Pressure relief structure and battery

Abstract

This utility model relates to the field of battery pressure relief technology, specifically to a pressure relief structure and a battery. The pressure relief structure includes: a first sheet, a second sheet, and a metal bonding layer connecting the first sheet and the second sheet. The first sheet has a protrusion. This utility model utilizes the metal bonding layer to connect the first sheet and the second sheet, thereby enabling the pressure relief structure to perform a sealing function under normal use. When the temperature inside the battery cell reaches a threshold, the metal bonding layer melts, thereby opening the pressure relief hole to release the pressure and temperature inside the casing. At the same time, the protrusion provided on the first sheet can prevent liquid metal from flowing into the battery cell and causing a short circuit when the metal bonding layer melts and liquefies, thereby improving the safety and performance of the battery.

Description

Technical Field

[0008] ,

[0007] , ,

[0001] The utility model relates to the technical field of the pressure relief structure of batteries, and particularly relates to a pressure relief structure and a battery. Background Art

[0002] In the technical field of lithium-ion batteries, a traditional pressure relief mechanism uses a low melting point polymer insulating film as a sealing layer. Before the battery fails at high temperature, the polymer insulating film melts to achieve pressure relief of the battery, avoiding safety accidents such as explosion caused by gas expansion in the battery. However, the reliability of pressure relief and sealing of the polymer insulating film is relatively low, and it is difficult to effectively ensure the safety performance and service performance of the battery. ... Summary of the Utility Model

[0003] In view of this, the utility model provides a pressure relief structure and a battery to solve the problem that the reliability of pressure relief and sealing of the traditional pressure relief mechanism is relatively low, and it is difficult to effectively ensure the safety performance and service performance of the battery.

[0004] In a first aspect, the utility model provides a pressure relief structure, which is installed at the liquid injection hole of the battery; comprising: a first sheet body, which is provided with a through hole along the thickness direction; the through hole is used for communicating with the liquid injection hole; a second sheet body, which is located on one side of the first sheet body along the thickness direction of the first sheet body; in a plane perpendicular to the thickness direction of the first sheet body, the projection of the second sheet body covers the projection of the through hole; a metal bonding layer, which is connected between the first sheet body and the second sheet body; the metal bonding layer can melt when the temperature reaches a threshold value; wherein, a first convex part is provided on the first sheet body, and the first convex part protrudes towards the side close to the second sheet body; the through hole is arranged on the first convex part.

[0005] In an optional embodiment, the first sheet body further comprises a first edge part, and the first edge part extends around the first convex part; the metal bonding layer is connected between the first edge part and the second sheet body.

[0006] ... In an optional embodiment, along the thickness direction of the first sheet body, the size of the first edge part is H1, 0.02 ≤ H1 ≤ 0.2 mm; and / or, along the thickness direction of the first sheet body, the size of the first convex part protruding from the first edge part is H2, 0.01 mm < H2 < 0.1 mm.

[0007] In an optional embodiment, the first convex part has an inner wall and an outer wall, the inner wall encloses the through hole, and the outer wall is connected to the first edge part; in a direction perpendicular to the thickness direction of the first sheet body, on the side of the first convex part close to the second sheet body, the distance between the inner wall and the outer wall is L1; in a direction perpendicular to the thickness direction of the first sheet body, the distance between the connection part of the outer wall and the first edge part and the inner wall is L2; wherein, 0 < L1 ≤ L2, and L2 ≥ 0.02 mm. <000001...In one alternative embodiment, the second sheet includes a second edge portion and a second protrusion, the second edge portion extending around the second protrusion; the second protrusion is disposed protruding toward the side closer to the first sheet, and along the thickness direction of the first sheet, the second protrusion is opposite to the through hole, and a metal adhesive layer is connected between the second edge portion and the first sheet.

[0009] In one alternative embodiment, on a plane perpendicular to the thickness direction of the first sheet, the projected area of ​​the through hole is greater than the projected area of ​​the second protrusion, and the projection of the through hole covers the projection of the second protrusion.

[0010] In one optional embodiment, the dimension of the second edge portion along the thickness direction of the first sheet is H3, where 0.02 ≤ H3 ≤ 0.5 mm; and / or, along the thickness direction of the first sheet, the dimension of the second protrusion extending beyond the second edge portion is H4, the dimension of the injection hole is H5, and the dimension of the through hole is H; H4 <H+H5+1mm。

[0011] In one optional embodiment, on a plane perpendicular to the thickness direction of the first sheet, the projection of the first sheet covers the projection of the second sheet, and the distance between the projection edge of the first sheet and the projection edge of the second sheet is L3, where L3>0.2mm; and / or, a tin plating layer is provided on the side of the first sheet facing the metal bonding layer; and / or, a tin plating layer is provided on the side of the second sheet facing the metal bonding layer.

[0012] Secondly, this utility model also provides a battery, comprising: a housing having an installation cavity and an injection hole, the injection hole communicating with the installation cavity; an electrode assembly located within the installation cavity; an electrolyte located within the installation cavity; and the aforementioned pressure relief structure, the pressure relief structure being installed at the injection hole, and a first plate being connected to the housing.

[0013] In one alternative embodiment, the metal bonding layer is immersed in the electrolyte for 24 hours at 25°C, and the mass loss of the metal bonding layer is R, where R≤1%.

[0014] In the technical solution of this utility model, a metal bonding layer is used to connect the first sheet and the second sheet, thereby enabling the pressure relief structure to perform a sealing function under normal use. When the temperature inside the cell reaches a threshold, the metal bonding layer melts, thereby opening the pressure relief hole to release the pressure and temperature inside the casing. At the same time, a protrusion is provided on the first sheet. When the metal bonding layer melts and liquefies, the protrusion can prevent liquid metal from flowing into the cell and causing a short circuit, thereby improving the safety and performance of the battery. Attached Figure Description

[0015] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of a battery according to an embodiment of the present utility model;

[0017] Figure 2 This is a top view of a pressure relief structure according to an embodiment of the present utility model;

[0018] Figure 3 This is a top view of another pressure relief structure according to an embodiment of the present utility model;

[0019] Figure 4 This is a top view of another pressure relief structure according to an embodiment of the present utility model;

[0020] Figure 5 for Figure 4 Sectional view along the middle AA direction Figure 1 ;

[0021] Figure 6 This is a cross-sectional view of a pressure relief structure according to an embodiment of the present invention. Figure 2 ;

[0022] Figure 7 This is a cross-sectional view of a pressure relief structure according to an embodiment of the present invention. Figure 3 ;

[0023] Figure 8 This is a cross-sectional view of a pressure relief structure according to an embodiment of the present invention. Figure 4 ;

[0024] Figure 9 This is a schematic diagram of the structure of the first sheet in the thickness direction according to an embodiment of the present invention;

[0025] Figure 10 This is a schematic diagram of the structure of the second sheet in the thickness direction according to an embodiment of the present invention.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1. Shell; 11. Top wall;

[0028] 2. Pressure relief structure;

[0029] 21. First piece; 211. Through hole; 212. First edge portion; 213. First protrusion; 2131. Inner wall; 2132. Outer wall;

[0030] 22. Second sheet; 221. Second edge portion; 222. Second protrusion;

[0031] 23. Metal bonding layer;

[0032] 24. Tin plating;

[0033] 3. Injection hole;

[0034] 4. Positive terminal;

[0035] 5. Negative terminal;

[0036] X, the thickness direction of the first sheet. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0038] With the rapid development of new energy technologies, lithium-ion batteries, due to their advantages such as high energy density, high voltage, and long cycle life, are widely used in various portable electronic devices (mobile phones, digital cameras, etc.), as well as electric vehicles and power tools. In recent years, with the increasing demands for fast charging and capacity in battery cells, the internal temperature of the battery cell can rise rapidly under high temperatures or during short circuits, potentially causing fires and explosions, resulting in irreparable losses. Therefore, preventing thermal runaway of battery cells places higher demands on their safety performance.

[0039] A steel-cased battery cell comprises electrode assemblies, electrolyte, a casing, and a pressure relief mechanism. The electrode assemblies and electrolyte are located inside the casing, while the pressure relief mechanism is mounted on the casing. The pressure relief mechanism maintains a sealed environment within the casing, isolating moisture and air. When the battery cell experiences a violent impact or is improperly used during charging and discharging, the cell temperature rises rapidly. At this high temperature, the electrolyte decomposes, and the SEI (SEI Solid Electrolyte Interface, negative electrode electrolyte interface film) and CEI (Cathode Electrolyte Interface, positive electrode electrolyte interface film) further decompose, exacerbating the positive and negative electrode side reactions and generating high-temperature, high-pressure gas inside. At this point, the pressure relief mechanism can release pressure before thermal runaway, preventing the battery cell from catching fire or exploding due to gas expansion.

[0040] In traditional solutions, the pressure relief mechanism uses a low-melting-point polymer insulating film as a sealing layer. Before the battery fails due to high temperature, the polymer insulating film melts to relieve pressure. However, as a polymer material, the polymer insulating film has a wide melting point range, typically 5–10°C, making it difficult to precisely control its melting threshold. This can result in situations where the battery cell reaches the pressure relief temperature, but the polymer insulating film has not melted. Furthermore, the polymer insulating film retains some viscosity in its molten state, resulting in poor flowability and an inability to fully open the pressure relief channel, leading to poor pressure relief performance. Therefore, using a polymer insulating film as a sealing layer results in low reliability of pressure relief and makes it difficult to effectively guarantee the battery's safety performance.

[0041] Furthermore, as a polymer material, the polymer insulating film has a large molecular weight distribution, resulting in uneven molecular weight distribution across the entire film layer. Regions with lower molecular weights also have lower melting points, making the polymer insulating film prone to melting before reaching its melting threshold, leading to battery leakage. Moreover, polymer materials are easily swollen by organic solvents in the electrolyte, reducing the adhesion of the polymer insulating film and posing a risk of gas and liquid leakage during long-term use. Therefore, using a polymer insulating film as a sealing layer results in low sealing reliability, making it difficult to effectively guarantee battery performance.

[0042] To solve the above problems, this utility model provides a pressure relief structure and a battery. The following describes the process in conjunction with... Figures 1 to 10 The following describes embodiments of the present invention.

[0043] According to an embodiment of the present invention, on one hand, a pressure relief structure 2 is provided, such as... Figure 1 As shown, the pressure relief mechanism is installed at the battery's filler hole 3. Specifically, as... Figures 2-10 As shown, the pressure relief structure 2 includes a first sheet 21, a second sheet 22, and a metal bonding layer 23. Along the thickness direction X of the first sheet, the first sheet 21 has a through hole 211 for communicating with the injection hole 3. Along the thickness direction X of the first sheet, the second sheet 22 is located on one side of the first sheet 21. On a plane perpendicular to the thickness direction X of the first sheet, the projection of the second sheet 22 overlaps the projection of the through hole 211. The metal bonding layer 23 connects the first sheet 21 and the second sheet 22, and the metal bonding layer 23 is capable of melting when the temperature reaches a threshold.

[0044] The first piece 21 and the second piece 22 can be rectangular or circular (e.g., ...). Figure 2 As shown), elliptical (as shown) Figure 3 (as shown) or other regular or irregular shapes. The through-hole 211 can also be rectangular, circular (as shown) Figure 2 As shown), elliptical (as shown) Figure 3(As shown) or other regular or irregular shapes. The shapes of the first piece 21, the second piece 22, and the through hole 211 can be the same or different. This utility model does not specifically limit the shapes of the first piece 21, the second piece 22, and the through hole 211. Their specific shapes can be adjusted according to the suitability of the battery structure, so as to maximize the use of battery space and improve the energy density of the battery.

[0045] Furthermore, the temperature of thermal runaway in a battery is typically between 160°C and 180°C. In order to release pressure before the battery thermally fails, the melting point of the metal bonding layer 23 is less than 160°C, preferably less than 130°C. Understandably, the melting point of the metal bonding layer 23 is also the aforementioned temperature threshold.

[0046] Understandably, when the pressure relief structure 2 is installed on the battery casing 1, the first piece 21 connects the casing 1 and the second piece 22; while the metal bonding layer 23 connects the first piece 21 and the second piece 22, keeping the through hole 211 closed. At this time, the second piece 22 covers the through hole 211 on the first piece 21 to provide a seal, ensuring that the electrochemical system inside the casing 1 is not affected by external moisture. When the temperature inside the cell reaches a threshold, the metal bonding layer 23 melts and undergoes a phase change, becoming liquid or gaseous. Under the pressure inside the cell, the second piece 22 is pushed away from the first piece 21, the through hole 211 opens, and the pressure and temperature inside the casing 1 are released through the through hole 211.

[0047] Furthermore, in some embodiments, such as Figure 5 As shown, the first sheet 21 has a first protrusion 213, which protrudes towards the side closest to the second sheet 22. A through hole 211 is provided on the first protrusion 213. By providing the first protrusion 213, when the metal bonding layer 23 melts and undergoes a phase change to form a liquid, the first protrusion 213 can prevent the molten metal liquid from entering the interior of the housing 1 through the through hole 211, avoiding contact with internal electrode components and preventing short circuits, thus ensuring the safety of the battery.

[0048] In some embodiments, such as Figure 6 As shown, the second sheet 22 has a second protrusion 222, which protrudes towards the side closest to the first sheet 21. Along the thickness direction X of the first sheet, the second protrusion 222 is opposite to the through hole 211. When the metal bonding layer 23 melts and undergoes a phase change to form a liquid, the second protrusion 222 can prevent the molten metal liquid from entering the housing 1 through the through hole 211, avoiding contact with internal electrode components and preventing short circuits, thus ensuring battery safety.

[0049] In some embodiments, such as Figure 7 and Figure 8As shown, the first sheet 21 has a first protrusion 213, which protrudes towards the side closest to the second sheet 22. The second sheet 22 has a second protrusion 222, which protrudes towards the side closest to the first sheet 21. A through hole 211 is provided on the first protrusion 213 and is opposite to the second protrusion 222 along the thickness direction X of the first sheet. When the metal bonding layer 23 melts and undergoes a phase change to form a liquid, the first protrusion 213 and the second protrusion 222 can simultaneously prevent the molten metal liquid from entering the housing 1 through the through hole 211, avoiding contact with internal electrode components and preventing short circuits, thus ensuring battery safety.

[0050] In the above embodiment, a metal bonding layer 23 connects the first sheet 21 and the second sheet 22, thereby enabling the pressure relief structure 2 to perform a sealing function under normal use. When the temperature inside the cell reaches a threshold, the metal bonding layer 23 melts, allowing the pressure relief structure 2 to perform a pressure relief function. As a metallic material, the metal bonding layer 23 has a single melting point and good liquid metal fluidity, allowing it to melt when the temperature inside the cell reaches the threshold, fully opening the through-hole 211. This ensures high reliability of pressure relief, preventing safety accidents such as fires and explosions, and improving battery safety performance. Furthermore, as a metallic material, the metal bonding layer 23 does not exhibit uneven melting points in its overall structure compared to polymer materials, thus preventing melting before the temperature inside the cell reaches the threshold and avoiding leakage. Moreover, compared to polymer materials, metallic materials have better corrosion resistance in electrolytes and do not experience adhesion attenuation during long-term use, resulting in high sealing reliability and improved battery performance.

[0051] Furthermore, the metal bonding layer 23 can be made of an elemental metal or an alloy. Specifically, the metal bonding layer 23 can include one or more metal elements such as tin, bismuth, lead, indium, gallium, and cadmium. These metal elements and their alloys have low melting points, good wettability, and low viscosity, enabling them to melt quickly and relieve pressure. Preferably, the metal bonding layer 23 is made of an alloy, more preferably a tin-bismuth alloy. Tin-bismuth alloys do not contain lead, cadmium, or other metal elements harmful to the human body, and they have good corrosion resistance and strong stability.

[0052] Specifically, the first sheet 21 and the second sheet 22 can be connected by low-temperature brazing or high-frequency brazing, and the aforementioned metal bonding layer 23 can be formed between the first sheet 21 and the second sheet 22.

[0053] Furthermore, in some embodiments, such as Figures 5-8 and Figure 9As shown, the first sheet body 21 further includes a first edge portion 212 that extends around the first convex portion 213. The metal bonding layer 23 is connected between the first edge portion 212 and the second sheet body 22. In this embodiment, the through hole 211 is provided on the first convex portion 213, and the metal bonding layer 23 is connected between the first edge portion 212 and the second sheet body 22, that is, the metal bonding layer 23 is located on the outer peripheral side of the through hole 211 and the first convex portion 213. When the metal bonding layer 23 melts, the first convex portion 213 can effectively block the metal liquid and prevent the metal liquid from entering the housing 1 through the through hole 211, further ensuring the safety of the battery.

[0054] In some embodiments, as Figure 5 shown, along the thickness direction X of the first sheet body, the dimension of the first edge portion 212 is H1, 0.02 mm ≤ H1 ≤ 0.2 mm, preferably 0.05 mm ≤ H1 ≤ 0.15 mm. For example, H1 can be 0.02 mm, 0.05 mm, 0.07 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.17 mm, 0.2 mm or within the range composed of any two of the above values, etc. The temperature of the battery housing 1 is transmitted to the metal bonding layer 23 through the first edge portion 212. H1 ≤ 0.2 mm is beneficial for the housing 1 to transfer heat to the metal bonding layer, causing the metal bonding layer 23 to melt in time, thereby realizing the pressure relief function, reducing the safety risks such as explosion and fire of the battery, and improving the safety of the battery. H1 ≥ 0.02 mm ensures the structural strength of the first sheet body 21, avoiding deformation of the first edge portion 212 due to too small thickness and causing sealing failure problems. Moreover, if H1 < 0.02 mm, problems such as difficult process production will also occur, which is not conducive to processing and manufacturing. Therefore, by reasonably controlling the value of H1, it is possible to balance improving the safety and sealing performance of the battery, and it is beneficial to the processing and manufacturing of the first sheet body 21.

[0055] In some embodiments, along the thickness direction X of the first sheet body, the dimension by which the first convex portion 213 protrudes from the first edge portion 212 is H2, 0.01 mm < H2 < 0.1 mm. For example, H2 can be 0.011 mm, 0.02 mm, 0.03 mm, 0.05 mm, 0.07 mm, 0.09 mm, 0.099 mm, etc. When H2 ≤ 0.01 mm, there is a risk that the liquid metal flows into the interior of the housing 1, causing thermal runaway. When H2 ≥ 0.1 mm, the metal bonding layer is not easily welded, which is not conducive to the assembly of the pressure relief structure 2. Therefore, by reasonably controlling the value of H2, it is possible to improve the reliability of the first convex portion 213 in blocking the liquid metal and is also beneficial to the assembly of the pressure relief structure 2.

[0056] Furthermore, in some embodiments, as Figure 5As shown, the first convex portion 213 has an inner wall 2131 and an outer wall 2132. The inner wall 2131 encloses a through hole 211, and the outer wall 2132 is connected to the first edge portion 212. In the direction perpendicular to the thickness direction X of the first sheet, on the side of the first convex portion 213 close to the second sheet 22, the distance between the inner wall 2131 and the outer wall 2132 is L1. In the direction perpendicular to the thickness direction X of the first sheet, the distance between the connection of the outer wall 2132 and the first edge portion 212 and the inner wall 2131 is L2. Among them, 0 < L1 ≤ L2, and L2 ≥ 0.02 mm.

[0057] It should be noted that the direction perpendicular to the thickness direction X of the first sheet is also the Figure 5 Y direction shown. When the first sheet sheet sheet 21 is circular, the Y direction is also the radial direction of the first sheet 21. When the first sheet 21 is non-circular, the Y direction can be any direction on the plane perpendicular to the thickness direction X of the first sheet. For example, when the first sheet 21 is rectangular, the Y direction can be the length direction of the first sheet 21 or the width direction of the first sheet 21.

[0058] It can be understood that when L1 = L2, in the thickness direction X of the first sheet, the cross-sectional shape of the first convex portion 213 is rectangular; when L1 < L2, the cross-sectional shape of the first convex portion 213 is a regular trapezoid. If L1 > L2, the cross-sectional shape of the first convex portion 213 is an inverted trapezoid. Processing the first convex portion 213 with an inverted trapezoidal cross-sectional shape on the first sheet 21 has a complex processing technology and is difficult to form. And when L2 < 0.02 mm, due to the too small distance between the inner wall 2131 and the outer wall 2132 of the first convex portion 213, there are also problems of difficult forming and poor processability. Therefore, by reasonably controlling the value of L2 and making L1 ≤ L2, it is beneficial to the processing and manufacturing of the first sheet 21.

[0059] Furthermore, in some embodiments, as Figures 5-8 and Figure 10 shown, the second sheet 22 further includes a second edge portion 221, and the second edge portion 221 extends around the second convex portion 222. The metal bonding layer 23 is connected between the second edge portion 221 and the first sheet 21. In this embodiment, in the thickness direction X of the first sheet, the through hole 211 is opposite to the second convex portion 222, and the metal bonding layer 23 is connected between the second edge portion 221 and the first sheet 21, that is, the metal bonding layer 23 is located on the outer peripheral side of the through hole 211 and the second convex portion 222. When the metal bonding layer 23 melts, the second convex portion 222 can effectively block the metal liquid and prevent the metal liquid from entering the housing 1 through the through hole 211, further ensuring the safety of the battery.

[0060] It can be understood that in Figure 8 and Figure 9In the illustrated embodiment, the metal bonding layer 23 is connected between the first edge portion 212 and the second edge portion 221.

[0061] In some embodiments, on a plane perpendicular to the thickness direction X of the first sheet, the projected area of the through hole 211 is larger than the projected area of the second convex portion 222, and the projection of the through hole 211 covers the projection of the second convex portion 222. With such a setting, interference between the second convex portion 222 and the first sheet 21 is avoided, which is beneficial to the assembly of the first sheet 21 and the second sheet 22.

[0062] Furthermore, in some embodiments, as Figure 7 shown, along the thickness direction X of the first sheet, the dimension of the second edge portion 221 is H3, where 0.02 ≤ H3 ≤ 0.5 mm, preferably 0.02 ≤ H3 ≤ 0.2 mm. For example, H3 can be 0.02 mm, 0.05 mm, 0.07 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm or within the range composed of any two of the above values. The temperature of the battery housing 1 can also be transmitted to the metal bonding layer 23 through the second edge portion 221. When H3 > 0.5 mm, it is not conducive to the housing 1 transferring heat to the metal bonding layer, reducing the temperature sensitivity of the pressure relief mechanism and thus reducing the safety of the battery. When H3 < 0.02 mm, the structural strength of the second sheet 22 is weak, and it is easily damaged due to bumps, etc., and the sealing performance is poor. Moreover, when the dimension of H3 is too small, it is not conducive to processing and forming. Therefore, by reasonably controlling the value of H3, it is possible to balance improving the safety and sealing performance of the battery, and it is beneficial to the processing and manufacturing of the second sheet 22.

[0063] In some embodiments, as Figure 7 and Figure 10 shown, along the thickness direction X of the first sheet, the dimension by which the second convex portion 222 protrudes from the second edge portion 221 is H4, the dimension of the liquid injection hole 3 is H5, and the dimension of the through hole 211 is H. It can be understood that when the first sheet 21 is provided with the above-mentioned first convex portion 213, H = H1 + H2. When the first sheet 21 is not provided with the above-mentioned first convex portion 213, H is also the thickness of the first sheet 21.

[0064] Among them, H4 < H + H5 + 1 mm. When the second convex portion H4 > H + H5 + 1 mm, the dimension by which the second convex portion 222 extends into the housing 1 is too large, there is a risk of contacting the electrode assembly, and it is easy to cause a short circuit.

[0065] In some embodiments, 0.02mm ≤ H4 ≤ 0.04mm. For example, H4 can be 0.02mm, 0.025mm, 0.03mm, 0.035mm, 0.04mm, or within any two of the above values. When H4 < 0.02mm, the second protrusion 222 becomes less effective at preventing liquid metal from entering the casing 1, making it difficult to ensure battery safety. When H4 > 0.04mm, the size of the second protrusion 222 embedded in the through hole 211 and the injection hole 3 is too large. After the liquid metal melts, the second sheet 22 is difficult to detach from the first sheet 21, resulting in poor reliability of pressure relief.

[0066] In some embodiments, 0.04mm ≤ H5 ≤ 0.2mm. For example, H5 can be 0.04mm, 0.05mm, 0.1mm, 0.15mm, 0.2mm, or within any two of the above values. It will be understood that, as Figure 7 As shown, the injection hole 3 is located on the top wall 11 of the housing 1, and the size H5 of the injection hole 3 is the thickness of the top wall 11. When H5 < 0.04 mm, the thickness of the top wall 11 is too small, which can easily cause insufficient strength of the housing 1. When H5 > 0.2 mm, the thickness of the top wall 11 is too large, occupying a large battery space and reducing the energy density of the battery.

[0067] In some embodiments, such as Figure 7 As shown, on a plane perpendicular to the thickness direction X of the first sheet, the projection of the first sheet 21 overlaps the projection of the second sheet 22, and the distance between the projection edge of the first sheet 21 and the projection edge of the second sheet 22 is L3, where L3 > 0.2 mm, preferably 0.5 mm ≤ L3 ≤ 1 mm. For example, L3 can be 0.21 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, etc. The first sheet 21 and the shell 1 are usually connected by welding, such as by laser welding. When L3 ≤ 0.2 mm, the first sheet 21 is easily interfered with by the second sheet 22 during welding to the shell 1, making welding difficult; and the heat generated during welding is easily transferred to the metal bonding layer 23, causing partial melting of the metal bonding layer 23, reducing the sealing performance of the pressure relief structure 2. When L3 > 1 mm, the pressure relief structure 2 occupies too much space, reducing space utilization. Therefore, properly controlling the value of L3 can improve manufacturability, increase space utilization, and prevent the metal welded layer of the pressure relief structure 2 from failing prematurely during assembly, thus ensuring the sealing performance of the pressure relief structure 2.

[0068] In some embodiments, such as Figure 8As shown, the first sheet 21 has a tin plating layer 24 on the side facing the metal bonding layer 23, and the second sheet 22 also has a tin plating layer 24 on the side facing the metal bonding layer 23. The tin plating layer has better adhesion to the metal bonding layer 23, and the tin plating layer helps to improve the connection strength between the first sheet 21, the second sheet 22 and the metal bonding layer.

[0069] In some embodiments not shown in the figures, the tin plating layer 24 may be provided only on the side of the first sheet 21 facing the metal bonding layer 23 to improve the connection strength between the first sheet 21 and the metal bonding layer. Alternatively, the tin plating layer 24 may be provided only on the side of the second sheet 22 facing the metal bonding layer 23 to improve the connection strength between the second sheet 22 and the metal bonding layer.

[0070] According to an embodiment of the present invention, another aspect, a battery is also provided, such as... Figure 1 As shown, the battery includes a casing 1, an electrode assembly, an electrolyte, and the aforementioned pressure relief structure 2. The casing 1 has a mounting cavity and the aforementioned electrolyte injection hole 3, which communicates with the mounting cavity. The electrode assembly and electrolyte are located within the mounting cavity. The pressure relief structure 2 is installed at the electrolyte injection hole 3, and the first plate 21 is connected to the casing 1. Since the battery of this invention has the aforementioned pressure relief structure 2, it has the same technical effects as the pressure relief structure 2 of this invention, and will not be described in detail here.

[0071] This utility model does not specifically limit the shape of the shell 1; the shell 1 can be columnar, sheet-like, cubic, or other regular or irregular shapes. Specifically, as shown... Figures 5-7 As shown, the first piece 21 has a top wall 11, and an injection hole 3 is disposed on the top wall 11. The first piece 21 is installed at the injection hole 3 and connected to the top wall 11, such as by bonding, welding, or one-piece molding, and preferably by laser welding.

[0072] Understandably, the housing may also include a bottom wall and side walls, with the top wall 11, bottom wall, and side walls together enclosing the aforementioned receiving cavity. The top wall 11, bottom wall, and side walls may be integrally formed. Alternatively, the housing 1 may include a main body and a cover body, the main body being a hollow structure with an opening, and the cover body being sealed to the opening of the main body. The main body forms the aforementioned bottom wall and side walls, and the cover body forms the aforementioned top wall 11.

[0073] Furthermore, the electrolyte may include a Li salt and its organic solvent, wherein the Li salt content is 10-20% by mass of the electrolyte. The Li salt includes at least one or more of lithium hexafluorophosphate (LiPF6), lithium bis(oxalato)borate (LiBOB), lithium difluorooxalato)borate (LiDFOB), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The organic solvent includes at least one or more of dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethylene carbonate (EC).

[0074] Furthermore, in some embodiments, the metal bonding layer 23 is immersed in the electrolyte for 24 hours at 25°C, and the mass loss of the metal bonding layer 23 is R, where R ≤ 1%. The mass loss of the metal bonding layer 23 in the electrolyte reflects its corrosion resistance. By reasonably controlling the value of R, the pressure relief structure 2 can maintain its sealing integrity during long-term service, preventing electrolyte leakage or external moisture intrusion, and further ensuring the reliability of battery applications.

[0075] The method for testing the mass loss of the metal bonding layer 23 is as follows: Weigh the metal bonding layer 23 before immersion and record it as m0; after immersing the metal bonding layer 23 in the electrolyte at 25℃ for 24 hours, weigh the metal bonding layer 23 after immersion and record it as m1. R=(m1 / m0)×100%.

[0076] Furthermore, this utility model does not specifically limit the structure of the electrode assembly; the electrode assembly can be a wound structure or a stacked structure. Specifically, the electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator, which are stacked together, with the separator disposed between the positive and negative electrode plates. The positive electrode plate has a positive tab, and the negative electrode plate has a negative tab.

[0077] Furthermore, such as Figure 1 As shown, the battery also includes a positive terminal 4 and a negative terminal 5, which are disposed on the housing 1. The housing 1 has two through holes for mounting the positive terminal 4 and the negative terminal 5. The positive terminal 4 is mounted on the housing 1 and connected to the positive tab through one of the through holes; the negative terminal is mounted on the housing 1 and connected to the negative tab through the other through hole.

[0078] The battery of this invention is a reusable secondary battery, which refers to a battery that can be charged and discharged multiple times. The battery can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, lead-acid battery, nickel-manganese battery, nickel-cadmium battery, nickel-phosphate battery, etc.

[0079] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A pressure relief structure, installed at the electrolyte filling hole (3) of a battery; characterized in that, Comprising: A first sheet body (21), which is provided with a through hole (211) along the thickness direction (X); the through hole (211) is used to communicate with the liquid injection hole (3); A second sheet body (22), which is located on one side of the first sheet body (21) along the thickness direction (X) of the first sheet body; in a plane perpendicular to the thickness direction (X) of the first sheet body, the projection of the second sheet body (22) covers the projection of the through hole (211); A metal bonding layer (23), which is connected between the first sheet body (21) and the second sheet body (22); the metal bonding layer (23) can be melted when the temperature reaches a threshold value; Wherein, a first convex portion (213) is provided on the first sheet body (21), and the first convex portion (213) protrudes toward the side close to the second sheet body (22); the through hole (211) is provided on the first convex portion (213).

2. The pressure relief structure according to claim 1, characterized in that, The first sheet body (21) further includes a first edge portion (212), and the first edge portion (212) extends around the first convex portion (213); the metal bonding layer (23) is connected between the first edge portion (212) and the second sheet body (22).

3. The pressure relief structure according to claim 2, characterized in that, Along the thickness direction (X) of the first sheet body, the size of the first edge portion (212) is H1, and 0.02 ≤ H1 ≤ 0.2 mm; and / or, Along the thickness direction (X) of the first sheet body, the size by which the first convex portion (213) protrudes from the first edge portion (212) is H2, and 0.01 mm < H2 < 0.1 mm.

4. The pressure relief structure according to claim 2, characterized in that, The first convex portion (213) has an inner wall (2131) and an outer wall (2132), the inner wall (2131) encloses the through hole (211), and the outer wall (2132) is connected to the first edge portion (212); On the side of the first convex portion (213) close to the second sheet body (22) in a plane perpendicular to the thickness direction (X) of the first sheet body, the distance between the inner wall (2131) and the outer wall (2132) is L1; On the side of the outer wall (2132) and the first edge portion (212) in a plane perpendicular to the thickness direction (X) of the first sheet body, the distance between the connection portion of the outer wall (2132) and the first edge portion (212) and the inner wall (2131) is L2; Wherein, 0 < L1 ≤ L2, and L2 ≥ 0.02 mm.

5. The pressure relief structure according to any one of claims 1-4, characterized in that, The second sheet body (22) includes a second edge portion (221) and a second convex portion (222), the second edge portion (221) extends around the second convex portion (222), and the second convex portion (222) protrudes toward the side close to the first sheet body (21); Along the thickness direction (X) of the first sheet body, the second convex portion (222) is opposite to the through hole (211); the metal bonding layer (23) is connected between the second edge portion (221) and the first sheet body (21).

6. The pressure relief structure according to claim 5, characterized in that, In a plane perpendicular to the thickness direction (X) of the first sheet body, the projection area of the through hole (211) is larger than the projection area of the second convex portion (222), and the projection of the through hole (211) covers the projection of the second convex portion (222).

7. The pressure relief structure according to claim 5, characterized in that, Along the thickness direction (X) of the first sheet, the dimension of the second edge portion (221) is H3, 0.02≤H3≤0.5mm; and / or, Along the thickness direction (X) of the first sheet body, the second protrusion (222) protrudes from the second edge portion (221) by a dimension of H4, the injection hole (3) has a dimension of H5, and the through hole (211) has a dimension of H4. <H+H5+1mm。 8. The pressure relief structure according to any one of claims 1-4, characterized in that, On a plane perpendicular to the thickness direction (X) of the first sheet, the projection of the first sheet (21) overlaps the projection of the second sheet (22), and the distance between the projection edge of the first sheet (21) and the projection edge of the second sheet (22) is L3, where L3 > 0.2 mm; and / or, The first sheet (21) has a tin plating layer (24) on the side facing the metal bonding layer (23); and / or, The second sheet (22) has a tin plating layer (24) on the side facing the metal bonding layer (23).

9. A battery, characterized in that, include: The housing (1) is provided with an installation cavity and the injection hole (3), and the injection hole (3) is connected to the installation cavity; The electrode assembly is located within the mounting cavity; Electrolyte, located within the mounting cavity; The pressure relief structure (2) as described in any one of claims 1-8 is installed at the injection hole (3), and the first piece (21) is connected to the housing (1).

10. The battery according to claim 9, characterized in that, At 25°C, the metal bonding layer (23) is immersed in the electrolyte for 24 hours, and the mass loss of the metal bonding layer (23) is R, where R ≤ 1%.

Images