized to install the pressure relief component 20, without affecting the normal deformation and pressure relief of the metal deformation member 21.

[0068] As another example, as Figure 9 and Figure 10 As shown, the pressure relief component 20 is disposed outside the receiving cavity 11. The seal 22 is respectively connected to the second surface 123 and the protective layer 213 on the surface of the active deformation layer 211. The active deformation layer 211 is closer to the first sidewall 12 than the passive deformation layer 212. The metal deformation member 21 is located outside the receiving cavity 11. When the battery cell assembly 30 undergoes a thermal runaway, the edges of the active deformation layer 211 and the passive deformation layer 212 bend towards the side away from the battery cell assembly 30, and the region farther away from the center of the metal deformation member 21 has a greater amount of deformation, so that at least a part of the first through hole 121 is opened, and the gas within the receiving cavity 11 is discharged to the outside through the first through hole 121 to achieve pressure relief.

[0069] Or as Figure 11As shown, the seal 22 is respectively connected to the second surface 123 and the passive deformation layer 213. The passive deformation layer 212 is closer to the first side wall 12 than the active deformation layer 211, and the metal deformation member 21 is located outside the accommodation cavity 11. When the battery cell assembly 30 undergoes thermal runaway, the central regions of the active deformation layer 211 and the passive deformation layer 212 bend away from the battery cell assembly 30, and the region closer to the center of the metal deformation member 21 has a greater amount of deformation, so that at least a part of the first through hole 121 is opened.

[0070] The pressure relief component 20 is arranged outside the accommodation cavity 11, and it is easier to install and connect the pressure relief component 20 to the housing 10 on the outside of the housing 10. When the secondary battery 100 undergoes thermal runaway, since the metal deformation member 21 bends away from the accommodation cavity 11, which is consistent with the direction of the gas discharging outward from the accommodation cavity 11, the blocking of the metal deformation member 21 to the gas flow is reduced, and the pressure relief speed is increased. In addition, when the battery cell assembly 30 generates a large amount of gas and heat in a very short time, the metal deformation member 21 located outside the housing 10 can be directly flushed open by the pressure relief gas to completely open the first through hole 121, enabling timely and fastest pressure relief, and further reducing the probability of explosion and fire of the secondary battery 100.

[0071] In some embodiments, along the thickness direction X of the pressure relief component 20, the seal 22 can directly abut against the protective layer 213 on the surface of the active deformation layer 211, or the seal 22 can directly abut against the protective layer 213 on the surface of the passive deformation layer 212. In other embodiments, the seal 22 can be connected to the protective layer 213 on the surface of the active deformation layer 211 or the protective layer 213 on the surface of the passive deformation layer 212 through other components. For example, a composite layer that connects and fixes the protective layer 213 on the surface of the active deformation layer 211 and the seal 22 under normal working conditions. When the secondary battery 100 undergoes thermal runaway, the bonding performance of the composite layer decreases, which is beneficial to the thermal deformation of the active deformation layer 211.

[0072] In some embodiments, please refer to Figure 12 and Figure 13 The pressure relief component 20 further includes a connecting member 23, and the connecting member 23 is fixed to the first surface 122 or the second surface 123 of the first side wall 12. Taking the connecting member 23 being fixed to the second surface 123 of the first side wall 12 as an example, the connecting member 23 is provided with a second through hole 231, and the second through hole 231 communicates with the first through hole 121. The connecting member 23 has a sheet-like structure. One side surface of the connecting member 23 is connected to the second surface 123 of the housing 10, the other side surface of the connecting member 23 is connected to the seal 22, the connecting member 23 is connected to the protective layer 213 on the surface of the active deformation layer 211 through the seal 22, and the metal deformation member 21 covers the second through hole 231.

[0073] The seal 22 and the housing 10 are connected by adding a connecting member 23. On the one hand, it can reduce the probability of the seal 22 aging and failing, resulting in a decrease in the sealing performance at the first through hole 121. On the other hand, it can reduce the difficulty of installing and fixing the seal 22 and the housing 10. Specifically, since the volume of the housing 10 is much larger than the volumes of the seal 22 and the metal deformation member 21, due to the material of the seal 22, it is difficult to directly connect the seal 22 to the housing 10. By adding the connecting member 23 as an intermediate connecting body, the volume of the connecting member 23 can be comparable to the volume of the seal 22 and the volume of the metal deformation member 21, and the material of the connecting member 23 can be various, which increases the connection methods between the connecting member 23 and the housing 10 and reduces the installation difficulty. For example, during the installation process, the seal 22 is activated by high-temperature pressurization, so that the seal 22 is fixedly connected to the metal deformation member 21 and the connecting member 23 respectively to form a whole, and then the connecting member 23 is connected to the housing 10 in various ways such as hot pressing, glue bonding, welding, snap connection, and snap-fitting connection.

[0074] In some embodiments, the connecting member 23 is a metal ring, and the interior of the metal ring has a second through hole 231. The metal ring is connected to the first side wall 12 of the housing 10 by laser welding. Setting the connecting member 23 into a ring shape has several advantages. On the one hand, it is convenient for welding the connecting member 23 to the housing 10. On the other hand, it makes the force on the circumferential direction of the connecting member 23 uniform and reduces stress concentration. Moreover, the pressure relief hole can be made smaller by controlling the inner diameter of the ring. For example, if the inner diameter of the ring is smaller than the diameter of the first through hole 121, the pressure can be relieved through the inner diameter of the connecting member 23 at this time. The material of the connecting member 23 is preferably at least one of aluminum, nickel, stainless steel, etc., which is beneficial to welding the connecting member 23 to the housing 10 and reducing the probability of the connecting member 23 corroding and rusting. In other embodiments, the connecting member 23 can also be other shapes, such as rectangular, oval or irregular shapes, etc.

[0075] In some embodiments, such as Figure 14As shown, the outer diameter D2 of the connecting member 23 and the diameter D1 of the first through hole 121 satisfy: D2 > D1; and / or, the outer diameter D3 of the active deformation layer 211 and the outer diameter D2 of the connecting member 23 satisfy: D3 ≤ D2, and the outer diameter D3 of the active deformation layer 211 and the diameter D4 of the second through hole 231 of the connecting member 23 satisfy: D3 > D4. Setting the outer diameter of the connecting member 23 to be greater than the diameter of the first through hole 121 enables the connecting member 23 to be fixedly connected to the first side wall 12. Setting the outer diameter of the active deformation layer 211 to be less than or equal to the outer diameter of the connecting member 23 can reduce the difficulty of laser welding the connecting member 23 to the housing 10. Especially when the outer diameter of the active deformation layer 211 is less than the outer diameter of the connecting member 23, the connecting member 23 protrudes radially from the active deformation layer 211, and there can be a sufficient welding area to weld with the housing 10. Setting the outer diameter of the active deformation layer 211 to be greater than the diameter of the second through hole 231 can ensure that the active deformation layer 211 can completely cover the second through hole 231 to seal the second through hole 231 under normal working conditions.

[0076] In some embodiments, the diameter D1 of the first through hole 121 satisfies: 0.5 mm ≤ D1 ≤ 5.5 mm. The inventor found that for the currently mainstream-sized secondary battery 100, setting the diameter of the first through hole 121 between 0.5 millimeters and 5.5 millimeters can enable the exhaust rate of the first through hole 121 to be greater than or equal to the gas generation rate during thermal runaway of the battery cell assembly 30 when the secondary battery 100 undergoes thermal runaway, thereby meeting the requirement of pressure relief. And on the basis of ensuring that the exhaust rate of the first through hole 121 is greater than or equal to the gas generation rate during thermal runaway of the battery cell assembly 30, the smaller the diameter of the first through hole 121, the less water vapor, oxygen, etc. outside the secondary battery 100 enter the receiving cavity 11 through the first through hole 121, thereby reducing the side reaction rate of the battery cell assembly 30 caused by water vapor and oxygen, and reducing the risk of explosion and fire of the battery cell assembly 30. Based on the setting of the diameter of the first through hole 121, the outer diameter D2 of the connecting member 23 satisfies: 1 mm ≤ D2 ≤ 6 mm; and / or, the diameter D4 of the second through hole 231 satisfies: 0.1 mm ≤ D4 ≤ 4 mm; and / or, the outer diameter D3 of the active deformation layer 211 satisfies: 0.1 mm ≤ D3 ≤ 6 mm.

[0077] In some embodiments, please refer to Figure 12 , the battery cell assembly 30 is disposed in the receiving cavity 11. The battery cell assembly 30 has a head 31, and the head 31 is opposite to and spaced from the first side wall 12 of the housing 10 to have a spaced space 30a, where the head 31 of the battery cell assembly 30 is the end where the tab of the battery cell assembly 30 extends. The pole assembly 40 is disposed through the first side wall 12, and the pole assembly 40 is electrically connected to the head 31 of the battery cell assembly 30. More specifically, the pole assembly 40 is electrically connected to the tab in the battery cell assembly 30.

[0078] In the embodiment of the present application, both the pressure relief component 20 and the terminal component 40 are arranged on the first side wall 12 of the housing 10. On the one hand, the arrangement of the terminal component 40 enables the head 31 of the battery cell component 30 to be spaced from the first side wall 12. By arranging the pressure relief component 20 on the inner side of the first side wall 12, the interval space 30a between the battery cell component 30 and the first side wall 12 can be fully utilized, and the pressure relief component 20 arranged on the inner side of the first side wall 12 can sense the temperature inside the housing 10 in a timely manner and respond more promptly; or when the pressure relief component 20 is welded to the outer side of the first side wall 12, the interval space 30a can reduce the transfer of welding heat to the battery cell component 30 and reduce the negative impact of heat on the battery cell component 30. On the other hand, during the thermal runaway of the battery cell component 30, the released gas will accumulate in the interval space 30a between the battery cell component 30 and the first side wall 12, and arranging the pressure relief component 20 on the first side wall 12 is beneficial to the rapid pressure relief of the gas.

[0079] Certainly, in other embodiments, a first through hole 121 may be provided on other side walls of the housing 10 to arrange the pressure relief component 20 on other side walls of the housing 10, and the first through hole 121 is preferably arranged to communicate the outside with the space between the battery cell component 30 and the first side wall 12, which is beneficial to the pressure relief of the gas.

[0080] The present application also provides an embodiment of an electronic device. The electronic device includes a secondary battery for providing electrical energy. For the structure and function of the secondary battery, reference may be made to the above embodiments and will not be elaborated here.

[0081] An embodiment of the present application provides a secondary battery 100, which includes a housing 10 and a pressure relief component 20. The housing 10 is provided with a receiving cavity 11. The housing 10 includes a first side wall 12, and a through first through hole 121 is provided in the first side wall 12 along its thickness direction X. The pressure relief component 20 is disposed on the first side wall 12 and covers the first through hole 121. The pressure relief component 20 includes a metal deformation member 21 and a sealing member 22. The metal deformation member 21 includes an active deformation layer 211 and a passive deformation layer 212. A protective layer 213 is provided on the outer surface of the metal deformation member 21. The protective layer 213 isolates the active deformation layer 211 and the passive deformation layer 212 from the outside. The sealing member 22 connects the protective layer on the outer surface of the active deformation layer 211 and the first side wall 12; the coefficient of thermal expansion G1 of the active deformation layer 211 is greater than the coefficient of thermal expansion G2 of the passive deformation layer 212. In the secondary battery 100 of the embodiment of the present application, by providing the metal deformation member 21 as a pressure relief structure, the characteristic of metal expanding when heated is effectively utilized, the action response speed of the pressure relief component 20 can be increased to improve the pressure relief efficiency, and by covering the protective layer 213 on the outer surfaces of the active deformation layer 211 and the passive deformation layer 212, on the one hand, the protective layer 213 separates the active deformation layer 211 and the passive deformation layer 212 from the outside, thereby reducing the probability of electrochemical corrosion caused by direct contact between the active deformation layer 211 and the passive deformation layer 212 and water vapor, oxygen, etc. in the outside world. On the other hand, the protective layer 213 covers the active deformation layer 211 and the passive deformation layer 212, which helps to eliminate the stress concentration during bending deformation of the two, ensures the stable deformation performance and reset performance of the active deformation layer 211 and the passive deformation layer 212, and prolongs the service life of the active deformation layer 211 and the passive deformation layer 212.

[0082] The above are only the embodiments of the present application, and do not limit the patent scope of the present application accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied to other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. A secondary battery, characterized in that, Comprising: A housing having a receiving cavity, the housing including a first side wall, and the first side wall being provided with a first through hole along its thickness direction; A pressure relief component disposed on the first side wall and covering the first through hole, the pressure relief component including a metal deformation member and a sealing member, the metal deformation member including an active deformation layer and a passive deformation layer, a protective layer being provided on the outer surface of the metal deformation member, the sealing member connecting the protective layer and the first side wall, the active deformation layer being closer to the first side wall, or the passive deformation layer being closer to the first side wall; the coefficient of thermal expansion G1 of the active deformation layer is greater than the coefficient of thermal expansion G2 of the passive deformation layer.

2. The secondary battery according to claim 1, wherein Along the stacking direction of the active deformation layer and the passive deformation layer, the thickness H1 of the protective layer satisfies: 0.01 mm ≤ H1 ≤ 0.1 mm.

3. The secondary battery according to claim 1, wherein The protective layer includes a first layer and a second layer, the first layer being disposed on the outer surface after the active deformation layer and the passive deformation layer are stacked, along the thickness direction of the active deformation layer, the second layer is located between the active deformation layer and the passive deformation layer, and the second layer is connected to the first layer.

4. The secondary battery according to claim 3, wherein The protective layer and the sealing member are integrally formed.

5. The secondary battery according to claim 1, wherein The protective layer includes at least one of a galvanized layer, a nickel-plated layer, a chromium-plated layer, a copper-plated layer, an epoxy resin or a polyurethane or a polyester organic layer, a ceramic layer, a polytetrafluoroethylene layer, an anodized layer, and a phosphated layer.

6. The secondary battery according to claim 1, wherein The melting point T1 of the protective layer and the melting point T2 of the sealing member satisfy: T1 - T2 ≥ 15 °C.

7. The secondary battery according to claim 1, wherein The melting point T1 of the protective layer and the operating temperature T3 of the active deformation layer satisfy: T1 - T3 ≥ 10 °C, and / or The melting point T1 of the protective layer and the operating temperature T4 of the passive deformation layer satisfy: T1 - T4 ≥ 10 °C.

8. The secondary battery according to any one of claims 1-7, wherein Along the thickness direction of the first side wall, the first side wall has a first surface and a second surface, the first surface defining a partial boundary of the receiving cavity, the second surface facing away from the receiving cavity, and the first through hole penetrating through the first surface and the second surface; The metal deformation member is located inside the receiving cavity, and the sealing member is respectively connected to the protective layer on the surface of the first surface and the active deformation layer, or the sealing member is respectively connected to the protective layer on the surface of the first surface and the passive deformation layer; Or, The metal deformation member is located outside the receiving cavity, and the sealing member is respectively connected to the protective layer on the surface of the second surface and the active deformation layer, or the sealing member is respectively connected to the protective layer on the surface of the second surface and the passive deformation layer.

9. The secondary battery according to claim 8, wherein The pressure relief component includes a connecting member which is fixed to the first side wall and covers the first through hole. The connecting member is provided with a second through hole which is communicated with the first through hole. The sealing member is connected to the connecting member, and the metal deformation member covers the second through hole.

10. The secondary battery according to claim 9, wherein the connecting member is a metal ring, and the metal ring is welded to the first side wall.

11. The secondary battery according to claim 10, wherein the outer diameter D2 of the connecting member and the diameter D1 of the first through hole satisfy: D2 > D1; and / or, the outer diameter D3 of the active deformation layer and the outer diameter D2 of the connecting member satisfy: D3 ≤ D2, and the outer diameter D3 of the active deformation layer and the diameter D4 of the second through hole of the connecting member satisfy: D3 > D4.

12. The secondary battery according to claim 11, wherein the diameter D1 of the first through hole satisfies: 0.5 mm ≤ D1 ≤ 5.5 mm; and / or, the outer diameter D2 of the connecting member satisfies: 1 mm ≤ D2 ≤ 6 mm; and / or, the outer diameter D3 of the active deformation layer satisfies: 0.1 mm ≤ D3 ≤ 6 mm; and / or, the diameter D4 of the second through hole satisfies: 0.1 mm ≤ D4 ≤ 4 mm.

13. The secondary battery according to claim 1, wherein the material of the active deformation layer includes at least one of nickel-chromium-iron alloy, nickel, copper, copper-tin-zinc alloy, copper-zinc alloy or alloy steel; the material of the passive deformation layer includes at least one of nickel-iron alloy, invar alloy, nickel-chromium-iron or manganese-copper-nickel; the material of the connecting member includes at least one of aluminum, nickel, and stainless steel.

14. The secondary battery according to claim 1, wherein the secondary battery includes a battery cell assembly and a terminal assembly. The battery cell assembly is disposed in the receiving cavity. The battery cell assembly has a head which is opposite to and spaced from the first side wall. The terminal assembly penetrates through the first side wall, and the terminal assembly is electrically connected to the head of the battery cell assembly.

15. An electronic device, characterized in that, including the secondary battery according to any one of claims 1-14.

Images