Secondary battery and electronic device

Abstract

A secondary battery and an electronic device. The secondary battery comprises an electrode assembly and a bonding part. The bonding part includes a substrate layer, a first metal particle layer, and a first bonding layer, which are stacked in a first direction. The first metal particle layer is located between the substrate layer and the first bonding layer. The first metal particle layer includes at least one layer of metal particles. The first bonding layer is bonded to the electrode assembly. In the secondary battery, the first metal particle layer includes at least one layer of metal particles. Compared with the ordinary adhesive tape, the bonding part having the first metal particle layer itself has high structural strength and good support force. In addition, the first metal particle layer enables the bonding part to have high ductility, reduces the risk of brittle fracture when resisting an external impact, and increases the pass rate of a blunt nail puncture and extrusion test for a secondary battery, thereby improving the safety performance of the secondary battery.

Description

Secondary batteries and electronic devices

[0001] This application claims priority to Chinese Patent Application No. 202510198761.0, filed on February 21, 2025, entitled "Secondary Battery and Electronic Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of energy storage technology, and in particular to a secondary battery and electronic device. Background Technology

[0003] Pouch batteries are typically bonded together using adhesive tape, but existing tapes (such as polyimide or polyester tape) have relatively weak structural strength. When the battery is subjected to external impacts (such as blunt force trauma), existing tapes cannot protect it, resulting in reduced battery safety. Summary of the Invention

[0004] In view of the above, this application provides a secondary battery that is beneficial to improving safety performance.

[0005] Embodiments of this application provide a secondary battery, which includes an electrode assembly and an adhesive. The adhesive includes a substrate layer, a first metal particle layer, and a first adhesive layer stacked along a first direction. The first metal particle layer is located between the substrate layer and the first adhesive layer. The first metal particle layer includes at least one layer of metal particles. The first adhesive layer is bonded to the electrode assembly.

[0006] In the aforementioned secondary battery, the first metal particle layer includes at least one layer of metal particles. Compared to ordinary adhesive tape, the adhesive with the first metal particle layer has high structural strength and good support. At the same time, the first metal particle layer with high ductility can reduce the risk of brittle fracture when the adhesive resists external impact, improve the pass rate of the secondary battery in the blunt puncture extrusion test, and thus improve the safety performance of the secondary battery.

[0007] In some embodiments of this application, the average particle size of the metal particles is D1, 1μm≤D1≤20μm, so that the structural strength and ductility of the first metal particle layer are balanced. When the secondary battery is subjected to blunt burr compression, the first metal particle layer can resist the impact of external force, and the first metal particle layer is not easy to break brittlely, which can reduce the generation of burrs and debris, which helps to reduce the risk of damage to the electrode assembly, thereby improving the safety performance of the secondary battery.

[0008] In some embodiments of this application, 5μm≤D1≤10μm is used to further balance the structural strength and ductility of the first metal particle layer. When the secondary battery is subjected to blunt puncture compression, the first metal particle layer can resist external impact, and the first metal particle layer is not prone to brittle fracture, which can reduce the generation of burrs and debris, thereby reducing the risk of damage to the electrode assembly and improving the safety performance of the secondary battery.

[0009] In some embodiments of this application, the first metal particle layer contacts the substrate layer and the first adhesive layer respectively, so as to improve the structural stability of the adhesive.

[0010] In some embodiments of this application, the thickness of the substrate layer along the first direction is T1, where 1.2D1≤T1≤24μm, to improve the insulation stability of the adhesive and the energy density and flatness of the secondary battery.

[0011] In some embodiments of this application, the metal particles include at least one of copper, aluminum, gold, silver, iron, or nickel to meet the structural strength and ductility requirements of the first metal particle layer.

[0012] In some embodiments of this application, the substrate layer includes at least one of polyester film, polyimide film, polypropylene film, polyethylene film, polytetrafluoroethylene film, or silicone rubber film to meet the insulation requirements of the substrate layer.

[0013] In some embodiments of this application, the first metal particle layer includes two layers of metal particles to improve the structural stability of the first metal particle layer and further improve the structural strength and ductility of the first metal particle layer. When the secondary battery is subjected to blunt burr compression, the first metal particle layer can resist external impact, and the first metal particle layer is not prone to brittle fracture, which can reduce the generation of burrs and debris, which helps to reduce the risk of damage to the electrode assembly, thereby improving the safety performance of the secondary battery.

[0014] In some embodiments of this application, the electrode assembly includes a first electrode, a separator, a second electrode, and a first tab. The polarity of the first electrode is opposite to that of the second electrode. The first electrode includes a first current collector and a first active material layer disposed on the first current collector. The first active material layer has a groove, and the first tab is disposed within the groove. An adhesive is bonded to the first electrode and covers the groove to improve the insulation stability between the portion of the first tab located within the groove and the adjacent second electrode. Furthermore, when the secondary battery is subjected to blunt force compression, the first metal particle layer in the adhesive can resist external impact, and the first metal particle layer is not prone to brittle fracture, which reduces the generation of burrs and debris, thereby reducing the risk of damage to the portion of the first tab located within the groove and improving the safety performance of the secondary battery.

[0015] In some embodiments of this application, the electrode assembly includes a first electrode, a separator, a second electrode, and a first tab. The polarity of the first electrode is opposite to that of the second electrode. The first electrode includes a first current collector and a first active material layer disposed on the first current collector. The first active material layer has a groove, and the first tab is disposed within the groove. An adhesive is bonded to the second electrode with the bonding position opposite to the groove, thereby improving the insulation stability between the portion of the first tab located within the groove and the adjacent second electrode. Furthermore, when the secondary battery is subjected to blunt force compression, the first metal particle layer in the adhesive can resist external impact, and the first metal particle layer is not prone to brittle fracture, which reduces the generation of burrs and debris, thus reducing the risk of damage to the portion of the first tab located within the groove, thereby improving the safety performance of the secondary battery.

[0016] In some embodiments of this application, the first electrode includes a first current collector, which is a nickel foil. The metal particles of the adhesive bonded to the first electrode are nickel metal particles, so that the material of the metal particles of the adhesive bonded to the first electrode is consistent with the material of the first current collector, thereby reducing the risk of electrochemical corrosion and improving the safety performance of the secondary battery.

[0017] In some embodiments of this application, the first electrode includes a first current collector, which is a copper foil. The metal particles of the adhesive bonded to the first electrode are copper metal particles, so that the material of the metal particles of the adhesive bonded to the first electrode is consistent with the material of the first current collector, thereby reducing the risk of electrochemical corrosion and improving the safety performance of the secondary battery.

[0018] In some embodiments of this application, the second electrode includes a second current collector, which is a nickel foil. The metal particles of the adhesive bonded to the second electrode are nickel metal particles, so that the metal particle material of the adhesive bonded to the second electrode is consistent with the material of the second current collector, thereby reducing the risk of electrochemical corrosion and improving the safety performance of the secondary battery.

[0019] In some embodiments of this application, the second electrode includes a second current collector, which is a copper foil. The metal particles of the adhesive attached to the second electrode are copper metal particles, so that the material of the metal particles of the adhesive attached to the second electrode is consistent with the material of the second current collector, thereby reducing the risk of electrochemical corrosion and improving the safety performance of the secondary battery.

[0020] In some embodiments of this application, the adhesive is bonded to the outer surface of the outermost electrode sheet of the electrode assembly and covers the end of the electrode assembly to improve the structural stability of the electrode assembly. Furthermore, when the secondary battery is subjected to blunt force compression, the first metal particle layer can resist external impact, and the first metal particle layer is not prone to brittle fracture, reducing the generation of burrs and debris, which helps to reduce the risk of damage to the end of the electrode assembly, thereby improving the safety performance of the secondary battery.

[0021] In some embodiments of this application, the metal particles of the adhesive are aluminum metal particles to reduce the risk of electrochemical corrosion and improve the safety performance of the secondary battery.

[0022] Embodiments of this application also provide an electronic device, which includes any of the secondary batteries described in the above embodiments. Attached Figure Description

[0023] Figure 1 is a schematic diagram of the structure of a secondary battery in one embodiment of this application.

[0024] Figure 2 is a schematic diagram of the structure of the adhesive component of the secondary battery in one embodiment of this application.

[0025] Figure 3 is a schematic diagram of the structure of the adhesive component of the secondary battery in another embodiment of this application.

[0026] Figure 4 is a schematic diagram of the structure of the adhesive component of the secondary battery in another embodiment of this application.

[0027] Figure 5 is a schematic diagram of the structure of the adhesive component of the secondary battery in another embodiment of this application.

[0028] Figure 6 is a schematic flowchart of a method for preparing a secondary battery in one embodiment of this application.

[0029] Figure 7 is a schematic diagram of the structure of an electronic device in one embodiment of this application.

[0030] Key Component Symbols: Secondary Battery 100A, 100B, 100C, 100D; Electronic Device 200; Electrode Assembly 10; Terminal End 10A; First Electrode 11; Groove 11A; First Current Collector 111; First Active Material Layer 112; Separator 12; Second Electrode 13; First Empty Foil Area 13A; Second Current Collector 131; Second Active Material Layer 132; Adhesive Component 20; Substrate Layer 21; First Metal Particle Layer 22; Metal Particles 221, 221A, 221B; First Adhesive Layer 23; Second Adhesive Layer 24; Second Metal Particle Layer 25; First Direction Z

[0031] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0032] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0033] It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or may also have a component that is centrally located. When a component is considered to be "set" on another component, it can be directly set on the other component or may also have a component that is centrally located.

[0034] When one value is considered "equal" to another, it means that they are equal within a set deviation range, which is within 5%. In other words, if at least one of the two values ​​fluctuates within the set deviation range, they are considered approximately equal even if their values ​​are not equal. Similarly, when one value is considered to have a "1:1" ratio with another, it means that they are equal within a set deviation range, which is within 5%. Again, if at least one of the two values ​​fluctuates within the set deviation range, they are considered equal in ratio even if their values ​​are not equal.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. The term "overlap" as used herein refers to the overlapping of the projected portions of two components or the coincidence of the projected portions of two components.

[0036] Embodiments of this application provide a secondary battery, which includes an electrode assembly and an adhesive. The adhesive includes a substrate layer, a first metal particle layer, and a first adhesive layer stacked along a first direction. The first metal particle layer is located between the substrate layer and the first adhesive layer. The first metal particle layer includes at least one layer of metal particles. The first adhesive layer is bonded to the electrode assembly.

[0037] In the aforementioned secondary battery, the first metal particle layer includes at least one layer of metal particles. Compared to ordinary adhesive tape, the adhesive with the first metal particle layer has high structural strength and good support. At the same time, the first metal particle layer with high ductility can reduce the risk of brittle fracture when the adhesive resists external impact, improve the pass rate of the secondary battery in the blunt puncture extrusion test, and thus improve the safety performance of the secondary battery.

[0038] The embodiments of this application will be further described below with reference to the accompanying drawings.

[0039] Example 1

[0040] Please refer to Figures 1 and 2 together. One embodiment of this application provides a secondary battery 100A. The secondary battery 100A refers to a battery that can be used again after being discharged by recharging to activate the active materials.

[0041] The secondary battery 100A includes an electrode assembly 10 and an adhesive component 20. The electrode assembly 10 is formed by winding or stacking a positive electrode, a separator, and a negative electrode in sequence. The electrode assembly 10 is used to convert chemical energy into electrical energy.

[0042] The adhesive component 20 is bonded to the electrode assembly 10 to achieve both bonding and insulation. Optionally, the adhesive component 20 is located on the inner or outer side of the electrode assembly 10.

[0043] The adhesive component 20 includes a substrate layer 21, a first metal particle layer 22, and a first adhesive layer 23 stacked along a first direction Z. The substrate layer 21 is insulating, and the first metal particle layer 22 is located between the substrate layer 21 and the first adhesive layer 23. The first metal particle layer 22 includes at least one layer of metal particles 221. The first adhesive layer 23 is bonded to the electrode assembly 10.

[0044] In some embodiments, metal particles 221 are uniformly coated onto the surface of the substrate layer 21 using a cold spraying technique.

[0045] Compared to ordinary adhesive tape, the adhesive 20 with the first metal particle layer 22 has high structural strength and good support. At the same time, the first metal particle layer 22 with high ductility can reduce the risk of brittle fracture when the adhesive resists external impact, improve the pass rate of the blunt puncture extrusion test of the secondary battery 100A, and thus improve the safety performance of the secondary battery 100A.

[0046] Furthermore, during the self-discharge test of the secondary battery 100A, the first metal particle layer 21 is less prone to burrs and can also reduce the K value of the self-discharge of the secondary battery 100A, which is beneficial to improving the self-discharge phenomenon.

[0047] In some embodiments, the average particle size of the metal particles 221 is D1, where 1 μm ≤ D1 ≤ 20 μm. When D1 is too small (e.g., less than 1 μm), the grain size of the first metal particle layer 22 is easily too small and the grain boundary area is large, resulting in increased resistance to dislocation movement. The first metal particle layer 22 has high structural strength but insufficient ductility. When the secondary battery 100A is subjected to blunt pressure, the first metal particle layer 22 is prone to brittle fracture, generating burrs and debris, which can cause short circuits in the electrode assembly 10. When D1 is too large (e.g., greater than 20 μm), the grain size of the first metal particle layer 22 is easily too large and the grain boundary area is small, resulting in decreased resistance to dislocation movement. The first metal particle layer 22 has strong ductility but insufficient structural strength. When the secondary battery 100A is subjected to blunt pressure, the first metal particle layer 22 is easily deformed, thereby weakening the resistance of the first metal particle layer 22 to external forces. By limiting the size of 1μm≤D1≤20μm, the structural strength and ductility of the first metal particle layer 22 are balanced. When the secondary battery 100A is subjected to blunt force compression, the first metal particle layer 22 can resist the impact of external force, and the first metal particle layer 22 is not prone to brittle fracture, which can reduce the generation of burrs and debris, thereby reducing the risk of damage to the electrode assembly 10 and improving the safety performance of the secondary battery 100A.

[0048] Optionally, D1 can be any value within the range of 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, and any other value within the range of 1μm≤D1≤20μm.

[0049] Furthermore, 5μm≤D1≤10μm is used to further balance the structural strength and ductility of the first metal particle layer 22. When the secondary battery 100A is subjected to blunt puncture compression, the first metal particle layer 22 can resist external impact, and the first metal particle layer 22 is not prone to brittle fracture, which can reduce the generation of burrs and debris, thereby reducing the risk of damage to the electrode assembly 10 and improving the safety performance of the secondary battery 100A.

[0050] It should be noted that D1 can be adjusted according to the different positions of the adhesive 20 in the electrode assembly 10 so that the first metal particle layer 22 of the adhesive 20 located in different positions has different structural strength and ductility, thereby making it easier for the adhesive 20 to adapt to the needs of different positions.

[0051] Please continue referring to Figure 2. In some embodiments, the first metal particle layer 22 includes a layer of metal particles 221, and the thickness of the first metal particle layer 22 is D. 1， In order to reduce the overall thickness of the adhesive 20.

[0052] Please continue to refer to Figure 2. In some embodiments, the first metal particle layer 22 contacts the substrate layer 21 and the first adhesive layer 23 respectively to improve the structural stability of the adhesive 20.

[0053] Please refer to Figure 2. In some embodiments, the average spacing of the metal particles 221 is L1, where 0.4D1 ≤ L1 ≤ 0.6D1. When L1 is too small (e.g., less than 0.4D1), the first metal particle layer 22 is prone to insufficient ductility, and the close arrangement of the metal particles 221 during processing can make it difficult to release stress, increasing processing difficulty. When L1 is too large (e.g., greater than 0.6D1), the structural strength of the first metal particle layer 22 is prone to insufficient. By limiting 0.4D1 ≤ L1 ≤ 0.6D1, the structural strength and ductility of the first metal particle layer 22 are balanced. When the secondary battery 100A is subjected to blunt force compression, the first metal particle layer 22 can resist external impact, and the first metal particle layer 22 is less prone to brittle fracture, which reduces the generation of burrs and debris, thus reducing the risk of damage to the electrode assembly 10 and improving the safety performance of the secondary battery 100A. Furthermore, it also helps the metal particles 221 to be evenly distributed on the surface of the substrate layer 21, reducing the risk that the first metal particle layer 22 may be affected by uneven local thickness, thus affecting the consistency of its deformation resistance and flatness.

[0054] Optionally, L1 can be any value within the range of 0.4D1, 0.5D1, 0.6D1, and any other value within the range of 0.4D1≤L1≤0.6D1.

[0055] In some embodiments, the metal particles 221 include at least one of copper, aluminum, gold, silver, iron, or nickel to meet the structural strength and ductility requirements of the first metal particle layer 22.

[0056] In some embodiments, the substrate layer 21 includes at least one of a polyester film, a polyimide film, a polypropylene film, a polyethylene film, a polytetrafluoroethylene film, or a silicone rubber film to meet the insulation requirements of the substrate layer 21.

[0057] Please refer to Figure 2. In some embodiments, the thickness of the substrate layer 21 is T1, where 1.2D1 ≤ T1 ≤ 24 μm. When the thickness of the substrate layer 21 is too small (e.g., less than 1.2D1), when the secondary battery 100A is subjected to blunt force compression, the metal particles 221 can easily puncture the substrate layer 21, leading to a decrease in the insulation stability of the adhesive 20. When the thickness of the substrate layer 21 is too large (e.g., greater than 24 μm), the adhesive 20 can easily become too thick, resulting in a decrease in the energy density of the secondary battery 100A and also affecting the flatness of the secondary battery 100A. By limiting 1.2D1 ≤ T1 ≤ 24 μm, the insulation stability of the adhesive 20, as well as the energy density and flatness of the secondary battery 100A, are improved.

[0058] It is understandable that the thickness of the substrate layer 21 will have a certain impact on the ductility of the substrate layer 21. By limiting it to 1.2D1≤T1≤24μm, it is also beneficial for the ductility of the substrate layer 21 to form a synergistic effect with the ductility of the first metal particle layer 22.

[0059] Optionally, T1 can be any value within the range of 1.2μm, 2.4μm, 3.6μm, 4.8μm, 6μm, 7.2μm, 8.4μm, 9.6μm, 10.8μm, 12μm, 13.2μm, 14.4μm, 15.6μm, 16.8μm, 18μm, 19.2μm, 20.4μm, 12.6μm, 22.8μm, 24μm, and any other value within the range of 1.2D1≤T1≤24μm.

[0060] In some embodiments, the first adhesive layer 23 includes at least one of acrylic adhesive, pressure-sensitive adhesive, acrylic adhesive, rubber-based adhesive, or polyurethane adhesive to meet the bonding requirements of the first adhesive layer 23.

[0061] Please refer to Figures 1 and 2 together. In some embodiments, the electrode assembly 10 includes a first electrode 11, a diaphragm 12, a second electrode 13, and a first tab 14. The polarity of the first electrode 11 is opposite to that of the second electrode 13.

[0062] In some embodiments, the first electrode 11 is provided with a groove 11A, one end of the first tab 14 is disposed in the groove 11A, and the other end of the first tab 14 extends out of the electrode assembly 10. Specifically, the first electrode 11 includes a first current collector 111 and a first active material layer 112. Along the thickness direction of the first current collector 111, at least one surface of the first current collector 111 is provided with the first active material layer 112, and the first active material layer 112 is provided with a groove 11A that exposes the first current collector 111.

[0063] The adhesive 20 is bonded to the first electrode 11 and covers the groove 11A to improve the insulation stability between the portion of the first tab 14 located in the groove 11A and the adjacent second electrode 13. Furthermore, when the secondary battery 100A is subjected to blunt force compression, the first metal particle layer 22 in the adhesive 20 can resist external impact, and the first metal particle layer 22 is less prone to brittle fracture, reducing the generation of burrs and debris. This helps to reduce the risk of damage to the portion of the first tab 14 located in the groove 11A, thereby improving the safety performance of the secondary battery 100A.

[0064] Referring to Figures 1 and 2, in some embodiments, the adhesive 20 is bonded to the second electrode 13 with the bonding position opposite to the groove 11A, thereby improving the insulation stability between the portion of the first tab 14 located in the groove 11A and the adjacent second electrode 13. Furthermore, when the secondary battery 100A is subjected to blunt force compression, the first metal particle layer 22 in the adhesive 20 can resist external impact, and the first metal particle layer 22 is less prone to brittle fracture, reducing the generation of burrs and debris. This helps to reduce the risk of damage to the portion of the first tab 14 located in the groove 11A, thereby improving the safety performance of the secondary battery 100A. Specifically, along the thickness direction of the electrode assembly 10, the bonding position of the adhesive 20 is located at the portion of the second electrode 13 closest to the groove 11A, and the groove 11A and the adhesive 20 are arranged on both sides of the separator 12 along the thickness direction of the electrode assembly 10.

[0065] In some embodiments, the first electrode 11 is a negative electrode and the second electrode 13 is a positive electrode. The size of the adhesive 20 bonded to the first electrode 11 and covering the groove 11A is smaller than the size of the adhesive 20 bonded to the second electrode 13 at the position opposite to the groove 11A, so as to reduce the risk of lithium plating at the edge of the groove 11A.

[0066] In some embodiments, the first current collector 111 is made of a metallic material, and the metallic particles 221 of the adhesive 20 bonded to the first electrode 11 are made of the same material as the first current collector 111, so as to reduce the risk of electrochemical corrosion and improve the safety performance of the secondary battery 100A.

[0067] Optionally, the first current collector 111 is a nickel foil, and the metal particles 221 of the adhesive 20 bonded to the first electrode 11 are nickel metal particles; or the first current collector 111 is a copper foil, and the metal particles 221 of the adhesive 20 bonded to the first electrode 11 are copper metal particles.

[0068] Please refer to Figures 1 and 2 together. In some embodiments, the second electrode 13 includes a second current collector 131 and a second active material layer 132. The second active material layer 132 is provided on at least one surface of the second current collector 131 along its thickness direction. The second current collector 131 is made of a metallic material. The material of the metal particles 221 of the adhesive 20 bonded to the second electrode 13 is the same as that of the second current collector 131 to reduce the risk of electrochemical corrosion and improve the safety performance of the secondary battery 100A.

[0069] Optionally, the second current collector 131 is a nickel foil, and the metal particles 221 of the adhesive 20 bonded to the second electrode 13 are nickel metal particles; or the second current collector 131 is a copper foil, and the metal particles 221 of the adhesive 20 bonded to the second electrode 13 are copper metal particles.

[0070] Please refer to Figures 1 and 2 together. In some embodiments, the adhesive 20 is bonded to the outer surface of the outermost electrode of the electrode assembly 10 and covers the terminal end 10A of the electrode assembly 10 to improve the structural stability of the electrode assembly 10. Furthermore, when the secondary battery 100A is subjected to blunt force compression, the first metal particle layer 22 can resist external impact, and the first metal particle layer 22 is less prone to brittle fracture, reducing the generation of burrs and debris, which helps to reduce the risk of damage to the terminal end 10A of the electrode assembly 10, thereby improving the safety performance of the secondary battery 100A. Specifically, taking Figure 1 as an example, the outermost electrode of the electrode assembly 10 is the second electrode 13. The outer surface of the current collector of the outermost electrode of the electrode assembly 10 includes a first empty foil area 13A without the second active material layer 132 coated. The terminal end 10A of the electrode assembly 10 is disposed on the first empty foil area 13A, and the adhesive 20 is bonded to the first empty foil area 13A and the terminal end 10A of the electrode assembly 10.

[0071] Please refer to Figures 1 and 2 together. In some embodiments, the outermost electrode of the electrode assembly 10 is a positive electrode, and the current collector material of the outermost electrode of the electrode assembly 10 includes aluminum. The metal particles 221 of the adhesive 20, which is bonded to the outer surface of the outermost electrode of the electrode assembly 10 and covers the end 10A of the electrode assembly 10, are aluminum metal particles to reduce the risk of electrochemical corrosion and improve the safety performance of the secondary battery 100A.

[0072] Example 2

[0073] Please refer to Figures 1 and 3 together. One embodiment of this application also provides a secondary battery 100B. The difference between secondary battery 100B and secondary battery 100A is:

[0074] The first metal particle layer 22 includes two layers of metal particles 221 to improve the structural stability of the first metal particle layer 22, and further improve the structural strength and ductility of the first metal particle layer 22. When the secondary battery 100B is subjected to blunt burr compression, the first metal particle layer 22 can resist the impact of external force, and the first metal particle layer 22 is not easy to break brittlely, which can reduce the generation of burrs and debris, which helps to reduce the risk of damage to the electrode assembly 10, thereby improving the safety performance of the secondary battery 100B.

[0075] In some embodiments, along the first direction Z, a layer of metal particles 221 near the first adhesive layer 23 is defined as metal particle 221A, and a layer of metal particles 221 near the substrate layer 21 is defined as metal particle 221B. A portion of metal particle 221A is disposed between the gaps of two adjacent metal particles 221B to improve the structural stability of the first metal particle layer 22. During the fabrication process, metal particles 221B are uniformly coated onto the surface of the substrate layer 21 using cold spraying technology, and metal particles 221A are uniformly coated onto the surface of metal particle 221A using cold spraying technology.

[0076] Apart from the differences mentioned above, the parameters of secondary battery 100B and secondary battery 100A are roughly the same. Please refer to the description of secondary battery 100A above.

[0077] Example 3

[0078] Please refer to Figures 1 and 4 together. One embodiment of this application also provides a secondary battery 100C. The difference between secondary battery 100C and secondary battery 100A is:

[0079] The adhesive 20 includes a second adhesive layer 24 along the first direction Z, the second adhesive layer 24 being attached to the surface of the substrate layer 21 away from the first metal particle layer 22.

[0080] When the adhesive member 20 is located inside the electrode assembly 10, the second adhesive layer 24 is bonded to the diaphragm 12 adjacent to the adhesive member 20 to improve the structural stability of the electrode assembly 10. Optionally, the adhesive member 20 being located inside the electrode assembly 10 includes the following situations: the adhesive member 20 is bonded to the first electrode 11 and covers the groove 11A; the adhesive member 20 is bonded to the second electrode 13 and the bonding position is opposite to the groove 11A.

[0081] When the adhesive 20 is located on the outside of the electrode assembly 10, the second adhesive layer 24 is bonded to the packaging bag enclosing the electrode assembly 10 to improve the structural stability of the electrode assembly 10. Optionally, the adhesive 20 being located on the outside of the electrode assembly 10 includes the following cases: the adhesive 20 is bonded to the outer surface of the outermost electrode sheet of the electrode assembly 10 and covers the terminal end 10A of the electrode assembly 10.

[0082] Apart from the differences mentioned above, the parameters of the secondary battery 100C and the secondary battery 100A are roughly the same. Please refer to the description of the secondary battery 100A above.

[0083] Example 4

[0084] Please refer to Figures 1 and 5 together. One embodiment of this application also provides a secondary battery 100D. The difference between secondary battery 100D and secondary battery 100C is:

[0085] The adhesive component 20 includes a second metal particle layer 25, which is connected between the substrate layer 21 and the second adhesive layer 24 along the first direction Z. The second metal particle layer 25 has the same parameters as the first metal particle layer 22. When the secondary battery 100D is subjected to blunt force compression, the first metal particle layer 22 and the second metal particle layer 25 in the adhesive component 20 can resist external impact. Furthermore, the first metal particle layer 22 and the second metal particle layer 25 are not prone to brittle fracture, which can reduce the generation of burrs and debris, thereby reducing the risk of damage to the electrode assembly 10 and improving the safety performance of the secondary battery 100D.

[0086] Apart from the differences mentioned above, the parameters of the secondary battery 100D and the secondary battery 100C are roughly the same. Please refer to the description of the secondary battery 100C above.

[0087] Referring to Figure 6, one embodiment of this application also provides a method for preparing a secondary battery, including the following steps:

[0088] Provide a substrate layer 21;

[0089] The surface of the substrate layer 21 is cleaned.

[0090] Metal particles are sprayed onto the surface of the substrate layer 21 by a cold spraying process to form a first metal particle layer 22.

[0091] The adhesive is sprayed onto the surface of the first metal particle layer 22 by a thermal spraying process to form the first adhesive layer 23.

[0092] The first adhesive layer 23 is bonded to the electrode assembly 10.

[0093] In some embodiments, the surface of the substrate layer 21 is cleaned with ethanol to remove surface impurities, which helps to improve the adhesion of the first metal particle layer 22 to the substrate layer 21.

[0094] Referring to Figure 7, one embodiment of this application also provides an electronic device 200. The electronic device 200 includes a secondary battery (100A, 100B, 100C, 100D) as described in any of the above embodiments. The electronic device 200 can be a vehicle, mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, or power tool, etc.

[0095] In the aforementioned secondary batteries (100A, 100B, 100C, 100D) and electronic device 200, the first metal particle layer 22 is located between the substrate layer 21 and the first adhesive layer 23. The first metal particle layer 22 includes at least one layer of metal particles 221. Compared with ordinary adhesive tape, the adhesive component 20 itself has high structural strength and good support force. At the same time, the first metal particle layer 22 with high ductility can reduce the risk of brittle fracture when the adhesive component resists external impact, improve the pass rate of the blunt puncture extrusion test of the secondary battery 100A, and thus improve the safety performance of the secondary battery 100A.

[0096] The embodiments and comparative examples provided below illustrate the implementation of this application in more detail. Various tests and evaluations were conducted according to the methods described below. Furthermore, unless otherwise specified, "parts" and "%" are quality standards.

[0097] 1. Secondary battery blunt puncture and compression test

[0098] First, the secondary batteries to be tested were pretreated under the following conditions: test temperature 20±5℃, constant current discharge at 0.5C to 3.0V, rest for 10 minutes, constant current charging at 0.5C to 4.53V, constant voltage charging at 4.53V to 0.05C, and rest for 10 minutes. The appearance was checked and photographed before and after the test. After pretreatment, the sample was placed on the test platform, and a blunt nail with a diameter of 6mm was used. The pressing force was 1600N, and the drop speed was 300N / min. The test was performed at the center of the negative electrode tab of the sample. During the test, the voltage and surface temperature rise of the secondary battery were monitored. If the secondary battery did not explode or catch fire during the test, the blunt nail compression test was passed; otherwise, the blunt nail compression test failed. 100 secondary batteries were tested, and the number of batteries that passed the test was X, resulting in a pass rate of X / 100.

[0099] 2. Secondary battery self-discharge test

[0100] The test temperature was 20±5℃. The battery was discharged to 3.0V using a constant current of 0.2C, and then charged for 2280s using a constant current of 0.5C. The battery was left to stand at high temperature for 2 days to eliminate polarization, and then left to stand at room temperature for 2 days to allow the secondary battery temperature to drop to room temperature and eliminate the influence of temperature on the test. The circuit voltage OCV1 was measured. The battery was left to stand at room temperature for 3 more days, and the final voltage OCVB was measured. The value of K was calculated as (OCV1-OCVB) / Δt and the data was recorded.

[0101] 3. Test methods for particle size and average spacing of metal particles

[0102] Select a 10mm long and 10mm wide adhesive sample and mount it on a conductive substrate, such as conductive tape or conductive carbon film. Fix the prepared sample on the SEM sample stage. Place the sample stage into the SEM sample chamber and evacuate to ensure a high vacuum environment. Select an appropriate accelerating voltage based on the properties of different metal adhesive tapes, typically between 1-30kV (under accelerating voltage, the adhesive tape layer will be destroyed, exposing the intermediate metal particles). Adjust parameters such as scanning speed and scanning range to obtain a clear image. Select points to measure and record the average spacing between metal particles, taking ten spacings in each of the X and Y directions to calculate the average value. Randomly select 10-20 metal particles, measure their diameter, and calculate the average diameter.

[0103] 4. Test method for adhesive thickness

[0104] Select a 10mm long and 10mm wide adhesive sample and flatten it on the optical microscope testing platform. Turn on the optical thickness gauge, align it with the adhesive sample, and read the thickness value displayed on the instrument. Take points in a 3x3 array in the X and Y directions and calculate the average value as the thickness of the adhesive.

[0105] 5. Substrate layer thickness test method

[0106] Select a 10mm long and wide adhesive sample and prepare its cross-section using methods such as mechanical cutting, grinding, polishing, and liquid nitrogen brittle fracture to ensure a smooth cross-section without obvious damage. Use ultrasonic cleaning or organic solvent cleaning to remove surface contaminants and residues. Load the sample onto a fixture with the cross-section facing upwards. Use an optical microscope to measure the thickness of the non-metallic particle-covered area of ​​the sample. Take 9 points in the linear direction and calculate the average value as the substrate layer thickness.

[0107] Example 1:

[0108] A secondary battery, with an initial thickness of 4.8 mm, a length of 87 mm, and a width of 64 mm at 50% SOC, is assembled as follows:

[0109] (1) Preparation of negative electrode sheet: The negative electrode active materials artificial graphite, conductive carbon black (Super P), and styrene-butadiene rubber (SBR) are mixed in a weight ratio of 96:1.5:2.5, and deionized water is added as a solvent to prepare a slurry with a weight percentage of 50 wt%. The slurry is stirred evenly and uniformly coated on one surface of copper foil. Then, it is dried at 110°C to obtain a negative electrode sheet with a single-sided coating of negative electrode active material. When preparing a double-sided coated negative electrode sheet, the above steps are repeated on the other surface of the negative electrode sheet to obtain a negative electrode sheet with a double-sided coating of negative electrode active material. Then, the coated electrode sheet is cold-pressed to a thickness of 105 μm, grooves are set on the negative electrode active material, and the negative electrode tabs are welded to the copper foil exposed in the grooves.

[0110] (2) Preparation of the positive electrode sheet: Lithium cobalt oxide (LiCoO2), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) were mixed in a weight ratio of 97.5:1.0:1.5. N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 75 wt%, and the mixture was stirred evenly. The slurry was uniformly coated on one surface of an aluminum foil and then dried at 90°C to obtain a positive electrode sheet with a single-sided coating of the positive electrode active material. When preparing a double-sided coated positive electrode sheet, the above coating steps were repeated on the other surface of the aluminum foil. The coated electrode sheet was then cold-pressed to a thickness of 95 μm, grooves were formed on the positive electrode active material, and the positive electrode tabs were welded to the aluminum foil exposed in the grooves.

[0111] (3) Preparation of electrolyte: In a dry argon atmosphere, ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) are first mixed in a mass ratio of EC:EMC:DEC = 30:50:20 to form a basic organic solvent. Then, lithium salt lithium hexafluorophosphate (LiPF6) is added to the basic organic solvent to dissolve and mix evenly to obtain an electrolyte with a lithium salt concentration of 1.15 mol / L.

[0112] (4) Preparation of the diaphragm: A three-layer diaphragm is adopted, which includes an adhesive layer, a substrate layer and an adhesive layer stacked together. The first substrate layer is made of polyethylene (PE), the adhesive layer is made of PVDF, and the adhesive layer also contains inorganic boehmite particles.

[0113] (5) Electrode assembly fabrication: The positive electrode, separator, and negative electrode are wound and arranged. An adhesive is placed at the groove where the negative electrode tab is located (defined as position A), an adhesive is placed at the position opposite the positive electrode to the groove (defined as position B), and adhesives are placed on the outer surface of the outermost electrode of the electrode assembly and at the end of the electrode assembly (defined as position C). The adhesives at positions A, B, and C satisfy: D1 = 5 μm.

[0114] (6) Secondary battery assembly: Place the dented aluminum-plastic film in the assembly fixture with the dent facing upwards, place the electrode assembly in the dent, and apply external force to press it firmly. Then cover the electrode assembly with another dented aluminum-plastic film with the dent facing downwards, and heat seal the two aluminum-plastic films around their perimeter by hot pressing to obtain the assembled electrode assembly.

[0115] (7) Electrolyte injection and encapsulation: Electrolyte is injected into the assembled electrode assembly, and after vacuum encapsulation, standing, hot pressing formation, shaping and other processes, a secondary battery is obtained.

[0116] Comparative Example 1: A 16µm thick layer of green adhesive was applied at positions A, B, and C of the electrode assembly. It should be noted that all other parameters of Comparative Example 1 are the same as those of Example 1.

[0117] Comparative Example 2: A 24µm stainless steel sheet with metal adhesive tape was placed at position A of the electrode assembly. It should be noted that all other parameters of Comparative Example 2 are the same as those of Example 1.

[0118] Comparative Example 3: A 24µm stainless steel sheet with metal adhesive tape was placed at position B of the electrode assembly. It should be noted that all other parameters of Comparative Example 3 are the same as those of Example 1.

[0119] Comparative Example 4: A 24µm stainless steel sheet with metal adhesive tape was placed at position C of the electrode assembly. It should be noted that all other parameters of Comparative Example 3 are the same as those of Example 1.

[0120] Comparative Example 5: 24µm stainless steel sheet adhesive tape was applied at positions A, B, and C of the electrode assembly. It should be noted that all other parameters of Comparative Example 5 were the same as those of Example 1.

[0121] Table 1

[0122] (Except for the parameters mentioned in Table 1, all other parameters in Examples 1-10 are the same as those in Example 1, T1 = 1.2D1; L1 = 0.5D1) Note: In Table 1, "\" indicates that the parameter is not included.

[0123] As can be seen from Comparative Examples 1-5 and Examples 1-10, the first metal particle layer is located between the substrate layer and the first adhesive layer. The first metal particle layer includes at least one layer of metal particles, which can improve the pass rate of the blunt puncture extrusion test of the secondary battery and help to improve the self-discharge phenomenon.

[0124] As shown in Examples 1 and 5-9, limiting the diameter to 1μm ≤ D1 ≤ 20μm improves the pass rate of the blunt puncture extrusion test for secondary batteries and helps to reduce self-discharge. Furthermore, further limiting the diameter to 5μm ≤ D1 ≤ 10μm further improves the pass rate of the blunt puncture extrusion test for secondary batteries and helps to reduce self-discharge. It should be noted that when D1 > 20μm, the adhesive thickness becomes too large, leading to a significant decrease in the energy density of the secondary battery; therefore, examples with D1 > 20μm were not included.

[0125] As can be seen from Comparative Examples 8 and 10, the first metal particle layer includes two layers of metal particles, which can further improve the pass rate of the blunt puncture and extrusion test of the secondary battery and help improve the self-discharge phenomenon.

[0126] Table 2

[0127] (Except for the parameters mentioned in Table 1, all other parameters in Examples 1-10 are the same as those in Example 1, D1 = 5 μm)

[0128] As shown in Comparative Examples 1 and 11-13, limiting T1 to ≥ 1.2D1 can improve the pass rate of the blunt puncture extrusion test of the secondary battery and help to improve the self-discharge phenomenon. It should be noted that when T1 > 24 μm, the thickness of the adhesive will be too large, which will lead to a significant reduction in the energy density of the secondary battery. Therefore, examples with T1 > 24 μm were not included.

[0129] In addition, those skilled in the art may make other changes within the spirit of this application. Of course, all such changes made in accordance with the spirit of this application should be included within the scope disclosed in this application.

Claims

1. A secondary battery characterized by comprising: The secondary battery includes: Electrode assembly; An adhesive component comprising a substrate layer, a first metal particle layer, and a first adhesive layer stacked along a first direction, wherein the first metal particle layer is located between the substrate layer and the first adhesive layer, the first metal particle layer comprising at least one layer of metal particles, and the first adhesive layer is bonded to the electrode assembly.

2. The secondary battery according to claim 1, wherein The average particle size of the metal particles is D1, where 1μm≤D1≤20μm.

3. The secondary battery according to claim 2, wherein 5μm≤D1≤10μm.

4. The secondary battery according to claim 1, wherein The first metal particle layer is in contact with the substrate layer and the first adhesive layer, respectively.

5. The secondary battery according to claim 1, wherein Along the first direction, the thickness of the substrate layer is T1, where 1.2D1≤T1≤24μm.

6. The secondary battery according to claim 1, wherein The metal particles include at least one of copper, aluminum, gold, silver, iron, or nickel.

7. The secondary battery according to claim 1, wherein The substrate layer includes at least one of polyester film, polyimide film, polypropylene film, polyethylene film, polytetrafluoroethylene film, or silicone rubber film.

8. The secondary battery as described in any one of claims 1 to 7, characterized in that, The first metal particle layer comprises two layers of the metal particles.

9. The secondary battery as described in claim 1, characterized in that, The electrode assembly includes a first electrode, a diaphragm, a second electrode, and a first tab. The polarity of the first electrode is opposite to that of the second electrode. The first electrode includes a first current collector and a first active material layer disposed on the first current collector. The first active material layer has a groove, and the first tab is disposed in the groove. The adhesive is bonded to the first electrode and covers the groove.

10. The secondary battery as described in claim 1, characterized in that, The electrode assembly includes a first electrode, a diaphragm, a second electrode, and a first tab. The polarity of the first electrode is opposite to that of the second electrode. The first electrode includes a first current collector and a first active material layer disposed on the first current collector. The first active material layer has a groove, and the first tab is disposed in the groove. The adhesive is bonded to the second electrode and the bonding position is opposite to the groove.

11. The secondary battery as described in claim 9, characterized in that, The first electrode includes a first current collector, which is a nickel foil; The metal particles of the adhesive bonded to the first electrode are nickel metal particles; or The first current collector is a copper foil; The metal particles of the adhesive attached to the first electrode are copper metal particles.

12. The secondary battery as described in claim 10, characterized in that, The second electrode includes a second current collector, which is a nickel foil; The metal particles of the adhesive bonded to the second electrode are nickel metal particles; or The second current collector is a copper foil; The metal particles of the adhesive attached to the second electrode are copper metal particles.

13. The secondary battery as described in claim 1, characterized in that, The adhesive is bonded to the outer surface of the outermost electrode sheet of the electrode assembly and covers the end of the electrode assembly.

14. The secondary battery as described in claim 13, characterized in that, The metal particles in the adhesive are aluminum metal particles.

15. An electronic device, characterized in that, The electronic device includes a secondary battery as described in any one of claims 1 to 14.

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