Pressure relief mechanism and preparation method thereof, cover plate, battery and power utilization device

Abstract

The invention discloses a pressure relief mechanism and a preparation method thereof, a battery and an electric device. The pressure relief mechanism comprises a metal valve body; the anti-corrosion coating is arranged on at least one part of the surface of the metal valve body, the swelling rate of the anti-corrosion coating soaked in electrolyte for 24 h at the temperature of 60 DEG C is smaller than or equal to 2%, the electrolyte is formed by mixing ethylene carbonate and dimethyl carbonate according to the volume ratio of 1: 1 to serve as a solvent, LiPF6 serves as lithium salt, and the concentration of the lithium salt is 1 mol / L. Therefore, anions and cations in the electrolyte can be prevented from permeating into the coating to corrode the metal valve body, the corrosion-resistant effect of the pressure relief mechanism is improved, and the risk of opening the valve in advance or battery cell leakage is reduced.

Description

Technical Field

[0001] This application belongs to the field of batteries, and more particularly, to a pressure relief mechanism, a preparation method thereof, a battery, and an electrical device. Background Art

[0002] As an energy storage device, batteries are widely used in various fields. Taking lithium-ion batteries as an example, they have the characteristics of being green, environmentally friendly, high-energy, and low-carbon. They are not only used in energy storage power systems such as hydroelectric, thermal, wind, and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, and ships, as well as in many fields such as military equipment and aerospace. With the development of current society, people's requirements for batteries are also getting higher and higher. Summary of the Invention

[0003] In view of the technical problems in the background art, this application provides a pressure relief mechanism, aiming to improve the corrosion resistance of the pressure relief mechanism and reduce the risk of premature valve opening or electrolyte leakage from the battery cell.

[0004] To achieve the above object, a first aspect of this application provides a pressure relief mechanism, which includes:

[0005] A metal valve body;

[0006] An anti-corrosion coating, the anti-corrosion coating is provided on at least a part of the surface of the metal valve body, and the swelling rate of the anti-corrosion coating when immersed in the electrolyte at 60 °C for 24 h ≤ 2%, and the electrolyte is a mixture of ethylene carbonate and dimethyl carbonate in a volume ratio of 1:1 as a solvent, and LiPF 6 is used as the lithium salt and mixed at a lithium salt concentration of 1 mol / L.

[0007] The pressure relief mechanism of this application has the following beneficial effects: It can block the penetration of anions and cations in the electrolyte into the coating to corrode the metal valve body, improve the corrosion resistance of the pressure relief mechanism, and reduce the risk of premature valve opening or electrolyte leakage from the battery cell.

[0008] In some embodiments of this application, the swelling rate of the anti-corrosion coating when immersed in the electrolyte at 60 °C for 24 h ≤ 1%, optionally ≤ 0.2%. Meeting the given conditions is beneficial to further improving the corrosion resistance of the pressure relief mechanism.

[0009] In some embodiments of this application, the anti-corrosion coating is provided on at least a part of the surface of the metal valve body in the area where there are indentations. Meeting the given conditions is beneficial to further reducing the risk of premature valve opening or electrolyte leakage from the pressure relief mechanism.

[0010] In some embodiments of the present application, the anti-corrosion coating comprises a thermosetting resin and a toughening agent. Meeting the given conditions is beneficial to improving the corrosion resistance effect of the pressure relief mechanism and can also take into account the flexibility of the anti-corrosion coating, which is beneficial to the normal valve opening of the pressure relief mechanism under the opening pressure.

[0011] In some embodiments of the present application, the thermosetting resin comprises at least one of epoxy resin, phenolic resin, polyimide resin, urea-formaldehyde resin, polyether ether ketone, and polybenzimidazole resin.

[0012] In some embodiments of the present application, the anti-corrosion coating comprises a three-dimensional network structure. Meeting the given conditions is beneficial to further improving the corrosion resistance effect of the pressure relief mechanism.

[0013] In some embodiments of the present application, based on the total mass of the anti-corrosion coating, the mass percentage content of the thermosetting resin is 40% to 99%, and can be optionally 80% to 95%. Meeting the given conditions is beneficial to making the anti-corrosion coating have a lower swelling rate and improving the corrosion resistance effect of the pressure relief mechanism.

[0014] In some embodiments of the present application, based on the total mass of the anti-corrosion coating, the mass percentage content of the toughening agent is 1% to 60%, and can be optionally 5% to 15%. Meeting the given conditions can make the anti-corrosion coating have good flexibility.

[0015] In some embodiments of the present application, the raw material composition of the anti-corrosion coating comprises: 40 to 99 parts by weight of the prepolymer and / or monomer of the thermosetting resin, 1 to 60 parts by weight of the toughening agent, and 0 to 5 parts by weight of the curing agent. Meeting the given conditions is beneficial to further reducing the swelling rate of the anti-corrosion coating and taking into account the flexibility of the anti-corrosion coating at the same time.

[0016] In some embodiments of the present application, there is a covalent bond connection between the metal valve body and the anti-corrosion coating. Meeting the given conditions can reduce the risk of peeling off of the anti-corrosion coating during use.

[0017] In some embodiments of the present application, the covalent bond comprises an ester bond and / or an ether bond. Meeting the given conditions is beneficial to realizing the covalent bond combination of the metal valve body and the anti-corrosion coating and improving the bonding strength between the two.

[0018] In some embodiments of the present application, the thickness of the anti-corrosion coating ≥ 1 μm; and / or, the metal valve body comprises two oppositely arranged first surfaces and second surfaces, and at least one of the first surface and the second surface is provided with the anti-corrosion coating. Meeting the given conditions can enable the anti-corrosion coating to play an effective protective role on the metal valve body.

[0019] In some embodiments of the present application, the thickness of the anti-corrosion coating provided on the first surface is ≥ 1 μm, and it can be optionally 20 μm - 70 μm. Meeting the given conditions can effectively protect the first surface of the metal valve body.

[0020] In some embodiments of the present application, the thickness of the anti-corrosion coating provided on the second surface is ≥ 1 μm, and it can be optionally 10 μm - 70 μm, and further optionally 10 μm - 30 μm. Meeting the given conditions can effectively protect the second surface of the metal valve body.

[0021] In some embodiments of the present application, the total thickness of the anti-corrosion coating provided on the first surface and the second surface is ≥ 1 μm, and it can be optionally 10 μm - 140 μm, and further optionally 20 μm - 100 μm.

[0022] In some embodiments of the present application, the mass retention rate of the anti-corrosion coating after being kept at 600 °C for 10 min is ≥ 75%. The anti-corrosion coating meeting the given conditions has good thermal stability.

[0023] In some embodiments of the present application, in the pressure relief mechanism, at 25 °C, the resistance between the metal valve body and the anti-corrosion coating is ≥ 1 GΩ. The anti-corrosion coating meeting the given conditions has good insulation, which is beneficial to further reducing the risk of electrochemical corrosion of the pressure relief mechanism.

[0024] In some embodiments of the present application, the tensile shear strength of the anti-corrosion coating is ≥ 15 MPa. The anti-corrosion coating meeting the given conditions has a high bonding strength with the metal valve body and is not easy to fall off during long-term use.

[0025] In some embodiments of the present application, the flexibility of the anti-corrosion coating meets the requirement that it can be bent 30° around a shaft rod with a curvature radius of 40 mm. The anti-corrosion coating meeting the given conditions has good flexibility, which is beneficial to the normal valve opening of the pressure relief mechanism.

[0026] The second aspect of the present application provides a method for manufacturing the pressure relief mechanism of the first aspect of the present application, which includes: forming an anti-corrosion coating on at least a part of the surface of the metal valve body. Using this method can improve the corrosion resistance effect of the pressure relief mechanism.

[0027] In some embodiments of the present application, the method for preparing the pressure relief mechanism may include: activating the surface of the metal valve body; mixing a toughening agent, a prepolymer and / or a monomer of a thermosetting resin with an organic solvent to obtain a coating slurry; coating the coating slurry on at least a part of the surface of the metal valve body after the activation treatment, and performing crosslinking and curing. Adopting this method is beneficial to forming a corrosion-resistant coating on the surface of the metal valve body, which has a low swelling rate in the electrolyte, good thermal stability, good flexibility, good insulation, and high bonding strength with the metal valve body.

[0028] In some embodiments of the present application, the activation treatment includes alkali washing and / or plasma treatment.

[0029] In some embodiments of the present application, the toughening agent includes an organic material and / or an inorganic nano filler. The organic material includes at least one of natural rubber, nitrile rubber, styrene-butadiene rubber, nylon, bismaleimide, glass fiber, polyurethane; and / or, the inorganic nano filler includes at least one of boehmite, alumina, zinc oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, barium oxide, nickel oxide, tin oxide, cerium oxide, yttrium oxide, hafnium oxide, aluminum hydroxide, magnesium hydroxide, silicon carbide, boron carbide, aluminum nitride, silicon nitride, boron nitride, magnesium fluoride, calcium fluoride, barium fluoride, barium sulfate, magnesium aluminum silicate, lithium magnesium silicate, sodium magnesium silicate, bentonite, hectorite, zirconium titanate, barium titanate, Pb(Zr,Ti)O 3 、Pb 1-m La m Zr 1-n Ti n O 3 、Pb(Mg 1 / 3 Nb 2 / 3 )O 3 PbTiO 3 、and at least one of their respective modified inorganic particles, 0 < m < 1, 0 < n < 1. Optionally, the inorganic nano filler includes at least one of alumina, magnesium oxide, calcium oxide, and barium oxide.

[0030] In some embodiments of the present application, the coating slurry further includes a curing agent. Optionally, the curing agent includes at least one of hexamethylenetetramine, paraformaldehyde, aniline, ammonia gas, formaldehyde, sodium phenylacetate, p-toluenesulfonyl chloride, and benzenesulfonyl chloride.

[0031] The third aspect of the present application provides a cover plate, which includes: the pressure relief mechanism of the first aspect of the present application, or the pressure relief mechanism prepared by using the method for preparing the pressure relief mechanism of the second aspect of the present application.

[0032] The fourth aspect of the present application provides a battery, which includes: the pressure relief mechanism of the first aspect of the present application, or the pressure relief mechanism prepared by using the method for preparing the pressure relief mechanism of the second aspect of the present application, or the cover plate of the third aspect of the present application.

[0033] In some embodiments of the present application, the battery includes a battery cell, and the pressure relief mechanism is located above and / or below the battery cell.

[0034] In some embodiments of the present application, the first surface of the metal valve body in the pressure relief mechanism faces the inside of the battery cell.

[0035] The fifth aspect of the present application provides an electrical device, which includes: the battery of the fourth aspect of the present application.

[0036] The additional aspects and advantages of the present application will be partially given in the following description, partially become apparent from the following description, or be understood through the practice of the present application. Description of the Drawings

[0037] The above and / or additional aspects and advantages of the present application will become apparent and be easily understood from the description of the embodiments in conjunction with the following drawings, where:

[0038] Figure 1 is a schematic structural diagram of a pressure relief mechanism according to an embodiment of the present application.

[0039] Figure 2 is a schematic structural diagram of a pressure relief mechanism according to another embodiment of the present application.

[0040] Figure 3 is a schematic structural diagram of a pressure relief mechanism according to yet another embodiment of the present application.

[0041] Figure 4 is a schematic structural diagram of a battery according to an embodiment of the present application.

[0042] Figure 5 is a schematic structural diagram of a battery module according to an embodiment of the present application.

[0043] Figure 6 is a schematic structural diagram of a battery pack according to an embodiment of the present application.

[0044] Figure 7 is an exploded view of a battery pack according to an embodiment of the present application.

[0045] Figure 8 is a schematic diagram of an embodiment of an electrical device using the battery according to an embodiment of the present application as a power source.

[0046] Description of the Reference Numerals:

[0047] 11: Metal valve body; 11a: First side; 11b: Second side; 12: Anti-corrosion coating; 1: Battery; 2: Battery module; 3: Battery pack; 4: Upper box body; 5: Lower box body. Detailed implementation manners

[0048] The present application will be further described below in conjunction with specific implementation manners. It should be understood that these specific implementation manners are only used to illustrate the present application and not to limit the scope of the present application.

[0049] Hereinafter, the implementation manners of the positive electrode active material, its preparation method, positive electrode sheet, battery and electrical device of the present application specifically disclosed will be described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters are omitted and repeated descriptions of actually identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0050] The "range" disclosed in the present application is defined in the form of a lower limit and / or an upper limit. A given range is defined by selecting a lower limit and / or an upper limit, and the selected lower limit and / or upper limit define the boundary of a particular range. The range defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range not explicitly recorded, and any lower limit can be combined with other lower limits to form a range not explicitly recorded. Similarly, any upper limit can be combined with any other upper limit to form a range not explicitly recorded. In addition, each separately disclosed point or single value itself can be used as a lower limit or an upper limit and combined with any other point or single value or combined with other lower limits or upper limits to form a range not explicitly recorded. For example, if ranges of 60 to 120 and 80 to 110 are listed for a specific parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also anticipated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all anticipated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In the present application, unless otherwise stated, the numerical range "a to b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 to 5" have been fully listed herein, and "0 to 5" is only an abbreviated representation of these numerical combinations. In addition, when it is stated that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0051] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution, and such a technical solution shall be considered to be included in the disclosure of the present application.

[0052] Unless otherwise specified, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution, and such a technical solution shall be considered to be included in the disclosure of the present application.

[0053] Unless otherwise specified, all steps of the present application can be carried out in sequence or randomly, preferably in sequence. For example, the method includes steps S1 and S2, indicating that the method may include steps S1 and S2 carried out in sequence, or may also include steps S2 and S1 carried out in sequence. For example, it is mentioned that the method may further include step S3, indicating that step S3 can be added to the method in any order. For example, the method may include steps S1, S2, and S3, or may also include steps S1, S3, and S2, or may include steps S3, S1, and S2, etc.

[0054] Unless otherwise specified, the terms "comprising" and "including" mentioned in the present application mean open-ended, and can also be closed-ended. For example, the "comprising" and "including" can mean that other components not listed may also be included or comprised, or may only include or comprise the listed components.

[0055] Unless otherwise specified, in the present application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) while B is true (or exists); or both A and B are true (or exist).

[0056] Unless otherwise specified, in the present application, the term "and / or" is merely a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, or B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0057] In the present application, the terms "a plurality of" and "a variety of" mean two or more than two.

[0058] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the technical field to which this application belongs; the terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "comprising" and "having" and any variations thereof in the specification, claims and above-mentioned drawings of this application are intended to cover non-exclusive inclusion. Unless otherwise specified, the terms used in this application have the well-known meanings commonly understood by those skilled in the art. Unless otherwise specified, the numerical values of the various parameters mentioned in this application can be measured by various commonly used measurement methods in the art (for example, they can be tested according to the methods given in the embodiments of this application).

[0059] With the continuous promotion of the theme of green environmental protection, the application of batteries has penetrated into all aspects of life, including vehicles, electronic devices, energy storage devices, etc. However, with the continuous popularization of battery applications, people's requirements for batteries are getting higher and higher. In order to make the energy density of lithium-ion batteries higher and improve the space utilization rate, the arrangement method of inverting the battery cells in the battery pack has emerged. After the battery cells are arranged in an inverted manner, the out-of-control exhaust and the bottom ball impact space of the battery pack share the same space, and the battery exhaust and safety space are integrated, improving the space utilization rate of the battery pack. However, after the battery cells are arranged in an inverted manner, the risk of corrosion of the weak structure of the pressure relief mechanism (such as the explosion-proof valve, etc.) increases greatly. For example, in the scratched area inside the explosion-proof valve, because the scratched position is relatively weak and the inside of the explosion-proof valve is immersed in the electrolyte for a long time, it is very easy to be corroded by the electrolyte, resulting in premature opening of the valve or leakage of liquid, leading to deterioration of the battery cell performance. Therefore, how to improve the corrosion resistance of the pressure relief mechanism is an important research direction at present.

[0060] In this application, by providing an anti-corrosion coating on at least a part of the surface of the metal valve body, and selecting an anti-corrosion coating with a swelling rate ≤ 2% when immersed in an electrolyte (using ethylene carbonate and dimethyl carbonate mixed in a volume ratio of 1:1 as the solvent, and LiPF 6 as the lithium salt, prepared according to a lithium salt concentration of 1 mol / L) at 60 °C for 24 h, it is possible to prevent the penetration of anions and cations in the electrolyte into the coating and corrode the metal valve body, improve the corrosion resistance of the pressure relief mechanism, and reduce the risk of premature valve opening or battery cell liquid leakage.

[0061] The pressure relief mechanism disclosed in the embodiments of the present application is applicable to secondary batteries, and the batteries disclosed in the embodiments of the present application can be used in electrical equipment using the battery as a power source or various energy storage systems using the battery as an energy storage element. The electrical equipment may include, but is not limited to, mobile phones, tablets, laptop computers, electric toys, power tools, battery cars, electric vehicles, ships, spacecraft, etc. Among them, the electric toys may include fixed or mobile electric toys, such as game consoles, electric vehicle toys, electric ship toys, electric airplane toys, etc., and the spacecraft may include airplanes, rockets, space shuttles, spaceships, etc.

[0062] In a first aspect of the present application, a pressure relief mechanism is provided, which includes: a metal valve body; an anti-corrosion coating provided on at least a part of the surface of the metal valve body, and the anti-corrosion coating has a swelling rate ≤ 2% when immersed in an electrolyte at 60 °C for 24 h. The electrolyte is a mixture of ethylene carbonate and dimethyl carbonate in a volume ratio of 1:1 as a solvent, and LiPF 6 is used as a lithium salt and mixed at a lithium salt concentration of 1 mol / L.

[0063] Reference Figures 1 to 3 Understand that the pressure relief mechanism of the first aspect of the present application includes a metal valve body 11 and an anti-corrosion coating 12, and the anti-corrosion coating 12 is provided on at least a part of the surface of the metal valve body 11. Exemplarily, the metal valve body 11 may include two first surfaces 11a and second surfaces 11b oppositely arranged along its thickness direction, and the anti-corrosion coating 12 may be provided on at least a part of the surface of the first surface 11a (reference Figure 1 Understand), or may be provided on at least a part of the surface of the second surface 11b (reference Figure 2 Understand), or may be provided on at least a part of the surface of the first surface 11a and at least a part of the surface of the second surface 11b at the same time (reference Figure 3 Understand). In addition, the swelling rate of the anti-corrosion coating 12 when immersed in the electrolyte at 60 °C for 24 h is ≤ 2%, for example, it may be ≤ 2%, ≤ 1.8%, ≤ 1.5%, ≤ 1.2%, ≤ 1%, ≤ 0.8%, ≤ 0.5%, ≤ 0.2%, ≤ 0.15%, ≤ 0.1%, ≤ 0.08%, ≤ 0.05%, ≤ 0.01%, etc., or may be a range composed of any of the above values.

[0064] Among them, the swelling rate of the anti-corrosion coating described in the present application refers to the degree of change in the attached volume of the anti-corrosion coating after being immersed in the electrolyte at 60 °C for 24 h. The specific test process is: using ethylene carbonate and dimethyl carbonate in a volume ratio of 1:1 as a solvent, and LiPF 6As a lithium salt, an electrolyte solution is prepared according to a lithium salt concentration of 1 mol / L; a test sample of a metal valve body with an anti-corrosion coating is immersed in a container filled with the electrolyte solution, and soaked at a constant temperature of 60 °C for 24 h. Conventional instruments and conventional methods are used to measure the volume change of the test sample before and after soaking. The swelling rate of the anti-corrosion coating after soaking in the electrolyte solution at 60 °C for 24 h = (V 1 -V 0 ) / V 0 × 100%, where V 0 is the volume of the test sample before soaking, and V 1 is the volume of the test sample after soaking.

[0065] In this application, the swelling rate of the anti-corrosion coating provided on the surface of the metal valve body in the electrolyte solution is relatively low. It has good volume stability during contact with the electrolyte solution, can effectively improve the permeability of the electrolyte solution in the anti-corrosion coating, and then block the penetration of anions and cations in the electrolyte solution into the coating to corrode the metal valve body, improve the corrosion resistance of the pressure relief mechanism, and reduce the risk of premature valve opening or electrolyte leakage from the battery cell. Taking a battery cell using a metal housing as an example, when the battery cell housing and the pressure relief mechanism are connected to the negative electrode and are negatively charged, under the conditions caused by the battery cell, the pressure relief mechanism is not prone to corrosion and leakage. Furthermore, when this metal valve body is used in a battery cell, such as in battery cells arranged upside down in a battery pack, the risk of premature valve opening or electrolyte leakage from the battery cell and the probability of subsequent deterioration of the battery cell performance or thermal runaway can be reduced, and the service life of the battery cell can be extended.

[0066] The pressure relief mechanism of this application has the following beneficial effects: It can block the penetration of anions and cations in the electrolyte solution into the coating to corrode the metal valve body, improve the corrosion resistance of the pressure relief mechanism, and reduce the risk of premature valve opening or electrolyte leakage from the battery cell.

[0067] Furthermore, on the basis of meeting the above conditions, the pressure relief mechanism of the first aspect of this application can further select the composition of the anti-corrosion coating, the connection method between the anti-corrosion coating and the metal valve body, the thickness and installation position of the anti-corrosion coating, etc. to further optimize the performance of the pressure relief mechanism. That is, on the basis of meeting the above conditions, one or more of the following conditions can also be optionally met.

[0068] In some embodiments of this application, the pressure relief mechanism may include, but is not limited to, one or more of an explosion-proof valve, a gas valve, a pressure relief valve, a safety valve, etc.

[0069] In the present application, the pressure relief mechanism refers to an element or component that is actuated to release the internal pressure or temperature when the internal pressure or temperature of the battery cell reaches a predetermined threshold. The value of this threshold varies according to different design requirements and depends on the material of one or several of the positive electrode sheet, negative electrode sheet, electrolyte, and separator membrane in the battery cell. The pressure relief mechanism can be in the form of, for example, an explosion-proof valve, a gas valve, a pressure relief valve, or a safety valve, and specifically, a pressure-sensitive or temperature-sensitive element or structure can be used. When the internal pressure or temperature of the battery cell reaches the predetermined threshold, the pressure relief mechanism performs an action or a weak structure provided in the pressure relief mechanism is damaged and cracked, thereby forming an opening or channel for the release of the internal pressure or temperature. Optionally, the actions generated by the pressure relief mechanism can include, but are not limited to: at least a part of the pressure relief mechanism breaks, shatters, is torn, or opens, and so on.

[0070] In some embodiments of the present application, the swelling rate of the anti-corrosion coating when immersed in the electrolyte at 60 °C for 24 h is ≤1%, optionally ≤0.2%. Selecting an anti-corrosion coating that meets the given conditions is beneficial to further improve the volume stability during the contact between the pressure relief mechanism and the electrolyte, reduce the permeability of the electrolyte in the anti-corrosion coating, and further help to block the penetration of anions and cations in the electrolyte into the coating to corrode the metal valve body, improve the corrosion resistance effect of the pressure relief mechanism, and reduce the risk of premature valve opening or electrolyte leakage from the battery cell.

[0071] In some embodiments of the present application, the specific material of the metal valve body can be a conventional selection in the art, for example, it can include, but is not limited to, a metal aluminum valve body, an aluminum alloy valve body, etc.

[0072] In some embodiments of the present application, an anti-corrosion coating can be provided on at least a part of the surface of the area where the metal valve body is formed with a notch. Optionally, the metal valve body is provided with an anti-corrosion coating on at least a part of the surface of the area where the notch is formed at least on the side facing the inside of the battery cell. Meeting the given conditions is beneficial to further reduce the risk of premature valve opening or electrolyte leakage of the pressure relief mechanism.

[0073] In some embodiments of the present application, the anti-corrosion coating can include a thermosetting resin and a toughening agent.

[0074] Selecting an anti-corrosion coating with a thermosetting resin is beneficial to improving the thermal stability, dimensional stability and swelling rate of the coating in the electrolyte, thereby improving the corrosion resistance of the pressure relief mechanism. Selecting an anti-corrosion coating with a toughening agent is beneficial to improving the flexibility of the coating, reducing the risk of increased difficulty in opening the valve of the pressure relief mechanism due to the provision of an anti-corrosion coating, and is beneficial to the normal opening of the valve of the pressure relief mechanism under the valve opening pressure. Among them, the thermosetting resin can be obtained by cross-linking and curing reaction using the corresponding prepolymer and / or monomer according to the specific type of resin. The prepolymer and / or monomer can form a complex three-dimensional network structure during the cross-linking and curing reaction, which is beneficial to reducing the erosion of the electrolyte, further blocking the anions and cations in the electrolyte from penetrating into the coating, and improving the corrosion resistance of the pressure relief mechanism.

[0075] In some embodiments of the present application, the thermosetting resin may include but is not limited to at least one of epoxy resin, phenolic resin, polyimide resin, urea-formaldehyde resin, polyetheretherketone, polybenzimidazole resin, etc. The above resin can not only cross-link into a three-dimensional network structure, but also has good thermal stability, good adhesion and insulation, low swelling rate in the electrolyte, strong bonding with the pressure relief mechanism, and is not easy to fall off during use, which can further improve the corrosion resistance of the pressure relief mechanism.

[0076] In some embodiments of the present application, the toughening agent may include organic materials and / or inorganic nanofillers. When the pressure relief mechanism is impacted by external force, the organic toughening agent and the interface layer mainly play a role in force conduction, while the inorganic nanofillers are dispersed in the three-dimensional network structure, mainly bearing the force and dispersing the force to various areas of the coating, thereby achieving a toughening effect. Optionally, the organic material used as the toughening agent may include but is not limited to natural rubber, nitrile rubber, styrene-butadiene rubber, nylon, bismaleimide, glass fiber, and polyester. At least one of urethane; the inorganic nanofiller may include but is not limited to boehmite, aluminum oxide, zinc oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, barium oxide, nickel oxide, tin oxide, cerium oxide, yttrium oxide, hafnium oxide, aluminum hydroxide, magnesium hydroxide, silicon carbide, boron carbide, aluminum nitride, silicon nitride, boron nitride, magnesium fluoride, calcium fluoride, barium fluoride, barium sulfate, magnesium aluminum silicate, lithium magnesium silicate, sodium magnesium silicate, bentonite, hectorite, zirconium titanate, barium titanate, Pb(Zr,Ti)O 3 , Pb 1-m La m Zr 1-n Ti n O 3 、Pb(Mg 1 / 3 Nb 2 / 3 ) 3 PbTiO 3, and at least one of their respective modified inorganic particles, where 0 < m < 1 and 0 < n < 1. Optionally, the inorganic nano-fillers may include, but are not limited to, at least one of alumina, magnesia, calcium oxide, and barium oxide.

[0077] During the actual operation process, one or more of the conventional testing methods such as infrared testing, thermogravimetric analysis, EDS energy spectrum analysis, mechanical testing, XRD testing, etc. can be combined to determine whether there are thermosetting resins and toughening agents in the anti-corrosion coating and to determine their types. For example, the appearance morphology, mechanical properties, and chemical stability of the anti-corrosion coating, such as hardness, brittleness, glossiness, etc., can be combined to judge whether there is a thermosetting resin in the anti-corrosion coating; infrared testing can be performed on the anti-corrosion coating and combined with the characteristic peaks at different positions of the infrared spectrum to roughly judge the chemical formula structure and type of the thermosetting resin; thermogravimetric analysis can be performed on the anti-corrosion coating to further judge the type of the thermosetting resin; for another example, when there are inorganic nano-fillers in the anti-corrosion coating, the anti-corrosion coating can be further ablated and combined with XRD testing, and the type of the inorganic nano-fillers can be judged according to the crystal structure of the residue.

[0078] Selecting an anti-corrosion coating including a thermosetting resin and a toughening agent can improve the thermal stability, dimensional stability, swelling rate in the electrolyte, and flexibility of the coating, which is not only beneficial to improving the corrosion resistance effect of the pressure relief mechanism but also takes into account the flexibility of the anti-corrosion coating, facilitating the normal valve opening of the pressure relief mechanism under the opening pressure.

[0079] In some embodiments of the present application, the anti-corrosion coating may include a three-dimensional network structure. Meeting the given conditions is beneficial to further blocking the penetration of anions and cations in the electrolyte into the coating and improving the corrosion resistance effect of the pressure relief mechanism.

[0080] In some embodiments of the present application, based on the total mass of the anti-corrosion coating, the mass percentage content of the thermosetting resin may be 40% - 99%, optionally 80% - 95%; and / or, the mass percentage content of the toughening agent may be 1% - 60%, optionally 5% - 15%.

[0081] For example, based on the total mass of the anti-corrosion coating, the mass percentage content of the thermosetting resin may be 40%, 50%, 60%, 70%, 80%, 90%, 99%, etc., or may be any range composed of the above values. Increasing the content of the thermosetting resin is beneficial to further improving the thermal stability, dimensional stability, and swelling rate of the anti-corrosion coating in the electrolyte, and improving the corrosion resistance effect of the pressure relief mechanism. Meeting the given conditions can make the anti-corrosion coating have a lower swelling rate and improve the corrosion resistance effect of the pressure relief mechanism.

[0082] Based on the total mass of the anti-corrosion coating, the mass percentage content of the toughening agent can be 1%, 5%, 10%, 15%, 20%, 30%, 40%, 50%, 60%, etc., or can be any range composed of the above values. Increasing the content of the toughening agent is beneficial to further improving the flexibility of the anti-corrosion coating, and further beneficial to the normal valve opening of the pressure relief mechanism under the opening pressure. Meeting the given conditions can make the anti-corrosion coating have good flexibility.

[0083] Optionally, based on the total mass of the anti-corrosion coating, the mass percentage content of the thermosetting resin can be 40% - 99%, and the mass percentage content of the toughening agent can be 1% - 60%; additionally optionally, based on the total mass of the anti-corrosion coating, the mass percentage content of the thermosetting resin can be 80% - 95%, and the mass percentage content of the toughening agent can be 5% - 15%. Meeting the given conditions can make the anti-corrosion coating have both a lower swelling rate and good flexibility, which can not only improve the corrosion resistance of the pressure relief mechanism but also be beneficial to the normal valve opening of the pressure relief mechanism under the opening pressure. Among them, the contents of the thermosetting resin and the toughening agent in the anti-corrosion coating can be measured by conventional technical means such as infrared testing and thermogravimetric analysis.

[0084] In some embodiments of the present application, the raw material composition of the anti-corrosion coating includes: 40 to 99 parts by weight of the prepolymer and / or monomer of the thermosetting resin, 1 to 60 parts by weight of the toughening agent, and 0 to 5 parts by weight of the curing agent.

[0085] When forming the anti-corrosion coating, adding the curing agent can further promote the crosslinking and curing of the prepolymer and / or monomer of the thermosetting resin to form a complex three-dimensional network structure, which is beneficial to further reducing the swelling rate of the anti-corrosion coating, blocking the penetration of anions and cations in the electrolyte into the coating, and improving the corrosion resistance of the pressure relief mechanism. Exemplarily, the weight parts of the thermosetting resin can be 40, 50, 60, 70, 80, 90, 99, etc., the weight parts of the toughening agent can be 1, 5, 10, 15, 20, 30, 40, 50, 60, etc., and the weight parts of the curing agent can be 0, 0.1, 0.5, 1, 2, 3, 4, 5, etc. Based on the dosages of the prepolymer and / or monomer of the thermosetting resin and the toughening agent, the content of the curing agent meeting the given conditions is not only beneficial to further reducing the swelling rate of the anti-corrosion coating but also beneficial to taking into account the flexibility of the anti-corrosion coating and reducing the risk of increased brittleness of the anti-corrosion coating caused by excessive crosslinking.

[0086] Meeting the given conditions is beneficial to further reducing the swelling rate of the anti-corrosion coating, while taking into account the flexibility of the anti-corrosion coating, which is beneficial to the normal valve opening of the pressure relief mechanism while improving the corrosion resistance of the pressure relief mechanism.

[0087] In some embodiments of the present application, there may be a covalent bond connection between the metal valve body and the anti-corrosion coating.

[0088] The anti-corrosion coating is covalently bonded to the metal valve body, which can improve the bonding strength between the anti-corrosion coating and the metal valve body, making the anti-corrosion coating have the advantages of low swelling rate in the electrolyte and not being easily detached, which is beneficial to further improving the corrosion resistance of the pressure relief mechanism, especially improving its corrosion resistance when in contact with the electrolyte for a long time. In the actual process, raw materials including the prepolymer and / or monomer of the thermosetting resin can be dispersed in an organic solvent to form a coating slurry, and then the coating slurry is coated on the surface of the metal valve body for cross-linking and curing reaction to prepare the anti-corrosion coating. Before coating the coating slurry on the surface of the metal valve body, the metal valve body can be surface-treated so that its surface has active groups that can react with the functional groups carried by the prepolymer and / or monomer. Then, during the cross-linking and curing reaction process, the active groups on the surface of the metal valve body can react with the functional groups carried by the prepolymer and / or monomer to form a covalent bond, improving the bonding strength between the anti-corrosion coating and the metal valve body. Methods such as XPS test analysis and infrared test can be used to obtain the types and bond energies of chemical bonds existing in the pressure relief mechanism, and combined with the material of the metal valve body and the functional groups that the thermosetting resin may carry, it can be judged whether there is a covalent bond connection between the metal valve body and the anti-corrosion coating.

[0089] Meeting the given conditions can further reduce the risk of the anti-corrosion coating peeling off during use and further improve the corrosion resistance of the pressure relief mechanism.

[0090] In some embodiments of the present application, the covalent bond may include an ester bond and / or an ether bond.

[0091] The thermosetting resin usually contains a large amount of phenolic hydroxyl groups and hydroxymethyl groups. Forming an ester bond and / or an ether bond between the anti-corrosion coating and the metal valve body is more conducive to achieving covalent bond binding between the two. Specifically, the metal valve body can be alkali-washed or plasma-treated to make its surface carry more hydroxyl groups and carboxyl groups. During the process of cross-linking and curing to form the anti-corrosion coating, the hydroxyl groups carried by the prepolymer and / or monomer of the thermosetting resin can react with the groups on the surface of the metal valve body to generate ester bonds and ether bonds, and the anti-corrosion coating is fixed on the surface of the metal valve body by means of covalent bond binding. Methods such as infrared test can be used to judge whether there are ester bonds and / or ether bonds in the pressure relief mechanism, and combined with XPS test analysis and the material of the metal valve body, the groups and bond energies that the thermosetting resin may carry, it can be judged whether the ester bonds and / or ether bonds also exist between the anti-corrosion coating and the metal valve body.

[0092] Meeting the given conditions is conducive to achieving covalent bond binding between the metal valve body and the anti-corrosion coating and improving the bonding strength between the two.

[0093] In some embodiments of the present application, the thickness of the anti-corrosion coating can be ≥ 1 μm. The thickness of the anti-corrosion coating can be measured by a film thickness tester. Increasing the thickness of the anti-corrosion coating is beneficial to improving the corrosion resistance of the pressure relief mechanism, and meeting the given conditions can enable the anti-corrosion coating to effectively protect the metal valve body.

[0094] In some embodiments of the present application, the metal valve body can include two relatively arranged first surfaces and second surfaces, and at least one of the first surface and the second surface can be provided with an anti-corrosion coating.

[0095] Combined Figures 1 to 3 Understand that the metal valve body 11 can include two relatively arranged first surfaces 11a and second surfaces 11b, and at least one of the first surface 11a and the second surface 11b can be provided with an anti-corrosion coating 12. Optionally, the first surface 11a and the second surface 11b are relatively arranged along the thickness direction of the metal valve body; additionally, the first surface 11a can be located on the side of the pressure relief mechanism close to the inside of the battery cell. Refer to Figure 1 Understand that the anti-corrosion coating 12 provided on the first surface 11a is beneficial to improving the corrosion resistance of the area of the pressure relief mechanism located inside the battery cell; refer to Figure 1 Understand that the anti-corrosion coating 12 provided on the second surface 11b is beneficial to improving the corrosion resistance of the area of the pressure relief mechanism located outside the battery cell, and is beneficial to avoiding the corrosion that the pressure relief mechanism may be caused during the liquid injection process or the battery cell usage environment. Additionally, the first surface 11a can be provided with an anti-corrosion coating 12. Compared with the second surface 11b, the first surface 11a of the metal valve body has a higher probability and longer time of contact with the electrolyte. Especially for the battery cells arranged in an inverted manner, the first surface 11a is immersed in the electrolyte for a long time. Setting the anti-corrosion coating 12 on the first surface 11a can further be beneficial to improving the corrosion resistance of the pressure relief mechanism and reducing the risk of premature valve opening or battery cell leakage. Meeting the given conditions can improve the corrosion resistance of the pressure relief mechanism.

[0096] In some embodiments of the present application, the thickness of the anti-corrosion coating provided on the first surface can be ≥ 1 μm, and can be optionally 20 μm to 70 μm.

[0097] Refer to Figure 1Understand that, for example, the thickness of the anti-corrosion coating 12 provided on the first surface 11a can be 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, etc., or can be a range composed of any of the above values. Meeting the given conditions can effectively protect the first surface of the metal valve body. Optionally, the thickness of the anti-corrosion coating 12 provided on the first surface 11a can be 20 μm to 70 μm. Increasing the thickness of the anti-corrosion coating is beneficial to improving the corrosion resistance effect of the pressure relief mechanism. The probability of corrosion of the first surface of the metal valve body in contact with the electrolyte is higher. The thickness of the anti-corrosion coating located on the first surface 11a meets the given conditions. On the one hand, it can play a good protective role in the first surface of the pressure relief mechanism and improve the corrosion resistance of the pressure relief mechanism. On the other hand, it can also reduce the risk of a significant increase in the opening pressure of the pressure relief mechanism that may be caused by an overly large thickness of the anti-corrosion coating. Thus, while improving the corrosion resistance effect of the pressure relief mechanism, it is further beneficial to the normal valve opening of the pressure relief mechanism.

[0098] In some embodiments of the present application, the thickness of the anti-corrosion coating provided on the second surface ≥ 1 μm, can be optionally 10 μm to 70 μm, and can be further optionally 10 μm to 30 μm.

[0099] Reference Figure 2 Understand that, for example, the thickness of the anti-corrosion coating 12 provided on the second surface 11b can be 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, etc., or can be a range composed of any of the above values. Meeting the given conditions can effectively protect the second surface of the metal valve body. Optionally, the thickness of the anti-corrosion coating 12 provided on the second surface 11b can be 10 μm to 70 μm. Meeting the given conditions can, on the one hand, play a good protective role in the second surface of the pressure relief mechanism and improve the corrosion resistance of the pressure relief mechanism. On the other hand, it can also reduce the risk of a significant increase in the opening pressure of the pressure relief mechanism that may be caused by an overly large thickness of the anti-corrosion coating. Further optionally, the thickness of the anti-corrosion coating 12 provided on the second surface 11b can be 10 μm to 30 μm. Compared with the first surface, the probability and degree of corrosion of the second surface of the metal valve body in contact with the electrolyte are relatively low. Meeting the given conditions can, while improving the corrosion resistance effect of the pressure relief mechanism, be further beneficial to the normal valve opening of the pressure relief mechanism.

[0100] In some embodiments of the present application, the total thickness of the anti-corrosion coatings provided on the first surface and the second surface can ≥ 1 μm, can be optionally 10 μm to 140 μm, and can be further optionally 20 μm to 100 μm.

[0101] Reference Figure 3Understand that, for example, the total thickness of the anti-corrosion coating 12 provided on the first surface 11a and the second surface 11b can be 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, etc., or can be a range composed of any of the above values. Optionally, the total thickness of the anti-corrosion coating 12 provided on the first surface 11a and the second surface 11b can be 10 μm to 140 μm, and further optionally can be 20 μm to 100 μm. Meeting the given conditions can not only play a good protective role for the pressure relief mechanism but also be beneficial to the normal valve opening of the pressure relief mechanism. Optionally, the thickness of the anti-corrosion coating 12 provided on the first surface 11a can be greater than or equal to the thickness of the anti-corrosion coating 12 provided on the second surface 11b. Meeting the given conditions is beneficial to obtaining a good corrosion resistance effect on the basis of a relatively small total thickness of the anti-corrosion coating, so that it can not only play a good protective role for the pressure relief mechanism but also be beneficial to the normal valve opening of the pressure relief mechanism.

[0102] In some embodiments of the present application, the mass retention rate of the anti-corrosion coating after being kept at 600 °C for 10 min can be ≥ 75%.

[0103] For example, the mass retention rate of the anti-corrosion coating after being kept at 600 °C for 10 min can be ≥ 75%, 80%, ≥ 85%, ≥ 90%, etc., or can be a range composed of any of the above values. The mass retention rate can be measured by thermogravimetric analysis and is equal to the mass remaining amount of the anti-corrosion coating after being kept at 600 °C for 10 min divided by the initial mass of the anti-corrosion coating and then multiplied by 100%. In the actual operation process, the given conditions can be met by forming a thermosetting resin in the anti-corrosion coating, etc. The anti-corrosion coating that meets the given conditions has a relatively high thermal stability and can maintain good structural stability and chemical stability at high temperatures, which is beneficial to further improving the corrosion resistance effect of the pressure relief mechanism during the long-term use of the battery cell and extending the service life.

[0104] In some embodiments of the present application, in the pressure relief mechanism, at 25 °C, the resistance between the metal valve body and the anti-corrosion coating can be ≥ 1 GΩ.

[0105] For example, at 25°C, the resistance between the metal valve body and the anti-corrosion coating can be ≥1 GΩ, ≥1.2 GΩ, ≥1.5 GΩ, ≥2 GΩ, ≥5 GΩ, etc. The anti-corrosion coating that meets the given conditions has good insulation, which is conducive to further reducing the risk of electrochemical corrosion of the pressure relief mechanism. During actual operation, the given conditions can be met by adjusting the material of the anti-corrosion coating, etc. Optionally, after the pressure relief mechanism is kept at 400°C for 30 minutes, the resistance between the metal valve body and the anti-corrosion coating at 25°C can be ≥1 GΩ. The anti-corrosion coating that meets the given conditions has both good thermal stability and insulation, which can further reduce the risk of electrochemical corrosion of the pressure relief mechanism.

[0106] In some embodiments of the present application, the tensile shear strength of the anti-corrosion coating can be ≥15 Mpa.

[0107] For example, the tensile shear strength of the anti-corrosion coating can be ≥15 Mpa, ≥18 Mpa, ≥20 Mpa, ≥25 Mpa, ≥30 Mpa, etc., or can be in the range composed of any of the above values. The tensile shear strength of the anti-corrosion coating can be tested with reference to GB / T 7124-2008 / ISO 4587:2003. During actual operation, the given conditions can be met by adjusting the covalent bond combination between the anti-corrosion coating and the metal valve body and / or the crosslinking degree of the resin in the anti-corrosion coating, etc. The anti-corrosion coating that meets the given conditions has a high bonding strength with the metal valve body and is not easy to fall off during long-term use.

[0108] In some embodiments of the present application, the flexibility of the anti-corrosion coating can meet: bending a 40 mm radius of curvature shaft rod by 30°, that is, the anti-corrosion coating is bent by 30° with a 40 mm radius of curvature shaft rod, and the coating does not fall off and has no cracks. The flexibility of the anti-corrosion coating can be measured by a three-point bending test with reference to GB6742-86. During actual operation, the given conditions can be met by adding a toughening agent to the anti-corrosion coating and / or adjusting the crosslinking degree of the resin in the anti-corrosion coating, etc. The anti-corrosion coating that meets the given conditions has good flexibility, which is conducive to the normal valve opening of the pressure relief mechanism.

[0109] The second aspect of the present application provides a method for preparing the pressure relief mechanism of the first aspect of the present application, which includes: forming an anti-corrosion coating on at least a part of the surface of the metal valve body. The features and effects described for the pressure relief mechanism of the first aspect of the present application also apply to the method for preparing the pressure relief mechanism of the second aspect of the present application, and will not be repeated here. Generally speaking, using this method can improve the corrosion resistance effect of the pressure relief mechanism.

[0110] In some embodiments of the present application, the method for preparing the pressure relief mechanism may include: activating the surface of the metal valve body; mixing a toughening agent, a prepolymer and / or monomer of a thermosetting resin with an organic solvent to obtain a coating slurry; coating the coating slurry on at least a part of the surface of the activated metal valve body and performing crosslinking curing. Adopting this method is beneficial to forming an anti-corrosion coating on the surface of the metal valve body, which has a low swelling rate in the electrolyte, good thermal stability, good flexibility, good insulation, and high bonding strength with the metal valve body. In the service environment of long-term contact with the electrolyte, the anti-corrosion coating is not prone to swelling and peeling, which is beneficial to the normal valve opening of the pressure relief mechanism while improving the corrosion resistance of the pressure relief mechanism.

[0111] In some embodiments of the present application, the toughening agent may include, but is not limited to, organic materials and / or inorganic nano-fillers. The organic materials may include, but are not limited to, at least one of natural rubber, nitrile rubber, styrene-butadiene rubber, nylon, bismaleimide, glass fiber, polyurethane; the inorganic nano-fillers may include, but are not limited to, at least one of alumina, magnesia, calcium oxide, barium oxide.

[0112] In some embodiments of the present application, the thermosetting resin may include, but is not limited to, at least one of epoxy resin, phenolic resin, polyimide resin, urea-formaldehyde resin, polyether ether ketone, polybenzimidazole resin, etc. Optionally, based on the total mass of the prepolymer and / or monomer of the thermosetting resin, the mass percentage content of hydroxymethyl in the prepolymer and / or monomer may be 10% - 15%, such as 10%, 11%, 12%, 13%, 14%, 15%, etc., or may be a range composed of any of the above values. Meeting the given conditions can take into account both the crosslinking degree and flexibility of the thermosetting resin, which is beneficial to making the anti-corrosion coating have a lower swelling rate in the electrolyte, improving the corrosion resistance of the pressure relief mechanism, and also beneficial to the normal valve opening of the pressure relief mechanism.

[0113] It should be noted that the above features and beneficial effects such as the selection of the toughening agent, thermosetting resin, relative dosage, the setting position and thickness of the anti-corrosion coating have been described in detail above and will not be repeated here.

[0114] In some embodiments of the present application, the type of the organic solvent may be a conventional selection in the art, such as it may include, but is not limited to, alcohol solvents. Optionally, the mass percentage concentration of the organic solvent in the coating slurry may be 20% - 99%, and further optionally 30% - 60%.

[0115] In some embodiments of the present application, the activation treatment may include alkali washing and / or plasma treatment.

[0116] By performing the activation treatment on the metal valve body, hydroxyl groups and / or carboxyl groups can be carried on the surface of the metal valve body, which is conducive to forming ether bond and / or ester bond connections between the metal valve body and the anti-corrosion coating, thereby improving the bonding strength therebetween. Among them, the alkaline cleaning solution, alkaline cleaning temperature, and alkaline cleaning time used for alkaline cleaning can all be conventional selections in the art. For example, alkaline cleaning can be carried out at room temperature, the alkaline cleaning solution can include but is not limited to sodium hydroxide solution and / or potassium hydroxide solution, etc., and the alkaline cleaning time can be not less than 0.5 min. Exemplarily, the metal valve body can be immersed in a sodium hydroxide solution at room temperature for 1 min, and the mass percentage concentration of sodium hydroxide in the solution can be selected from 1% to 3%. Alkaline cleaning is not only conducive to removing impurities on the surface of the metal valve body but also enables its surface to carry hydroxyl groups and / or carboxyl groups. The plasma treatment can use air as the gas source to activate the surface of the metal valve body at a preset treatment pressure (which can be selected from 50 Pa to 150 Pa). Specifically, the oxide layer on the surface of the metal valve body can be removed in advance using sandpaper. For example, the metal valve body can be polished successively with 200#, 500#, 1000#, and 3000# sandpapers, and then the metal valve body can be subjected to plasma treatment.

[0117] In some embodiments of the present application, the coating methods for coating the coating slurry on at least a part of the surface of the metal valve body after the activation treatment include but are not limited to at least one of spraying, scraping, spin coating, dip coating, etc.

[0118] In some embodiments of the present application, the temperature of the crosslinking and curing can be ≤ 300 °C, for example, it can be 25 °C, 50 °C, 80 °C, 100 °C, 120 °C, 150 °C, 180 °C, 200 °C, 250 °C, 300 °C, etc., or it can be a range composed of any of the above values. Optionally, the temperature of the crosslinking and curing can be 100 °C to 180 °C. Meeting the given conditions is not only conducive to obtaining a high curing efficiency but also can reduce the risk of generating more bubbles in the anti-corrosion coating due to too high a curing temperature, which is beneficial to improving the protection effect of the anti-corrosion coating on the metal valve body. Optionally, the crosslinking and curing can be completed by means of stepwise temperature increase. Exemplarily, the metal valve body coated with the coating slurry can be placed in an oven and kept warm at 45 °C, 65 °C, 85 °C, 105 °C, 125 °C, and 150 °C for 10 min respectively. The curing method of stepwise temperature increase is beneficial to further reducing the structural defects of the anti-corrosion coating and improving its protection effect on the metal valve body.

[0119] In some embodiments of the present application, the coating slurry can also include a curing agent. The dosage and beneficial effects of the curing agent have been described in detail in the foregoing part and will not be elaborated here. Optionally, the curing agent can include but is not limited to at least one of hexamethylenetetramine, paraformaldehyde, aniline, ammonia gas, formaldehyde, sodium phenylacetate, p-toluenesulfonyl chloride, and benzenesulfonyl chloride.

[0120] The third aspect of the present application provides a cover plate, which includes: the pressure relief mechanism of the first aspect of the present application, or the pressure relief mechanism prepared by using the method for preparing the pressure relief mechanism of the second aspect of the present application. Optionally, the cover plate of the third aspect of the present application can be used in an electric core. Exemplarily, the electric core may include a housing and the cover plate, at least one end of the housing has an opening, and the cover plate is used to seal the opening.

[0121] In some embodiments of the present application, the cover plate of the third aspect of the present application and the pressure relief mechanism may be integrally formed.

[0122] In some embodiments of the present application, the cover plate of the third aspect of the present application may include a light cover plate and a pressure relief mechanism through hole penetrating in the thickness direction of the light cover plate. The pressure relief mechanism is arranged in the pressure relief mechanism through hole and welded to the light cover plate. In addition, the cover plate may optionally include other conventional components or structural designs other than the light cover plate and the pressure relief mechanism. Exemplarily, the cover plate may include, but is not limited to, lower plastic and / or upper plastic. Optionally, the light cover plate may include, but is not limited to, at least one of a pole through hole, a liquid injection hole, and an exhaust port.

[0123] The fourth aspect of the present application provides a battery, which includes: the pressure relief mechanism of the first aspect of the present application, or the pressure relief mechanism prepared by using the method for preparing the pressure relief mechanism of the second aspect of the present application, or the cover plate of the third aspect of the present application. Thereby, the risk of the battery opening the valve or leaking liquid in advance can be reduced.

[0124] A battery refers to a battery that can be activated by charging after discharging and can continue to be used.

[0125] In some embodiments, the battery includes a battery cell, and the pressure relief mechanism can be located at the upper and / or lower part of the battery cell. Exemplarily, the battery can include a battery cell, and the battery cell includes a housing and a cover plate for closing the open end of the housing. Among them, the pressure relief mechanism can be provided on the cover plate. In the battery, the battery cell can be placed upright, that is, the cover plate is located at the top of the battery cell. At this time, the pressure relief mechanism is located at the upper part of the battery cell. Or, the battery cell can also be placed upside down, that is, the cover plate is located at the bottom of the battery cell. At this time, the pressure relief mechanism is located at the bottom of the battery cell. And / or, the pressure relief mechanism can be provided on the housing, such as on the bottom wall of the housing opposite to the cover plate and / or on the side wall of the housing connected to the cover plate. At this time, the pressure relief mechanism can also be located at the upper and / or lower part of the battery cell by placing the battery cell upright or upside down. It can be understood that even if the pressure relief mechanism is always in contact with the electrolyte at the lower part of the battery cell, it can still achieve a good corrosion resistance effect based on the low swelling rate of the anti-corrosion coating, reducing the risk of premature valve opening or battery cell leakage. Optionally, the pressure relief mechanism can be integrally formed with the cover plate, and / or the pressure relief mechanism can be integrally formed with the housing.

[0126] In some embodiments, the first surface of the metal valve body in the pressure relief mechanism faces the inside of the battery cell. The feature of providing the anti-corrosion coating on the first surface of the metal valve body has been described in the foregoing part, and will not be repeated here. Meeting the given conditions is beneficial to further improving the corrosion resistance effect of the pressure relief mechanism.

[0127] Generally, a battery includes a positive electrode plate, a negative electrode plate, a separator, and an electrolyte. During the charging and discharging process of the battery, active ions are embedded and removed back and forth between the positive electrode plate and the negative electrode plate. The separator is arranged between the positive electrode plate and the negative electrode plate to play a role in isolation. The electrolyte plays a role in conducting ions between the positive electrode plate and the negative electrode plate. Among them, the raw material composition and structure of the positive electrode plate, the raw material composition and structure of the negative electrode plate, the material and structural characteristics of the separator, the composition of the electrolyte, etc. can all be conventional selections in the art.

[0128] The embodiments of the present application do not particularly limit the type of the battery, and it can include but is not limited to lithium batteries, sodium batteries, etc.

[0129] The embodiments of the present application do not particularly limit the shape of the battery, and it can be cylindrical, square or any other shape. For example Figure 4 is a battery 1 with a square structure as an example.

[0130] In some embodiments, the battery can include an outer package. The outer package is used to encapsulate the positive electrode plate, the negative electrode plate, and the electrolyte.

[0131] In some embodiments, the outer package may include a housing and a cover plate. The housing may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose to form a receiving cavity. The housing has an opening communicating with the receiving cavity, and the cover plate can be disposed on the opening to close the receiving cavity.

[0132] The positive electrode plate, the negative electrode plate and the separator can be formed into an electrode assembly by a winding process or a stacking process. The electrode assembly is encapsulated in the receiving cavity. The number of electrode assemblies included in the battery can be one or several, which can be adjusted according to requirements.

[0133] In some embodiments, the outer package of the battery can include a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell.

[0134] The outer package of the battery can also include a soft package, such as a pouch soft package. The material of the soft package can be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0135] In some embodiments, the battery can be either a battery cell (which can be understood as an electric core) or a battery module or battery pack assembled from battery cells. The number of batteries included in the battery module or battery pack can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.

[0136] Figure 5 is the battery module 2 as an example. Refer to Figure 5 , in the battery module 2, a plurality of batteries 1 can be arranged in sequence along the length direction of the battery module 2. Of course, they can also be arranged in any other way. Further, the plurality of batteries 1 can be fixed by fasteners.

[0137] The battery module 2 can further include a housing having a receiving space, and a plurality of batteries 1 are received in the receiving space. In some embodiments, the above battery module can also be assembled into a battery pack, and the number of battery modules included in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0138] Figure 6 and Figure 7 is the battery pack 3 as an example. Refer to Figure 6 and Figure 7 , in the battery pack 3, it can include a battery box and a plurality of battery modules 2 disposed in the battery box. The battery box includes an upper box body 4 and a lower box body 5. The upper box body 4 can be disposed on the lower box body 5 to form a closed space for receiving the battery modules 2. The plurality of battery modules 2 can be arranged in the battery box in any way.

[0139] The fifth aspect of the present application provides an electrical device, which includes: the battery of the fourth aspect of the present application.

[0140] Specifically, the battery can serve as the power source of the electrical device or as the energy storage unit of the electrical device. The electrical device may include, but is not limited to, mobile devices (such as mobile phones, laptops), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks), electric trains, ships, satellites, and energy storage systems.

[0141] Figure 8 is an example of an electrical device. The electrical device includes a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. Another example of an electrical device may include a mobile phone, a tablet computer, a laptop. This electrical device generally requires thinness and lightness, and a battery can be used as the power source.

[0142] Hereinafter, embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application and should not be construed as a limitation of the present application. For those not specified in the embodiments regarding specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in the field or according to the product specifications. For reagents or instruments not specified as to the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0143] In the following embodiments and comparative examples, the specific implementation manner with an explosion-proof valve as the pressure relief mechanism will be described.

[0144] Example 1

[0145] 1. Preparation of secondary battery

[0146] Preparation of positive electrode sheet:

[0147] Mix the positive electrode active material LiFePO, conductive agent Super P (SP), and polyvinylidene fluoride (PVDF) in a mass ratio of 97:1:2 and add them to N-methylpyrrolidone (NMP), stir and disperse to make a positive electrode active paste. The positive electrode active paste is coated on both sides of an aluminum foil with a thickness of 13 μm with equal thickness, and the surface density of single-sided coating is 0.35 g / 1540.25 mm 2 , after coating, dry, cold press, slit, and prepare to obtain the positive electrode sheet.

[0148] Preparation of negative electrode sheet:

[0149] The graphite as the negative electrode active material, SP as the conductive agent, sodium carboxymethyl cellulose, and styrene-butadiene rubber (SBR) were mixed in a mass ratio of 97:1:1:1 and added to deionized water, stirred and dispersed to prepare a negative electrode active paste. The negative electrode active paste was coated on both sides with equal thickness on a copper foil with a thickness of 6 μm, and the surface density of the single-sided coating was 0.155 g / 1540.25 mm2. After coating, it was dried, cold-pressed, slit, and a negative electrode plate was prepared.

[0150] Preparation of electrolyte:

[0151] At 25 °C, ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain a mixed solvent, and then LiPF 6 was dissolved in the above-mentioned mixed solvent to obtain an electrolyte, where the concentration of LiPF 6 was 1 mol / L.

[0152] Separator: A porous polyethylene film with a thickness of 7 μm was used as the separator.

[0153] Preparation of pressure relief mechanism:

[0154] At room temperature, a 500-μm-thick metal aluminum valve body was placed in a sodium hydroxide solution with a mass percentage concentration of 2 wt%, and soaked for 2 min; the toughening agent inorganic particles (aluminum oxide) and the prepolymer of the thermosetting resin (phenolic resin) were dissolved in anhydrous ethanol, an organic solvent, in a mass ratio of 30:70 to obtain a coating paste. Among the first surface and the second surface that are oppositely arranged along the thickness direction of the metal valve body after alkali immersion, the obtained coating paste was coated on the first surface, and the metal valve body with the coating paste was placed in an oven for stepwise temperature-rising crosslinking and curing, and kept warm at 45 °C, 65 °C, 85 °C, 105 °C, 125 °C, and 150 °C for 10 min each to obtain an explosion-proof valve.

[0155] The obtained explosion-proof valve was welded into the explosion-proof valve through-hole of the light aluminum sheet, so that the first surface of the explosion-proof valve was located on the side of the light aluminum sheet facing the inside of the housing (wherein, the metal aluminum valve body has a notch, and the thickness of the notch area is less than the thickness of the metal aluminum valve body, the light aluminum sheet, and the housing); the above-mentioned positive electrode plate, separator, and negative electrode plate were stacked and wound in sequence, formed, and an electrode assembly was obtained; the electrode was placed in an aluminum housing, the above-prepared electrolyte was added, and the housing was sealed with a cover plate including the above-mentioned light aluminum sheet. After processes such as encapsulation, standing, formation, and aging, a battery was obtained.

[0156] 2. Testing of pressure relief mechanism

[0157] (1) Swelling rate test of anti-corrosion coating

[0158] Mix ethylene carbonate and dimethyl carbonate in a volume ratio of 1:1 to obtain an organic solvent. Mix a lithium salt with a concentration of 1 mol / L of LiPF 6 with the organic solvent to obtain an electrolyte solution, and transfer the electrolyte solution to a constant temperature bath at 60°C for heating. Immerse the prepared pressure relief mechanism in the electrolyte solution at 60°C for 24 hours. Measure the volume of the pressure relief mechanism sample before and after immersion respectively. The swelling rate of the anti-corrosion coating after being immersed in the electrolyte solution at 60°C for 24 hours = (V 1 -V 0 ) / V 0 ×100%, where V 0 is the volume of the sample to be tested before immersion, and V 1 is the volume of the sample to be tested after immersion.

[0159] (2) Flexibility test of the anti-corrosion coating

[0160] Refer to GB6742-86 to test the bending of a shaft rod with a curvature radius of 40 mm by 30°, and observe whether there is peeling or cracking of the anti-corrosion coating.

[0161] (3) Insulation test of the anti-corrosion coating

[0162] After keeping the pressure relief mechanism at 400°C for 30 minutes and then naturally cooling it to 25°C, measure the resistance between the metal valve body and the anti-corrosion coating. When anti-corrosion coatings are formed on both the first side and the second side of the metal valve body, use the anti-corrosion coating on the first side as the test object.

[0163] (4) Thermal stability test of the anti-corrosion coating

[0164] Heat the pressure relief mechanism at a rate of 10°C / min to 600°C and keep it for 10 minutes, and calculate the mass retention rate of the anti-corrosion coating based on the mass change of the pressure relief mechanism before and after heating and the mass of the metal aluminum valve body.

[0165] (5) Shear strength test of the anti-corrosion coating

[0166] Refer to GB / T 7124-2008 / ISO 4587:2003 to test the tensile shear strength of the anti-corrosion coating.

[0167] (6) Corrosion resistance of the pressure relief mechanism

[0168] For the above explosion-proof valve, invert the secondary battery so that the explosion-proof valve is at the bottom of the secondary battery. Connect the housing and the explosion-proof valve to the negative electrode to make it negatively charged. After standing for a period of time, disassemble the secondary battery and observe the corrosion condition of the explosion-proof valve.

[0169] Note: It should be noted that in the secondary battery used to test the corrosion resistance of the explosion-proof valve, anti-corrosion coatings with the same composition and thickness as those on the first and second surfaces of the metal aluminum valve body are also provided on the inner and outer surfaces of its housing and the surfaces of the cover plate's polished aluminum sheet facing the inside and outside of the battery. The thickness at the notch of the explosion-proof valve is thinner, and under the same conditions, corrosion and liquid leakage will occur preferentially in other areas.

[0170] (7) Opening pressure test of the pressure relief mechanism

[0171] Fix and seal the pressure relief mechanism with a fixture, and inflate the closed space jointly formed by the fixture and the pressure relief mechanism until the pressure relief mechanism opens. The pressure at the opening moment is the opening pressure of the pressure relief mechanism under this specific fixture. In the above-mentioned secondary battery, its housing and cover plate form the fixture for fixing the explosion-proof valve. Connect the ventilation pipeline of the pressure test equipment to the liquid injection hole of the battery, and inflate the closed space jointly formed by the housing, cover plate and explosion-proof valve at a speed of 10 KPa / s until the explosion-proof valve opens, and record the pressure at the opening moment, which is the opening pressure of the explosion-proof valve.

[0172] Examples 2 - 26 and Comparative Examples 1 - 4

[0173] The differences between Examples 2 - 26 and Comparative Examples 1 - 4 and Example 1 are shown in Table 1 in detail. Among them, in Example 3, alkali immersion treatment was not carried out before forming the anti-corrosion coating on the surface of the metal aluminum valve body.

[0174] Carry out relevant tests on the pressure relief mechanisms taking the explosion-proof valve as an example in Examples 1 - 26 and Comparative Examples 1 - 4. The test results are shown in Table 2 in detail. In Table 2, for the corrosion resistance time and liquid leakage situation of the explosion-proof valve, the values before and after "&" respectively represent the corrosion resistance time and the liquid leakage situation. Taking Example 1 as an example, the statement "1Y&no liquid leakage" means that the corrosion resistance time of the explosion-proof valve is one year, and no liquid leakage occurred after one year; taking Comparative Example 1 as an example, the statement "8h&5D liquid leakage" means that the corrosion resistance time of the explosion-proof valve is 8h, corrosion occurred after 8h, and liquid leakage occurred after 5 days; correspondingly, the statement "3D&10D liquid leakage" means that the corrosion resistance time of the explosion-proof valve is 3 days, and liquid leakage occurred after 10 days.

[0175] Table 1 Differences between Examples 1 - 26 and Comparative Examples 1 - 4

[0176]

[0177]

[0178] Table 2 Test results of Examples 1 - 26 and Comparative Examples 1 - 4

[0179]

[0180]

[0181] Conclusion:

[0182] Based on the comprehensive implementation examples 1 to 26, comparative examples 1 to 4, and Tables 1 to 2, it can be seen that the anti-corrosion coating formed on the surface of the explosion-proof valve with a swelling rate ≤ 2% after being immersed in the electrolyte at 60°C for 24 hours can effectively block the infiltration of anions and cations in the electrolyte into the coating, improve the corrosion resistance of the explosion-proof valve, and reduce the risk of electrolyte leakage in the battery cell; optionally, setting an anti-corrosion coating on the side of the explosion-proof valve facing the inside of the battery case can further reduce the risk of the explosion-proof valve being corroded by the electrolyte. Optionally, the swelling rate of the anti-corrosion coating can be ≤ 1%, and further optionally can be ≤ 0.2%. Furthermore, introducing a toughening agent into the anti-corrosion coating can also take into account the shear strength and flexibility of the anti-corrosion coating; performing alkali immersion treatment on the metal valve body before forming the anti-corrosion coating can further improve the adhesion of the anti-corrosion coating; in addition, the anti-corrosion coating with a swelling rate ≤ 2% can achieve a good anti-corrosion effect at a relatively low thickness and will not have an obvious impact on the opening pressure of the explosion-proof valve. Optionally, the total thickness of the anti-corrosion coating can be ≥ 15 μm, and further optionally can be 20 μm to 70 μm; additionally, the thickness of the anti-corrosion coating provided on the first surface of the explosion-proof valve can be optionally 20 μm to 70 μm. In summary, the pressure relief mechanism in this application has good corrosion resistance.

[0183] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be covered within the scope of the claims and the description of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A pressure relief mechanism, characterized in that, comprising: a metal valve body; Anti-corrosion coating, the anti-corrosion coating is provided on at least a part of the surface of the metal valve body, the swelling rate of the anti-corrosion coating immersed in the electrolyte at 60 °C for 24 h is ≤ 2%, and the electrolyte uses ethylene carbonate and dimethyl carbonate mixed in a volume ratio of 1:1 as the solvent, and uses LiPF 6 as the lithium salt, and is mixed according to a lithium salt concentration of 1 mol / L.

2. The pressure relief mechanism according to claim 1, characterized in that, the swelling rate of the anti-corrosion coating immersed in the electrolyte at 60 °C for 24 h is ≤ 1%, optionally ≤ 0.2%.

3. The pressure relief mechanism according to claim 1 or 2, characterized in that, meeting at least one of the following conditions: the anti-corrosion coating is provided on at least a part of the surface of the area where the metal valve body has a notch; the anti-corrosion coating comprises a thermosetting resin and a toughening agent; the anti-corrosion coating comprises a three-dimensional network structure.

4. The pressure relief mechanism according to claim 3, characterized in that, the thermosetting resin comprises at least one of epoxy resin, phenolic resin, polyimide resin, urea-formaldehyde resin, polyether ether ketone, and polybenzimidazole resin.

5. The pressure relief mechanism according to claim 3 or 4, characterized in that, based on the total mass of the anti-corrosion coating, the mass percentage content of the thermosetting resin is 40% - 99%, optionally 80% - 95%; and / or, the mass percentage content of the toughening agent is 1% - 60%, optionally 5% - 15%.

6. The pressure relief mechanism according to any one of claims 3 - 5, characterized in that, the raw material composition of the anti-corrosion coating comprises: 40 - 99 parts by weight of the prepolymer and / or monomer of the thermosetting resin, 1 - 60 parts by weight of the toughening agent, and 0 - 5 parts by weight of the curing agent.

7. The pressure relief mechanism according to any one of claims 1 - 6, characterized in that, there is a covalent bond connection between the metal valve body and the anti-corrosion coating.

8. The pressure relief mechanism according to claim 7, characterized in that, the covalent bond comprises an ester bond and / or an ether bond.

9. The pressure relief mechanism according to any one of claims 1 - 8, characterized in that, the thickness of the anti-corrosion coating ≥ 1 μm; and / or, the metal valve body comprises two relatively arranged first surfaces and second surfaces, and at least one of the first surface and the second surface is provided with the anti-corrosion coating.

10. The pressure relief mechanism according to claim 9, characterized in that, meeting at least one of the following conditions: the thickness of the anti-corrosion coating provided on the first surface ≥ 1 μm, optionally 20 μm - 70 μm; the thickness of the anti-corrosion coating provided on the second surface ≥ 1 μm, optionally 10 μm - 70 μm, further optionally 10 μm - 30 μm; the total thickness of the anti-corrosion coating provided on the first surface and the second surface is ≥ 1 μm, optionally 10 μm - 140 μm, further optionally 20 μm - 100 μm.

11. The pressure relief mechanism according to any one of claims 1 - 10, characterized in that, meeting at least one of the following conditions: the mass residue rate of the anti-corrosion coating when kept at 600 °C for 10 min ≥ 75%; in the pressure relief mechanism, at 25 °C, the resistance between the metal valve body and the anti-corrosion coating ≥ 1 GΩ; the tensile shear strength of the anti-corrosion coating ≥ 15 MPa; The flexibility of the anti-corrosion coating meets the requirement that it can be bent by 30° around a shaft rod with a curvature radius of 40 mm.

12. A method for preparing the pressure relief mechanism according to any one of claims 1 to 11, characterized in that, it includes: forming an anti-corrosion coating on at least a part of the surface of the metal valve body.

13. The method according to claim 12, characterized in that, it includes: activating the surface of the metal valve body; mixing a toughening agent, a prepolymer and / or a monomer of a thermosetting resin with an organic solvent to obtain a coating slurry; coating the coating slurry on at least a part of the surface of the metal valve body after the activation treatment, and performing crosslinking curing.

14. The method according to claim 13, characterized in that, it meets at least one of the following conditions: the activation treatment includes alkali washing and / or plasma treatment; The toughening agent includes organic materials and / or inorganic nano-fillers. The organic materials include at least one of natural rubber, nitrile rubber, styrene-butadiene rubber, nylon, bismaleimide, glass fiber, and polyurethane; and / or, the inorganic nano-fillers include at least one of boehmite, alumina, zinc oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, barium oxide, nickel oxide, tin oxide, cerium oxide, yttrium oxide, hafnium oxide, aluminum hydroxide, magnesium hydroxide, silicon carbide, boron carbide, aluminum nitride, silicon nitride, boron nitride, magnesium fluoride, calcium fluoride, barium fluoride, barium sulfate, magnesium aluminum silicate, lithium magnesium silicate, sodium magnesium silicate, bentonite, hectorite, zirconium titanate, barium titanate, Pb(Zr,Ti)O 3 、Pb 1-m La m Zr 1-n Ti n O 3 、Pb(Mg 1 / 3 Nb 2 / 3 )O 3 PbTiO 3 、and at least one of their respective modified inorganic particles, 0 < m < 1, 0 < n < 1. Optionally, the inorganic nano-fillers include at least one of alumina, magnesium oxide, calcium oxide, and barium oxide; the coating slurry further includes a curing agent. Optionally, the curing agent includes at least one of hexamethylenetetramine, paraformaldehyde, aniline, ammonia gas, formaldehyde, sodium phenylacetate, p-toluenesulfonyl chloride, and benzenesulfonyl chloride.

15. A cover plate, characterized in that, it includes: the pressure relief mechanism according to any one of claims 1 to 11, or the pressure relief mechanism prepared by the method according to any one of claims 12 to 14.

16. A battery, characterized in that, it includes: the pressure relief mechanism according to any one of claims 1 to 11, or the pressure relief mechanism prepared by the method according to any one of claims 12 to 14, or the cover plate according to claim 15.

17. The battery according to claim 16, characterized in that, the battery includes an electrode core, and the pressure relief mechanism is located at the upper part and / or the lower part of the electrode core.

18. The battery according to claim 17, characterized in that, the first surface of the metal valve body in the pressure relief mechanism faces the inside of the electrode core.

19. An electrical device, characterized in that, it includes the battery according to any one of claims 16 to 18.

Images