Secondary battery and electric device

Abstract

The invention discloses a secondary battery and electric equipment. The secondary battery comprises a shell, an electrode assembly and a sealing element, the shell comprises a first shell body and a second shell body, and the first shell body and the second shell body are connected in the first direction and jointly form a containing cavity. The containing cavity is filled with electrolyte, and the electrode assembly is arranged in the containing cavity. The sealing piece is arranged on the periphery of the first shell and the periphery of the second shell in a surrounding mode and seals the connecting position of the first shell and the second shell. The sealing piece comprises a first adhesive layer, a second adhesive layer and a metal layer, the first adhesive layer and the second adhesive layer are arranged on the two sides of the metal layer respectively in the thickness direction of the metal layer, and the first adhesive layer is bonded with the first shell and the second shell. And the first adhesive layer is beneficial to improving the bonding stability of the sealing element and the shell. Through the metal layer, the sealing performance of the sealing element on the first shell and the second shell is improved. Through the second glue layer, the risk of damage and failure of the metal layer can be reduced, and the sealing performance of the sealing element on the first shell and the second shell can be maintained.

Description

Technical Field

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

[0002] Current secondary batteries include steel-shell batteries and soft-pack batteries. Generally speaking, both steel-shell batteries and soft-pack batteries include a shell and an electrode assembly disposed in the shell. The shell of the steel-shell battery includes a first shell and a second shell, and the first shell and the second shell are sealed and connected by welding. Summary of the invention

[0003] Regarding the secondary battery in the prior art, the inventors have found that stress is generated during the process of sealing and connecting the first shell and the second shell by welding. Such stress can easily lead to defects such as cracks in the weld, thereby affecting the sealing of the secondary battery.

[0004] In view of the above situation, it is necessary to provide a secondary battery that is conducive to improving the sealing performance of the first shell and the second shell.

[0005] In a first aspect, the present application provides a secondary battery, comprising a housing, an electrode assembly and a seal. The housing comprises a first shell and a second shell, the first shell and the second shell are connected along a first direction, and together form a receiving cavity. The receiving cavity is filled with an electrolyte, and the electrode assembly is arranged in the receiving cavity. The seal is arranged around the periphery of the first shell and the second shell, and seals the junction between the first shell and the second shell. The seal comprises a first glue layer, a second glue layer and a metal layer, along the thickness direction of the metal layer, the first glue layer and the second glue layer are respectively arranged on both sides of the metal layer, and the first glue layer is bonded to the first shell and the second shell.

[0006] The seal includes a first adhesive layer, which is bonded to the first shell and the second shell. The first adhesive layer is conducive to improving the stability of the bonding between the seal and the shell. The seal includes a metal layer, which is arranged on the side of the first adhesive layer away from the shell. The water barrier of the metal layer is better than that of the first adhesive layer, which is conducive to improving the sealing of the seal to the first shell and the second shell. The seal includes a second adhesive layer, which is arranged on the side of the metal layer away from the first adhesive layer. The second adhesive layer can protect the metal layer, which is conducive to reducing the risk of failure due to damage of the metal layer, so as to maintain the sealing of the seal to the first shell and the second shell during the long-term use of the secondary battery.

[0007] In one or more of the above embodiments, the sealing member includes a first fixing portion and a second fixing portion provided at two ends along its extension direction, and along the thickness direction of the sealing member, the projection of the first fixing portion overlaps with the projection of the second fixing portion. The first adhesive layer of the second fixing portion is fixed to the second adhesive layer of the first fixing portion.

[0008] In this case, the first fixing part and the second fixing part are stacked along the thickness direction of the seal, and the fixing method of the first adhesive layer to the second adhesive layer can reduce the risk of electrolyte corroding the metal layer and causing failure of the fixing of the first adhesive layer or the second adhesive layer to the metal layer, and can make the seal have higher stability, which is beneficial to improving the sealing effect of the seal on the outer shell, thereby helping to reduce the risk of secondary battery leakage failure.

[0009] In one or more of the above embodiments, the first adhesive layer of the second fixing part is fixed to the second adhesive layer of the first fixing part by welding. Compared with the direct bonding method, the welding fixing method is beneficial to improving the stability of the seal. Moreover, during welding, the first adhesive layer of the second fixing part melts, while the second adhesive layer of the first fixing part does not melt, which can reduce the possibility of the second adhesive layer adhering to the heating instrument, pulling the seal when the heating instrument is withdrawn, resulting in a decrease in the bonding effect between the first adhesive layer and the first shell and the second shell, and can reduce the possibility of the second adhesive layer being deformed by pulling, resulting in a decrease in the protective effect on the metal layer, thereby helping to further improve the sealing effect of the seal on the outer shell.

[0010] In one or more of the above embodiments, the first adhesive layer is configured to be able to melt or lose adhesion when heated, and constitutes a part of the pressure relief channel connected to the receiving cavity. The melting point of the first adhesive layer is T1, and the melting point of the second adhesive layer is T2, and T2>T1. When the secondary battery has thermal runaway, the melting or loss of adhesion of the first adhesive layer can timely relieve the pressure of the receiving cavity, which is beneficial to improve the safety of the secondary battery. T2>T1 is beneficial to improve the convenience of melting the first adhesive layer of the second fixing part while the second adhesive layer of the first fixing part does not melt during welding.

[0011] In one or more of the above embodiments, T2-T1≥10° C. The melting point difference between the first adhesive layer and the second adhesive layer is greater than 10° C., which is conducive to more conveniently controlling the melting of the first adhesive layer of the second fixing part while the second adhesive layer of the first fixing part does not melt.

[0012] In one or more of the above embodiments, 95℃≤T1≤130℃. 95℃≤T1 can ensure that the first adhesive layer will not melt or lose adhesion in advance before the secondary battery has thermal runaway, which is beneficial to maintaining the sealing effect of the seal on the shell. T1≤130℃ can ensure that the first adhesive layer will melt or lose adhesion in time to relieve the pressure of the receiving cavity when the secondary battery has thermal runaway, which is beneficial to further improve the safety of the secondary battery.

[0013] In one or more of the above embodiments, the thickness of the seal is d0, 20μm≤d0≤1000μm. When 20μm≤d0, the seal is not too thin, which can make the overall strength of the seal higher, which is conducive to reducing the risk of the seal being damaged after the secondary battery falls, causing the secondary battery to leak and fail. When d0≤1000μm, the seal is not too thick, and under the premise of ensuring that the seal has sufficient overall strength, the space required for the seal can be reduced, which is conducive to reducing the loss of energy density of the secondary battery.

[0014] In one or more of the above embodiments, 28μm≤d0≤300μm. 28μm≤d0 can make the overall strength of the seal higher, which is conducive to further reducing the risk of damage to the seal after the secondary battery falls, resulting in leakage and failure of the secondary battery. d0≤300μm can make the overall strength of the seal meet most falling conditions, while further reducing the space required for the seal, which is conducive to further reducing the loss of energy density of the secondary battery.

[0015] In one or more of the above embodiments, the thickness of the first adhesive layer is d1, the thickness of the second adhesive layer is d2, and the thickness of the metal layer is d3, 7μm≤d1≤500μm, 6μm≤d2≤500μm, and 7μm≤d3≤250μm. In this case, the first adhesive layer, the second adhesive layer, and the metal layer are not too thin, which is conducive to reducing the risk of the first adhesive layer being corroded and failing by the electrolyte, and is conducive to reducing the risk of the second adhesive layer being damaged after the secondary battery falls, resulting in the damage of the metal layer and failure, or the metal layer being corroded and failing. The first adhesive layer, the second adhesive layer, and the metal layer are not too thick, which is conducive to thinning the seal, thereby helping to reduce the loss of energy density of the secondary battery.

[0016] In one or more of the above embodiments, 10μm≤d1≤200μm, 8μm≤d2≤200μm. 10μm≤d1 and 8μm≤d2 can make the first glue layer and the second glue layer thicker, which is beneficial to further reduce the risk of the first glue layer being corroded and failing by the electrolyte, and is beneficial to further reduce the risk of the second glue layer being damaged after the secondary battery falls, resulting in the damage and failure of the metal layer or the failure of the metal layer being corroded. d1≤200μm and d2≤200μm can make the thickness of the first glue layer basically meet the requirement of not being corroded and failing by the electrolyte, and the thickness of the second glue layer meet the requirement of most falling situations, while further reducing the loss of energy density of the secondary battery.

[0017] In one or more of the above embodiments, 10μm≤d3≤150μm. 10μm≤d3 can make the metal layer thicker, which is beneficial to further reduce the risk of metal layer failure due to damage or corrosion after the second adhesive layer is damaged. d3≤150μm can make the thickness of the metal layer basically meet the requirements of not being damaged or corroded, while further reducing the loss of secondary battery energy density.

[0018] In one or more of the above embodiments, the first adhesive layer includes a first portion bonded to the first shell and a second portion bonded to the second shell, and along the first direction, the minimum size of the first portion is W1, and the minimum size of the second portion is W2, 0.1mm≤W1≤3mm, 0.1mm≤W2≤3mm. 0.1mm≤W1 and 0.1mm≤W2 can make the area of ​​the first adhesive layer bonded to the first shell and the second shell larger, and can make it difficult for the electrolyte to erode the first adhesive layer in a direction parallel to the first direction, which is beneficial to reducing the risk of premature leakage and failure of the secondary battery in a direction parallel to the first direction, thereby helping to extend the service life of the secondary battery. W1≤3mm and W2≤3mm can make it difficult for the first adhesive layer to exceed the shell in a direction parallel to the first direction, which is beneficial to reducing the loss of energy density of the secondary battery.

[0019] In one or more of the above embodiments, 0.3mm≤W1≤1.5mm, 0.3mm≤W2≤1.5mm. 0.3mm≤W1 and 0.3mm≤W2 can make the bonding area of ​​the first adhesive layer and the first shell and the second shell larger, and can make it more difficult for the electrolyte to erode the first adhesive layer in a direction parallel to the first direction, which is beneficial to further reduce the risk of premature leakage and failure of the secondary battery in a direction parallel to the first direction, thereby helping to extend the service life of the secondary battery. W1≤1.5mm and W2≤1.5mm can make it more difficult for the first adhesive layer to exceed the shell in a direction parallel to the first direction, which is beneficial to further reduce the loss of energy density of the secondary battery.

[0020] In one or more of the above embodiments, the positive electrode of the electrode assembly is electrically connected to the first shell, and the negative electrode of the electrode assembly is electrically connected to the second shell. The first shell and the second shell are insulated, which is conducive to reducing the risk of short circuit of the secondary battery.

[0021] In one or more of the above embodiments, the first shell includes a first wall and a first side wall connected to the periphery of the first wall, and the second shell includes a second wall and a second side wall connected to the periphery of the second wall, and along the first direction, the first side wall and the second side wall are arranged opposite to each other with a gap, which is conducive to improving the convenience of bonding the first adhesive layer to the first shell and the second shell.

[0022] In one or more of the above embodiments, the secondary battery further includes an insulating member, which is disposed in the gap and connects the first side wall and the second side wall. The insulating member is helpful to improve the convenience of insulating the first shell and the second shell.

[0023] In one or more of the above embodiments, the insulating member is integrally formed with the first adhesive layer. In this case, the insulating member can be directly formed by cooling after a portion of the first adhesive layer is melted and enters the gap between the first side wall and the second side wall, which can make the assembly process of the secondary battery more convenient and is conducive to simplifying the process flow of preparing the secondary battery. In addition, the insulating member is integrally arranged with the first adhesive layer, which can fully fit the gap between the first side wall and the second side wall, which is conducive to further improving the sealing performance of the sealing member to the first shell and the second shell.

[0024] In one or more of the above embodiments, the material of the first adhesive layer includes at least one of polyolefin, fluororubber and polyurethane. The material of the second adhesive layer includes at least one of polyolefin, fluoropolymer, polyetheretherketone, fluororubber and polyurethane. The first adhesive layer and the second adhesive layer can have a high resistance to electrolyte corrosion, which is conducive to reducing the possibility of electrolyte corrosion of the first adhesive layer, resulting in the first adhesive layer and the shell peeling off, or the first adhesive layer of the second fixed part and the second adhesive layer of the first fixed part peeling off, thereby helping to reduce the risk of leakage failure of the secondary battery. In addition, it is also conducive to reducing the risk of corrosion of the metal layer after the electrolyte corrodes the first adhesive layer.

[0025] The second aspect of the present application provides an electrical device, comprising the secondary battery of the first aspect of the present application. The secondary battery has good sealing performance, and the electrolyte is not easy to leak, which is conducive to extending the service life of the electrical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A top view of a secondary battery provided in accordance with an embodiment of the present application.

[0027] Figure 2 A front view of a secondary battery provided in accordance with an embodiment of the present application.

[0028] Figure 3 An exploded view of a secondary battery provided in one embodiment of the present application.

[0029] Figure 4 For an embodiment of the present application Figure 1 Cross-section along the midline AA.

[0030] Figure 5 For an embodiment of the present application Figure 2 Cross-section along section line BB.

[0031] Figure 6An overall schematic diagram of an electrical device provided in one embodiment of the present application.

[0032] Main component symbols 1000, electrical equipment; 100, secondary battery; 10, outer shell; 101, receiving cavity; 102, corner portion; 103, adhesive; 11, first shell; 111, first wall; 112, first side wall; 12, second shell; 121, second wall; 122, second side wall; 20, electrode assembly; 201, first pole lug bundle; 202, second pole lug bundle; 21, first pole piece; 22, second pole piece; 23, diaphragm; 30, sealing member; 301, first fixing portion; 302, second fixing portion; 31, first adhesive layer; 311, first part; 312, second part; 32, second adhesive layer; 33, metal layer; 40, insulating member; X, first direction. DETAILED DESCRIPTION

[0033] 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.

[0034] 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.

[0035] Unless otherwise specified, the term "plurality" as used herein means two or more than two.

[0036] The terms "first", "second", etc. are only used to distinguish different objects and shall not be understood as indicating or implying relative importance or implying the quantity, specific order or primary and secondary relationship of the indicated technical features.

[0037] 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 of the related listed items.

[0038] It should be understood that, considering the actual processing tolerance factors, in the technical solution of the present application, when the two elements are arranged parallel / vertically and in the same direction, there may be a certain angle between the two elements, and a tolerance of 0-±10% is allowed between the two elements. A tolerance of 0-±10% is allowed between the two elements greater than, equal to or less than.

[0039] An embodiment of the present application provides a secondary battery, including a housing, an electrode assembly and a seal. The housing includes a first shell and a second shell, the first shell and the second shell are connected along a first direction, and together form a receiving cavity. The receiving cavity is filled with an electrolyte, and the electrode assembly is arranged in the receiving cavity. The seal is arranged around the outer periphery of the first shell and the second shell, and seals the junction between the first shell and the second shell. The seal includes a first glue layer, a second glue layer and a metal layer, along the thickness direction of the metal layer, the first glue layer and the second glue layer are respectively arranged on both sides of the metal layer, and the first glue layer is bonded to the first shell and the second shell.

[0040] In the secondary battery of the present application, the seal includes a first adhesive layer, the first adhesive layer is bonded to the first shell and the second shell, and the first adhesive layer is conducive to improving the stability of the bonding between the seal and the shell. The seal includes a metal layer, the metal layer is arranged on the side of the first adhesive layer away from the shell, the water barrier of the metal layer is better than the water barrier of the first adhesive layer, which is conducive to improving the sealing of the seal to the first shell and the second shell. The seal includes a second adhesive layer, the second adhesive layer is arranged on the side of the metal layer away from the first adhesive layer, the second adhesive layer can protect the metal layer, which is conducive to reducing the risk of failure due to damage of the metal layer, so as to maintain the sealing of the seal to the first shell and the second shell during the long-term use of the secondary battery.

[0041] Some embodiments of the present application will be described below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0042] See also Figures 1 to 4 The embodiment of the present application provides a secondary battery 100, including a housing 10, an electrode assembly 20 and a sealing member 30, wherein the electrode assembly 20 is accommodated in the housing 10. The sealing member 30 is a component for sealing the housing 10.

[0043] See also Figure 4 The housing 10 is provided with a receiving cavity 101 , the receiving cavity 101 is filled with electrolyte, and the electrode assembly 20 is disposed in the receiving cavity 101 .

[0044] In some embodiments, please refer to Figure 3 and Figure 4 The housing 10 includes a first shell 11 and a second shell 12 . The first shell 11 and the second shell 12 are connected along a first direction X and together form a receiving cavity 101 .

[0045] In some embodiments, the first direction X is parallel to the thickness direction of the housing 10. In some other embodiments, the first direction X is parallel to the length direction or the width direction of the housing 10.

[0046] In some embodiments, the first housing 11 is insulated from the second housing 12. In some other embodiments, the first housing 11 is electrically connected to the second housing 12.

[0047] In some embodiments, the housing 10 is a metal housing, and the material of the housing 10 includes at least one of steel alloy, aluminum alloy and copper alloy. The material of the first shell 11 and the second shell 12 includes at least one of steel alloy, aluminum alloy and copper alloy.

[0048] In some embodiments, see Figure 3 The first housing 11 includes a first wall 111 and a first side wall 112, and the second housing 12 includes a second wall 121 and a second side wall 122. The first side wall 112 is connected to the periphery of the first wall 111, and the second side wall 122 is connected to the periphery of the second wall 121. Along the first direction X, the first side wall 112 and the second side wall 122 are arranged opposite to each other with a gap.

[0049] In some embodiments, see Figure 3 The housing 10 includes a corner portion 102 , a portion of the corner portion 102 is disposed on the first side wall 112 , and another portion of the corner portion 102 is disposed on the second side wall 122 .

[0050] See also Figure 3 The electrode assembly 20 includes a first electrode piece 21 , a second electrode piece 22 and a diaphragm 23 . The second electrode piece 22 has a polarity opposite to that of the first electrode piece 21 . The diaphragm 23 separates the first electrode piece 21 from the second electrode piece 22 .

[0051] In some embodiments, see Figure 3 and Figure 4 The electrode assembly 20 is a stacked structure, a plurality of first electrode sheets 21 and a plurality of second electrode sheets 22 are alternately stacked, and a diaphragm 23 is disposed between any adjacent first electrode sheets 21 and second electrode sheets 22 .

[0052] In some embodiments, the electrode assembly 20 is a winding structure, in which a single first electrode sheet 21 and a single second electrode sheet 22 are stacked and wound, and the separator 23 is disposed between the first electrode sheet 21 and the second electrode sheet 22 .

[0053] In some embodiments, the first electrode sheet 21 is a negative electrode sheet, and the second electrode sheet 22 is a positive electrode sheet. In some embodiments, the first electrode sheet 21 is a positive electrode sheet, and the second electrode sheet 22 is a negative electrode sheet. In the thickness direction of the electrode assembly 20, the projection of the negative electrode sheet covers the projection of the positive electrode sheet.

[0054] In some embodiments, the first pole piece 21 includes a first current collector and a first active material layer, and the first current collector is disposed on two opposite sides of the first active material layer along the thickness direction. The second pole piece 22 includes a second current collector and a second active material layer, and the second current collector is disposed on two opposite sides of the second active material layer along the thickness direction. In some embodiments, when the first pole piece 21 or the second pole piece 22 is the outermost pole piece of the electrode assembly 20, the side of the current collector facing away from the interior of the electrode assembly 20 may not be provided with an active material layer.

[0055] In some embodiments, the material of the first current collector includes at least one of copper, nickel, tantalum, and titanium, and the material of the second current collector includes at least one of aluminum, nickel, tantalum, and titanium.

[0056] In some embodiments, the material of the first active material layer includes at least one of graphite, hard carbon, soft carbon, silicon, silicon-oxygen material, and silicon-carbon material. The material of the second active material layer includes at least one of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium manganese iron phosphate, or lithium manganese oxide.

[0057] In some embodiments, the diaphragm 23 is an insulating film material such as a polyethylene film, a polypropylene film, a polyester film, or a polyimide film.

[0058] In some embodiments, the positive electrode of the electrode assembly 20 is electrically connected to the first shell 11, and the negative electrode of the electrode assembly 20 is electrically connected to the second shell 12, wherein the first shell 11 and the second shell 12 are insulated, which helps to reduce the risk of short circuit of the secondary battery 100.

[0059] In some embodiments, see Figure 3 The secondary battery 100 further includes a plurality of first tabs connected to the first pole piece 21, and the plurality of first tabs are gathered to form a first tab bundle 201. The secondary battery 100 further includes a plurality of second tabs connected to the second pole piece 22, and the plurality of second tabs are gathered to form a second tab bundle 202. One of the first tab bundle 201 and the second tab bundle 202 is electrically connected to the first shell 11, and the other of the first tab bundle 201 and the second tab bundle 202 is electrically connected to the second shell 12.

[0060] In some embodiments, see Figure 4 The secondary battery 100 further includes an insulating member 40. The insulating member 40 is disposed in the gap between the first side wall 112 and the second side wall 122, and connects the first side wall 112 and the second side wall 122. The insulating member 40 is advantageous in improving the convenience of insulating the first shell 11 and the second shell 12.

[0061] In some embodiments, one of the positive electrode and the negative electrode of the electrode assembly 20 is electrically connected to the housing 10, and the other of the positive electrode and the negative electrode of the electrode assembly 20 is insulated and connected to the housing 10, wherein the first housing 11 is electrically connected to the second housing 12. For example, one of the positive electrode and the negative electrode of the electrode assembly 20 is electrically connected to the housing 10, and the other of the positive electrode and the negative electrode of the electrode assembly 20 is electrically connected to a pole (not shown), and the pole is insulated and disposed on the housing 10.

[0062] Please refer to Figures 1 to 4 The sealing member 30 is disposed around the outer periphery of the first shell 11 and the second shell 12, and seals the joint between the first shell 11 and the second shell 12. Along the thickness direction of the sealing member 30, the projection of the sealing member 30 at least partially overlaps with the projection of the first shell 11 and the second shell 12.

[0063] In some embodiments, along the first direction X, the projection of the first shell 11 and the projection of the second shell 12 are both located in a closed area surrounded by the projection of the seal 30. In some other embodiments, along the first direction X, the projection of the first shell 11 is located in a closed area surrounded by the projection of the seal 30, and the projection of the second shell 12 at least partially overlaps with the projection of the seal 30.

[0064] See also Figure 4 and Figure 5 The sealing member 30 includes a first adhesive layer 31, a second adhesive layer 32 and a metal layer 33. The first adhesive layer 31 and the second adhesive layer 32 are respectively arranged on both sides of the metal layer 33 along the thickness direction of the metal layer 33. The first adhesive layer 31 is bonded to the first shell 11 and the second shell 12. It should be understood that the metal layer 33 is arranged on the side of the first adhesive layer 31 away from the housing 10, and the second adhesive layer 32 is arranged on the side of the metal layer 33 away from the first adhesive layer 31.

[0065] In some embodiments, the first adhesive layer 31 is bonded to the first side wall 112 of the first shell 11 and the second side wall 122 of the second shell 12, which is beneficial to improve the convenience of bonding the first adhesive layer 31 to the first shell 11 and the second shell 12.

[0066] In some embodiments, see Figure 4The first adhesive layer 31 includes a first portion 311 and a second portion 312. The first portion 311 is bonded to the first shell 11, and the second portion 312 is bonded to the second shell 12. Along the first direction X, the minimum size of the first portion 311 is W1, and the minimum size of the second portion 312 is W2, 0.1mm≤W1≤3mm, 0.1mm≤W2≤3mm. 0.1mm≤W1 and 0.1mm≤W2 can make the bonding area of ​​the first adhesive layer 31 and the first shell 11 and the second shell 12 larger, and can make it difficult for the electrolyte to erode the first adhesive layer 31 in the direction parallel to the first direction X, which is conducive to reducing the risk of premature leakage failure of the secondary battery 100 in the direction parallel to the first direction X, thereby helping to extend the service life of the secondary battery 100. W1≤3mm and W2≤3mm can make it difficult for the first adhesive layer 31 to exceed the shell 10 in the direction parallel to the first direction X, which is conducive to reducing the loss of energy density of the secondary battery 100.

[0067] In some embodiments, 0.3mm≤W1≤1.5mm, 0.3mm≤W2≤1.5mm. 0.3mm≤W1 and 0.3mm≤W2 can make the first adhesive layer 31 more bonded to the first shell 11 and the second shell 12, and make it more difficult for the electrolyte to corrode the first adhesive layer 31 in a direction parallel to the first direction X, which is beneficial to further reduce the risk of premature leakage failure of the secondary battery 100 in a direction parallel to the first direction X, thereby helping to extend the service life of the secondary battery 100. W1≤1.5mm and W2≤1.5mm can make it more difficult for the first adhesive layer 31 to extend beyond the housing 10 in a direction parallel to the first direction X, which is beneficial to further reduce the loss of energy density of the secondary battery 100.

[0068] In some embodiments, see Figure 4 The secondary battery 100 further includes an adhesive 103, which bonds the outer shell 10 and the electrode assembly 20, thereby reducing the risk of the electrode assembly 20 moving in the receiving cavity 101 and causing the first shell 11 and / or the second shell 12 to peel off from the first adhesive layer 31. In some embodiments, the adhesive 103 is disposed between the outer shell 10 and the electrode assembly 20 along the thickness direction of the electrode assembly 20.

[0069] In some embodiments, the first adhesive layer 31 and the metal layer 33, as well as the second adhesive layer 32 and the metal layer 33, are fixed by gluing, so that the first adhesive layer 31, the second adhesive layer 32 and the metal layer 33 are compounded into a whole. In some embodiments, the first adhesive layer 31 and the metal layer 33, as well as the second adhesive layer 32 and the metal layer 33, are fixed by hot pressing, so that the first adhesive layer 31, the second adhesive layer 32 and the metal layer 33 are compounded into a whole.

[0070] In some embodiments, the first adhesive layer 31 is bonded to the first shell 11 and the second shell 12 after high temperature activation. In some embodiments, the seal 30 is clamped by a heating instrument, and heat is transferred to the seal 30, so that the first adhesive layer 31 is melted for high temperature activation. Among them, the parameters such as the heating temperature or power of the heating instrument are adjustable. It should be understood that high temperature refers to a temperature greater than or equal to the melting point of the first adhesive layer 31, but should not be too high to reduce the impact on the second adhesive layer 32, the metal layer 33, etc. In some other embodiments, the first adhesive layer 31 is directly bonded to the first shell 11 and the second shell 12.

[0071] The seal 30 includes a first adhesive layer 31, which is bonded to the first shell 11 and the second shell 12. The first adhesive layer 31 is conducive to improving the stability of the bonding between the seal 30 and the shell 10. The seal 30 includes a metal layer 33, which is arranged on the side of the first adhesive layer 31 away from the shell 10. The water barrier of the metal layer 33 is better than that of the first adhesive layer 31, which is conducive to improving the sealing of the seal 30 to the first shell 11 and the second shell 12. The seal 30 includes a second adhesive layer 32, which is arranged on the side of the metal layer 33 away from the first adhesive layer 31. The second adhesive layer 32 can protect the metal layer 33, which is conducive to reducing the risk of damage and failure of the metal layer 33, so as to maintain the sealing of the seal 30 to the first shell 11 and the second shell 12 during the long-term use of the secondary battery 100.

[0072] In some embodiments, the insulating member 40 is integrally formed with the first adhesive layer 31. In this case, the insulating member 40 can be directly formed by a portion of the first adhesive layer 31 being melted and then entering the gap between the first side wall 112 and the second side wall 122 and then being cooled, which can make the assembly process of the secondary battery 100 more convenient and is conducive to simplifying the process flow of preparing the secondary battery 100. In addition, the insulating member 40 is integrally arranged with the first adhesive layer 31, which can fully fit the gap between the first side wall 112 and the second side wall 122, which is conducive to further improving the sealing performance of the sealing member 30 to the first shell 11 and the second shell 12.

[0073] In some other embodiments, the insulating member 40 is provided separately from the first adhesive layer 31. In this case, the insulating member 40 does not depend on the melting condition of the first adhesive layer 31, and the sealing member 30 can be provided after the insulating member 40 is provided between the first shell 11 and the second shell 12, so that the insulation reliability between the first shell 11 and the second shell 12 can be higher.

[0074] In some embodiments, see Figure 5 Along the extending direction of the sealing member 30 , the sealing member 30 includes a first fixing portion 301 and a second fixing portion 302 which are arranged at two ends.

[0075] In some embodiments, along the thickness direction of the seal 30, the projection of the first fixing portion 301 overlaps with the projection of the second fixing portion 302, and the first adhesive layer 31 of the second fixing portion 302 is fixed to the second adhesive layer 32 of the first fixing portion 301. In this case, along the thickness direction of the seal 30, the first fixing portion 301 and the second fixing portion 302 are stacked, and the fixing method of the first adhesive layer 31 to the second adhesive layer 32 can reduce the risk of electrolyte corroding the metal layer 33, resulting in the failure of the fixing of the first adhesive layer 31 or the second adhesive layer 32 to the metal layer 33, and can make the seal 30 have a higher stability, which is conducive to improving the sealing effect of the seal 30 on the housing 10, thereby helping to reduce the risk of leakage failure of the secondary battery 100.

[0076] In some embodiments, the first fixing portion 301 and the second fixing portion 302 are stacked at the corner portion 102 , which can utilize part of the space of the corner portion 102 , thereby facilitating reducing the loss of energy density of the secondary battery 100 .

[0077] In some other embodiments, along the thickness direction of the seal 30, the projection of the first fixing portion 301 is separated from the projection of the second fixing portion 302, and the first adhesive layer 31, the metal layer 33, and the second adhesive layer 32 are each continuous rings. The seal 30 has heat shrinkability, and before sealing, the seal 30 has a larger size so that it can be inserted into the joint of the first shell 11 and the second shell 12; after sealing, the size of the seal 30 is reduced to be able to seal the joint of the first shell 11 and the second shell 12.

[0078] In some embodiments, the first adhesive layer 31 of the second fixing portion 302 is directly bonded to the second adhesive layer 32 of the first fixing portion 301 .

[0079] In some embodiments, the first adhesive layer 31 of the second fixing portion 302 is welded and fixed to the second adhesive layer 32 of the first fixing portion 301. Compared with the direct bonding method, the welding and fixing method is conducive to improving the stability of the sealing member 30. In addition, during welding, the first adhesive layer 31 of the second fixing portion 302 melts, while the second adhesive layer 32 of the first fixing portion 301 does not melt, which can reduce the possibility that the second adhesive layer 32 adheres to the heating instrument, and the sealing member 30 is pulled when the heating instrument is withdrawn, resulting in a decrease in the bonding effect between the first adhesive layer 31 and the first shell 11 and the second shell 12, and can reduce the possibility that the second adhesive layer 32 is deformed by pulling, resulting in a decrease in the protection effect on the metal layer 33, thereby further improving the sealing effect of the sealing member 30 on the housing 10.

[0080] In some embodiments, the first adhesive layer 31 can melt or lose adhesion due to heat, and constitute a part of the pressure relief channel connected to the receiving cavity 101. When the secondary battery 100 has thermal runaway, the melting or loss of adhesion of the first adhesive layer 31 can timely release pressure from the receiving cavity 101, which is beneficial to improving the safety of the secondary battery 100.

[0081] In some embodiments, the melting point of the first adhesive layer 31 is T1, the melting point of the second adhesive layer 32 is T2, and T2>T1. This is beneficial to improve the convenience of melting the first adhesive layer 31 of the second fixing part 302 while the second adhesive layer 32 of the first fixing part 301 does not melt during welding.

[0082] In some embodiments, T2-T1≥10° C. The melting point difference between the first adhesive layer 31 and the second adhesive layer 32 is greater than 10° C., which is conducive to more conveniently controlling the first adhesive layer 31 of the second fixing part 302 to melt while the second adhesive layer 32 of the first fixing part 301 does not melt.

[0083] In some embodiments, 95°C≤T1≤130°C. For example, T1 is 95°C, 100°C, 110°C, and 130°C. 95°C≤T1 can ensure that the first adhesive layer 31 will not melt or lose adhesion in advance before the secondary battery 100 has thermal runaway, which is beneficial to maintaining the sealing effect of the seal 30 on the housing 10. T1≤130°C can ensure that when the secondary battery 100 has thermal runaway, the first adhesive layer 31 will melt or lose adhesion in time to relieve the pressure of the receiving cavity 101, which is beneficial to further improve the safety of the secondary battery 100.

[0084] In some embodiments, 140°C≤T2≤500°C. For example, T2 is 140°C, 150°C, 200°C, 300°C, and 500°C. 140°C≤T2 can ensure that the difference in melting point between the first adhesive layer 31 and the second adhesive layer 32 is greater than 10°C. T2≤500°C, the melting point of the second adhesive layer 32 is not too high, so that at least a portion of the material can be applied to the second adhesive layer 32.

[0085] In some embodiments, the material of the first adhesive layer 31 is a polymer resistant to electrolyte, and the polymer of the first adhesive layer 31 includes at least one of polyolefin, fluororubber and polyurethane. The material of the second adhesive layer 32 is a polymer resistant to electrolyte, and the polymer of the second adhesive layer 32 includes at least one of polyolefin, fluoropolymer, polyetheretherketone, fluororubber and polyurethane. Among them, polyolefin can include polypropylene and polyethylene, etc., and fluoropolymer can be polytetrafluoroethylene, etc. In this case, the first adhesive layer 31 and the second adhesive layer 32 can have high resistance to electrolyte corrosion, which is conducive to reducing the possibility of electrolyte corrosion of the first adhesive layer 31, resulting in the first adhesive layer 31 and the shell 10 peeling off, or the first adhesive layer 31 of the second fixing part 302 and the second adhesive layer 32 of the first fixing part 301 peeling off, thereby helping to reduce the risk of leakage failure of the secondary battery 100. In addition, it is also conducive to reducing the risk of corrosion of the metal layer 33 after the electrolyte corrodes the first adhesive layer 31.

[0086] In some embodiments, the first adhesive layer 31 includes a single layer or multiple layers of a high molecular polymer, and the second adhesive layer 32 includes a single layer or multiple layers of a high molecular polymer.

[0087] In some embodiments, see Figure 4 , the thickness of the seal 30 is d0, 20μm≤d0≤1000μm. For example, d0 is 20μm, 50μm, 100μm, 200μm, 300μm, 500μm and 1000μm. 20μm≤d0, the seal 30 is not too thin, which can make the overall strength of the seal 30 higher, which is beneficial to reduce the risk of the seal 30 being damaged after the secondary battery 100 falls, resulting in leakage and failure of the secondary battery 100. d0≤1000μm, the seal 30 is not too thick, and on the premise of ensuring that the seal 30 has sufficient overall strength, the space required for the seal 30 can be reduced, which is beneficial to reduce the loss of energy density of the secondary battery 100.

[0088] In some embodiments, the thickness of the sealing member 30 may be non-uniform, with the thickness of the sealing member 30 at its thinnest portion being greater than or equal to 20 μm, and the thickness of the sealing member 30 at its thickest portion being less than or equal to 1000 μm.

[0089] In some embodiments, 28μm≤d0≤300μm. For example, d0 is 28μm, 50μm, 100μm, 150μm, 200μm, 250μm and 300μm. 28μm≤d0 can make the overall strength of the seal 30 higher, which is conducive to further reducing the risk of damage to the seal 30 after the secondary battery 100 falls, resulting in leakage and failure of the secondary battery 100. d0≤300μm, while the overall strength of the seal 30 can meet most falling conditions, it can further reduce the space required for the seal 30, which is conducive to further reducing the loss of energy density of the secondary battery 100.

[0090] In some embodiments, the thickness of the seal 30 may be non-uniform, with the thickness of the seal 30 at its thinnest portion being greater than or equal to 28 μm, and the thickness of the seal 30 at its thickest portion being less than or equal to 300 μm.

[0091] In some embodiments, the thickness of the sealing member 30 is equal to the sum of the thicknesses of the first adhesive layer 31 , the second adhesive layer 32 , and the metal layer 33 .

[0092] In some embodiments, the thickness of the first adhesive layer 31 is d1, the thickness of the second adhesive layer 32 is d2, the thickness of the metal layer 33 is d3, 7μm≤d1≤500μm, 6μm≤d2≤500μm, and 7μm≤d3≤250μm. For example, d1 is 7μm, 50μm, 100μm, 200μm, 300μm, and 500μm, d2 is 6μm, 50μm, 100μm, 200μm, 300μm, and 500μm, and d3 is 7μm, 20μm, 50μm, 100μm, 200μm, and 250μm. In this case, the first glue layer 31, the second glue layer 32 and the metal layer 33 are not too thin, which is conducive to reducing the risk of the first glue layer 31 being corroded and failed by the electrolyte, and is conducive to reducing the risk of the second glue layer 32 being damaged after the secondary battery 100 falls, resulting in the damage of the metal layer 33 and failure or the metal layer 33 being corroded and failed. The first glue layer 31, the second glue layer 32 and the metal layer 33 are not too thick, which is conducive to thinning the seal 30, thereby helping to reduce the loss of energy density of the secondary battery 100. It should be understood that the first glue layer 31, the second glue layer 32 and the metal layer 33 are not the optional maximum thickness at the same time. For example, the thickness of the first glue layer 31 is 500μm, the thickness of the second glue layer 32 is 250μm, and the thickness of the metal layer 33 is 250μm.

[0093] In some embodiments, 10μm≤d1≤200μm, 8μm≤d2≤200μm. For example, d1 is 10μm, 50μm, 100μm, 150μm and 200μm, and d2 is 8μm, 50μm, 100μm, 150μm and 200μm. 10μm≤d1 and 8μm≤d2 can make the first glue layer 31 and the second glue layer 32 thicker, which is beneficial to further reduce the risk of the first glue layer 31 being corroded and failed by the electrolyte, and is beneficial to further reduce the risk of the second glue layer 32 being damaged after the secondary battery 100 falls, resulting in the damage and failure of the metal layer 33 or the corrosion and failure of the metal layer 33. d1≤200μm and d2≤200μm can make the thickness of the first glue layer 31 basically meet the requirements of not being corroded and failed by the electrolyte, and the thickness of the second glue layer 32 meets the requirements of most falling situations, while further reducing the loss of energy density of the secondary battery 100.

[0094] In some embodiments, since the first adhesive layer 31 is more likely to contact the electrolyte than the second adhesive layer 32 and the first adhesive layer 31 needs to be welded to the second adhesive layer 32 , the thickness of the first adhesive layer 31 needs to be greater than that of the second adhesive layer 32 .

[0095] In some embodiments, 10μm≤d3≤150μm. For example, d3 is 10μm, 50μm, 100μm and 150μm. 10μm≤d3 can make the metal layer 33 thicker, which is conducive to further reducing the risk of damage and failure of the metal layer 33 or corrosion failure of the metal layer 33 after the second adhesive layer 32 is damaged. d3≤150μm can make the thickness of the metal layer 33 basically meet the requirements of not being damaged and failed or not being corroded and failed, while further reducing the loss of energy density of the secondary battery 100.

[0096] In some embodiments, the material of the metal layer 33 includes at least one of steel, aluminum, nickel, silver, copper, and alloys thereof.

[0097] In some embodiments, the metal layer 33 is a single layer or a multi-layer structure. For example, the multi-layer structure can be a steel layer plus an aluminum layer or a nickel layer plus a copper layer.

[0098] See also Figure 6 One embodiment of the present application provides an electric device 1000, comprising the secondary battery 100 as described above. The secondary battery 100 has good sealing performance, and the electrolyte is not easy to leak, which is conducive to extending the service life of the electric device 1000. The electric device 1000 includes but is not limited to electronic devices such as mobile phones, tablet computers and laptops.

[0099] In addition, those skilled in the art should recognize that the above embodiments are only used to illustrate the present application and are not intended to limit the present application. As long as they are within the essential scope of the present application, appropriate changes and modifications to the above embodiments are within the scope disclosed in the present application.

Claims

1. A secondary battery, characterized in that: include: A housing, the housing comprising a first housing and a second housing, the first housing and the second housing being connected along a first direction and forming a receiving cavity together; the receiving cavity is filled with an electrolyte; An electrode assembly, wherein the electrode assembly is disposed in the receiving cavity; A sealing member, wherein the sealing member is disposed around the outer circumference of the first shell and the second shell and seals the joint between the first shell and the second shell; the sealing member comprises a first adhesive layer, a second adhesive layer and a metal layer, wherein along the thickness direction of the metal layer, the first adhesive layer and the second adhesive layer are respectively disposed on both sides of the metal layer, and the first adhesive layer is bonded to the first shell and the second shell.

2. The secondary battery according to claim 1, characterized in that: The seal includes a first fixing portion and a second fixing portion arranged at two ends along its own extension direction. Along the thickness direction of the seal, the projection of the first fixing portion overlaps with the projection of the second fixing portion; the first adhesive layer of the second fixing portion is fixed to the second adhesive layer of the first fixing portion.

3. The secondary battery according to claim 2, characterized in that: The first adhesive layer of the second fixing portion is welded and fixed to the second adhesive layer of the first fixing portion.

4. The secondary battery according to claim 3, characterized in that: The first adhesive layer is configured to be melted or debonded by heat, and constitutes a part of the pressure relief channel connected to the receiving cavity; the melting point of the first adhesive layer is T1, the melting point of the second adhesive layer is T2, and T2>T1.

5. The secondary battery according to claim 4, characterized in that: T2-T1≥10℃.

6. The secondary battery according to claim 5, characterized in that: 95℃≤T1≤130℃。 7. The secondary battery according to claim 1, characterized in that: The thickness of the sealing member is d0, 20 μm≤d0≤1000 μm.

8. The secondary battery according to claim 7, characterized in that: 28μm≤d0≤300μm.

9. The secondary battery according to claim 7, characterized in that: The thickness of the first adhesive layer is d1, the thickness of the second adhesive layer is d2, the thickness of the metal layer is d3, 7μm≤d1≤500μm, 6μm≤d2≤500μm, 7μm≤d3≤250μm.

10. The secondary battery according to claim 9, characterized in that: 10μm≤d1≤200μm, 8μm≤d2≤200μm.

11. The secondary battery according to claim 9, characterized in that: 10μm≤d3≤150μm.

12. The secondary battery according to claim 1, characterized in that: The first adhesive layer includes a first portion bonded to the first shell and a second portion bonded to the second shell. Along the first direction, the minimum size of the first portion is W1, and the minimum size of the second portion is W2, 0.1mm≤W1≤3mm, 0.1mm≤W2≤3mm.

13. The secondary battery according to claim 12, characterized in that: 0.3mm≤W1≤1.5mm, 0.3mm≤W2≤1.5mm.

14. The secondary battery according to claim 1, characterized in that: The positive electrode of the electrode assembly is electrically connected to the first shell, and the negative electrode of the electrode assembly is electrically connected to the second shell; the first shell and the second shell are insulated.

15. The secondary battery according to claim 14, characterized in that: The first shell includes a first wall and a first side wall connected to the periphery of the first wall, and the second shell includes a second wall and a second side wall connected to the periphery of the second wall. Along the first direction, the first side wall and the second side wall are arranged opposite to each other and have a gap.

16. The secondary battery according to claim 15, characterized in that: The secondary battery further includes an insulating member disposed in the gap and connecting the first side wall and the second side wall.

17. The secondary battery according to claim 16, characterized in that: The insulating member and the first adhesive layer are integrally formed.

18. The secondary battery according to any one of claims 1 to 17, characterized in that: The material of the first adhesive layer includes at least one of polyolefin, fluororubber and polyurethane; the material of the second adhesive layer includes at least one of polyolefin, fluoropolymer, polyetheretherketone, fluororubber and polyurethane.

19. An electrical equipment, characterized in that: The invention comprises the secondary battery according to any one of claims 1 to 18.

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