Secondary battery and electronic device

Abstract

The invention discloses a secondary battery and an electronic device. The secondary battery comprises an electrode assembly and a bonding piece. The bonding piece comprises a base material layer, a first metal particle layer and a first bonding layer which are stacked in the first direction, and the first metal particle layer is located between the base material layer and the first bonding layer. The first metal particle layer comprises at least one layer of metal particles. The first adhesive layer is adhered to the electrode assembly. In the secondary battery, the first metal particle layer comprises at least one layer of metal particles, and compared with common gummed paper, the bonding piece with the first metal particle layer is high in structural strength and has good supporting force, and meanwhile, the first metal particle layer can enable the bonding piece to have relatively high ductility; and the risk of brittle fracture is reduced when the external force impact is resisted, and the blunt thorn extrusion test passing rate of the secondary battery is improved, so that the safety performance of the secondary battery is improved.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a secondary battery and an electronic device. Background Art

[0002] Soft-pack batteries are usually bonded with adhesive tape, but existing adhesive tape (such as polyimide adhesive tape or polyester adhesive tape) has a weak structural strength. When the battery is impacted by external forces (such as blunt thorns and squeezing), the existing adhesive tape cannot protect the battery, resulting in reduced battery safety performance. Summary of the invention

[0003] In view of the above situation, the present application provides a secondary battery, which is beneficial to improving safety performance.

[0004] An embodiment of the present application provides a secondary battery, the secondary battery comprising an electrode assembly and an adhesive. The adhesive comprises 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 comprises at least one layer of metal particles. The first adhesive layer is bonded to the electrode assembly.

[0005] In the above-mentioned secondary battery, the first metal particle layer includes at least one layer of metal particles. Compared with ordinary adhesive tape, the adhesive with the first metal particle layer itself has high structural strength and good supporting force. At the same time, the first metal particle layer with high ductility can reduce the risk of brittle fracture when the adhesive resists external force impact, thereby improving the pass rate of the blunt puncture extrusion test of the secondary battery, and thus improving the safety performance of the secondary battery.

[0006] In some embodiments of the present 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 squeezed by a blunt thorn, the first metal particle layer can withstand external force impact, and the first metal particle layer is not prone to brittle fracture, which can reduce the generation of burrs and debris, which is beneficial to reduce the risk of damage to the electrode assembly, thereby improving the safety performance of the secondary battery.

[0007] In some embodiments of the present application, 5μm≤D1≤10μm, so as to further balance the structural strength and ductility of the first metal particle layer. When the secondary battery is squeezed by a blunt thorn, the first metal particle layer can withstand external force impact, and the first metal particle layer is not prone to brittle fracture, which can reduce the generation of burrs and debris, and is beneficial to reduce the risk of damage to the electrode assembly, thereby improving the safety performance of the secondary battery.

[0008] In some embodiments of the present application, the first metal particle layer is in contact with the substrate layer and the first bonding layer respectively to improve the structural stability of the bonding member.

[0009] In some embodiments of the present application, along the first direction, the thickness of the substrate layer is T1, 1.2D1≤T1≤24 μm, so as to improve the insulation stability of the adhesive and improve the energy density and flatness of the secondary battery.

[0010] In some embodiments of the present application, the metal particles include at least one of copper, aluminum, gold, silver, iron or nickel to meet the requirements of structural strength and ductility of the first metal particle layer.

[0011] In some embodiments of the present application, the substrate layer 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.

[0012] In some embodiments of the present 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 squeezed by a blunt thorn, the first metal particle layer can withstand external force impact, and the first metal particle layer is not prone to brittle fracture, which can reduce the generation of burrs and debris, which is beneficial to reduce the risk of damage to the electrode assembly, thereby improving the safety performance of the secondary battery.

[0013] In some embodiments of the present application, the electrode assembly includes a first pole piece, a diaphragm, a second pole piece and a first pole piece. The polarity of the first pole piece is opposite to that of the second pole piece. The first pole piece includes a first current collector and a first active material layer disposed on the first current collector. The first active material layer is provided with a groove, and the first pole piece is disposed in the groove. The adhesive is bonded to the first pole piece and covers the groove to improve the insulation stability between the portion of the first pole piece located in the groove and the adjacent second pole piece. In addition, when the secondary battery is squeezed by a blunt thorn, the first metal particle layer in the adhesive can resist external force impact, and the first metal particle layer is not prone to brittle fracture, which can reduce the generation of burrs and debris, which is beneficial to reduce the risk of damage to the portion of the first pole piece located in the groove, thereby improving the safety performance of the secondary battery.

[0014] In some embodiments of the present application, the electrode assembly includes a first pole piece, a diaphragm, a second pole piece and a first pole piece. The polarity of the first pole piece is opposite to that of the second pole piece. The first pole piece includes a first current collector and a first active material layer disposed on the first current collector. The first active material layer is provided with a groove, and the first pole piece is disposed in the groove. The adhesive is bonded to the second pole piece and the bonding position is opposite to the groove to improve the insulation stability between the portion of the first pole piece located in the groove and the adjacent second pole piece. In addition, when the secondary battery is squeezed by a blunt thorn, the first metal particle layer in the adhesive can resist external force impact, and the first metal particle layer is not prone to brittle fracture, which can reduce the generation of burrs and debris, which is beneficial to reduce the risk of damage to the portion of the first pole piece located in the groove, thereby improving the safety performance of the secondary battery.

[0015] In some embodiments of the present application, the first pole piece includes a first current collector, the first current collector is nickel foil, and the metal particles of the adhesive bonded to the first pole piece are nickel metal particles, so that the metal particle material of the adhesive bonded to the first pole piece 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.

[0016] In some embodiments of the present application, the first pole piece includes a first current collector, the first current collector is copper foil, and the metal particles of the adhesive bonded to the first pole piece are copper metal particles, so that the metal particle material of the adhesive bonded to the first pole piece 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 the present application, the second pole piece includes a second current collector, the second current collector is nickel foil, and the metal particles of the adhesive bonded to the second pole piece are nickel metal particles, so that the metal particle material of the adhesive bonded to the second pole piece 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.

[0018] In some embodiments of the present application, the second pole piece includes a second current collector, the second current collector is copper foil, and the metal particles of the adhesive bonded to the second pole piece are copper metal particles, so that the metal particle material of the adhesive bonded to the second pole piece 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 the present application, the adhesive is bonded to the outer surface of the pole piece of the outermost circle of the electrode assembly and covers the end of the electrode assembly to improve the structural stability of the electrode assembly. In addition, when the secondary battery is squeezed by a blunt thorn, the first metal particle layer can resist the impact of external force, and the first metal particle layer is not prone to brittle fracture, which can reduce the generation of burrs and debris, which is conducive to reducing the risk of damage to the end of the electrode assembly, thereby improving the safety performance of the secondary battery.

[0020] In some embodiments of the present 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.

[0021] An embodiment of the present application further provides an electronic device, which includes any one of the secondary batteries in the above embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of a secondary battery in one embodiment of the present application.

[0023] Figure 2 It is a schematic structural diagram of an adhesive component of a secondary battery in one embodiment of the present application.

[0024] Figure 3 It is a schematic structural diagram of an adhesive component of a secondary battery in another embodiment of the present application.

[0025] Figure 4 It is a schematic structural diagram of an adhesive component of a secondary battery in another embodiment of the present application.

[0026] Figure 5 It is a schematic structural diagram of an adhesive component of a secondary battery in another embodiment of the present application.

[0027] Figure 6 It is a schematic flow chart of a method for preparing a secondary battery in one embodiment of the present application.

[0028] Figure 7 It is a schematic diagram of the structure of an electronic device in one embodiment of the present application.

[0029] Main component symbols Secondary batteries 100A, 100B, 100C, 100D, Electronic device 200 Electrode assembly 10 End terminal 10A The first pole piece 11 Groove 11A First current collector 111 First active material layer 112 Diaphragm 12 The second pole piece 13 First empty foil area 13A Second current collector 131 Second active material layer 132 Adhesive 20 Base material 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 The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0031] It should be noted that when an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be a centrally disposed element at the same time. When an element is considered to be "disposed" on another element, it may be directly disposed on the other element or there may be a centrally disposed element at the same time.

[0032] When a value is considered to be "equal" to another value, it means that the two are equal within the set deviation, and the set deviation range is within 5%. In other words, when at least one of the two values ​​fluctuates within the set deviation range, even if their values ​​are not equal, they are still judged to be roughly equal. When a value is considered to have a ratio of "1:1" to another value, it means that the two are equal within the set deviation, and the set deviation range is within 5%. In other words, when at least one of the two values ​​fluctuates within the set deviation range, even if their values ​​are not equal, they are still judged to be equal in ratio.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more related listed items. The term "overlap" used herein refers to the overlap of the projections of two parts or the overlap of the projections of two parts.

[0034] An embodiment of the present application provides a secondary battery, the secondary battery comprising an electrode assembly and an adhesive. The adhesive comprises 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 comprises at least one layer of metal particles. The first adhesive layer is bonded to the electrode assembly.

[0035] In the above-mentioned secondary battery, the first metal particle layer includes at least one layer of metal particles. Compared with ordinary adhesive tape, the adhesive with the first metal particle layer itself has high structural strength and good supporting force. At the same time, the first metal particle layer with high ductility can reduce the risk of brittle fracture when the adhesive resists external force impact, thereby improving the pass rate of the blunt puncture extrusion test of the secondary battery, and thus improving the safety performance of the secondary battery.

[0036] The embodiments of the present application are further described below in conjunction with the accompanying drawings.

[0037] Example 1 Please also read Figure 1 and Figure 2One embodiment of the present application provides a secondary battery 100A. The secondary battery 100A refers to a battery that can be used continuously by activating active materials through charging after discharge.

[0038] The secondary battery 100A includes an electrode assembly 10 and an adhesive 20. The electrode assembly 10 is formed by winding or stacking a positive electrode sheet, a separator and a negative electrode sheet arranged in sequence. The electrode assembly 10 is used to convert chemical energy into electrical energy.

[0039] The adhesive member 20 is bonded to the electrode assembly 10 to achieve bonding and insulation isolation. Optionally, the adhesive member 20 is disposed on the inner side or the outer side of the electrode assembly 10 .

[0040] The adhesive member 20 includes a substrate layer 21, a first metal particle layer 22, and a first bonding layer 23 stacked along a first direction Z. The substrate layer 21 has insulating properties, and the first metal particle layer 22 is located between the substrate layer 21 and the first bonding layer 23. The first metal particle layer 22 includes at least one layer of metal particles 221. The first bonding layer 23 is bonded to the electrode assembly 10.

[0041] In some embodiments, the metal particles 221 are uniformly coated on the surface of the substrate layer 21 by cold spraying technology.

[0042] Compared with ordinary adhesive tape, the adhesive 20 with the first metal particle layer 22 has high structural strength and good supporting force. 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 force impact, thereby improving the pass rate of the blunt thorn extrusion test of the secondary battery 100A, and thus improving the safety performance of the secondary battery 100A.

[0043] Furthermore, when the secondary battery 100A is subjected to a self-discharge test, the first metal particle layer 21 is less likely to generate burrs, and the K value of the self-discharge of the secondary battery 100A can be reduced, which is beneficial to improving the self-discharge phenomenon.

[0044] In some embodiments, the average particle size of the metal particles 221 is D1, 1μm≤D1≤20μm. When D1 is too small (for example, less than 1μm), it is easy to make the grain size of the first metal particle layer 22 too small and the grain boundary area large, thereby increasing the resistance to dislocation movement. The first metal particle layer 22 has high structural strength but insufficient ductility. When the secondary battery 100A is squeezed by a blunt thorn, the first metal particle layer 22 is prone to brittle fracture and can produce burrs and debris. The burrs and debris can cause the electrode assembly 10 to short-circuit. When D1 is too large (for example, greater than 20μm), it is easy to make the grain size of the first metal particle layer 22 too large and the grain boundary area small, thereby reducing the resistance to dislocation movement. The first metal particle layer 22 has strong ductility but insufficient structural strength. When the secondary battery 100A is squeezed by a blunt thorn, the first metal particle layer 22 is easily deformed, thereby weakening the first metal particle layer 22's resistance to external forces. By limiting 1μm≤D1≤20μm, the structural strength and ductility of the first metal particle layer 22 are balanced. When the secondary battery 100A is squeezed by a blunt thorn, the first metal particle layer 22 can withstand external force 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, thereby improving the safety performance of the secondary battery 100A.

[0045] Optionally, D1 is 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm and any other value in the range of 1μm≤D1≤20μm.

[0046] Furthermore, 5μm≤D1≤10μm, so as to further balance the structural strength and ductility of the first metal particle layer 22. When the secondary battery 100A is squeezed by a blunt thorn, the first metal particle layer 22 can withstand external force impact, and the first metal particle layer 22 is not prone to brittle fracture, which can reduce the generation of burrs and debris, which is beneficial to reduce the risk of damage to the electrode assembly 10, thereby improving the safety performance of the secondary battery 100A.

[0047] 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 at different positions has different structural strengths and ductility, thereby facilitating the adhesive 20 to adapt to the requirements of different positions.

[0048] Please continue reading 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， This is to reduce the overall thickness of the adhesive member 20 .

[0049] Please continue reading Figure 2 In some embodiments, the first metal particle layer 22 is in contact with the substrate layer 21 and the first adhesive layer 23 respectively to improve the structural stability of the adhesive member 20 .

[0050] Please continue reading Figure 2 In some embodiments, the average spacing of the metal particles 221 is L1, 0.4D1≤L1≤0.6D1. When L1 is too small (for example, less than 0.4D1), the ductility of the first metal particle layer 22 is likely to be insufficient, and during the processing, the close arrangement of the metal particles 221 also makes it difficult to release the stress during the processing, which easily leads to increased processing difficulty. When L1 is too large (for example, greater than 0.6D1), the structural strength of the first metal particle layer 22 is likely to be 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 squeezed by a blunt thorn, the first metal particle layer 22 can resist external force impact, and the first metal particle layer 22 is not easy to brittle fracture, which can reduce the generation of burrs and debris, which is beneficial to reduce the risk of damage to the electrode assembly 10, thereby improving the safety performance of the secondary battery 100A. Moreover, it is also beneficial for the metal particles 221 to be evenly distributed on the surface of the substrate layer 21 , thereby reducing the risk of the first metal particle layer 22 being affected in terms of consistency of deformation resistance and flatness due to uneven local thickness.

[0051] Optionally, L1 is one of 0.4D1, 0.5D1, 0.6D1 and any other value in the range of 0.4D1≤L1≤0.6D1.

[0052] In some embodiments, the metal particles 221 include at least one of copper, aluminum, gold, silver, iron, or nickel to meet the requirements of structural strength and ductility of the first metal particle layer 22 .

[0053] 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 .

[0054] Please continue reading Figure 2In some embodiments, the thickness of the substrate layer 21 is T1, 1.2D1≤T1≤24μm. When the thickness of the substrate layer 21 is too small (for example, less than 1.2D1), when the secondary battery 100A is squeezed by a blunt thorn, the metal particles 221 easily pierce the substrate layer 21, resulting in a decrease in the insulation stability of the adhesive 20. When the thickness of the substrate layer 21 is too large (for example, greater than 24μm), it is easy to make the thickness of the adhesive 20 too large, resulting in a decrease in the energy density of the secondary battery 100A, and it is also easy to affect the flatness of the secondary battery 100A. By limiting 1.2D1≤T1≤24μm, the insulation stability of the adhesive 20 is improved, and the energy density and flatness of the secondary battery 100A are improved.

[0055] It is understandable that the thickness of the substrate layer 21 has a certain influence on the ductility of the substrate layer 21 . By limiting 1.2D1≤T1≤24 μm, 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 .

[0056] Optionally, T1 is 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 in the range of 1.2D1≤T1≤24μm.

[0057] In some embodiments, the first adhesive layer 23 includes at least one of acrylic adhesive, pressure-sensitive adhesive, acrylate adhesive, rubber-based adhesive, or polyurethane adhesive to meet the bonding requirements of the first adhesive layer 23 .

[0058] Please also read Figure 1 and Figure 2 In some embodiments, the electrode assembly 10 includes a first electrode piece 11 , a diaphragm 12 , a second electrode piece 13 and a first electrode tab 14 , and the polarity of the first electrode piece 11 is opposite to the polarity of the second electrode piece 13 .

[0059] In some embodiments, the first pole piece 11 is provided with a groove 11A, one end of the first pole tab 14 is disposed in the groove 11A, and the other end of the first pole tab 14 extends out of the electrode assembly 10. Specifically, the first pole piece 11 includes a first current collector 111 and a first active material layer 112, and 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.

[0060] The adhesive 20 is bonded to the first pole piece 11 and covers the groove 11A to improve the insulation stability between the portion of the first pole tab 14 located in the groove 11A and the adjacent second pole piece 13. In addition, when the secondary battery 100A is squeezed by a blunt thorn, the first metal particle layer 22 in the adhesive 20 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, which is beneficial to reduce the risk of damage to the portion of the first pole tab 14 located in the groove 11A, thereby improving the safety performance of the secondary battery 100A.

[0061] Please also read Figure 1 and Figure 2 In some embodiments, the adhesive 20 is bonded to the second pole piece 13 and the bonding position is opposite to the groove 11A to improve the insulation stability between the portion of the first pole piece 14 located in the groove 11A and the adjacent second pole piece 13. In addition, when the secondary battery 100A is squeezed by a blunt thorn, the first metal particle layer 22 in the adhesive 20 can resist external force impact, and the first metal particle layer 22 is not prone to brittle fracture, which can reduce the generation of burrs and debris, which is beneficial to reduce the risk of damage to the portion of the first pole piece 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 pole piece 13 closest to the groove 11A, and the groove 11A and the adhesive 20 are arranged on both sides of the diaphragm 12 along the thickness direction of the electrode assembly 10.

[0062] In some embodiments, the first pole piece 11 is a negative pole piece, and the second pole piece 13 is a positive pole piece. The size of the adhesive 20 bonded to the first pole piece 11 and covering the groove 11A is smaller than the size of the adhesive 20 bonded to the second pole piece 13 at a position opposite to the groove 11A, so as to reduce the risk of lithium deposition at the edge of the groove 11A.

[0063] In some embodiments, the first current collector 111 is made of a metal material, and the material of the metal particles 221 of the adhesive 20 bonded to the first electrode sheet 11 is consistent with that of the first current collector 111 to reduce the risk of electrochemical corrosion and improve the safety performance of the secondary battery 100A.

[0064] Optionally, the first current collector 111 is nickel foil, and the metal particles 221 of the adhesive 20 bonded to the first pole piece 11 are nickel metal particles; or the first current collector 111 is copper foil, and the metal particles 221 of the adhesive 20 bonded to the first pole piece 11 are copper metal particles.

[0065] Please also read Figure 1 and Figure 2In some embodiments, the second pole piece 13 includes a second current collector 131 and a second active material layer 132. Along the thickness direction of the second current collector 131, at least one surface of the second current collector 131 is provided with the second active material layer 132. The second current collector 131 is made of a metal material, and the material of the metal particles 221 of the adhesive 20 bonded to the second pole piece 13 is consistent with the material of the second current collector 131, so as to reduce the risk of electrochemical corrosion and improve the safety performance of the secondary battery 100A.

[0066] Optionally, the second current collector 131 is nickel foil, and the metal particles 221 of the adhesive 20 bonded to the second pole piece 13 are nickel metal particles; or the second current collector 131 is copper foil, and the metal particles 221 of the adhesive 20 bonded to the second pole piece 13 are copper metal particles.

[0067] Please also read Figure 1 and Figure 2 In some embodiments, the adhesive 20 is bonded to the outer surface of the outermost pole piece of the electrode assembly 10 and covers the end 10A of the electrode assembly 10 to improve the structural stability of the electrode assembly 10. In addition, when the secondary battery 100A is squeezed by a blunt thorn, 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, which is beneficial to reduce the risk of damage to the end 10A of the electrode assembly 10, thereby improving the safety performance of the secondary battery 100A. Specifically, Figure 1 For example, the outermost electrode piece of the electrode assembly 10 is the second electrode piece 13, the outer surface of the current collector of the outermost electrode piece of the electrode assembly 10 includes a first empty foil area 13A that is not coated with the second active material layer 132, the tail end 10A of the electrode assembly 10 is arranged on the first empty foil area 13A, and the adhesive 20 is bonded to the first empty foil area 13A and the tail end 10A of the electrode assembly 10.

[0068] Please also read Figure 1 and Figure 2 In some embodiments, the outermost pole piece of the electrode assembly 10 is a positive pole piece, and the material of the current collector of the outermost pole piece of the electrode assembly 10 includes aluminum. The metal particles 221 of the adhesive 20 bonded to the outer surface of the outermost pole piece of the electrode assembly 10 and covering the tail 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.

[0069] Example 2 Please also read Figure 1 and Figure 3 One embodiment of the present application further provides a secondary battery 100B. The difference between the secondary battery 100B and the secondary battery 100A is that: 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 squeezed by a blunt thorn, the first metal particle layer 22 can withstand external force impact, and the first metal particle layer 22 is not prone to brittle fracture, which can reduce the generation of burrs and debris, which is beneficial to reduce the risk of damage to the electrode assembly 10, thereby improving the safety performance of the secondary battery 100B.

[0070] In some embodiments, along the first direction Z, a layer of metal particles 221 close to the first adhesive layer 23 is defined as metal particles 221A, and a layer of metal particles 221 close to the substrate layer 21 is defined as metal particles 221B, and a portion of the metal particles 221A is disposed between the gaps between two adjacent metal particles 221B to improve the structural stability of the first metal particle layer 22. During the preparation process, the metal particles 221B are uniformly coated on the surface of the substrate layer 21 by the cold spraying technology, and the metal particles 221A are uniformly coated on the surface of the metal particles 221A by the cold spraying technology.

[0071] Except for the above differences, the parameters of the secondary battery 100B are substantially the same as those of the secondary battery 100A, and reference may be made to the description of the secondary battery 100A.

[0072] Example 3 Please also read Figure 1 and Figure 4 One embodiment of the present application further provides a secondary battery 100C. The difference between the secondary battery 100C and the secondary battery 100A is that: The adhesive member 20 includes a second adhesive layer 24 . Along the first direction Z, the second adhesive layer 24 is connected to a surface of the substrate layer 21 away from the first metal particle layer 22 .

[0073] When the adhesive 20 is located on the inner side of the electrode assembly 10, the second adhesive layer 24 is bonded to the separator 12 adjacent to the adhesive 20 to improve the structural stability of the electrode assembly 10. Optionally, the adhesive 20 is located on the inner side of the electrode assembly 10 including the following situations: the adhesive 20 is bonded to the first pole piece 11 and covers the groove 11A; the adhesive 20 is bonded to the second pole piece 13 and the bonding position is opposite to the groove 11A.

[0074] When the adhesive 20 is located outside the electrode assembly 10, the second adhesive layer 24 is bonded to the packaging bag that wraps the electrode assembly 10 to improve the structural stability of the electrode assembly 10. Optionally, the adhesive 20 is located outside the electrode assembly 10, including the following situations: the adhesive 20 is bonded to the outer surface of the outermost electrode sheet of the electrode assembly 10 and covers the end 10A of the electrode assembly 10.

[0075] Except for the above differences, the parameters of the secondary battery 100C are substantially the same as those of the secondary battery 100A, and reference may be made to the description of the secondary battery 100A.

[0076] Example 4 Please also read Figure 1 and Figure 5 One embodiment of the present application further provides a secondary battery 100D. The difference between the secondary battery 100D and the secondary battery 100C is that: The adhesive 20 includes a second metal particle layer 25, and the second metal particle layer 25 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 squeezed by a blunt thorn, the first metal particle layer 22 and the second metal particle layer 25 in the adhesive 20 can resist external force impact, and 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, which is beneficial to reduce the risk of damage to the electrode assembly 10, thereby improving the safety performance of the secondary battery 100D.

[0077] Except for the above differences, the parameters of the secondary battery 100D and the secondary battery 100C are substantially the same, and reference may be made to the description of the secondary battery 100C.

[0078] See also Figure 6 One embodiment of the present application also provides a method for preparing a secondary battery, comprising the following steps: Providing a substrate layer 21; Cleaning the surface of the substrate layer 21; Spraying metal particles onto the surface of the substrate layer 21 by a cold spraying process to form a first metal particle layer 22; Spraying an adhesive onto the surface of the first metal particle layer 22 by a thermal spraying process to form a first adhesive layer 23; The first bonding layer 23 is bonded to the electrode assembly 10 .

[0079] In some embodiments, the surface of the substrate layer 21 is cleaned with ethanol to remove surface impurities, which is beneficial to improving the adhesion of the first metal particle layer 22 on the substrate layer 21 .

[0080] See also Figure 7 One embodiment of the present application further provides an electronic device 200. The electronic device 200 includes the secondary battery (100A, 100B, 100C, 100D) in any of the above embodiments. The electronic device 200 can be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, etc.

[0081] In the above-mentioned secondary batteries (100A, 100B, 100C, 100D) and electronic devices 200, the first metal particle layer 22 is located between the substrate layer 21 and the first adhesive layer 23, and the first metal particle layer 22 includes at least one layer of metal particles 221. Compared with ordinary adhesive tape, the adhesive 20 itself has high structural strength and good supporting force. 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 force impact, thereby improving the pass rate of the blunt puncture extrusion test of the secondary battery 100A, and thereby improving the safety performance of the secondary battery 100A.

[0082] Hereinafter, the embodiments of the present application will be described in more detail with reference to Examples and Comparative Examples. Various tests and evaluations were performed according to the following methods. In addition, unless otherwise specified, "parts" and "%" are by mass.

[0083] 1. Secondary battery blunt puncture compression test First, the secondary battery to be tested is pretreated. The treatment conditions are: the test temperature is 20±5℃, the current is discharged to 3.0V with a constant current of 0.5C, and it is left to stand for 10min. It is charged to 4.53V with a constant current of 0.5C, and charged to 0.05C with a constant voltage of 4.53V, and it is left to stand for 10min. The appearance is checked before and after the test and photos are taken. After the pretreatment is completed, the sample is placed on the test table, and a blunt nail with a diameter of 6mm, an extrusion force of 1600N, and a drop speed of 300N / Min is used to test the center of the negative pole ear of the sample. The voltage and surface temperature rise of the secondary battery are monitored during the test. During the test, if the secondary battery does not explode or catch fire during the test, it means that the blunt thorn extrusion test has passed, otherwise, the blunt thorn extrusion test has failed. 100 secondary batteries were tested, and the number of secondary batteries that passed the test was X, and the test pass rate was X / 100.

[0084] 2. Secondary battery self-discharge test The test temperature is 20±5℃, and the battery is discharged to 3.0V with a constant current of 0.2C, and charged for 2280s with a constant current of 0.5C. The battery is left at high temperature for 2 days to eliminate polarization, and left at room temperature for 2 days to reduce the temperature of the secondary battery to room temperature to eliminate the influence of temperature on the test. The circuit voltage OCV1 is measured, and the battery is left at room temperature for another 3 days to measure the final voltage OCVB. The K value = (OCV1-OCVB) / Δt is calculated and the data is recorded.

[0085] 3.Method for testing the particle size and average spacing of metal particles Select a 10mm long and 10mm wide adhesive sample and load it on a conductive substrate, such as conductive tape or conductive carbon film; fix the processed sample on the SEM sample stage; put the sample stage into the SEM sample chamber and evacuate to ensure a high vacuum environment; select a suitable acceleration voltage according to the properties of different metal adhesive tapes, usually between 1-30kV (under the acceleration voltage, the adhesive layer of the adhesive tape will be destroyed, exposing the metal particles in the middle); adjust the scanning speed, scanning range and other parameters to obtain a clear image; select points to measure and record the average spacing between metal particles, and take ten spacings in the X and Y directions to calculate the average value; randomly select 10-20 metal particles, measure the metal particle size and calculate the average metal particle size.

[0086] 4. Test method for thickness of adhesive parts Select a piece of adhesive sample with a length of 10mm and a width of 10mm, and stick the adhesive flatly on the optical microscope test platform; turn on the optical thickness gauge and align it with the adhesive tape sample and read the thickness value displayed on the instrument; take points in an array of 3 times 3 in the X and Y directions, and calculate the average value as the thickness of the adhesive.

[0087] 5. Substrate layer thickness test method Select a bonding sample with a length and width of 10 mm, prepare the cross section of the sample by mechanical cutting, grinding, polishing and liquid nitrogen brittle fracture, and ensure that the cross section is flat and has no obvious damage; use ultrasonic cleaning or organic solvent cleaning to remove surface contaminants and residues; load the sample on a fixture with the cross section facing up; turn on 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 thickness of the substrate layer.

[0088] Embodiment 1: 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. The assembly process is as follows: (1) Preparation of negative electrode sheet: Mix the negative electrode active materials artificial graphite, conductive carbon black (Super P), and styrene-butadiene rubber (SBR) in a weight ratio of 96:1.5:2.5, add deionized water as a solvent, prepare a slurry with a weight percentage of 50wt%, and stir evenly. The slurry is evenly coated on one surface of the copper foil, and then dried at 110°C to obtain a negative electrode sheet coated with a negative electrode active material layer on one side. When preparing a double-sided coated negative electrode sheet, repeat the above steps on the other surface of the negative electrode sheet to obtain a negative electrode sheet coated with a negative electrode active material layer on both sides. Then the coated electrode sheet is cold pressed to a thickness of 105μm, a groove is set on the negative electrode active material, and the negative electrode tab is welded to the copper foil exposed in the groove.

[0089] (2) Preparation of positive electrode sheet: The positive electrode active materials lithium cobalt oxide (LiCoO2), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) are mixed in a weight ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP) is added as a solvent to prepare a slurry with a solid content of 75wt%, and stirred evenly. The slurry is evenly coated on one surface of the aluminum foil, and then dried at 90°C to obtain a positive electrode sheet coated with positive electrode active material on one side. When preparing a double-sided coated positive electrode sheet, repeat the above coating steps on the other surface of the aluminum foil. The coated electrode sheet is then cold pressed to a thickness of 95μm, a groove is set on the positive electrode active material, and the positive electrode tab is welded to the aluminum foil exposed in the groove.

[0090] (3) Preparation of electrolyte: In a dry argon atmosphere, ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) were 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) was added to the basic organic solvent to dissolve and mix well to obtain an electrolyte with a lithium salt concentration of 1.15 mol / L.

[0091] (4) Preparation of diaphragm: A three-layer diaphragm is used, which includes a stacked adhesive layer, a substrate layer and an adhesive layer. The first substrate layer is made of polyethylene (PE), the binder in the adhesive layer is PVDF, and the adhesive layer also contains inorganic particles of boehmite.

[0092] (5) Preparation of electrode assembly: The positive electrode sheet, separator and negative electrode sheet are wound and arranged. An adhesive is arranged at the groove where the negative electrode tab is located (defined as position A), an adhesive is arranged at the position where the positive electrode sheet is opposite to the groove (defined as position B), and an adhesive is arranged on the outer surface of the outermost electrode sheet of the electrode assembly and the end of the electrode assembly (defined as position C). Among them, the adhesives at positions A, B and C meet the following requirements: D1 = 5 μm.

[0093] (6) Secondary battery assembly: Place the aluminum-plastic film with holes punched and formed in an assembly fixture, with the holes facing upward, place the electrode assembly in the holes, and apply external force to press it. Then, cover the electrode assembly with another aluminum-plastic film with holes punched and formed, with the holes facing downward, and heat-seal the four sides of the two aluminum-plastic films by hot pressing to obtain an assembled electrode assembly.

[0094] (7) Liquid injection packaging: The electrolyte is injected into the assembled electrode assembly, and after vacuum packaging, static standing, hot pressing, shaping and other processes, a secondary battery is produced.

[0095] Comparative Example 1: 16 um thick green glue is respectively set at positions A, B, and C of the electrode assembly. It should be noted that the other parameters of Comparative Example 1 are the same as those of Example 1.

[0096] Comparative Example 2: A 24 um stainless steel sheet metal adhesive tape is placed at position A of the electrode assembly. It should be noted that the other parameters of Comparative Example 2 are the same as those of Example 1.

[0097] Comparative Example 3: A 24 um stainless steel sheet metal adhesive tape is placed at position B of the electrode assembly. It should be noted that the other parameters of Comparative Example 3 are the same as those of Example 1.

[0098] Comparative Example 4: 24 um stainless steel sheet metal adhesive tape is placed at position C of the electrode assembly. It should be noted that the other parameters of Comparative Example 3 are the same as those of Example 1.

[0099] Comparative Example 5: 24 um stainless steel sheet metal adhesive tape is respectively set at positions A, B, and C of the electrode assembly. It should be noted that the other parameters of Comparative Example 5 are the same as those of Example 1.

[0100] It can be seen from Comparative Examples 1-5 and Examples 1-10 that the first metal particle layer is located between the substrate layer and the first adhesive layer, and 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 is beneficial to improving the self-discharge phenomenon.

[0101] It can be seen from Examples 1 and 5-9 that by limiting 1μm≤D1≤20μm, the pass rate of the blunt thorn extrusion test of the secondary battery can be improved and the self-discharge phenomenon can be improved. Moreover, by further limiting 5μm≤D1≤10μm, the pass rate of the blunt thorn extrusion test of the secondary battery can be further improved and the self-discharge phenomenon can be improved. It should be noted that when D1>20μm, the thickness of the adhesive will be too large, resulting in a significant reduction in the energy density of the secondary battery, so an embodiment of D1>20μm is not set.

[0102] It can be seen from Comparative Examples 8 and 10 that the first metal particle layer includes two layers of metal particles, which can further improve the pass rate of the blunt puncture extrusion test of the secondary battery and is beneficial to improving the self-discharge phenomenon.

[0103] It can be seen from comparative examples 1 and 11-13 that by limiting T1≥1.2D1, the pass rate of the blunt puncture compression test of the secondary battery can be improved and the self-discharge phenomenon can be improved. It should be noted that when T1>24μm, the thickness of the adhesive will be too large, resulting in a significant decrease in the energy density of the secondary battery, so an embodiment with T1>24μm is not provided.

[0104] In addition, those skilled in the art may also make other changes within the spirit of the present application. Of course, these changes made according to the spirit of the present application should be included in the scope disclosed in the present application.

Claims

1. A secondary battery, characterized in that: The secondary battery comprises: Electrode assembly; An adhesive component, the adhesive component includes a substrate layer, a first metal particle layer and a first bonding layer stacked along 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, and the first bonding 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, 1 μm≤D1≤20 μm.

3. The secondary battery according to claim 2, characterized in that: 5μm≤D1≤10μm.

4. The secondary battery according to claim 1, wherein: The first metal particle layer is in contact with the base material 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, 1.2D1≤T1≤24 μm.

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 a polyester film, a polyimide film, a polypropylene film, a polyethylene film, a polytetrafluoroethylene film or a silicone rubber film.

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

9. The secondary battery according to claim 1, wherein: The electrode assembly includes a first pole piece, a diaphragm, a second pole piece and a first pole ear. The polarity of the first pole piece is opposite to that of the second pole piece. The first pole piece includes a first current collector and a first active material layer arranged on the first current collector. The first active material layer is provided with a groove. The first pole ear is arranged in the groove. The adhesive is bonded to the first pole piece and covers the groove.

10. The secondary battery according to claim 1, wherein: The electrode assembly includes a first pole piece, a diaphragm, a second pole piece and a first pole ear. The polarity of the first pole piece is opposite to that of the second pole piece. The first pole piece includes a first current collector and a first active material layer arranged on the first current collector. The first active material layer is provided with a groove. The first pole ear is arranged in the groove. The adhesive is bonded to the second pole piece and the bonding position is opposite to the groove.

11. The secondary battery according to claim 9, characterized in that The first pole piece includes a first current collector, and the first current collector is a nickel foil; The metal particles of the adhesive bonded to the first pole piece are nickel metal particles; or The first current collector is copper foil; The metal particles of the adhesive bonded to the first pole piece are copper metal particles.

12. The secondary battery according to claim 10, characterized in that The second pole piece includes a second current collector, and the second current collector is a nickel foil; The metal particles of the adhesive bonded to the second pole piece are nickel metal particles; or The second current collector is copper foil; The metal particles of the adhesive bonded to the second pole piece are copper metal particles.

13. The secondary battery according to claim 1, wherein: The adhesive is bonded to the outer surface of the pole piece of the outermost circle of the electrode assembly and covers the tail end of the electrode assembly.

14. The secondary battery according to claim 13, characterized in that: The metal particles of the adhesive are aluminum metal particles.

15. An electronic device, characterized in that: The electronic device includes the secondary battery according to any one of claims 1 to 14.

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