Cover plate assembly and battery cell

Abstract

The application discloses a cover plate assembly and a battery monomer, and relates to the technical field of batteries, wherein the cover plate assembly comprises a cover plate body, an explosion-proof valve and a containing structure, the cover plate body is provided with an explosion-proof port, the explosion-proof valve is arranged at the explosion-proof port, the containing structure is arranged on one side of the cover plate body facing a battery cell shell, the containing structure is provided with a containing cavity, the containing cavity is filled with a reactant, and the melting point of the containing structure is lower than a preset opening temperature of the explosion-proof valve; in the technical scheme provided by the embodiment of the application, when the containing structure is melted by high temperature in the initial stage of thermal runaway, the reactant in the containing structure will rapidly react with electrolyte, thereby generating a large amount of gas and heat, the gas generated by the reaction accumulates in the battery cell shell, the internal pressure of the battery rapidly increases, the explosion-proof valve is opened in advance, the internal pressure accumulation is avoided to cause explosion, and the safety of the battery is improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a cover plate assembly and a battery cell. Background Technology

[0002] Currently, the battery casing of a square battery includes a cell casing and a cover plate assembly. The casing of a single cell provides a sealed space to accommodate the electrode assembly and electrolyte. The positive and negative terminals are led out of the sealed space through the cover plate assembly.

[0003] The cover assembly usually has an explosion-proof port to connect the inside of the battery to the outside. An explosion-proof valve is installed on the explosion-proof port to release pressure in the event of battery thermal runaway. The explosion-proof valve will only open when the internal pressure of the battery reaches the preset opening pressure. However, in the early stage of battery thermal runaway, the internal pressure increases slowly and cannot reach the preset opening pressure to open the explosion-proof valve in advance, which increases the risk of thermal runaway. Utility Model Content

[0004] This application proposes a cover plate assembly and a battery cell, aiming to provide a cover plate assembly that can open the explosion-proof valve in advance for early pressure relief.

[0005] One embodiment of this application provides a cover plate assembly, comprising: The cover plate body has an explosion-proof opening; An explosion-proof valve is provided at the explosion-proof port; A receiving structure is provided on the side of the cover plate body facing the cell housing. The receiving structure has a receiving cavity filled with reactants. The melting point of the receiving structure is lower than the preset opening temperature of the explosion-proof valve.

[0006] In one embodiment, one of the receiving structure and the cover plate body is provided with a snap-fit ​​part, and the other is provided with a mating part, wherein the snap-fit ​​part snaps into the mating part.

[0007] In one embodiment, the receiving structure has an adhesive portion facing the cover plate body, and the receiving structure is bonded to the cover plate body through the adhesive portion.

[0008] In one embodiment, the containment structure is polypropylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinyl acetate, or polybutene.

[0009] In one embodiment, the reactant is deionized water, an aqueous solution of sodium hydroxide, or an aqueous solution of sodium chloride.

[0010] In one embodiment, the wall thickness of the receiving structure is 0.1 mm to 5 mm.

[0011] In one embodiment, the thickness of the receiving structure along the direction perpendicular to the cover plate body is 5 mm to 15 mm.

[0012] In one embodiment, the cover plate assembly further includes a pole assembly, which includes a positive pole and a negative pole, the positive pole and the negative pole passing through the cover plate body; the explosion-proof valve is disposed between the positive pole and the negative pole, and the receiving structure is disposed close to the explosion-proof valve.

[0013] In one embodiment, the cover plate assembly further includes a lower plastic layer disposed on the side of the cover plate body facing the cell housing, the lower plastic layer having a clearance hole, and the receiving structure passing through the clearance hole.

[0014] An embodiment of this application also proposes a battery cell, including a cell housing, an electrode assembly, and a cover plate assembly as described above, wherein the cover plate assembly and the cell housing enclose a receiving cavity, and the electrode assembly and the receiving structure are disposed in the receiving cavity.

[0015] This application utilizes an internal containment structure filled with reactants that react with the electrolyte. This containment structure can melt in the early stages of thermal runaway, and the gas generated by the reaction of the reactants with the electrolyte prematurely breaks through the explosion-proof valve, thus allowing for early pressure relief of the battery. Specifically, the explosion-proof valve is located at the explosion-proof opening of the cover body, and the containment structure is located on the same side of the explosion-proof valve, facing the battery cell casing. The containment structure has a cavity filled with reactants that can chemically react with the electrolyte, and the melting point of the containment structure is lower than the preset opening temperature of the explosion-proof valve. When the containment structure melts at high temperature in the early stages of thermal runaway, the reactants inside rapidly react with the electrolyte, generating a large amount of gas and heat. The gas accumulated in the battery cell casing causes a rapid increase in internal battery pressure, thereby opening the explosion-proof valve. This ensures pressure relief in the early stages of battery thermal runaway, preventing internal pressure buildup and potential explosion, reducing the risk of fire and explosion, and improving battery safety. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments or prior art of this application, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of a structure of an embodiment of the cover plate assembly provided in this application; Figure 2 for Figure 1 A partially enlarged view of the first embodiment of the accommodating structure at point A; Figure 3 for Figure 1 A partially enlarged view of the second embodiment of the accommodating structure at point A; Figure 4 An exploded structural diagram of the cover plate assembly provided in this application; Figure 5 This is an exploded structural diagram of an embodiment of a battery cell provided in this application.

[0018] Explanation of icon numbers: 100. Cover plate assembly; 1. Cover plate body; 11. Snap-fit ​​part; 1a. Explosion-proof port; 1b. Electrode lead-out hole; 1c. Liquid injection hole; 2. Explosion-proof valve; 3. Receiving structure; 31. Reactant; 32. Adhesive part; 3a. Receiving cavity; 3b. Fitting part; 4. Electrode assembly; 41. Positive electrode; 42. Negative electrode; 5. Lower plastic; 6. Upper plastic; 7. Sealing ring; 8. Press block; 200. Cell housing; 200a. Receiving cavity; 300. Electrode assembly; 400. Adapter piece. Detailed Implementation

[0019] The technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of several embodiments. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0020] It should be noted that if multiple embodiments of this application involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0021] Furthermore, if multiple embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text implies three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0022] Currently, battery cover assemblies typically have explosion-proof vents to connect the battery's interior to the outside environment. These vents are equipped with explosion-proof valves to release pressure in the event of thermal runaway. The explosion-proof valve typically includes a flexible diaphragm or spring mechanism, which are highly sensitive to pressure changes. When the internal battery pressure reaches a preset opening pressure, the diaphragm or spring is pushed to open the valve, releasing excess pressure. However, the explosion-proof valve only opens when the internal battery pressure reaches the preset opening pressure. In the early stages of thermal runaway, the internal pressure increases slowly, preventing the valve from opening prematurely.

[0023] In the early stages of battery thermal runaway, opening the explosion-proof valve as early as possible can effectively release excess gas and heat generated inside the battery, thereby slowing down the further rise in temperature and pressure. This helps to delay the process of thermal runaway, reduce the intensity of the internal reaction of the battery, and reduce the risk of battery casing rupture or explosion. The later the explosion-proof valve opens, the greater the risk of battery thermal runaway, and the worse the safety.

[0024] To address the aforementioned problems, this application proposes a cover plate assembly 100 to solve the technical issues mentioned above.

[0025] Please see Figure 1 In one embodiment of this application, the cover plate assembly 100 includes a cover plate body 1, an explosion-proof valve 2, and a receiving structure 3. The cover plate body 1 has an explosion-proof port 1a, the explosion-proof valve 2 is disposed at the explosion-proof port 1a, and the receiving structure 3 is disposed on the side of the cover plate body 1 facing the cell housing 200. The receiving structure 3 has a receiving cavity 3a, which is filled with a reactant 31. The melting point of the receiving structure 3 is lower than the preset opening temperature of the explosion-proof valve 2.

[0026] In the technical solution of this application, the preset opening temperature of the explosion-proof valve 2 is between 250°C and 300°C, and the melting point of the receiving structure 3 is controlled between 100°C and 220°C depending on its material, so as to ensure that the maximum melting point of the receiving structure 3 is also lower than the minimum value of the preset opening temperature of the explosion-proof valve 2, thereby reducing the opening temperature of the explosion-proof valve 2 and realizing pressure relief as early as possible in the initial stage of thermal runaway.

[0027] It should be noted that in the early stage of thermal runaway (thermal runaway without valve opening), heat is conducted to the containment structure 3, which melts and releases reactant 31 that can react with the battery cell. The reactant 31 reacts rapidly with the battery cell near the explosion-proof valve 2, releasing a large amount of heat and gas, which causes the internal pressure of the battery cell to increase instantaneously. This causes the explosion-proof valve 2 to open prematurely to release pressure before the normal battery cell opening temperature is reached.

[0028] Understandably, battery thermal runaway is usually caused by uncontrolled chemical reactions within the battery. These reactions release a large amount of heat, causing a rapid increase in the battery's internal temperature. For example, lithium dendrites in a lithium-ion battery penetrating the separator and causing a short circuit, or overcharging the battery leading to electrolyte decomposition, can both trigger exothermic reactions. Correspondingly, the pressure inside the cell casing 200 will gradually increase. Therefore, when a battery experiences thermal runaway, the change in its internal temperature is directly proportional to the change in pressure.

[0029] In the early stages of battery thermal runaway, the receiving structure 3 on the cover assembly 100 can be melted by a temperature higher than the normal operating temperature of the battery but lower than the preset opening temperature of the explosion-proof valve 2. This releases the reactants 31 stored in the receiving cavity 3a. The reactants 31 enter the cell housing 200 and react violently with the electrolyte inside the cell housing 200, releasing a large amount of gas. This rapidly increases the internal pressure of the battery, eventually rupturing the explosion-proof valve 2. Therefore, the cover assembly 100 can, in the early stages of battery thermal runaway when the internal pressure change is not significant (i.e., when the current pressure is lower than the preset opening pressure of the explosion-proof valve 2), activate the explosion-proof valve 2 by assisting in the chemical reaction that increases the internal pressure. This allows for early pressure relief, effectively reducing the risk of a continuous increase in internal battery pressure in the early stages of thermal runaway. It prevents battery explosion or rupture due to pressure buildup, significantly improving battery safety and providing the battery management system with more time to take further safety measures, such as cutting off the power or activating the cooling system, thereby maximizing the safety of users and equipment.

[0030] This application achieves early battery depressurization by providing a receiving structure 3 inside the casing and filling the receiving structure 3 with a reactant 31 that reacts with the electrolyte. The receiving structure 3 can melt in the early stages of thermal runaway, and the gas generated by the reaction of the reactant 31 with the electrolyte prematurely breaks through the explosion-proof valve 2. Specifically, the explosion-proof valve 2 is located at the explosion-proof port 1a of the cover body 1, and the receiving structure 3 is located on the same side as the explosion-proof valve 2 and on the side of the cover body 1 facing the cell casing 200. The receiving structure 3 has a receiving cavity 3a, which is filled with the reactant 31 that can chemically react with the electrolyte, and the melting point of the receiving structure 3 is lower than the preset opening temperature of the explosion-proof valve 2. When the containment structure 3 is melted by high temperature in the early stage of thermal runaway, the reactants 31 inside will react rapidly with the electrolyte, thereby generating a large amount of gas and heat. The gas generated by the reaction accumulates in the cell casing 200, causing the internal pressure of the battery to rise rapidly, thereby opening the explosion-proof valve 2, ensuring that the pressure can be released in the early stage of battery thermal runaway, avoiding the accumulation of internal pressure and causing an explosion, reducing the risk of fire and explosion, and improving the safety of the battery.

[0031] It should be noted that the receiving structure 3 can be a cubic structure, a cylindrical structure, or a conical structure. This application does not limit the specific shape of the receiving structure 3. In one embodiment of this application, the receiving structure 3 is a cuboid structure. For details, please refer to further reading. Figure 1 and combined Figure 2 and Figure 3 The cuboid structure has a regular geometric shape, which facilitates processing, manufacturing, and precise assembly into the cover assembly 100. Its regular shape allows the housing structure 3 to occupy a more reasonable amount of space within the cover assembly 100, better adapting to battery designs of different sizes and shapes. Furthermore, the cuboid structure melts relatively uniformly when heated, helping to ensure that the reactants 31 are released stably and rapidly when the housing structure 3 melts, thereby reacting with the electrolyte to generate a large amount of gas, rapidly increasing the internal pressure of the battery, and prematurely opening the explosion-proof valve 2, effectively reducing the risk of battery thermal runaway and improving battery safety.

[0032] Furthermore, to accommodate the shape of the housing structure 3, the internal cavity 3a of the housing structure 3 is also a cuboid space. The cuboid shape of the cavity 3a maximizes the use of the internal space of the housing structure 3, ensuring that the amount of reactant 31 is maximized. This allows for the release of more gas in the early stages of thermal runaway, more effectively increasing the internal pressure of the battery and opening the explosion-proof valve 2 earlier. In addition, the regular shape of the cuboid cavity 3a makes the distribution of reactant 31 more uniform and the reaction more complete, further improving the safety and reliability of the battery under thermal runaway conditions.

[0033] To prevent the reactant 31 within the containment cavity 3a from leaking into the battery and reacting with the electrolyte during normal operation, thus preventing battery damage, the containment cavity 3a in the containment structure 3 is a completely sealed cavity. This ensures that the reactant 31 will not leak or volatilize into the cavity, thereby preventing battery damage caused by accidental chemical reactions. This sealed containment cavity 3a ensures that the reactant 31 is only released and reacts with the electrolyte in the early stages of thermal runaway, when the containment structure 3 is melted by high temperatures, generating a large amount of gas to rapidly increase the internal pressure of the battery, allowing the explosion-proof valve 2 to open in advance for pressure relief. This not only improves battery safety but also extends battery life and ensures the stability and reliability of the battery under normal operating conditions.

[0034] Furthermore, the receiving structure 3 is an integral structure. To facilitate the addition of reactant 31, the receiving structure 3 has an addition hole (not shown in the figure). The position, shape, and size of the addition hole are not limited in this application. In the specific installation process, the reactant 31 is first added to the molded receiving structure 3 through the addition hole, and then the addition hole is sealed with a sealing plug to form a completely sealed cavity 3a. Finally, the receiving structure 3 is installed at the bottom of the cover plate body 1. By adopting an integral receiving structure 3 with a pre-designed addition hole, reactant 31 can be easily injected after molding, and then sealed with a sealing plug to form a completely sealed cavity. This ensures that reactant 31 does not leak or react prematurely, simplifies the assembly process, improves production efficiency and sealing reliability, and ensures stable operation of the battery under normal operating conditions, rapid response in case of thermal runaway, and early pressure relief, thereby improving safety.

[0035] It should be noted that the receiving structure 3 can be fixed to the bottom surface of the cover plate body 1 by means of bonding, snap-fitting or magnetic attraction. This application does not limit this. This application proposes two embodiments of fixing the receiving structure 3 by different fixing methods.

[0036] First Embodiment Please see Figure 2In the first embodiment of this application, the receiving structure 3 is fixed to the bottom surface of the cover body 1 by a snap-fit ​​method. Specifically, one of the receiving structure 3 and the cover body 1 is provided with a snap-fit ​​part 11, and the other is provided with a mating part 3b. That is, the receiving structure 3 may be provided with a snap-fit ​​part 11 and the cover body 1 may be provided with a mating part 3b; or the receiving structure 3 may be provided with a mating part 3b and the cover body 1 may be provided with a snap-fit ​​part 11. This application does not limit this. In this embodiment, the bottom surface of the cover body 1, that is, the side facing the inside of the battery, is provided with multiple hooks. Correspondingly, the receiving structure 3 is provided with a slot corresponding to the number of hooks on the side facing the cover body 1. Each hook engages with a slot to fix the receiving structure 3. The receiving structure 3 is fixed to the bottom surface of the cover plate body 1 by snap-fitting. The hooks and slots are matched one by one, which can achieve quick positioning and firm installation without the need for additional tools. This simplifies the assembly process, improves production efficiency, and facilitates later maintenance and replacement. The snap-fit ​​structure occupies little space, which is conducive to the compact layout inside the battery. It also ensures that the receiving structure 3 responds in time and falls off stably in the event of thermal runaway, thereby improving the safety and reliability of the battery.

[0037] Second Embodiment Please see Figure 3 In the second embodiment of this application, the receiving structure 3 is fixed to the bottom surface of the cover plate body 1 by adhesive bonding. Specifically, an electrolyte-resistant double-sided adhesive or an epoxy / modified acrylic structural adhesive is pre-coated on the top surface of the receiving structure 3. The structural adhesive forms an adhesive part 32, which is directly attached to and pressed firmly onto the bottom surface of the cover plate body 1. After curing under micro-pressure for 5-10 seconds, a high-strength bond can be formed. No additional mechanical parts are required, the process is simple, the sealing performance is good, and the adhesive layer thickness is 0.05-0.15 mm, which ensures the bonding strength without taking up additional battery height space.

[0038] To further improve the reliability and stability of the bonding, a mounting plate is provided on the top of the receiving structure 3. The area of ​​the mounting plate is larger than that of the receiving structure 3. The receiving structure 3 and the mounting plate are an integral structure, and the receiving structure 3 is bonded to the bottom surface of the cover plate body 1 through the mounting plate. The integrated mounting plate with an area larger than the receiving structure 3 significantly reduces the adhesive load per unit area, resists thermal expansion, vibration and electrolyte erosion, and prevents local debonding. At the same time, the mounting plate acts as a rigid transition layer, which evenly distributes the bonding stress, improves long-term stability, and ensures that the receiving structure 3 remains firmly positioned under high temperatures of thermal runaway, melts and detaches in time, and ensures the reliability of battery safe pressure relief.

[0039] To ensure that the containment structure 3 can melt and react with the electrolyte during the initial stage of thermal runaway, i.e., the relatively low temperature period (above 100°C and below 220°C), the melting point of the containment structure 3 should be below 220°C, thus guaranteeing that it can be melted in the early stages of thermal runaway. Therefore, the containment structure 3 can be one of the following: a polypropylene component made of polypropylene, a polychlorotrifluoroethylene component made of polychlorotrifluoroethylene, a polyvinylidene fluoride component made of polyvinylidene fluoride, a polyvinyl acetate component made of polyvinyl acetate, or a polybutene component made of polybutene. This application does not limit this; any material with a melting point above 100°C and below 250°C, that does not react with the electrolyte, and that has stable chemical properties is within the scope of protection of this application.

[0040] Among the aforementioned different materials used in the containment structure 3, the melting point of polypropylene is between 160°C and 170°C, that of polychlorotrifluoroethylene is between 213°C and 218°C, that of polyvinylidene fluoride is between 150°C and 185°C, that of polyvinyl acetate is between 120°C and 150°C, and that of polybutene is between 124°C and 130°C. Different materials can be selected to make the containment structure 3 according to actual needs. For example, when the battery is a high-density, high-capacity battery, pressure should be released as early as possible to prevent energy accumulation; therefore, a material with a relatively low melting point can be used to make the containment structure 3 to avoid battery explosion. Conversely, when the battery is a low-density, low-capacity battery, the pressure release time can be delayed while still meeting the pressure release requirements; in this case, a lower-cost material can be selected to reduce the product's manufacturing cost. By setting a low-temperature fusible containment structure 3, the explosion-proof valve 2 can open in advance to relieve pressure in the early stage of thermal runaway. The temperature of the explosion-proof valve 2 when it opens is reduced to below 250°C, thereby ensuring that the energy inside the battery can be released.

[0041] In the initial stage of thermal runaway, after the containment structure 3 melts, the reactant 31 inside it flows into the electrolyte, reacts violently with the electrolyte, and releases a large amount of gas, thereby increasing the pressure inside the cell casing 200 and breaking through the explosion-proof valve 2. It should be noted that the reactant 31 is an aqueous solution or pure water that does not produce a combustion or explosion reaction with the electrolyte but can react and release gas. For example, it can be a deionized water reactant, a sodium hydroxide aqueous solution reactant, a sodium chloride aqueous solution reactant, etc.

[0042] The effective component for the reaction between reactant 31 and the electrolyte is water. Specifically, this application encapsulates "water (or aqueous reactant 31)" as a trigger within the containment structure 3: once the thermal runaway temperature causes the fuse layer to melt, the water immediately undergoes a two-step hydrolysis with LiPF6 in the electrolyte (LiPF6 + H2O → LiF + HF + PF5, PF5 + 4H2O → H3PO4 + 5HF), instantly releasing a large amount of HF and heat; HF then reacts with Li2CO3 on the positive electrode surface to generate H2CO3, which is rapidly decomposed into CO2, while water is reduced at the negative electrode interface (2H2O + 2e). - →H₂↑+2OH - The series of reactions generates CO2 and H2 gases within milliseconds, which release heat in combination, causing the internal temperature and pressure of the battery cell to surge simultaneously. This causes the explosion-proof valve 2 to be breached prematurely, achieving proactive and rapid pressure relief before the temperature reaches the explosion point.

[0043] The various containment structures 3 and reactants 31 mentioned above can be randomly combined. None of the containment structures 3 will chemically react with the reactants 31, thus preventing accidental release of the reactants 31. The melting points of different melting materials such as polypropylene and polyvinylidene fluoride are distributed in a stepped manner from 120℃ to 250℃. The reactivity and gas production of deionized water, sodium hydroxide aqueous solution, and sodium chloride aqueous solution also vary. By randomly combining them, the trigger threshold can be arbitrarily set within the 120℃–250℃ range, and the gas production and heat generation rate can be precisely adjusted, achieving a modular design with one gas level per temperature. Simply changing the material grade of the containment structure 3 or the concentration of reactant 31 can meet differentiated safety level requirements, ensuring that the gas generation rate is compatible with the opening of the explosion-proof valve 2.

[0044] In one embodiment of this application, the receiving structure 3 is integrally injection molded. The wall thickness of the receiving structure 3 is 0.1mm to 5mm, and the appropriate wall thickness can be selected according to actual needs. A wall thickness of 0.1mm to 0.3mm is used for high-sensitivity scenarios: the battery has high energy density and the thermal runaway temperature rises extremely quickly, requiring the receiving structure 3 to melt instantly at around 120°C and immediately release the reactant 31 to open the explosion-proof valve 2 in advance. A wall thickness of 3mm to 5mm is suitable for slow-acting scenarios or scenarios with slow external heat sources: energy storage lithium iron phosphate, low-temperature environments, or scenarios requiring mechanical handling impact margin. The thicker wall can delay triggering, avoid malfunctions, and improve structural strength. The preferred wall thickness of the receiving structure 3 is 0.5mm. A wall thickness of 0.5mm can be completely melted through by the heat at the front end of the thermal runaway within 2-3 seconds, resulting in timely gas generation; at the same time, it is thick enough to withstand the micro-impacts caused by cover plate pressing, vibration, and electrolyte wetting, resulting in high molding yield and low cost, achieving the best balance between response speed and reliability.

[0045] The housing structure 3 is installed on the side of the cover body 1 facing the inside of the battery. To avoid structural interference between the housing structure 3 and the electrode assembly 300, adapter piece 400 and other components inside the battery, the thickness of the housing structure 3 along the direction perpendicular to the cover body 1 is 5mm to 15mm. That is, the maximum thickness of the housing structure 3 does not exceed 15mm. A thickness greater than or equal to 5mm ensures that the housing cavity 3a has a sufficient volume (approximately 1.5 to 2mL) to fill the reactant 31, which can instantly produce enough gas to break the valve. A thickness less than or equal to 15mm creates a 3 to 5mm safety clearance with the internal net height of the mainstream square battery, which is approximately 15 to 20mm. This prevents collisions and shearing with the fuse box during assembly shaking, electrode welding, or electrode expansion. This avoids the risk of short circuits and eliminates the need for additional supports or insulating partitions, achieving a compact design with top-mounted installation, zero interference, and high space utilization.

[0046] The cover plate assembly 100 proposed in this application also includes a terminal assembly 4, which includes a positive terminal 41 and a negative terminal 42. For details, please refer to further reference. Figure 1 and Figure 4 The positive electrode post 41 and the negative electrode post 42 are provided through the electrode post lead-out hole 1b on the cover plate body 1. The outward-facing ends of the positive electrode post 41 and the negative electrode post 42 are fixed to the upper plastic 6 by the pressure block 8. The electrode post assembly 4 is used for the connection between the internal electrode assembly 300 of the battery and the external circuit: the lower end of the electrode post is laser-welded to the electrode tab of the electrode assembly 300 through the adapter piece 400 or directly, and the upper end extends out of the cover plate body 1 and is connected to the busbar or module end plate; during charging and discharging, lithium ions are inserted / extracted between the positive and negative electrodes, and electrons are sequentially passed through the electrode post, the adapter piece 400, the electrode tab, and the active material to form an external circuit. The electrode post itself is made of copper (negative electrode) and aluminum (positive electrode) highly conductive materials to ensure high current and low loss transmission, and is insulated from the cover plate body 1 by the sealing ring 7 and the lower plastic 5.

[0047] The explosion-proof valve 2 is located between the positive terminal 41 and the negative terminal 42, with the receiving structure 3 positioned close to the explosion-proof valve 2. Positioning the explosion-proof valve 2 between the positive and negative terminals fully utilizes the current-free space between the positive and negative terminals 41 and 42. With the receiving structure 3 close to the explosion-proof valve, in the event of melting and gas generation, the distance between the high-pressure area and the explosion-proof port 1a is minimized, allowing the high-pressure gas flow to directly press against the valve without eddies or pressure drops, significantly reducing response time and minimizing the risk of accidental explosions and localized pressure dead zones.

[0048] This application also proposes a battery cell, which includes a cell housing 200, an electrode assembly 300, and a cover plate assembly 100 as described above. The cover plate assembly 100 and the cell housing 200 enclose a receiving cavity 200a. The electrode assembly 300 and the receiving structure 3 are disposed in the receiving cavity 200a. The specific structure of the cover plate assembly 100 is as described in the above embodiments. Since this battery cell adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here. The battery cell proposed in this application can be either a lithium-ion battery or a sodium-ion battery; this application makes no restriction on either. Whether using the LiPF6-carbonate electrolyte commonly found in lithium-ion batteries or the NaPF6 / NaFSI-ether / ester electrolyte commonly used in sodium-ion batteries, both contain fluoride salts that are extremely sensitive to water. Once the water trigger is introduced, hydrolysis, acid production, and gas evolution (CO2, H2, PF5 / SiF4, etc.) occur simultaneously, accompanied by a large amount of heat. Within seconds, the internal pressure and temperature of the cell surge, thereby opening the explosion-proof valve 2 to achieve premature pressure relief. Therefore, the water-based fuse solution in this application is applicable to both lithium-ion and sodium-ion batteries.

[0049] The above description is merely an exemplary embodiment of this application and does not limit the patent scope of this application. Any equivalent structural transformations made based on the technical concept of this application and the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A cover plate assembly, characterized in that, include: The cover body (1) has an explosion-proof opening (1a); An explosion-proof valve (2) is provided at the explosion-proof port (1a); The receiving structure (3) is located on the side of the cover plate body (1) facing the battery cell housing (200). The receiving structure (3) has a receiving cavity (3a) filled with reactant (31). The melting point of the receiving structure (3) is lower than the preset opening temperature of the explosion-proof valve (2).

2. The cover plate assembly as claimed in claim 1, characterized in that, One of the receiving structure (3) and the cover plate body (1) is provided with a snap-fit ​​part (11), and the other is provided with a mating part (3b), wherein the snap-fit ​​part (11) is snapped into the mating part (3b).

3. The cover plate assembly as claimed in claim 1, characterized in that, The receiving structure (3) is provided with an adhesive part (32) facing the cover plate body (1), and the receiving structure (3) is bonded to the cover plate body (1) through the adhesive part (32).

4. The cover plate assembly as described in any one of claims 1 to 3, characterized in that, The material of the containment structure (3) is polypropylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinyl acetate, or polybutene.

5. The cover plate assembly as described in any one of claims 1 to 3, characterized in that, The reactant (31) is deionized water, sodium hydroxide aqueous solution, or sodium chloride aqueous solution.

6. The cover plate assembly as described in any one of claims 1 to 3, characterized in that, The wall thickness of the receiving structure (3) is 0.1 mm to 5 mm.

7. The cover plate assembly as described in any one of claims 1 to 3, characterized in that, The thickness of the receiving structure (3) along the direction perpendicular to the cover plate body (1) is 5 mm to 15 mm.

8. The cover plate assembly as described in any one of claims 1 to 3, characterized in that, The cover plate assembly also includes a pole assembly (4), which includes a positive pole (41) and a negative pole (42), which are disposed through the cover plate body (1); the explosion-proof valve (2) is disposed between the positive pole (41) and the negative pole (42), and the receiving structure (3) is disposed close to the explosion-proof valve (2).

9. The cover plate assembly as claimed in claim 8, characterized in that, The cover plate assembly also includes a lower plastic (5), which is disposed on the side of the cover plate body (1) facing the cell housing (200). The lower plastic (5) is provided with a clearance hole, and the receiving structure (3) is disposed through the clearance hole.

10. A single battery cell, characterized in that, The device includes a cell housing (200), an electrode assembly (300), and a cover plate assembly (100) as described in any one of claims 1 to 9, wherein the cover plate assembly (100) and the cell housing (200) enclose a cavity (200a), and the electrode assembly (300) and the receiving structure (3) are disposed in the cavity (200a).

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