Battery

Abstract

The invention provides a battery which comprises a shell, and a cavity is defined by the shell; the shell comprises a first side wall, and a pressure relief through hole communicated with the cavity is formed in the first side wall; the pressure relief mechanism covers the pressure relief through hole and comprises a first metal sheet, a second metal sheet and an insulating rubber layer arranged between the first metal sheet and the second metal sheet; one side of the first metal sheet is connected with the first side wall, the side, deviating from the shell, of the first metal sheet is bonded with an insulating glue layer, and the side, deviating from the first metal sheet, of the insulating glue layer is bonded with a second metal sheet; the roughness of the first metal sheet is C1 (C1 < = 1 [mu] m), and / or the roughness of the second metal sheet is C2 (C2 < = 0.8 [mu] m). The battery provided by the invention has sealing performance and also has good safety performance.

Description

Technical Field

[0001] The invention belongs to the technical field of batteries, and in particular relates to a battery. Background Art

[0002] With the rapid development of new energy technologies, lithium-ion batteries are widely used in various portable electronic devices (mobile phones, digital cameras, etc.) as well as electric vehicles and power tools.

[0003] However, with the rapid charging and continuous improvement of the capacity of lithium-ion batteries, the battery will continue to generate heat when it is in a high temperature state or a sudden short circuit occurs. Thermal failure of the battery cell can cause safety problems such as fire and explosion. Therefore, to prevent thermal runaway of the battery cell, higher requirements are placed on the safety performance of the battery cell.

[0004] At present, the steel shell battery cell is composed of a positive electrode assembly, a negative electrode assembly, an isolation membrane, an electrolyte, a shell assembly and a pressure relief mechanism. The steel shell and the pressure relief mechanism are laser welded to form a closed environment for the battery cell to isolate moisture and air. When the battery cell encounters a violent impact during use or is improperly used during charging and discharging, the battery cell temperature rises sharply, the electrolyte decomposes under high temperature, and the CEI / SEI further decomposes, causing the positive and negative electrode side reactions to intensify, generating high-temperature and high-pressure gases inside. If the above gases cannot be discharged in time, the battery cell may cause fires and explosions due to flatulence and other safety accidents.

[0005] Therefore, providing a battery that has both sealing performance and good safety performance has become a problem to be solved. Summary of the invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide a battery. The battery provided by the present invention has both sealing performance and good safety performance.

[0007] The present invention provides a battery, comprising a shell, the shell being arranged to form a cavity; the shell comprising a first side wall, the first side wall being provided with a pressure relief through hole communicating with the cavity;

[0008] A pressure relief mechanism covering the pressure relief through hole, the pressure relief mechanism comprising a first metal sheet, a second metal sheet, and an insulating adhesive layer disposed between the first metal sheet and the second metal sheet; one side of the first metal sheet is connected to the first side wall, a side of the first metal sheet facing away from the shell is bonded to the insulating adhesive layer, and a side of the insulating adhesive layer facing away from the first metal sheet is bonded to the second metal sheet;

[0009] The roughness of the first metal sheet is C1, C1≤1μm,

[0010] And / or, the roughness of the second metal sheet is C2, C2≤0.8 μm.

[0011] Preferably, the thickness H of the pressure relief mechanism is 0.2 mm ≤ H ≤ 0.35 mm;

[0012] and / or, the thickness H1 of the first metal sheet is 0.05 mm ≤ H1 ≤ 0.1 mm;

[0013] and / or, the thickness H2 of the second metal sheet is 0.05 mm ≤ H2 ≤ 0.2 mm;

[0014] And / or, the thickness of the insulating adhesive is 0.02-0.08 mm.

[0015] Preferably, the Rockwell hardness of the first metal sheet is R1, 120HV≤R1≤190HV,

[0016] and / or, the ratio of the Rockwell hardness of the second metal sheet to the Rockwell hardness of the first metal sheet is greater than 1 / 2;

[0017] and / or, the Rockwell hardness of the shell is 120-180 HV,

[0018] And / or, a ratio of the Rockwell hardness of the shell to the Rockwell hardness of the first metal sheet is between 3:2 and 2:3.

[0019] Preferably, the surface of the first metal sheet and / or the second metal sheet further includes Cr element.

[0020] Preferably, the compression deformation percentage of the pressure relief mechanism in the thickness direction is 5% to 40% under the condition of 100 to 200°C;

[0021] and / or, the compression deformation percentage of the pressure relief mechanism in the thickness direction is less than 1% under the condition of 40-80°C;

[0022] And / or, the thickness ratio of the insulating rubber layer to the overall pressure relief structure is between 1:2 and 1:10.

[0023] Preferably, the first metal sheet is provided with a first through hole, and the area S1 of the first through hole is 0.25 mm 2 ≤S1≤3.2mm 2 ;

[0024] And / or, the area of ​​the first through hole is smaller than the area of ​​the pressure relief through hole;

[0025] And / or, the ratio of the area of ​​the first through hole to the area of ​​the pressure relief through hole is between 1:4 and 1:1;

[0026] And / or, the area of ​​the second metal sheet is greater than the area of ​​the first through hole, and the second metal sheet covers the first through hole; the area of ​​the second metal sheet and the area of ​​the first through hole are between 1:1 and 1:10.

[0027] Preferably, the insulating adhesive layer is provided with a second through hole, and the width of the overflowing adhesive of the insulating adhesive layer on the surface of the first metal sheet is W1, and W1 is ≥ 0.01 mm;

[0028] The width W2 of the overflowed adhesive of the insulating adhesive layer on the surface of the second metal sheet is 0.01mm≤W2≤0.5mm.

[0029] Preferably, the thickness H3 of the insulating adhesive layer is 0.02mm≤H3≤0.08mm.

[0030] Preferably, the insulating rubber layer is a ring-shaped insulating rubber layer with an inner diameter of 0.2 to 1.4 mm and an outer diameter of 1.5 to 3 mm.

[0031] Preferably, the insulating adhesive layer is a single-layer adhesive film;

[0032] And / or, the melting point range of the insulating adhesive layer is 70-145°C.

[0033] Preferably, the insulating adhesive layer comprises a first melting peak and a second melting peak, the first melting peak is 90-110° C., and the second melting peak is 115-135° C.;

[0034] And / or, the insulating adhesive layer further includes a third melting peak, and the third melting peak is 75±5°C.

[0035] Preferably, the insulating adhesive layer comprises a first adhesive film, a second adhesive film and a third adhesive film which are stacked, the first adhesive film having a side facing away from the second adhesive film and a side facing away from the shell of the first metal sheet, and the third adhesive film having a side facing away from the second adhesive film and a side facing away from the second adhesive film and a second metal sheet;

[0036] The thickness of the first layer of adhesive film is 3 to 20 μm;

[0037] and / or, the thickness of the second adhesive film is 5 to 30 μm;

[0038] and / or, the thickness of the third layer of adhesive film is 3 to 20 μm;

[0039] and / or, the thickness ratio of the first layer of adhesive film, the second layer of adhesive film and the third layer of adhesive film is between 1:3:1 and 3:1:3;

[0040] And / or, the melting point range of the insulating adhesive layer is T1, 70°C ≤ T1 ≤ 170°C;

[0041] And / or, the melting point of the first layer of adhesive film is 70-130°C;

[0042] And / or, the melting point of the second layer of adhesive film is 130-170°C;

[0043] And / or, the melting point of the third layer of adhesive film is 70-130°C;

[0044] and / or, the melting point of the second layer of adhesive film is higher than the melting point of the first layer of adhesive film;

[0045] And / or, the melting point of the second adhesive film layer is higher than the melting point of the third adhesive film layer.

[0046] Preferably, the bonding force between the insulating adhesive layer and the first metal sheet and the second metal sheet is F, 0.2N / mm 2 ≤F≤20N / mm 2 .

[0047] Preferably, at a room temperature of 20 to 30° C., the bonding force between the insulating adhesive layer and the first metal sheet and the second metal sheet is F1,7 N / mm 2 ≤F1≤20N / mm 2 ,

[0048] And / or, at a temperature of 120-130° C., the bonding force between the insulating adhesive layer and the first metal sheet and the second metal sheet is F2, 0.2 N / mm 2 ≤F2≤2N / mm 2 .

[0049] Preferably, the material of the insulating adhesive layer is selected from at least one of polyethylene, polypropylene, polybutylene, polyvinyl chloride, polypropylene chloride, polychloroprene, polyacrylic acid, polybutene acid, polyacrylate and polyacrylonitrile.

[0050] Preferably, the first metal sheet has a chamfer on a plane close to the shell, the chamfer is arranged at the edge of the first through hole of the first metal sheet and the outer diameter edge of the first metal sheet, and the ratio of the chamfer size to the outer diameter of the first metal sheet is between 1:20 and 1:1;

[0051] Preferably, a chamfer is formed on a side of the second metal sheet facing away from the insulating adhesive layer, and the ratio of the chamfer size to the thickness of the second metal sheet is between 20:1 and 1:1;

[0052] The chamfer size is 0.01 to 0.05 mm.

[0053] Compared with the prior art, the present invention provides a battery, including a shell, the shell is arranged to form a cavity; the shell includes a first side wall, the first side wall is provided with a pressure relief through hole connected to the cavity; a pressure relief mechanism covering the pressure relief through hole, the pressure relief mechanism includes a first metal sheet, a second metal sheet and an insulating adhesive layer arranged between the first metal sheet and the second metal sheet; one side of the first metal sheet is connected to the first side wall, the side of the first metal sheet facing away from the shell is bonded to the insulating adhesive layer, and the side of the insulating adhesive layer facing away from the first metal sheet is bonded to the second metal sheet; the roughness of the first metal sheet is C1, C1≤1μm, and / or the roughness of the second metal sheet is C2, C2≤0.8μm. Among them, controlling the roughness of the first metal sheet C1≤1μm is conducive to the insulating adhesive layer and the first metal sheet having better bonding performance, which can ensure the high bonding strength between the insulating adhesive layer and the metal sheet at room temperature, and at the same time, at high temperature, the pressure of the battery cell inflation can timely break the adhesive film and the metal sheet to achieve pressure relief. By controlling the roughness C2 of the second metal sheet to ≤ 0.8 μm, the roughness can be further reduced and the high temperature sensitivity of the voltage can be improved, so that the battery cell can be more easily depressurized at high temperatures. The battery provided by the present invention has both sealing performance and good safety performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 A schematic diagram of a thermal compression test (TMA) of a pressure relief mechanism provided by the present invention; wherein 1 is a push rod, 2 is a pressure relief mechanism, and 3 is a base;

[0055] Figure 2 : are the bottom view and top view of the pressure relief mechanism; wherein W1 is the width of the overflowing glue, and W2 is the width of the overflowing glue;

[0056] Figure 3 A schematic diagram of the structure of the pressure relief mechanism provided by the present invention; wherein, 11-shell; 111-pressure relief through hole; 21-first metal sheet; 22-second metal sheet; 23-insulating glue; 211-first through hole; 231-second through hole. H is the thickness of the pressure relief mechanism, H1 is the thickness of the first metal sheet, H2 is the thickness of the second metal sheet, and H3 is the thickness of the insulating glue layer;

[0057] Figure 4 A pressure relief mechanism test mold provided by the present invention; wherein 31 is a push rod, 32 is an upper mold, 321 is a third through hole, 33 is a lower mold, and 331 is a fourth through hole;

[0058] Figure 5 A schematic diagram of the structure of the battery provided by the present invention; wherein, 1-shell; 2-pressure relief mechanism; 3-pressure relief through hole; 4-positive electrode assembly; 5-negative electrode assembly. DETAILED DESCRIPTION

[0059] The present invention provides a battery, comprising a shell, the shell being arranged to form a cavity; the shell comprising a first side wall, the first side wall being provided with a pressure relief through hole communicating with the cavity;

[0060] A pressure relief mechanism covering the pressure relief through hole, the pressure relief mechanism comprising a first metal sheet, a second metal sheet, and an insulating adhesive layer disposed between the first metal sheet and the second metal sheet; one side of the first metal sheet is connected to the first side wall, a side of the first metal sheet facing away from the shell is bonded to the insulating adhesive layer, and a side of the insulating adhesive layer facing away from the first metal sheet is bonded to the second metal sheet;

[0061] The roughness of the first metal sheet is C1, C1≤1μm,

[0062] And / or, the roughness of the second metal sheet is C2, C2≤0.8 μm.

[0063] The battery provided by the present invention includes a pressure relief mechanism, wherein the upper and lower layers of the pressure relief mechanism are metal and the middle layer is a rubber layer, which can ensure the sealing of the battery cell under normal use and can also enable the battery cell to achieve pressure relief at a specific temperature to avoid safety accidents such as fire and explosion caused by flatulence of the battery cell.

[0064] In the present invention, in order to ensure the adhesion between the insulating glue and the first metal sheet and the second metal sheet, the roughness C1 of the first metal sheet is controlled, C1≤1μm, and can be 0.1~1μm, and further, can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, or any value between 0.1 and 1μm. The roughness C2 of the second metal sheet, C2≤0.8μm, can be 0.1~0.8μm, and further, can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or any value between 0.1 and 0.8μm.

[0065] The roughness of the first metal sheet is C1, C1≤1μm, which is conducive to the good bonding performance of the insulating glue and the first metal sheet, which can ensure the high bonding strength between the insulating glue layer and the metal sheet at room temperature. At the same time, at high temperatures, the pressure of the battery cell inflation can timely break the glue film and the metal sheet to achieve pressure relief. The roughness of the second metal sheet is C2, C2≤0.8μm, which further reduces the roughness and improves the high temperature sensitivity of the voltage, making it easier for the battery cell to achieve pressure relief at high temperatures.

[0066] In the present invention, the thickness H of the pressure relief mechanism, 0.2 mm ≤ H ≤ 0.35 mm, can be 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, or any value between 0.2 and 0.35 mm. The thickness of the pressure relief structure is the thickness of the pressure relief mechanism in the direction of passing through the first metal sheet, the insulating rubber layer, and the second metal sheet in sequence.

[0067] The present invention controls the thickness of the pressure relief mechanism to be within 0.2 mm ≤ H ≤ 0.35 mm, and does not need to reserve a large space for the pressure relief component, thereby making full use of the space of the shell and improving the energy density.

[0068] The thickness H1 of the first metal sheet, 0.05mm≤H1≤0.1mm, can be 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, or any value between 0.05, 0.06, 0.07, 0.08, 0.09, 0.1; the thickness H2 of the second metal sheet, 0.05mm≤H2≤0.2mm, can be 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, or any value between 0.05 and 0.2mm.

[0069] The thickness of the insulating glue is 30-50 μm, 30, 35, 40, 45, 50, or any value between 30 and 50 μm.

[0070] The body temperature of the battery cell is the highest, and the heat is transferred to the insulating rubber layer through the first metal sheet. When the thickness of the first metal sheet is H1≤0.1mm, it is conducive to the heat transfer to the insulating rubber layer through the first metal sheet, so that the insulating rubber layer reaches a molten state, which is conducive to the pressure relief mechanism to achieve the pressure relief function and avoid safety problems such as explosion and fire of the battery cell. The first metal sheet should be ≤0.1mm. However, the first metal sheet and the second metal sheet are too thin, the strength is insufficient, and they are easily damaged in collisions, and the sealing is poor. Therefore, the thickness H1 of the first metal sheet should be controlled within 0.05mm≤H1≤0.1mm to ensure the strength of the metal sheet. Similarly, the thickness H2 of the second metal sheet should also be controlled within 0.05mm≤H2≤0.2mm. Within the above range, the first metal sheet and the second metal sheet have good strength while also helping to improve the sealing performance and reliability of the pressure relief mechanism.

[0071] In the present invention, the Rockwell hardness of the first metal sheet is R1, 120HV≤R1≤190HV, and can be 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, or any value between 120 and 190HV; the ratio of the Rockwell hardness of the second metal sheet to the Rockwell hardness of the first metal sheet is greater than 1 / 2, preferably 2 / 3 to 4 / 3, and can be 2 / 3, 3 / 3, 4 / 3, or any value between 2 / 3 and 4 / 3;

[0072] The shell of the battery is a steel shell, and the Rockwell hardness of the steel shell is 120-180 HV, which can be 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, or any value between 120 and 180 HV; the ratio of the Rockwell hardness of the steel shell to the Rockwell hardness of the first metal sheet is between 3:2 and 2:3, which can be 3:2, 3:2.5, 3:3, 2.5:3, 2:3, or any value between 3:2 and 2:3.

[0073] Among them, the first metal sheet needs to have sufficient hardness and thickness to ensure that it will not deform under pressure after furnace temperature inflation, and give full play to the effect of melting and relieving pressure of the insulating rubber layer. The hardness of the hard shell of the second metal sheet can ensure that the deformation of the battery core is small during high-temperature inflation. Insufficient hardness is easy to swell, deform, squeeze the stacked core and cause a short circuit. The hardness of the steel shell will affect the key indicators of the difficulty of material stamping and quality molding. If the hardness is too large, it is difficult to mold and the shell quality is poor. In use, high hardness reduces the ductility and plasticity of the material to a certain extent, but it also improves the corrosion resistance and wear durability of the material. When the hardness of the steel shell meets 120~180HV, it can not only meet the quality requirements of the shell in daily use of the battery cell, have good corrosion resistance and wear resistance, but also reduce the manufacturing cost and molding difficulty of the steel shell.

[0074] In the present invention, the material of the first metal sheet and the second metal sheet can be one or more of nickel, nickel alloy and stainless steel.

[0075] In the present invention, the surfaces of the first metal sheet and the second metal sheet further include Cr element. In some specific embodiments of the present invention, a first film layer is disposed on the surface of the first metal sheet; a second film layer is disposed on the surface of the second metal sheet. The first film layer and / or the second film layer include Cr element.

[0076] Among them, the Cr element reacts with the hydrogen ions on the surface of the insulating glue to improve the bonding strength and ensure the reliability of the pressure relief mechanism. However, if the Cr content on the metal surface is too high and the bonding is too strong, the pressure relief mechanism will not open in time at high temperatures.

[0077] In the present invention, the mass proportion of Cr element in the first film layer and the second film layer is controlled to be less than 1%, and can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or any value between <1%; preferably 0.1% to 0.5%. In the present invention, when the mass proportion of Cr element in the first film layer and the second film layer is controlled to be in the range of 0.1% to 0.5%, it can ensure the high bonding strength between the insulating adhesive layer and the metal sheet at room temperature, and at the same time, at high temperature, the pressure of the battery cell inflation can timely break the adhesive film and the metal sheet to achieve pressure relief.

[0078] In the present invention, the first film layer and / or the second film layer also includes C element and O element, and the mass ratio of C element to O element is between 1:1 and 10:1, and can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, or any value between 1:1 and 10:1.

[0079] In the present invention, a force of 0.1N is used to compress the pressure relief mechanism, and the compression deformation of the pressure relief mechanism under different temperature conditions is controlled, so that the pressure relief mechanism can open at a specific temperature and release pressure in time to avoid safety accidents such as fire and explosion caused by inflation of the battery cell.

[0080] For specific test methods, see Figure 1 , Figure 1 A schematic diagram of a thermal compression test (TMA) of the pressure relief mechanism provided by the present invention. 1 is a push rod, 2 is a pressure relief mechanism, and 3 is a base. The test mechanism is arranged in a heating chamber, and when conducting a test, the pressure relief mechanism is placed on the surface of the base, wherein the first metal sheet is placed on the bottom layer and in contact with the base, and the second metal sheet is on the top layer, away from the base. A vertical force of 0.1N is applied to the pressure relief mechanism by the push rod, and the direction of the force is from the second metal sheet to the vertical direction of the first metal sheet. As the temperature in the heating chamber continues to rise, the temperature is heat-conducted to the insulating glue, the insulating glue layer begins to melt, and overflows to the surroundings under the action of the force, and the thickness of the pressure relief mechanism is reduced.

[0081] Specifically, when the temperature reaches 100-200°C, the compression deformation percentage can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, or any value between 5% and 40%. Furthermore, when the pressure relief mechanism is at 40-80°C, the compression deformation percentage in the thickness direction is <1%, which can be 0.01%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 0.99%. By controlling the compression deformation percentage of the pressure relief mechanism under different temperature conditions, it is possible to achieve pressure relief when the battery cell is inflated at high temperature, while ensuring the sealing of the battery cell in normal use.

[0082] In some specific embodiments of the present invention, when the temperature reaches 160°C, the compression deformation percentage of the pressure relief mechanism is 5% to 35%, which can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, or any value between 5% and 40%. At 80°C, the compression deformation percentage of the pressure relief mechanism is 0.01% to 0.5%, which can be 0.01%, 0.03%, 0.05%, 0.07%, 0.09%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, or any value between 0.01% and 0.5%.

[0083] In the present invention, the compression deformation percentage of the pressure relief mechanism in the thickness direction is calculated according to the formula shown in Formula I:

[0084] Compression deformation percentage = (m0-m x ) / m0*100% Formula I;

[0085] In formula I, m0 is the thickness of the pressure relief mechanism at an initial room temperature of 25±5°C;

[0086] m X The heating chamber is heated at 10°C / min according to a set program, and the thickness of the pressure relief mechanism is recorded as the temperature changes.

[0087] Moreover, the thickness ratio of the insulating rubber layer to the pressure relief mechanism as a whole is between 1:2 and 1:10, which can ensure the ability of the insulating layer to melt and relieve pressure, while ensuring the adhesion of the insulating rubber layer, so that the pressure relief mechanism has better strength, which is conducive to improving the sealing performance, and can also make the space occupied by the pressure relief mechanism as small as possible, so that the structure of the battery cell with the shell is smaller. Preferably, the thickness ratio of the insulating rubber layer to the pressure relief mechanism as a whole can be 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, or any value between 1:2 and 1:10.

[0088] Therefore, the present invention controls the ratio of the insulating rubber layer to the overall thickness of the pressure relief mechanism and controls the parameters of the thermal compression test so that the obtained pressure relief mechanism can have both sealing performance and safety performance after being applied to the steel shell battery.

[0089] In the present invention, the first metal sheet is provided with a first through hole, and the area S1 of the first through hole is 0.25 mm 2 ≤S1≤3.2mm 2 , can be 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 2.75, 3, 3.2, or 0.25-3.2 mm 2 any value between; in some specific embodiments of the present invention, the first metal sheet is a ring-shaped metal sheet.

[0090] When the battery core is at high temperature, the insulating rubber layer will melt and soften, and the volatilization of the electrolyte will generate pressure on the pressure relief mechanism. When the area of ​​the pressure relief hole is S1≤3.2mm 2 The pressure acting on the pressure relief mechanism can separate the insulating rubber layer and the first metal sheet, which can relieve pressure and prevent the battery core from catching fire and exploding. The area of ​​the pressure relief hole also affects the pressure relief speed. When 0.25mm 2 ≤S1, the gas can be released in time.

[0091] Furthermore, the area of ​​the first through hole is less than or equal to the area of ​​the pressure relief through hole, and the ratio of the area of ​​the first through hole to the area of ​​the pressure relief through hole is between 1:4 and 1:1, and can be 1:4, 1:3, 1:2, 1:1, or any value between 1:4 and 1:1.

[0092] The area of ​​the second metal sheet is greater than or equal to the area of ​​the first through hole and completely covers the first through hole. The ratio of the area of ​​the second metal sheet to the area of ​​the first through hole is between 1:1 and 1:10, and can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, or any ratio between 1:1 and 1:10.

[0093] In the present invention, the insulating adhesive layer is provided with a second through hole, and the width W1 of the overflow adhesive of the insulating adhesive layer on the surface of the first metal sheet is calculated from the edge exceeding the second metal sheet to the outer edge of the insulating adhesive, and W1 ≥ 0.01 mm;

[0094] The width W2 of the overflowed adhesive of the insulating adhesive layer on the surface of the second metal sheet is calculated from the edge of the first through hole to the inner edge of the second through hole of the insulating adhesive layer, and 0.01mm≤W2≤0.5mm.

[0095] In some specific embodiments of the present invention, the insulating adhesive layer is a ring-shaped insulating adhesive layer, the first metal sheet and the second metal sheet are bonded by the insulating adhesive layer, and the insulating adhesive layer is naturally cast outward on the surface of the first metal sheet, and the casting width is the width W1 of the overflowing adhesive, W1 ≥ 0.01mm, preferably 0.02-0.2mm, and can be 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, or any value between 0.02 and 0.2 mm; the insulating glue is naturally cast inward on the surface of the second metal sheet, and the casting width, that is, the width W2 of the overflow glue, 0.01mm≤W2≤0.5mm, can be 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, or any value between 0.01 and 0.5 mm.

[0096] See also Figure 2 , Figure 2 These are top and bottom views of the pressure relief mechanism. Figure 2 In the figure, W1 is the width of the overflowing glue, and W2 is the width of the overflowing glue.

[0097] During the manufacturing process of the pressure relief mechanism, the insulating glue will extend outward or inward along the metal sheet when it is heated and melted, forming a glue overflow area. The glue overflow area helps to improve the bonding ability of the insulating glue and the metal sheet and avoid poor bonding between the metal sheet and the insulating glue. Therefore, it is necessary to control the width of the overflow glue W1≥0.01mm; 0.01mm≤W2≤0.5mm. That is, the sealing function of the pressure relief mechanism can be guaranteed to prevent water vapor from entering the battery cell. At the same time, the pressure relief path of the insulating layer will not be too long, resulting in a reduced sensitivity of the pressure relief mechanism. By setting the diameter of the second metal sheet to be larger than the diameter of the first through hole, the first metal sheet can completely cover the first through hole, so that the sealing effect is better. The reduction in the bonding area can further shorten the length of the pressure relief path of the battery cell during thermal runaway, and the sensitivity of the pressure relief of the battery cell is higher.

[0098] In the present invention, the thickness H3 of the insulating rubber layer, 0.02mm≤H3≤0.08mm, can be 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, or any value between 0.02 and 0.08mm. The thicker the thickness of the insulating rubber layer, the more sensitive the pressure relief mechanism is to temperature. When the thickness H3≤0.02mm, it is difficult to achieve pressure relief before the battery cell fails. When the thickness is ≥0.08mm, the total thickness of the pressure relief mechanism will increase, the space occupied by the pressure relief mechanism will increase, and the structure of the battery cell with the shell will become larger.

[0099] The insulating rubber layer is a circular insulating rubber layer with an inner diameter of 0.2 to 1.4 mm, which can be 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, or any value between 0.2 and 1.4 mm, and an outer diameter of 1.5 to 3 mm, which can be 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, or any value between 1.5 and 3 mm.

[0100] The material of the insulating adhesive layer includes one or more of polyethylene, polypropylene, polybutylene, polyvinyl chloride, polypropylene chloride, polychloroprene, polyacrylic acid, polybutene acid, polyacrylate, and polyacrylonitrile.

[0101] The above materials not only have good resistance to electrolyte corrosion, which is beneficial to the reliability of the pressure relief mechanism under long-term use, but also have good ability to isolate water vapor, so that the pressure relief mechanism can achieve a sealing function; whether used alone or in combination, the insulating glue can form a molten state before reaching the thermal runaway temperature of the battery cell, thereby ensuring its pressure relief function.

[0102] See also Figure 3 , Figure 3 This is a structural schematic diagram of the pressure relief mechanism provided by the present invention. Figure 3 In the figure, 11 is the housing; 111 is the pressure relief hole; 21 is the first metal sheet; 22 is the second metal sheet; 23 is the insulating glue; 211 is the first hole; 231 is the second hole. H is the thickness of the pressure relief mechanism, H1 is the thickness of the first metal sheet, H2 is the thickness of the second metal sheet, and H3 is the thickness of the insulating glue layer.

[0103] In the present invention, the insulating adhesive layer is a single-layer adhesive film or a three-layer adhesive film.

[0104] Specifically, when the insulating adhesive layer is a single-layer adhesive film, the melting point of the insulating adhesive layer is 70-145°C.

[0105] In some specific embodiments of the present invention, the insulating adhesive layer comprises a first melting peak and a second melting peak, the first melting peak is 90-110°C, and the second melting peak is 115-135°C.

[0106] And / or, the insulating adhesive layer further includes a third melting peak, and the third melting peak is 75±5°C.

[0107] Preferably, the present invention controls the melting point of the single-layer film to not exceed 135°C, which can ensure that the single-layer film has melted and opened before the battery core reaches the temperature of thermal runaway, and the pressure relief mechanism can play a role in pressure relief, avoiding fire and explosion of the battery core. In addition, the low-melting point particles present in the single-layer film, and the lower melting point particles are modified propylene polymers with a melting point of 90 to 110°C. The lower melting point particles can make the temperature sensitivity of the pressure relief mechanism better, achieve pressure relief at a lower temperature, reduce the risk of safety problems such as explosion and fire in the battery core, and thus improve the safety performance of the battery core.

[0108] When the insulating film is a three-layer film, the insulating film contains one or more modified polymers of polypropylene and polybutylene, preferably polybutylene and its modified polymers having a lower melting point.

[0109] Specifically, the insulating adhesive layer includes a first adhesive film, a second adhesive film and a third adhesive film which are stacked, wherein the side of the first adhesive film facing away from the second adhesive film is bonded to the side of the first metal sheet facing away from the shell, and the side of the third adhesive film facing away from the second adhesive film is bonded to the second metal sheet.

[0110] The thickness of the first adhesive film is 3 to 20 μm, and can be 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or any value between 3 and 20 μm;

[0111] The thickness of the second layer of adhesive film is 5 to 30 μm, and can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, or any value between 3 and 20 μm;

[0112] The thickness of the third layer of adhesive film is 3 to 20 μm, and can be 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or any value between 3 and 20 μm.

[0113] The thickness ratio of the first layer of adhesive film, the second layer of adhesive film and the third layer of adhesive film is between 1:3:1 and 3:1:3, and can be 1:3:1, 2:3:2, 3:3:3, 3:2:3, 3:1:3, or any value between 1:3:1 and 3:1:3;

[0114] The melting point range of the insulating adhesive layer is T1, 70°C≤T1≤170°C.

[0115] In some specific embodiments of the present invention, the melting point of the first layer of adhesive film is 70-130°C, the melting point of the second layer of adhesive film is 130-170°C, and the melting point of the third layer of adhesive film is 70-130°C.

[0116] Specifically, the melting point of the first and third adhesive films is 70-130°C, preferably 75-100°C. The further lowering of the adhesive film melting point can achieve melting of the pressure relief mechanism at a lower temperature, play a role in pressure relief, and further improve the furnace temperature safety performance. In addition, the melting point of the first and third adhesive films is not less than 75°C, which can ensure that the insulating adhesive will not melt and cause water vapor to enter the battery cell under normal use, thereby ensuring the sealing of the pressure relief mechanism.

[0117] The melting point of the second layer of adhesive film is 130-170°C, the melting point of the second layer of adhesive film is higher than the melting point of the first layer of adhesive or the third layer of adhesive, and the melting point temperature of the third layer is equivalent to the melting point of the first layer of adhesive.

[0118] Compared with a single-layer adhesive film, a three-layer adhesive film adds a high-melting-point skeleton layer on the basis of a single-layer insulating adhesive. The skeleton layer is located between the single-layer insulating adhesives. The skeleton layer has a high melting point and good impact resistance, which can improve the reliability and sealing of the pressure relief mechanism.

[0119] In the present invention, the bonding force between the insulating adhesive layer and the first metal sheet and the second metal sheet is F, 0.2N / mm 2 ≤F≤20N / mm 2 .

[0120] Furthermore, the bonding force F is divided into a room temperature bonding force F1 and a thermal bonding force F2. When the pressure relief mechanism is at a room temperature of 20 to 30°C, the room temperature bonding force is 7 N / mm 2 ≤F1≤20N / mm 2 When the pressure relief mechanism is at a temperature of 120-130°C, its thermal bonding force F2 is 0.2N / mm 2 ≤F2≤1.5N / mm 2 .

[0121] Among them, the room temperature bonding force is controlled at 7N / mm 2 ~20N / mm 2 , can be 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or 7N / mm 2 ~20N / mm 2 When the pressure relief mechanism is at a temperature of 120-130°C, its thermal bonding force F2 is controlled at 0.2N / mm 2 ≤F≤1.5N / mm 2, can be 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, or 0.2 N / mm 2 ~1.5N / mm 2 Any value in between.

[0122] Through the dual control of room temperature bonding force and thermal bonding force, it is possible to ensure the sealing and reliability of the pressure relief mechanism at room temperature. When encountering impact, the insulating rubber layer will not peel off from the metal sheet and lose the sealing function. It can also ensure that when the insulating rubber layer melts and softens at high temperature, the air pressure in the shell can easily separate the insulating rubber layer and the metal sheet to achieve the pressure relief function.

[0123] In the present invention, the bonding force of the pressure relief structure is tested according to the following method:

[0124] Place the pressure relief mechanism on the test mold, and use the push rod to pass through the third through hole on the mold, the first through hole on the first metal sheet, and the second through hole on the insulating rubber layer in sequence, and push the second metal sheet to separate the first metal sheet, the insulating rubber layer, and the second metal sheet.

[0125] The maximum force during the above process at room temperature is the room temperature bonding force F1.

[0126] The mold and the pressure relief mechanism are heated to 120-130° C., and the maximum force during the above process is the thermal bonding force F2.

[0127] See also Figure 4 , Figure 4 The pressure relief mechanism test mold provided by the present invention is divided into an upper mold and a lower mold. Figure 4 In the figure, 31-push rod, 32-upper mold, 321-third through hole, 33-lower mold, 331-fourth through hole.

[0128] Specifically, the upper mold has a third through hole, the third through hole can accommodate the push rod, and the diameter of the push rod is smaller than the diameter of the second through hole of the insulating rubber layer. The lower mold has a fourth through hole, the diameter of the fourth through hole is larger than the diameter of the second metal sheet and smaller than the diameter of the first metal sheet. When testing, the first metal sheet is in a fixed state.

[0129] In the present invention, a chamfer may be present on the plane of the first metal sheet close to the shell, and the chamfer exists at the edge of the first through hole of the first metal sheet and the outer diameter edge of the first metal sheet. The ratio of the chamfer size to the outer diameter of the first metal sheet is between 1:20 and 1:1, and can be 1:20, 1:19, 1:18, 1:17, 1:16, 1:15, 1:14, 1:13, 1:12, 1:11, 1:10, 1:9, 1:8, 1:7, 1:6, 1:5, 1:4, 1:3, 1:2, 1:1, or any value between 1:20 and 1:1.

[0130] Preferably, there is a chamfer on the side of the second metal sheet facing away from the insulating rubber layer, and the ratio of the chamfer size to the thickness of the second metal sheet is between 20:1 and 1:1, and can be 20:1, 19:1, 18:1, 17:1, 16:1, 15:1, 14:1, 13:1, 12:1, 11:1, 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1, 1:1, or any value between 20:1 and 1:1.

[0131] The size of the chamfer is 0.01 to 0.05 mm, and can be 0.01, 0.02, 0.03, 0.04, 0.05, or any value between 0.01 and 0.05 mm.

[0132] Chamfering determines the machinability of the metal sheet. If the mold for making the metal sheet is not chamfered, it will be difficult to punch. The chamfering of the first metal sheet and the second metal sheet can not only reduce the difficulty of making the metal sheet, but also facilitate the welding of the pressure relief structure and the shell, making the connection method simple and convenient. Through the chamfering design, the manufacturing cost of the pressure relief assembly is lower.

[0133] In the present invention, the battery further comprises a shell, a shell cover, an electrode assembly and an electrolyte, the shell is arranged to form a cavity, and the accommodating space is used to accommodate the electrode assembly and the electrolyte.

[0134] In some specific embodiments of the present invention, the shell includes a shell bottom, a plurality of side walls surrounding the shell bottom, and a shell cover, and the shell bottom is square, L-shaped or other special-shaped structures; preferably, the shell is a steel shell.

[0135] Preferably, the shell includes a first side wall, the pressure relief through hole is arranged on the first side wall and is connected to the cavity, the pressure relief mechanism covers the pressure relief through hole, and the pressure relief through hole is used to inject electrolyte into the shell during the battery cell manufacturing process. The present invention adopts a pressure relief mechanism to cover the pressure relief through hole, and the pressure relief mechanism can be used to replace the sealing plate. The pressure relief through hole realizes the pressure relief function, and there is no need to reserve space for the pressure relief component. The space of the shell can be fully utilized to improve the energy density.

[0136] One side of the first metal sheet of the pressure relief mechanism is connected to the first side wall of the shell, the side of the first metal sheet facing away from the shell is connected to the insulating rubber layer, and the side of the insulating rubber layer facing away from the first metal sheet is connected to the second metal sheet.

[0137] The electrode assembly is arranged in the shell. The electrode assembly includes a stacked positive electrode sheet, a separator, and a negative electrode sheet; the pressure relief through hole of the battery provided by the present invention and the electrode column hole of the positive electrode column and the negative electrode assembly are located on the same side outer wall of the shell.

[0138] See also Figure 5 , Figure 5 This is a schematic structural diagram of a battery provided by the present invention. Figure 5 In the figure, 1-shell; 2-pressure relief mechanism; 3-pressure relief through hole; 4-electrode positive electrode assembly; 5-electrode negative electrode assembly.

[0139] The upper and lower layers of the pressure relief mechanism provided by the present invention are metal and the middle layer is a rubber layer, which can ensure the sealing of the battery cell under normal use and can also enable the battery cell to achieve pressure relief at a specific temperature to avoid safety accidents such as fire and explosion caused by inflation of the battery cell.

[0140] In order to further understand the present invention, the battery provided by the present invention is described below in conjunction with embodiments, and the protection scope of the present invention is not limited by the following embodiments.

[0141] Preparation of the pressure relief mechanism used in Example 1

[0142] The first metal sheet, the insulating glue, and the second metal sheet are hot-pressed and bonded in sequence to obtain a pressure relief mechanism, and then the pressure relief mechanism is welded to the steel shell with a diameter of 2.27 mm. 2 The battery cell is made at the pressure relief hole, and the Rockwell hardness of the steel shell is 140HV.

[0143] The obtained pressure relief mechanism comprises a first metal sheet, a second metal sheet and an insulating adhesive layer having adhesiveness;

[0144] Wherein, the first metal sheet and the second metal sheet are nickel sheets;

[0145] The first metal sheet is a circular metal sheet with an inner diameter of 1 mm, an outer diameter of 3.4 mm, and a thickness of 0.08 mm. The area of ​​the first through hole is 0.785 mm. 2 The Rockwell hardness of the first metal sheet is 140 HV and the roughness is 0.08 μm; the surface of the first metal sheet has a passivation layer, the passivation layer includes a Cr element, the content of the Cr element is 0.1% to 0.2%, the passivation layer also includes a C element and an O element, and the mass ratio of the C element to the O element is (6±1):1; one side of the first metal sheet is welded to the steel shell, and the side away from the shell is bonded to the insulating adhesive layer.

[0146] The second metal sheet is a non-porous circular metal sheet with a diameter of 2.5 mm and a thickness of 0.15 mm, and the Rockwell hardness of the second metal sheet is 140 HV and the roughness is 0.06 μm; the surface of the first metal sheet has a passivation layer, the passivation layer includes a Cr element, the content of the Cr element is 0.1% to 0.2%, and the passivation layer also includes a C element and an O element, and the mass ratio of the C element to the O element is (6±1):1;

[0147] The insulating rubber layer is a circular insulating rubber layer with a thickness of 0.04 mm, an inner diameter of 0.5 mm and an outer diameter of 2.2 mm.

[0148] The width of the overflowing glue of the insulating glue layer on the surface of the first metal sheet is 0.02 to 0.2 mm, and the width of the overflowing glue of the insulating glue layer on the surface of the second metal sheet is 0.2 to 0.3 mm;

[0149] The structure of the insulating rubber layer is a single-layer structure with a melting point of 100±5℃, 125±5℃; the main material is polypropylene.

[0150] The thermal compression deformation of the pressure relief mechanism at 160°C is 8%±1%, and the thermal compression deformation at 80°C is 0.02%±0.01%; the thickness ratio of the insulating rubber layer to the entire pressure relief mechanism is 0.04:(0.04+0.08+0.15)=1:6.75.

[0151] The room temperature bonding strength of the insulating adhesive layer is 15N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.09N / mm 2 .

[0152] Preparation of the pressure relief mechanism used in Example 2

[0153] On the basis of Example 1, the roughness of the first metal sheet is changed to 0.8 μm and the roughness of the second metal sheet is changed to 0.8 μm.

[0154] The room temperature bonding strength of the insulating adhesive layer is 10.92N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 0.88N / mm 2 .

[0155] Other conditions remain unchanged.

[0156] Preparation of the pressure relief mechanism used in Example 3

[0157] On the basis of Example 1, the content of Cr element in the surface passivation layer of the first metal sheet and the second metal sheet is changed to 0.4% to 0.5%;

[0158] The room temperature bonding strength of the insulating adhesive layer is 16.74N / mm 2The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.11N / mm 2 .

[0159] Other conditions remain unchanged.

[0160] Preparation of the pressure relief mechanism used in Example 4

[0161] On the basis of Example 1, the content of Cr element in the surface passivation layer of the first metal sheet and the second metal sheet is changed to 0.9%;

[0162] The room temperature bonding strength of the insulating adhesive layer is 17.14N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.45N / mm 2 .

[0163] Other conditions remain unchanged.

[0164] Preparation of the pressure relief mechanism used in Example 5

[0165] On the basis of Example 1, the thickness of the insulating rubber layer is changed to 0.03 mm, and the thickness ratio of the insulating rubber layer to the pressure relief mechanism as a whole is 0.03:(0.03+0.08+0.15)=1:8.66;

[0166] The thermal compression deformation of the pressure relief mechanism at 160°C is 5.5%±0.5%, and the thermal compression deformation at 80°C is 0.02%±0.01%.

[0167] The room temperature bonding strength of the insulating adhesive layer is 16.22N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.19N / mm 2 .

[0168] Other conditions remain unchanged.

[0169] Preparation of the pressure relief mechanism used in Example 6

[0170] On the basis of Example 1, the thickness of the insulating rubber layer is changed to 0.07 mm, and the thickness ratio of the insulating rubber layer to the pressure relief mechanism as a whole is 0.07:(0.07+0.08+0.15)=1:4.28;

[0171] The thermal compression deformation of the pressure relief mechanism at 160°C is 13%±1%, and the thermal compression deformation at 80°C is 0.02%±0.01%.

[0172] The room temperature bonding strength of the insulating adhesive layer is 9.7N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 0.72N / mm 2 .

[0173] Other conditions remain unchanged.

[0174] Preparation of the pressure relief mechanism used in Example 7

[0175] On the basis of Example 1, the thickness of the insulating rubber layer is changed to 0.07 mm, the thickness of the second metal sheet is changed to 0.08 mm, and the thickness ratio of the insulating rubber layer to the pressure relief mechanism as a whole is 0.07:(0.07+0.08+0.08)=1:3.28;

[0176] The thermal compression deformation of the pressure relief mechanism at 160°C is 18%±1%, and the thermal compression deformation at 80°C is 0.02%±0.01%.

[0177] The room temperature bonding strength of the insulating adhesive layer is 8.49N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 0.69N / mm 2 .

[0178] Other conditions remain unchanged.

[0179] Preparation of the pressure relief mechanism used in Example 8

[0180] On the basis of Example 1, the melting point of the insulating adhesive layer is changed to 106±5°C, 120±5°C;

[0181] The thermal compression deformation of the pressure relief mechanism at 160°C is 14.5%±0.5%, and the thermal compression deformation at 80°C is 0.04%±0.01%.

[0182] The room temperature bonding strength of the insulating adhesive layer is 14.5N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 0.74N / mm 2 .

[0183] Other conditions remain unchanged.

[0184] Preparation of the pressure relief mechanism used in Example 9

[0185] On the basis of Example 1, the melting point of the insulating adhesive layer is changed to 110±5°C, 120±5°C;

[0186] The thickness of the insulating rubber layer is changed to 0.07 mm, the thickness of the second metal sheet is changed to 0.08 mm, and the thickness ratio of the insulating rubber layer to the pressure relief mechanism is 0.07:(0.07+0.08+0.08)=1:3.28;

[0187] The thermal compression deformation of the pressure relief mechanism at 160°C is 29.5%±0.5%, and the thermal compression deformation at 80°C is 0.02%±0.01%.

[0188] The room temperature bonding strength of the insulating adhesive layer is 8.49N / mm 2The thermal bonding strength of the insulating adhesive layer at 120-130°C is 0.71N / mm 2 .

[0189] Other conditions remain unchanged.

[0190] Preparation of the pressure relief mechanism used in Example 10

[0191] On the basis of Example 1, the melting point of the insulating adhesive layer is changed to 110±5°C, 125±5°C;

[0192] The thermal compression deformation of the pressure relief mechanism at 160°C is 14.5%±0.5%, and the thermal compression deformation at 80°C is 0.02%±0.01%.

[0193] The room temperature bonding strength of the insulating adhesive layer is 10.67N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 0.63N / mm 2 .

[0194] Other conditions remain unchanged.

[0195] Preparation of the pressure relief mechanism used in Example 11

[0196] On the basis of Example 1, the melting point of the insulating adhesive layer is changed to 75±5°C, 110±5°C, 125±5°C;

[0197] The thermal compression deformation of the pressure relief mechanism at 160°C is 14.5%±0.5%, and the thermal compression deformation at 80°C is 0.4%±0.1%.

[0198] The room temperature bonding strength of the insulating adhesive layer is 7.28N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 0.4N / mm 2 .

[0199] Other conditions remain unchanged.

[0200] Preparation of the pressure relief mechanism used in Example 12

[0201] On the basis of Example 1, the Rockwell hardness of the first metal sheet is changed to 128 HV, and the Rockwell hardness of the second metal sheet is changed to 128 HV.

[0202] The room temperature bonding strength of the insulating adhesive layer is 13.5N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.08N / mm 2 .

[0203] Other conditions remain unchanged.

[0204] Preparation of the pressure relief mechanism used in Example 13

[0205] On the basis of Example 1, the Rockwell hardness of the first metal sheet is changed to 128 HV, and the Rockwell hardness of the second metal sheet is changed to 175 HV. The Rockwell hardness of the second metal sheet / the Rockwell hardness of the first metal sheet=1.36.

[0206] The room temperature bonding strength of the insulating adhesive layer is 14.4N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.1N / mm 2 .

[0207] Other conditions remain unchanged.

[0208] Preparation of the pressure relief mechanism used in Example 14

[0209] On the basis of Example 1, the Rockwell hardness of the first metal sheet is changed to 175 HV, and the Rockwell hardness of the second metal sheet is changed to 128 HV. The Rockwell hardness of the second metal sheet / the Rockwell hardness of the first metal sheet=0.73.

[0210] The room temperature bonding strength of the insulating adhesive layer is 16N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.07N / mm 2 .

[0211] Other conditions remain unchanged.

[0212] Preparation of the pressure relief mechanism used in Example 15

[0213] On the basis of Example 1, the Rockwell hardness of the first metal sheet is changed to 175 HV, and the Rockwell hardness of the second metal sheet is changed to 175 HV.

[0214] The room temperature bonding strength of the insulating adhesive layer is 16.6N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.17N / mm 2 .

[0215] Other conditions remain unchanged.

[0216] Preparation of the pressure relief mechanism used in Example 16

[0217] On the basis of Example 1, the structure of the insulating adhesive layer is changed to a three-layer structure:

[0218] The thickness of the first layer of film is 14mm, the melting point is 75±5℃, 100±5℃; the material includes polypropylene and polybutylene;

[0219] The second layer of film has a thickness of 12 mm, a melting point of 140 ± 5 ° C, and is made of polypropylene;

[0220] The thickness of the third layer of film is 14 mm, the melting point is 75±5℃, 100±5℃; the material includes polypropylene and polybutylene;

[0221] The thermal compression deformation of the pressure relief mechanism at 160°C is 8%±1%, and the thermal compression deformation at 80°C is 0.04%±0.01%.

[0222] The room temperature bonding strength of the insulating adhesive layer is 7.28N / mm 2 The thermal bonding force of the insulating adhesive layer at 120-130°C is 0.68N / mm 2 .

[0223] Other conditions remain unchanged.

[0224] Preparation of the pressure relief mechanism used in Comparative Example 1

[0225] On the basis of Example 1, the roughness of the first metal sheet is changed to 1.5 μm and the roughness of the second metal sheet is changed to 1.5 μm.

[0226] The room temperature bonding strength of the insulating adhesive layer is 5.85N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 0.73N / mm 2 .

[0227] Other conditions remain unchanged.

[0228] Preparation of the pressure relief mechanism used in Comparative Example 2

[0229] Based on Example 1, there is no passivation layer on the surface of the first metal sheet and the second metal sheet.

[0230] The room temperature bonding strength of the insulating adhesive layer is 3.18N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 0.38N / mm 2 .

[0231] Other conditions remain unchanged.

[0232] Preparation of the pressure relief mechanism used in Comparative Example 3

[0233] On the basis of Example 1, the content of Cr element in the surface passivation layer of the first metal sheet and the second metal sheet is changed to 1.2%.

[0234] The room temperature bonding strength of the insulating adhesive layer is 17.44N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.51N / mm 2 .

[0235] Other conditions remain unchanged.

[0236] Preparation of the pressure relief mechanism used in Comparative Example 4

[0237] On the basis of Example 1, the thickness of the insulating rubber layer is changed to 0.02 mm, and the thickness ratio of the insulating rubber layer to the pressure relief mechanism is 0.02:(0.02+0.08+0.15)=1:12.5

[0238] The thermal compression deformation of the pressure relief mechanism at 160°C is 3.5%±0.5%, and the thermal compression deformation at 80°C is 0.02%±0.01%.

[0239] The room temperature bonding strength of the insulating adhesive layer is 16.51N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.21N / mm 2 .

[0240] Other conditions remain unchanged.

[0241] Preparation of the pressure relief mechanism used in Comparative Example 5

[0242] On the basis of Example 1, the thickness of the insulating rubber layer is changed to 0.02 mm, and the thickness ratio of the insulating rubber layer to the pressure relief mechanism as a whole is 0.02:(0.02+0.08+0.15)=1:12.5;

[0243] The melting point of the insulating adhesive layer is 106±5℃, 120±5℃;

[0244] The room temperature bonding strength of the insulating adhesive layer is 21.1N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 2.2N / mm 2 .

[0245] Other conditions remain unchanged.

[0246] Preparation of the pressure relief mechanism used in Comparative Example 6

[0247] On the basis of Example 1, the melting point of the insulating adhesive layer is changed to 75±5°C, 110±5°C, 125±5°C;

[0248] The thermal compression deformation of the pressure relief mechanism at 160°C is 15%±1%, and the thermal compression deformation at 80°C is 0.02%±0.01%.

[0249] The room temperature bonding strength of the insulating adhesive layer is 3.64N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 0.17N / mm 2 .

[0250] Other conditions remain unchanged.

[0251] Preparation of the pressure relief mechanism used in Comparative Example 7

[0252] On the basis of Example 1, the Rockwell hardness of the first metal sheet is changed to 60 HV, and the Rockwell hardness of the second metal sheet is changed to 23 HV.

[0253] The room temperature bonding strength of the insulating adhesive layer is 10.4N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.07N / mm 2 .

[0254] Other conditions remain unchanged.

[0255] Preparation of the pressure relief mechanism used in Comparative Example 8

[0256] On the basis of Example 1, the Rockwell hardness of the first metal sheet is changed to 140 HV, and the Rockwell hardness of the second metal sheet is changed to 60 HV.

[0257] The room temperature bonding strength of the insulating adhesive layer is 10.9N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.01N / mm 2 .

[0258] Other conditions remain unchanged.

[0259] Lithium-ion battery preparation:

[0260] 1) Tablet preparation: The positive electrode active material, conductive agent, binder and solvent are mixed and evenly coated on the surface of the positive electrode substrate; wherein the positive electrode substrate is aluminum foil, and the positive electrode active material is mainly lithium cobalt oxide. The mixed material is coated, dried, rolled and die-cut to obtain a positive electrode sheet; The negative electrode active material, conductive agent, binder and solvent are mixed and evenly coated on the surface of the negative electrode substrate; wherein the negative electrode substrate is copper foil, and the negative electrode active material is mainly graphite. Then the mixed material is evenly coated, dried, rolled and die-cut to obtain a negative electrode sheet;

[0261] 2) Lamination welding: The prepared positive electrode sheet, negative electrode sheet and separator are laminated simultaneously, and the separator is placed between the positive and negative electrode sheets, wherein the area of ​​the separator is greater than the area of ​​the negative electrode sheet and greater than the area of ​​the positive electrode sheet; and a laminated core is obtained;

[0262] 3) The prepared coil core is placed in a steel shell and welded; after liquid injection, aging, and formation, the pressure relief mechanism is welded to cover the pressure relief hole of the shell. After OCV, a lithium-ion steel shell battery is obtained;

[0263] Test method:

[0264] 1) Pressure relief mechanism bonding test: simulate the pressure relief mechanism strength test, take the prepared pressure relief structure, place the pressure relief mechanism in the test mold described in claim 12, use an electronic universal testing machine to perform a dry push test, the pushing speed is 25mm / min, and obtain the bonding force of the insulating glue at room temperature. Heat the mold and the pressure relief mechanism to 125±5℃, use a push rod to pass through the third through hole on the mold, the first through hole on the first metal sheet, and the second through hole of the insulating glue layer in sequence, and push the second metal sheet. Separate the first metal sheet, the glue film, and the second metal sheet to obtain the thermal bonding force of the insulating glue.

[0265] 2) The hot box test method is as follows:

[0266] 130 degree hot box test: Under 37℃±3℃ environment, discharge at 0.2C to cut-off voltage 3.0V, and let stand for 10min; charge at 0.5C constant current and constant voltage to upper limit voltage 4.5V, cut-off current 0.02C, and test voltage, internal resistance, and thickness of fully charged state at 25℃±3℃. Put the fully charged battery into the test box, and heat up the test box at a temperature rise rate of (5±2)℃ / min. When the temperature in the box reaches 130℃±2℃, keep the temperature constant for 60min; after the test is completed, observe whether the battery cell catches fire. If it catches fire, it fails, otherwise it passes.

[0267] 3) Drop test

[0268] At 25℃±3℃, discharge at 0.2C to the lower limit voltage, let stand for 10 minutes, put the battery in a 25℃ constant temperature box, fully charge at 0.7C constant current, cut-off current 0.02C, and drop within 12-24h after full charge; drop 18 times at a height of 1.5m according to the national standard, observe whether the battery leaks, and record the qualified ratio;

[0269] 4) Thermal compression deformation test

[0270] Thermal compression test of pressure relief mechanism: simulate the changes of the insulating rubber layer of the pressure relief mechanism under heat / pressure, take the prepared pressure relief mechanism, and place it on the object table inside the test cavity. Close the cavity, use N2 protection, and apply a 0.1N force on the second metal sheet of the pressure relief mechanism through a glass push rod at room temperature (about 25°C), and record the thickness m0 of the pressure relief structure at this time. The cavity is heated at 10°C / min according to the set program, and the thickness m0 of the pressure relief mechanism is recorded as the temperature changes. X The value of the thickness change (mx / m0*100%) can characterize the degree of thermal compression of the pressure relief structure at different temperatures.

[0271] 5) High temperature and high humidity test

[0272] At 25℃±3℃, discharge to the lower limit voltage at 0.2C, let stand for 10 minutes, place the battery in a 25℃ constant temperature box, fully charge at 0.7C constant current, cut-off current 0.02C, and after fully charged. Place the battery in an environment with a temperature of 60℃ and a humidity of 95% for 336 hours, test the voltage, internal resistance, and thickness data of the fully charged state every 72 hours, and observe whether the pressure relief mechanism leaks, and record the qualified ratio after 336 hours.

[0273] Table 1

[0274]

[0275]

[0276] As shown in Table 1, compared with Example 1, Example 2 has the same thickness ratio between the insulating adhesive layer and the pressure relief structure, the same deformation percentage at 80°C and 160°C, the same polymer type, the same melting point, and the same bonding area of ​​the insulating adhesive layer, and the same hardness and thickness of the first metal sheet and the second metal sheet. When the roughness of the first metal sheet is 0.08μm and the roughness of the second metal sheet is 0.06μm, the room temperature bonding force between the insulating adhesive layer and the metal sheet is 15N / mm 2 The thermal bonding force of the insulating adhesive layer at 120-130°C is 1.09N / mm 2 The cell passes 100% of the hot box, drop and high temperature and humidity tests at 130°C; the roughness of the first metal sheet is 0.8μm, and the roughness of the second metal sheet is 0.6μm. The room temperature bonding strength between the insulating adhesive layer and the metal sheet is 10.92N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 0.88N / mm 2 , the hot box pass rate of the battery cell at 130°C is 100%, and the drop pass rate is 95%; as the roughness of the metal sheet increases, the room temperature bonding force between the insulating glue layer and the metal sheet decreases, and the reliability of the pressure relief structure decreases. The hot box, drop, high temperature and high humidity pass rates of Examples 1 and 2 are all greater than 80%. Therefore, the roughness of the first metal sheet is ≤1μm, and the roughness of the second metal sheet is ≤0.8μm, and the battery cell has a high hot box pass rate and reliability guarantee.

[0277] Compared with Example 1, Examples 3 and 4 are under the same thickness ratio of the insulating adhesive layer and the pressure relief structure as a whole, the same deformation percentage at 80°C and 160°C; the same polymer type, the same melting point, and the same bonding area of ​​the insulating adhesive layer; and the same hardness, thickness, and roughness of the first metal sheet and the second metal sheet. When the Cr content of the first metal sheet and the second metal sheet is 0.1%, the room temperature bonding strength of the insulating adhesive layer and the metal sheet is 15N / mm 2The thermal bonding force of the insulating adhesive layer at 120-130°C is 1.09N / mm 2 The cell's 130°C hot box, drop and high temperature and high humidity pass rates are 100%. When the Cr element content of the passivation layer on the surface of the first metal sheet and the second metal sheet is 0.5%, the room temperature bonding strength of the insulating adhesive layer is 16.74N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.11N / mm 2 The cell's 130°C hot box pass rate is 95%, and its drop and high temperature and high humidity pass rates are 100%. When the Cr content of the passivation layer on the surface of the first metal sheet and the second metal sheet is 0.9%, the room temperature bonding strength of the insulating glue layer and the metal sheet is 17.14N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.45N / mm 2 , the hot box pass rate of the battery cell at 130°C is 87.5%, and the drop and high temperature and high humidity pass rates are 100%. The hot box, drop, high temperature and high humidity pass rates of Examples 1, 3, and 4 are all greater than 80%. Therefore, when the Cr content of the passivation layer on the surface of the first metal sheet and the second metal sheet is ≤1%, the battery cell has a higher hot box pass rate and reliability guarantee. The Cr element content of the first metal sheet and the second metal sheet increases, and the bonding strength between the insulating glue layer and the metal sheet at high temperature is improved, which increases the risk of fire and explosion of the battery cell at high temperature.

[0278] Compared with Example 1, Examples 5, 6, and 7 are under the conditions that the polymer type, melting point, and bonding area of ​​the insulating adhesive layer are the same; and the hardness and roughness of the first metal sheet and the second metal sheet are the same. When the thickness of the insulating adhesive layer is 0.04 mm, the thermal compression deformation of the pressure relief mechanism at 160°C is 8%, and the thermal compression deformation at 80°C is 0.02%, the thickness ratio of the insulating adhesive layer to the pressure relief mechanism is 1:6.75, and the room temperature bonding strength of the insulating adhesive layer and the metal sheet is 15 N / mm 2 The thermal bonding force of the insulating adhesive layer at 120-130°C is 1.09N / mm 2 , the cell's 130°C hot box, drop and high temperature and high humidity pass rates are 100%. When the thickness of the insulating adhesive layer is 0.03mm, the thermal compression deformation of the pressure relief mechanism at 160°C is 5.5%, and the thermal compression deformation at 80°C is 0.02%, the thickness ratio of the insulating adhesive layer to the pressure relief mechanism is 1:8.66, and the room temperature bonding strength of the insulating adhesive layer is 16.22N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.19N / mm 2, the cell's 130°C hot box pass rate is 97.5%, and its drop and high temperature and high humidity pass rates are 100%. When the thickness of the insulating adhesive layer is 0.07mm, the thermal compression deformation of the pressure relief mechanism at 160°C is 13%, and the thermal compression deformation at 80°C is 0.02%, the thickness ratio of the insulating adhesive layer to the pressure relief mechanism is 1:4.28, and the room temperature bonding strength of the insulating adhesive layer is 9.7N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 0.72N / mm 2 , the cell's 130°C hot box pass rate is 100%, the drop pass rate is 87.5%, and the high temperature and high humidity pass rate is 95%. When the thickness of the insulating adhesive layer is 0.07mm, the thickness of the second metal sheet is 0.08mm, the thermal compression deformation of the pressure relief mechanism at 160°C is 18%, and the thermal compression deformation at 80°C is 0.02%, the thickness ratio of the insulating adhesive layer to the pressure relief mechanism is 1:3.28, and the room temperature bonding strength of the insulating adhesive layer is 8.49N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 0.69N / mm 2 , the hot box pass rate of the battery cell at 130°C is 100%, the drop pass rate is 85%, and the high temperature and high humidity pass rate is 95%. When the thickness ratio of the insulating rubber layer to the pressure relief mechanism as a whole is larger, the furnace temperature pass rate increases, and the drop and high temperature and high humidity pass rates decrease accordingly. The hot box, drop, and high temperature and high humidity pass rates of Examples 1, 5, 6, and 7 are all greater than 80%. Therefore, when the thickness ratio of the insulating rubber layer to the pressure relief mechanism as a whole is 1:2 to 1:10, the battery cell has a higher hot box pass rate and reliability guarantee.

[0279] Compared with Example 1, Examples 8, 9, 10, and 11 are under the conditions that the polymer type of the insulating adhesive layer is the same, the bonding area is the same, and the hardness, thickness, and roughness of the first metal sheet and the second metal sheet are the same. When the melting point of the insulating adhesive layer is 100±5℃ and 125±5℃, the thermal compression deformation of the pressure relief mechanism at 160℃ is 8%, and the thermal compression deformation at 80℃ is 0.02%, and the room temperature bonding force between the insulating adhesive layer and the metal sheet is 15N / mm 2 The thermal bonding force of the insulating adhesive layer at 120-130°C is 1.09N / mm 2 The cell's 130°C hot box, drop and high temperature and high humidity pass rates are 100%. When the melting point of the insulating adhesive layer is 106±5°C and 120±5°C, the thermal compression deformation of the pressure relief mechanism at 160°C is 14.5%, and the thermal compression deformation at 80°C is 0.04%. The room temperature bonding strength of the insulating adhesive layer is 14.5N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 0.74N / mm 2. The pass rate of the battery cell at 130°C hot box, drop and high temperature and high humidity is 100%. When the melting point of the insulating adhesive layer is 110±5°C and 120±5°C, the thickness of the insulating adhesive layer is 0.07mm, the thickness of the second metal sheet is 0.08mm, the thickness of the insulating adhesive layer and the pressure relief mechanism as a whole is 1:3.28, the thermal compression deformation of the pressure relief mechanism at 160°C is 29.5%, the thermal compression deformation at 80°C is 0.02%, and the room temperature bonding strength of the insulating adhesive layer is 8.49N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 0.71N / mm 2 The pass rate of the hot box at 130°C is 100%, the pass rate of the drop test is 87.5%, and the pass rate of high temperature and high humidity is 95%. When the melting point of the insulating adhesive layer is 110±5°C and 125±5°C, the thermal compression deformation of the pressure relief mechanism at 160°C is 14.5%, and the thermal compression deformation at 80°C is 0.02%. The room temperature bonding strength of the insulating adhesive layer is 10.67N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 0.63N / mm 2 , the hot box pass rate of the battery cell at 130℃ is 100%, the drop pass rate is 95%, and the high temperature and high humidity pass rate is 100%. When the melting point of the insulating adhesive layer is 75±5℃, 110±5℃, and 125±5℃; the thermal compression deformation of the pressure relief mechanism at 160℃ is 14.5%, and the thermal compression deformation at 80℃ is 0.4%. The room temperature bonding force of the insulating adhesive layer is 7.28N / mm2, and the thermal bonding force of the insulating adhesive layer at 120-130℃ is 0.4N / mm2. The hot box pass rate of the battery cell at 130℃ is 100%, the drop pass rate is 80%, and the high temperature and high humidity pass rate is 90%. In embodiments 1, 8, 9, 10, and 11, the hot box, drop, and high temperature and high humidity pass rates are all greater than 80%. Therefore, when the melting point of a single-layer insulating adhesive layer is between 70 and 145℃, the battery cell has a higher hot box pass rate and reliability guarantee.

[0280] Compared with Example 1, Examples 12, 13, 14, and 15 are under the same thickness ratio of the insulating adhesive layer and the pressure relief structure as a whole, the same deformation percentage at 80°C and 160°C; the same polymer type, the same melting point, and the same bonding area of ​​the insulating adhesive layer; and the same roughness and thickness of the first metal sheet and the second metal sheet. When the Rockwell hardness of the first metal sheet is 140HV, the Rockwell hardness of the second metal sheet is 140HV, and the ratio of the Rockwell hardness of the second metal sheet to the Rockwell hardness of the first metal sheet is 1, the room temperature bonding strength of the insulating adhesive layer is 15N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.09N / mm 2, the cell's 130°C hot box, drop and high temperature and high humidity pass rates are 100%. When the Rockwell hardness of the first metal sheet is 128HV, the Rockwell hardness of the second metal sheet is 128HV, and the Rockwell hardness ratio of the second metal sheet to the Rockwell hardness of the first metal sheet is 1, the room temperature bonding strength of the insulating adhesive layer is 13.5N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.08N / mm 2 The cell's 130°C hot box pass rate is 95%, and its drop and high temperature and high humidity pass rates are 100%. When the Rockwell hardness of the first metal sheet is 128HV, the Rockwell hardness of the second metal sheet is 175HV, and the Rockwell hardness of the second metal sheet / the Rockwell hardness of the first metal sheet is 1.36, the room temperature bonding strength of the insulating adhesive layer is 14.4N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.1N / mm 2 The cell's 130°C hot box pass rate is 95%, and its drop and high temperature and high humidity pass rates are 100%. When the Rockwell hardness of the first metal sheet is 175HV, the Rockwell hardness of the second metal sheet is 128HV, and the Rockwell hardness of the second metal sheet / the Rockwell hardness of the first metal sheet is 0.73HV, the room temperature bonding strength of the insulating adhesive layer is 16N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.07N / mm 2 The cell's 130°C hot box pass rate is 97.5%, and its drop and high temperature and high humidity pass rates are 100%. When the Rockwell hardness of the first metal sheet is 175HV, the Rockwell hardness of the second metal sheet is 175HV, and the Rockwell hardness of the second metal sheet / the Rockwell hardness of the first metal sheet is 1, the room temperature bonding strength of the insulating adhesive layer is 16.6N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.17N / mm 2 , the hot box pass rate of the battery cell at 130°C is 92.5%, and the drop and high temperature and high humidity pass rate is 100%. The hot box, drop, high temperature and high humidity pass rates of Examples 1, 12, 13, 14, and 15 are all greater than 80%. Therefore, when the Rockwell hardness of the first metal sheet and the second metal sheet is between 120 and 180 HV, and the Rockwell hardness of the second metal sheet / the Rockwell hardness of the first metal sheet is greater than 1 / 2, the battery cell has a higher hot box pass rate and reliability guarantee.

[0281] Compared with Example 1, Example 16 has the same thickness ratio and bonding area between the insulating adhesive layer and the pressure relief structure; the same roughness and thickness between the first metal sheet and the second metal sheet. When the insulating adhesive layer is a single-layer structure with a melting point of 100±5℃ and 125±5℃, the thermal compression deformation of the pressure relief mechanism at 160℃ is 8%, the thermal compression deformation at 80℃ is 0.02%, and the room temperature bonding strength between the insulating adhesive layer and the metal sheet is 15N / mm 2The thermal bonding force of the insulating adhesive layer at 120-130°C is 1.09N / mm 2 , the cell's 130°C hot box, drop and high temperature and high humidity pass rates are 100%. When the insulating adhesive is a three-layer structure with a melting point of 70-170°C, the thickness of the first layer of adhesive film is 14mm, the melting point is 75±5°C, 100±5°C; the thickness of the second layer of adhesive film is 12mm, the melting point is 140±5°C; the thickness of the third layer of adhesive film is 14mm, the melting point is 75±5°C, 100±5°C, the heat compression deformation of the pressure relief mechanism at 160°C is 8%, the heat compression deformation at 80°C is 0.04%, and the room temperature bonding strength of the insulating adhesive layer is 7.28N / mm 2 The thermal bonding force of the insulating adhesive layer at 120-130°C is 0.68N / mm 2 The cell's 130°C hot box pass rate is 100%, and its drop and high temperature and high humidity pass rate is 80%. Therefore, when the insulating adhesive layer is a three-layer structure with a melting point of 70-170°C, the cell still has a high hot box pass rate and reliability guarantee.

[0282] Compared with Examples 1 and 2, Comparative Example 1 is under the conditions that the thickness ratio of the insulating adhesive layer and the pressure relief structure as a whole is the same, the deformation percentages at 80°C and 160°C are the same; the polymer type of the insulating adhesive layer is the same, the melting point is the same, and the bonding area is the same; the hardness and thickness of the first metal sheet and the second metal sheet are the same. When the roughness of the first metal sheet is 0.08, the hot box, drop and high temperature and high humidity pass rates of the battery cell at 130°C are 100%. When the roughness of the first metal sheet is 0.8, the hot box pass rate of the battery cell at 130°C is 100%, the drop pass rate is 95%, and the high temperature and high humidity pass rate is 100%. When the roughness of the first metal sheet is 1.5, the hot box pass rate of the battery cell at 130°C is 100%, the drop pass rate is 70%, and the high temperature and high humidity pass rate is 80%. As the roughness of the metal sheet increases, the room-temperature bonding force between the insulating rubber layer and the metal sheet decreases, and the reliability and sealing of the pressure relief structure decrease. Therefore, when the roughness of the first metal sheet is less than 1 and the roughness of the second metal sheet is less than 0.8, the battery cell has better hot box pass rate and reliability.

[0283] Compared with Examples 1, 3, and 4, Comparative Examples 2 and 3 are under the conditions that the thickness ratio of the insulating adhesive layer and the pressure relief structure as a whole is the same, the deformation percentage at 80°C and 160°C is the same; the polymer type of the insulating adhesive layer is the same, the melting point is the same, and the bonding area is the same; the hardness, thickness, and roughness of the first metal sheet and the second metal sheet are the same. When the Cr element content of the first metal sheet and the second metal sheet is 0.1, the hot box, drop, and high temperature and high humidity pass rates of the battery cell at 130°C are 100%. When the Cr element content of the surface passivation layer of the first metal sheet and the second metal sheet is 0.5, the hot box pass rate of the battery cell at 130°C is 95%, and the drop and high temperature and high humidity pass rates are 100%. When the Cr element content of the surface passivation layer of the first metal sheet and the second metal sheet is 0.9%, the hot box pass rate of the battery cell at 130°C is 87.5%, and the drop and high temperature and high humidity pass rates are 100%. When the first metal sheet and the second metal sheet are not passivated, the hot box pass rate of the battery cell at 130°C is 100%, the drop pass rate is 30%, and the high temperature and high humidity pass rate is 40%. When the Cr element content of the passivation layer on the surface of the first metal sheet and the second metal sheet is 1.5%, the hot box pass rate of the battery cell at 130°C is 70%, and the drop and high temperature and high humidity pass rates are 100%. The hot box, drop, high temperature and high humidity pass rates of Examples 1, 3, and 4 are all greater than 80%. The hot box pass rate of Comparative Example 2 is only 70%. Therefore, the Cr content of the passivation layer on the surface of the first metal sheet and the second metal sheet is preferably ≤1%, and the battery cell has a higher hot box pass rate.

[0284] Comparative Examples 4, 5, and 6 Compared with Examples 1, 5, 6, and 7, the polymer type of the insulating adhesive layer is the same, the bonding area is the same; the hardness and roughness of the first metal sheet and the second metal sheet are the same. When the thickness of the insulating adhesive layer is 0.04 mm, the thermal compression deformation of the pressure relief mechanism at 160°C is 8%, the thickness ratio of the insulating adhesive layer to the pressure relief mechanism is 1:6.75, and the room temperature bonding force between the insulating adhesive layer and the metal sheet is 15 N / mm 2 The thermal bonding force of the insulating adhesive layer at 120-130°C is 1.09N / mm 2 When the cell passes the hot box, drop and high temperature and humidity tests at 130°C, the pass rate is 100%. When the thickness of the insulating adhesive layer is 0.03mm, the thermal compression deformation of the pressure relief mechanism at 160°C is 5.5%, the thickness ratio of the insulating adhesive layer to the pressure relief mechanism is 1:8.66, and the room temperature bonding strength of the insulating adhesive layer is 16.22N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.19N / mm 2When the cell passes the hot box test at 130°C at 97.5%, and the drop and high temperature and high humidity test passes 100%. When the thickness of the insulating adhesive layer is 0.07mm, the thermal compression deformation of the pressure relief mechanism at 160°C is 13%, the thickness ratio of the insulating adhesive layer to the pressure relief mechanism is 1:4.28, and the room temperature bonding strength of the insulating adhesive layer is 9.7N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 0.72N / mm 2 When the cell passes the hot box test at 130°C, the pass rate is 100%, the drop pass rate is 87.5%, and the high temperature and high humidity pass rate is 95%. When the thickness of the insulating adhesive layer is 0.07mm, the thickness of the second metal sheet is 0.08mm, the thermal compression deformation of the pressure relief mechanism at 160°C is 18%, the thickness ratio of the insulating adhesive layer to the pressure relief mechanism is 1:3.28, and the room temperature bonding strength of the insulating adhesive layer is 8.49N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 0.69N / mm 2 When the cell passes the hot box test at 130°C, the pass rate is 100%, the drop pass rate is 85%, and the high temperature and high humidity pass rate is 95%. When the thickness of the insulating adhesive layer is 0.02mm, the thermal compression deformation of the pressure relief mechanism at 160°C is 3.5, the thickness ratio of the insulating adhesive layer to the pressure relief mechanism is 1:12.5, and the room temperature bonding strength of the insulating adhesive layer is 16.51N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.21N / mm 2 When the cell passes the hot box test at 130°C at 75%, the drop test pass rate is 100%, and the high temperature and high humidity test pass rate is 100%. When the thickness of the insulating adhesive layer is 0.02mm, the thickness ratio of the insulating adhesive layer to the pressure relief mechanism is 1:12.5, and the room temperature bonding strength of the insulating adhesive layer is 21.1N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 2.2N / mm 2 When the cell passes the hot box test at 130°C at 50%, the drop test rate is 100%, and the high temperature and high humidity test rate is 100%. When the melting point of the insulating adhesive layer is 75±5°C, 110±5°C, and 125±5°C; the thermal compression deformation of the pressure relief mechanism at 160°C is 15%, and the room temperature bonding strength of the insulating adhesive layer is 3.64N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 0.17N / mm 2When the hot box pass rate of the battery cell at 130°C is 100%, the drop pass rate is 30%, and the high temperature and high humidity pass rate is 75%. When the thickness ratio of the insulating rubber layer to the pressure relief mechanism as a whole is larger, the furnace temperature pass rate increases, and the drop and high temperature and high humidity pass rates decrease accordingly. The hot box, drop, and high temperature and high humidity pass rates of Examples 1, 5, 6, and 7 are all greater than 80%. Therefore, the thickness ratio of the insulating rubber layer to the pressure relief mechanism as a whole is preferably 1:2 to 1:10, and the bonding strength of the insulating rubber layer is 7N to 20N / mm 2 The thermal bonding force of the insulating adhesive layer at 120-130°C is 0.2-2N / mm 2 Within the specified range, the battery cells have a high thermal box pass rate and reliability assurance.

[0285] Compared with Examples 1, 12, 13, 14, and 15, Comparative Examples 7 and 8 are under the conditions that the thickness ratio of the insulating adhesive layer and the pressure relief structure as a whole is the same, the deformation percentages at 80°C and 160°C are the same; the polymer type of the insulating adhesive layer is the same, the melting point is the same, and the bonding area is the same; the roughness and thickness of the first metal sheet and the second metal sheet are the same. When the Rockwell hardness of the first metal sheet is 120-180HV, and the Rockwell hardness of the second metal sheet / the Rockwell hardness of the first metal sheet is greater than 1 / 2, the hot box, drop, high temperature and high humidity pass rates are all greater than 80%. When the Rockwell hardness of the first metal sheet is 60HV, the Rockwell hardness of the second metal sheet is 23HV, and the Rockwell hardness of the second metal sheet / the Rockwell hardness of the first metal sheet is 0.38, the room temperature bonding strength of the insulating adhesive layer is 10.4N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.07N / mm 2 The cell's 130°C hot box pass rate is 95%, the drop pass rate is 52.5%, and the high temperature and high humidity pass rate is 100%. When the Rockwell hardness of the first metal sheet is 140HV, the Rockwell hardness of the second metal sheet is 60HV, and the Rockwell hardness of the second metal sheet / the Rockwell hardness of the first metal sheet is 0.43, the room temperature bonding strength of the insulating adhesive layer is 10.9N / mm 2 The thermal bonding strength of the insulating adhesive layer at 120-130°C is 1.01N / mm 2 The hot box pass rate of the battery cell at 130°C is 97.5%, the drop pass rate is 75%, and the high temperature and high humidity pass rate is 100%. When the hardness of the first metal sheet and the second metal sheet is less than 120HV, and the ratio of the Rockwell hardness of the second metal sheet to the Rockwell hardness of the first metal sheet is less than 1 / 2, the reliability of the pressure relief mechanism will be reduced, and the risk of drop failure will be greatly increased.

[0286] The present invention uses nickel sheets and nickel rings with appropriate thickness and hardness as sealing sheets. The pressure relief mechanism has a certain impact resistance and can resist external impact without serious deformation. The pressure relief mechanism is formed by bonding three layers of insulating glue or a single layer of glue with different melting points. When the battery cell is in a high temperature environment, the low melting point glue film is hot-melted, and the bonding force between the glue film and the metal sheet and between the glue films decreases, so that the opening can be realized, and the internal heat of the battery cell is released in advance to prevent the battery cell from catching fire.

[0287] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A battery, characterized in that: It comprises a shell, the shell is arranged to form a cavity; the shell comprises a first side wall, the first side wall is provided with a pressure relief through hole communicating with the cavity; A pressure relief mechanism covering the pressure relief through hole, the pressure relief mechanism comprising a first metal sheet, a second metal sheet, and an insulating adhesive layer disposed between the first metal sheet and the second metal sheet; one side of the first metal sheet is connected to the first side wall, a side of the first metal sheet facing away from the shell is bonded to the insulating adhesive layer, and a side of the insulating adhesive layer facing away from the first metal sheet is bonded to the second metal sheet; The roughness of the first metal sheet is C1, C1≤1μm, And / or, the roughness of the second metal sheet is C2, C2≤0.8 μm.

2. The battery according to claim 1, characterized in that The thickness H of the pressure relief mechanism is 0.2 mm ≤ H ≤ 0.35 mm; and / or, the thickness H1 of the first metal sheet is 0.05 mm ≤ H1 ≤ 0.1 mm; and / or, the thickness H2 of the second metal sheet is 0.05 mm ≤ H2 ≤ 0.2 mm; And / or, the thickness of the insulating adhesive is 0.02-0.08 mm.

3. The battery according to claim 1, characterized in that The Rockwell hardness of the first metal sheet is R1, 120HV≤R1≤190HV, and / or, the ratio of the Rockwell hardness of the second metal sheet to the Rockwell hardness of the first metal sheet is greater than 1 / 2; and / or, the Rockwell hardness of the shell is 120-180 HV, And / or, a ratio of the Rockwell hardness of the shell to the Rockwell hardness of the first metal sheet is between 3:2 and 2:

3.

4. The battery according to claim 1, characterized in that The surface of the first metal sheet and / or the second metal sheet also includes Cr element.

5. The battery according to claim 1, characterized in that The compression deformation percentage of the pressure relief mechanism in the thickness direction is 5% to 40% under the condition of 100 to 200°C; and / or, the compression deformation percentage of the pressure relief mechanism in the thickness direction is less than 1% under the condition of 40-80°C; And / or, the thickness ratio of the insulating rubber layer to the overall pressure relief structure is between 1:2 and 1:

10.

6. The battery according to claim 1, characterized in that The first metal sheet is provided with a first through hole, and the area S1 of the first through hole is 0.25 mm 2 ≤S1≤3.2mm 2 ; And / or, the area of ​​the first through hole is smaller than the area of ​​the pressure relief through hole; And / or, the ratio of the area of ​​the first through hole to the area of ​​the pressure relief through hole is between 1:4 and 1:1; And / or, the area of ​​the second metal sheet is greater than the area of ​​the first through hole, and the second metal sheet covers the first through hole; the area of ​​the second metal sheet and the area of ​​the first through hole are between 1:1 and 1:

10.

7. The battery according to claim 1, characterized in that The insulating adhesive layer is provided with a second through hole, and the width of the overflow adhesive of the insulating adhesive layer on the surface of the first metal sheet is W1, and W1 is ≥ 0.01 mm; The width W2 of the overflowed adhesive of the insulating adhesive layer on the surface of the second metal sheet is 0.01mm≤W2≤0.5mm.

8. The battery according to claim 1, characterized in that The thickness H3 of the insulating adhesive layer is 0.02mm≤H3≤0.08mm.

9. The battery according to claim 1, characterized in that The insulating rubber layer is a circular insulating rubber layer with an inner diameter of 0.2 to 1.4 mm and an outer diameter of 1.5 to 3 mm.

10. The battery according to claim 1, characterized in that The insulating adhesive layer is a single-layer adhesive film; And / or, the melting point range of the insulating adhesive layer is 70-145°C.

11. The battery according to claim 1, characterized in that The insulating adhesive layer includes a first melting peak and a second melting peak, the first melting peak is 90-110° C., and the second melting peak is 115-135° C.; And / or, the insulating adhesive layer further includes a third melting peak, and the third melting peak is 75±5°C.

12. The pressure relief mechanism according to claim 1, characterized in that: The insulating adhesive layer comprises a first adhesive film, a second adhesive film and a third adhesive film which are stacked, wherein a side of the first adhesive film facing away from the second adhesive film is bonded to a side of the first metal sheet facing away from the shell, and a side of the third adhesive film facing away from the second adhesive film is bonded to the second metal sheet; The thickness of the first layer of adhesive film is 3 to 20 μm; and / or, the thickness of the second adhesive film is 5 to 30 μm; and / or, the thickness of the third layer of adhesive film is 3 to 20 μm; and / or, the thickness ratio of the first layer of adhesive film, the second layer of adhesive film and the third layer of adhesive film is between 1:3:1 and 3:1:3; And / or, the melting point range of the insulating adhesive layer is T1, 70°C ≤ T1 ≤ 170°C; And / or, the melting point of the first layer of adhesive film is 70-130°C; And / or, the melting point of the second layer of adhesive film is 130-170°C; And / or, the melting point of the third layer of adhesive film is 70-130°C; and / or, the melting point of the second layer of adhesive film is higher than the melting point of the first layer of adhesive film; And / or, the melting point of the second adhesive film layer is higher than the melting point of the third adhesive film layer.

13. The battery according to claim 1, characterized in that The bonding force between the insulating adhesive layer and the first metal sheet and the second metal sheet is F, 0.2N / mm 2 ≤F≤20N / mm 2 .

14. The battery according to claim 1, characterized in that At room temperature of 20-30°C, the bonding force between the insulating adhesive layer and the first metal sheet and the second metal sheet is F1,7 N / mm 2 ≤F1≤20N / mm 2 , And / or, at a temperature of 120-130° C., the bonding force between the insulating adhesive layer and the first metal sheet and the second metal sheet is F2, 0.2 N / mm 2 ≤F2≤2N / mm 2 .

15. The battery according to claim 1, characterized in that The material of the insulating adhesive layer is selected from at least one of polyethylene, polypropylene, polybutylene, polyvinyl chloride, polypropylene chloride, polychloroprene, polyacrylic acid, polybutene acid, polyacrylate, and polyacrylonitrile.

16. The battery according to claim 1, characterized in that The first metal sheet has a chamfer on a plane close to the shell, the chamfer is arranged at an edge of the first through hole of the first metal sheet and an outer diameter edge of the first metal sheet, and the ratio of the chamfer size to the outer diameter of the first metal sheet is between 1:20 and 1:1; Preferably, a side of the second metal sheet facing away from the insulating adhesive layer has a chamfer, and the ratio of the chamfer size to the thickness of the second metal sheet is between 20:1 and 1:1; The chamfer size is 0.01 to 0.05 mm.

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