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 piece, the shell comprises a first shell body and a second shell body, the first shell body and the second shell body jointly form a containing cavity, and the electrode assembly is arranged in the containing cavity. The first shell comprises a first wall and a first side wall connected with the periphery of the first wall, and the second shell comprises a second wall and a second side wall connected with the periphery of the second wall. The shell is provided with a corner part, one part of the corner part is arranged on the first side wall, and the other part of the corner part is arranged on the second side wall. The sealing piece seals the joint of the first side wall and the second side wall. The sealing piece comprises a first fixing part and a second fixing part, and the first fixing part and the second fixing part are arranged on the corner part in a stacked mode in the thickness direction of the sealing piece. The fixing area of the sealing piece can be increased, and the stability of the sealing piece can be improved. The first fixing part and the second fixing part can utilize a part of the space of the corner part, so that the loss of the energy density of the secondary battery is reduced.

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] For the secondary battery in the prior art, the inventors found that stress is generated in the process of sealing the first shell and the second shell by welding, and these stresses are likely to cause defects such as cracks in the weld, thereby affecting the sealing of the secondary battery. In addition, the welding connection between the first shell and the second shell will lose the energy density of the secondary battery to a certain extent.

[0004] In view of the above situation, it is necessary to provide a secondary battery that can improve the sealing performance of the first shell and the second shell and reduce the loss of energy density of the secondary battery.

[0005] The first aspect of the present application provides a secondary battery, including a shell, an electrode assembly and a seal. The shell includes a first shell and a second shell, the first shell and the second shell together form a receiving cavity, the receiving cavity is filled with electrolyte, and the electrode assembly is arranged in the receiving cavity. 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 wall and the second wall are arranged opposite to each other, and the first side wall and the second side wall are connected. The shell is provided with a corner portion, a part of the corner portion is arranged on the first side wall, and the other part of the corner portion is arranged on the second side wall. The seal is arranged around the outer periphery of the first shell and the second shell, and seals the junction of the first side wall and the second side wall. The seal includes a first fixing portion and a second fixing portion arranged at two ends along its own extension direction, and along the thickness direction of the seal, the first fixing portion and the second fixing portion are stacked and arranged at the corner portion. The first fixing portion is fixedly connected to the second fixing portion.

[0006] The junction of the first side wall and the second side wall is sealed by the seal, which is conducive to improving the sealing of the first shell and the second shell. Along the thickness direction of the seal, the first fixing part and the second fixing part of the seal are stacked, which can increase the area of ​​the seal used for fixing, which is conducive to improving the stability of the seal. On the basis of the stacked arrangement, the first fixing part and the second fixing part are arranged at the corner part, so that the first fixing part and the second fixing part can utilize a part of the space of the corner part, which is conducive to reducing the loss of energy density of the secondary battery.

[0007] In one or more of the above embodiments, the seal also includes a third fixing portion, one end of the third fixing portion is connected to the first fixing portion, and the other end of the third fixing portion is connected to the second fixing portion. Along the extension direction of the corner portion, the corner portion has a first boundary and a second boundary, and along the direction perpendicular to the first boundary and the direction perpendicular to the second boundary, the projections of the first fixing portion and the second fixing portion are both located within the projection range of the third fixing portion. In this case, the additional space required for the stacked first fixing portion and the second fixing portion can be reduced, which is beneficial to reducing the loss of energy density of the secondary battery.

[0008] In one or more of the above embodiments, the corner portion is in an arc shape when viewed along the first direction. The first direction is parallel to the thickness direction of the shell. In this case, the shell can have a better anti-deformation ability at the corner portion, which is beneficial to reduce the risk of leakage caused by damage to the corner portion after the secondary battery falls. In addition, the space of the corner portion can be made more uniform, which is beneficial to improve the utilization of the space of the corner portion by the stacked first fixing portion and the second fixing portion.

[0009] In one or more of the above embodiments, the secondary battery further includes a first pole ear, the first pole ear is connected to the electrode assembly, and extends out of the electrode assembly in the second direction. Along the third direction, the projection of the corner portion overlaps at least partially with the projection of the first pole ear. The first direction, the second direction and the third direction are perpendicular to each other. In this case, the corner portion is arranged close to the first pole ear. Since a larger space for arranging the first pole ear is required between the electrode assembly and the shell, if the secondary battery falls, part of the seal located at the corner portion is more susceptible to damage. The first fixing portion and the second fixing portion are stacked and arranged at the corner portion close to the first pole ear, which can make the part of the seal located at the corner portion thicker, which is conducive to reducing the risk of leakage of the secondary battery due to damage to the seal. In addition, since a larger space for arranging the first pole ear is required between the electrode assembly and the shell, the space at the corner portion can be made larger, which can better accommodate the stacked first fixing portion and the second fixing portion, which is conducive to better reducing the loss of energy density of the secondary battery.

[0010] In one or more of the above embodiments, the electrode assembly includes a first edge, and the first pole ear extends out of the first edge along the second direction. Along the second direction, the distance between the first edge and the shell is D, and the radius of the corner portion is R, 0.77mm≤R≤D. 0.77mm≤R, which enables, in most cases, along the direction perpendicular to the first boundary and the direction perpendicular to the second boundary, the projections of the first fixing portion and the second fixing portion are both within the projection range of the third fixing portion, which is conducive to better reducing the loss of energy density of the secondary battery. R≤D makes it easy to have a spacing between the corner portion and the electrode assembly and the first pole ear, which is conducive to reducing the squeezing of the corner portion on the electrode assembly and the first pole ear.

[0011] In one or more of the above embodiments, when viewed along the first direction, the length of the corner portion is L1, and the length of the second fixing portion is L2. 0.3mm≤L2<L1. 0.3mm≤L2 can make the overlapping area of ​​the first fixing portion and the second fixing portion stacked larger, which is beneficial to improving the sealing of the fixed connection between the first fixing portion and the second fixing portion. L2<L1 can reduce the possibility of the first fixing portion and the second fixing portion respectively exceeding the first boundary and the second boundary along their respective extension directions, which is beneficial to better reduce the loss of secondary battery energy density.

[0012] In one or more of the above embodiments, the thickness of the seal is d0, 14μm≤d0≤300μm. 14μm≤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.

[0013] In one or more of the above embodiments, the seal includes a first glue layer and a metal layer, the first glue layer is bonded to the first shell and the second shell, and the metal layer is arranged on the side of the first glue layer away from the first shell and the second shell. The water barrier of the metal layer is better than that of the first glue layer, which is beneficial to improve the sealing of the seal to the first shell and the second shell. Moreover, under the same sealing requirements, since the water barrier of the metal layer is better than that of the first glue layer, compared with the seal only including the first glue layer, the seal including the metal layer can make the overall seal thinner, which is beneficial to reduce the loss of energy density of the secondary battery.

[0014] In one or more of the above embodiments, the sealant further comprises a second adhesive layer, which is disposed on a side of the metal layer away from the first adhesive layer. The second adhesive layer can protect the metal layer, which is beneficial to reducing the risk of damage and failure of the metal layer, thereby facilitating the sealant to maintain the sealing performance of the first shell and the second shell during the long-term use of the secondary battery.

[0015] 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.

[0016] In one or more of the above embodiments, the secondary battery further includes an insulating member, and along the first direction, the first side wall and the second side wall have a gap, and the insulating member is arranged in the gap and connects the first side wall and the second side wall. The insulating member is helpful to improve the convenience of the insulation setting of the first shell and the second shell.

[0017] In one or more of the above embodiments, the insulating member and the sealing member are integrally formed. In this case, the insulating member can be formed directly by cooling a portion of the sealing member after it is melted and enters the gap between the first shell and the second shell, which can make the assembly process of the secondary battery easier and help simplify the process of preparing the secondary battery. In addition, the insulating member and the sealing member are integrally arranged, which can fully fit the gap between the first shell and the second shell, which is conducive to further improving the sealing performance of the sealing member to the first shell and the second shell.

[0018] The second aspect of the present application provides an electric device, including 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 electric device. The secondary battery has less loss of energy density, and the battery capacity can be higher, which is conducive to improving the endurance of the electric device. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A top view of a secondary battery provided in accordance with an embodiment of the present application.

[0020] Figure 2 A front view of a secondary battery provided in accordance with an embodiment of the present application.

[0021] Figure 3 An exploded view of a secondary battery provided in one embodiment of the present application.

[0022] Figure 4 For an embodiment of the present application Figure 3 Magnified view of area C.

[0023] Figure 5 For an embodiment of the present application Figure 1 Cross-section along the midline AA.

[0024] Figure 6 For the first embodiment of this application Figure 2 Cross-section along section line BB.

[0025] Figure 7 The second embodiment of this application is Figure 2 Cross-section along section line BB.

[0026] Figure 8 The third embodiment of this application is Figure 2 Cross-section along section line BB.

[0027] Fig. 9 An overall schematic diagram of an electrical device provided in one embodiment of the present application.

[0028] Main component symbols 1000, electrical equipment; 100, secondary battery; 10, shell; 101, receiving cavity; 102, corner; 1021, first boundary; 1022, second boundary; 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 ear; 202, second pole ear; 21, first pole piece; 22, second pole piece; 23, diaphragm; 24, first edge; 30, sealing; 301, first fixing part; 302, second fixing part; 303, third fixing part; 31, first adhesive layer; 311, first part; 312, second part; 32, metal layer; 33, second adhesive layer; 40, insulating member; X, first direction. DETAILED DESCRIPTION

[0029] 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.

[0030] 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.

[0031] Unless otherwise specified, the term "plurality" as used herein means two or more than two.

[0032] 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.

[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 of the related listed items.

[0034] 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.

[0035] An embodiment of the present application provides a secondary battery, including a shell, an electrode assembly and a seal. The shell includes a first shell and a second shell, the first shell and the second shell together form a receiving cavity, the receiving cavity is filled with electrolyte, and the electrode assembly is arranged in the receiving cavity. 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 wall and the second wall are arranged opposite to each other, and the first side wall and the second side wall are connected. The shell is provided with a corner portion, a part of the corner portion is arranged on the first side wall, and the other part of the corner portion is arranged on the second side wall. The seal is arranged around the outer periphery of the first shell and the second shell, and seals the junction of the first side wall and the second side wall. The seal includes a first fixing portion and a second fixing portion arranged at two ends along its own extension direction, and along the thickness direction of the seal, the first fixing portion and the second fixing portion are stacked and arranged at the corner portion. The first fixing portion is fixedly connected to the second fixing portion.

[0036] In the secondary battery of the present application, the junction of the first side wall and the second side wall is sealed by a sealant, which is conducive to improving the sealing of the first shell and the second shell. Along the thickness direction of the sealant, the first fixed part and the second fixed part of the sealant are stacked, which can increase the area of ​​the sealant used for fixing, which is conducive to improving the stability of the sealant. On the basis of the stacked arrangement, the first fixed part and the second fixed part are arranged at the corner part, so that the first fixed part and the second fixed part can utilize a part of the space of the corner part, which is conducive to reducing the loss of energy density of the secondary battery.

[0037] 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.

[0038] Please refer to Figures 1 to 5 An embodiment of the present application provides a secondary battery 100 , including a housing 10 , an electrode assembly 20 , and a seal 30 . The electrode assembly 20 is accommodated in the housing 10 , and the seal 30 is used to seal the housing 10 .

[0039] See also Figure 5 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 .

[0040] In some embodiments, see Figure 5 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 .

[0041] 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.

[0042] 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.

[0043] 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.

[0044] In some embodiments, see Figure 3 The first housing 11 includes a first wall 111 and a first side wall 112, and the first side wall 112 connects the periphery of the first wall 111. The second housing 12 includes a second wall 121 and a second side wall 122, and the second side wall 122 connects the periphery of the second wall 121. Along the first direction X, the first wall 111 and the second wall 121 are arranged opposite to each other, and the first side wall 112 and the second side wall 122 are connected. In some embodiments, along the first direction X, there is a gap between the first side wall 112 and the second side wall 122.

[0045] In some embodiments, see Figure 3 The housing 10 includes a corner portion 102, a portion of which is disposed on the first side wall 112, and another portion of which is disposed on the second side wall 122. In the first housing 11, a portion of the corner portion 102 is a transition portion connecting two adjacent edges of the first side wall 112, and in the second housing 12, another portion of the corner portion 102 is a transition portion connecting two adjacent edges of the second side wall 122.

[0046] See also Figure 5 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 .

[0047] In some embodiments, see Figure 5 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 .

[0048] 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 .

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] In some embodiments, see Figure 3 The secondary battery 100 further includes a plurality of first pole tabs 201 and a plurality of second pole tabs 202 , wherein the first pole tabs 201 and the second pole tabs 202 are connected to the electrode assembly 20 and extend along a second direction Y. The second direction Y is perpendicular to the first direction X. In some embodiments, the first pole tab 201 is connected to the first pole piece 21 , and the second pole tab 202 is connected to the second pole piece 22 .

[0056] In some embodiments, a plurality of first tabs 201 are gathered to form a first tab bundle, and a plurality of second tabs 202 are gathered to form a second tab bundle. One of the first tab bundle and the second tab bundle is electrically connected to the first shell 11 , and the other of the first tab bundle and the second tab bundle is electrically connected to the second shell 12 .

[0057] In some embodiments, see Figure 5 The secondary battery 100 further includes an insulating member 40. Along the first direction X, 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.

[0058] 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.

[0059] Please refer to Figures 3 to 5 The sealing member 30 is disposed around the outer periphery of the first shell 11 and the second shell 12, and seals the junction of the first side wall 112 and the second side wall 122. 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. The sealing member 30 seals the junction of the first side wall 112 and the second side wall 122, which is conducive to improving the sealing performance of the first shell 11 and the second shell 12.

[0060] 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.

[0061] In some embodiments, see Figure 4 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.

[0062] In some embodiments, the first fixing portion 301 and the second fixing portion 302 are stacked along the thickness direction of the seal 30. The first fixing portion 301 is fixedly connected to the second fixing portion 302. In this case, the fixing area of ​​the seal 30 can be increased, which is conducive to improving the stability of the seal 30.

[0063] In some embodiments, the first fixing portion 301 and the second fixing portion 302 are stacked on the corner portion 102. On the basis of the stacked arrangement, the first fixing portion 301 and the second fixing portion 302 are arranged on the corner portion 102, so that the first fixing portion 301 and the second fixing portion 302 can use a part of the space of the corner portion 102, which is beneficial to reduce the loss of energy density of the secondary battery 100. The space of the corner portion 102 refers to the space formed by extending the two edges connected by the corner portion 102 to the intersection and the extended part and the corner portion 102.

[0064] 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 seal 30 is a continuous ring. The seal 30 has heat shrinkability, and before sealing, the seal 30 has a larger size so that it can be inserted into the junction of the first side wall 112 and the second side wall 122; after sealing, the size of the seal 30 is reduced to be able to seal the junction of the first side wall 112 and the second side wall 122.

[0065] In some embodiments, see Figures 6 to 8 , along the extending direction of the corner portion 102, the corner portion 102 has a first boundary 1021 and a second boundary 1022, and the first fixing portion 301 and the second fixing portion 302 are located between the first boundary 1021 and the second boundary 1022. Figures 6 to 8 The so-called first boundary 1021 and the second boundary 1022 refer to the boundaries where the two end surfaces of the corner portion 102 along its own extension direction are located when viewed along the first direction X.

[0066] In some embodiments, the seal 30 further includes a third fixing portion 303, one end of the third fixing portion 303 is connected to the first fixing portion 301, and the other end of the third fixing portion 303 is connected to the second fixing portion 302. In the direction perpendicular to the first boundary 1021 and the direction perpendicular to the second boundary 1022, the projections of the first fixing portion 301 and the second fixing portion 302 are both located within the projection range of the third fixing portion 303. In this case, the additional space required for the stacked first fixing portion 301 and the second fixing portion 302 can be reduced, which is beneficial to reducing the loss of energy density of the secondary battery 100. It should be understood that, considering the actual processing tolerance, the projections of the so-called first fixing portion 301 and the second fixing portion 302 are both located within the projection range of the third fixing portion 303, allowing a 10% error, that is, allowing up to 10% of the projections of the first fixing portion 301 and the second fixing portion 302 to be located outside the projection range of the third fixing portion 303.

[0067] In some embodiments, see Figure 6, when viewed along the first direction X, the corner portion 102 is in an arc shape. In this case, the housing 10 can have a better anti-deformation ability at the corner portion 102, which is conducive to reducing the risk of leakage caused by damage to the corner portion 102 after the secondary battery 100 falls. In addition, the space of the corner portion 102 can be made more uniform, which is conducive to improving the utilization of the space of the corner portion 102 by the stacked first fixing portion 301 and the second fixing portion 302.

[0068] In some embodiments, see Figure 7 , viewed along the first direction X, the corner portion 102 is in an elliptical arc shape. Figure 8 , viewed along the first direction X, the corner portion 102 is “L” shaped.

[0069] In some embodiments, along the third direction Z, the projection of the corner portion 102 overlaps at least partially with the projection of the first pole ear 201. The first direction X, the second direction Y and the third direction Z are perpendicular to each other. In this case, the corner portion 102 is arranged close to the first pole ear 201. Since a larger space is required between the electrode assembly 20 and the housing 10 for arranging the first pole ear 201, if the secondary battery 100 falls, the part of the seal 30 located at the corner portion 102 is more easily damaged. By stacking the first fixing portion 301 and the second fixing portion 302 at the corner portion 102 close to the first pole ear 201, the part of the seal 30 located at the corner portion 102 can be made thicker, which is conducive to reducing the risk of leakage of the secondary battery 100 caused by damage to the seal 30. Furthermore, since a larger space is required between the electrode assembly 20 and the housing 10 for arranging the first electrode tab 201 , the space of the corner portion 102 can be made larger to better accommodate the stacked first fixing portion 301 and the second fixing portion 302 , which is beneficial to better reduce the loss of energy density of the secondary battery 100 .

[0070] In some embodiments, see Figures 6 to 8 The electrode assembly 20 includes a first edge 24 , and the first electrode tab 201 extends out of the first edge 24 along the second direction Y. Along the second direction Y, the distance D between the first edge 24 and the housing 10 is.

[0071] In some embodiments, see Figure 6, when viewed along the first direction X, the corner portion 102 is in an arc shape, and the radius of the corner portion 102 is R, 0.77mm≤R≤D. 0.77mm≤R, in most cases, along the direction perpendicular to the first boundary 1021 and the direction perpendicular to the second boundary 1022, the projections of the first fixing portion 301 and the second fixing portion 302 are both located within the projection range of the third fixing portion 303, which is conducive to better reducing the loss of energy density of the secondary battery 100. R≤D, it is convenient to make the corner portion 102 have a spacing with the electrode assembly 20 and the first pole ear 201, which is conducive to reducing the compression of the electrode assembly 20 and the first pole ear 201 by the corner portion 102. The so-called most cases can be, for example, the thickness of the sealing member 30 is 14μm to 300μm, and when viewed along the first direction X, the size of the second fixing portion 302 along its own extension direction is at least 0.3mm.

[0072] In some embodiments, 1 mm ≤ D ≤ 3 mm.

[0073] In some embodiments, when viewed along the first direction X, the length of the corner portion 102 is L1, the length of the second fixing portion 302 is L2, and 0.3 mm ≤ L2 < L1. 0.3 mm ≤ L2 can make the overlapping area of ​​the first fixing portion 301 and the second fixing portion 302 stacked and arranged larger, which is beneficial to improving the sealing of the fixed connection between the first fixing portion 301 and the second fixing portion 302. L2 < L1 can reduce the possibility that the first fixing portion 301 and the second fixing portion 302 exceed the first boundary 1021 and the second boundary 1022 respectively along their respective extension directions, which is beneficial to better reduce the loss of energy density of the secondary battery 100.

[0074] In some embodiments, see Figure 5 The seal 30 includes a first adhesive layer 31 and a metal layer 32. The first adhesive layer 31 is bonded to the first shell 11 and the second shell 12. The metal layer 32 is arranged on the side of the first adhesive layer 31 away from the first shell 11 and the second shell 12. The water barrier of the metal layer 32 is better than that of the first adhesive layer 31, which is beneficial to improve the sealing of the seal 30 to the first shell 11 and the second shell 12. Moreover, under the same sealing requirements, since the water barrier of the metal layer 32 is better than that of the first adhesive layer 31, compared with the seal 30 only including the first adhesive layer 31, the seal 30 including the metal layer 32 can make the seal 30 thinner as a whole, which is beneficial to reduce the loss of energy density of the secondary battery 100.

[0075] In some embodiments, when the sealing member 30 includes a first adhesive layer 31 and a metal layer 32 , the first adhesive layer 31 of the second fixing portion 302 is fixedly connected to the metal layer 32 of the first fixing portion 301 .

[0076] In some embodiments, see Figure 5The seal 30 further includes a second adhesive layer 33, which is disposed on a side of the metal layer 32 away from the first adhesive layer 31. The second adhesive layer 33 can protect the metal layer 32, which is beneficial to reducing the risk of damage and failure of the metal layer 32, thereby maintaining the sealing performance of the seal 30 to the first shell 11 and the second shell 12 during the long-term use of the secondary battery 100.

[0077] In some embodiments, when the sealing member 30 includes a first adhesive layer 31, a metal layer 32, and a second adhesive layer 33, the first adhesive layer 31 of the second fixing portion 302 is fixedly connected to the metal layer 32 of the first fixing portion 301. Compared with the fixed connection between the first adhesive layer 31 and the metal layer 32, the fixed connection between the first adhesive layer 31 and the second adhesive layer 33 can make the fixed connection between the first fixing portion 301 and the second fixing portion 302 more stable, which is beneficial to improving the sealing effect of the sealing member 30 on the housing 10, thereby helping to reduce the risk of leakage failure of the secondary battery 100.

[0078] In some embodiments, the so-called fixed connection includes but is not limited to bonding or welding.

[0079] In some embodiments, the first adhesive layer 31 and the metal layer 32, as well as the second adhesive layer 33 and the metal layer 32, are fixed by gluing, so that the first adhesive layer 31, the metal layer 32, and the second adhesive layer 33 are compounded into a whole. In some embodiments, the first adhesive layer 31 and the metal layer 32, as well as the second adhesive layer 33 and the metal layer 32, are fixed by hot pressing, so that the first adhesive layer 31, the metal layer 32, and the second adhesive layer 33 are compounded into a whole.

[0080] In some embodiments, the first adhesive layer 31 is bonded to the first side wall 112 and the second side wall 122 , which is beneficial to improve the convenience of bonding the first adhesive layer 31 to the first shell 11 and the second shell 12 .

[0081] In some embodiments, see Figure 5 , the 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, W1≥0.3mm, W2≥0.3mm. In this case, the area where the first adhesive layer 31 is bonded to the first shell 11 and the second shell 12 is large, which can make it difficult for the electrolyte to erode the first adhesive layer 31 in a direction parallel to the first direction X, which is beneficial to reducing 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.

[0082] In some embodiments, the first adhesive layer 31 is bonded to the first shell 11 and the second shell 12 after being activated at high temperature. In some other embodiments, the first adhesive layer 31 is directly bonded to the first shell 11 and the second shell 12.

[0083] In some embodiments, see Figure 5 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.

[0084] In some embodiments, the insulating member 40 is integrally formed with the sealing member 30. In this case, the insulating member 40 can be directly formed by a portion of the sealing member 30 being melted and then entering the gap between the first shell 11 and the second shell 12 and then cooled, which can make the assembly process of the secondary battery 100 more convenient and help simplify the process of preparing the secondary battery 100. In addition, the insulating member 40 is integrally provided with the sealing member 30, which can fully fit the gap between the first shell 11 and the second shell 12, which is conducive to further improving the sealing performance of the sealing member 30 to the first shell 11 and the second shell 12.

[0085] In some embodiments, the insulating member 40 and the first adhesive layer 31 of the sealing member 30 are integrally formed.

[0086] In some other embodiments, the insulating member 40 is provided separately from the sealing member 30. In this case, the insulating member 40 does not depend on the melting condition of the sealing member 30, 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.

[0087] 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.

[0088] In some embodiments, the melting point of the first adhesive layer 31 is T1, 95°C≤T1≤130°C. For example, T1 is 95°C, 100°C, 110°C and 130°C. 95°C≤T1 can reduce the possibility of premature melting or loss of adhesion of the first adhesive layer 31 before thermal runaway of the secondary battery 100 occurs, which is beneficial to maintain the sealing effect of the seal 30 on the housing 10. T1≤130°C can ensure that the first adhesive layer 31 melts or loses adhesion in time to relieve the pressure of the receiving cavity 101 when thermal runaway occurs in the secondary battery 100, which is beneficial to further improve the safety of the secondary battery 100.

[0089] In some embodiments, the melting point of the second glue layer 33 is T2, 140°C≤T2≤500°C. For example, T2 is 140°C, 150°C, 200°C, 300°C and 500°C.

[0090] 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 33 is a polymer resistant to electrolyte, and the polymer of the second adhesive layer 33 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 33 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 being peeled off, or the first adhesive layer 31 of the second fixing part 302 and the second adhesive layer 33 of the first fixing part 301 being peeled 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 32 after the electrolyte corrodes the first adhesive layer 31.

[0091] 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 33 includes a single layer or multiple layers of a high molecular polymer.

[0092] In some embodiments, the material of the metal layer 32 includes at least one of steel, aluminum, nickel, silver, copper, and alloys thereof.

[0093] In some embodiments, the metal layer 32 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.

[0094] In some embodiments, see Figure 5, the thickness of the seal 30 is d0, 7μm≤d0≤1000μm. For example, d0 is 7μm, 50μm, 100μm, 200μm, 300μm, 500μm and 1000μm. 7μm≤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 damage to the seal 30 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.

[0095] 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 7 μm, and the thickness of the seal 30 at its thickest portion being less than or equal to 1000 μm.

[0096] In some embodiments, 14μm≤d0≤300μm. For example, d0 is 14μm, 50μm, 100μm, 150μm, 200μm, 250μm and 300μm. 14μm≤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 can make the overall strength of the seal 30 meet most falling conditions, while further reducing the space required for the seal 30, which is conducive to further reducing the loss of energy density of the secondary battery 100.

[0097] 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 14 μm, and the thickness of the seal 30 at its thickest portion being less than or equal to 300 μm.

[0098] In some embodiments, when the seal 30 includes a first adhesive layer 31, a metal layer 32 and a second adhesive layer 33, since the first adhesive layer 31 is easier to contact the electrolyte than the second adhesive layer 33, and the first adhesive layer 31 needs to be welded to the second adhesive layer 33, the thickness of the first adhesive layer 31 needs to be greater than the thickness of the second adhesive layer 33.

[0099] See also Fig. 9 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 energy density loss of the secondary battery 100 is small, and the battery capacity can be higher, which is conducive to improving the endurance 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.

[0100] 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 shell, the shell comprising a first shell and a second shell, the first shell and the second shell together forming a receiving cavity, the receiving cavity being filled with electrolyte; the first shell comprising a first wall and a first side wall connected to the periphery of the first wall, the second shell comprising a second wall and a second side wall connected to the periphery of the second wall; along a first direction, the first wall and the second wall are arranged opposite to each other, and the first side wall and the second side wall are connected; the shell is provided with a corner portion, a part of the corner portion is arranged on the first side wall, and another part of the corner portion is arranged on the second side wall; 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 periphery of the first shell and the second shell and seals the junction between the first side wall and the second side wall; the sealing member comprises a first fixing portion and a second fixing portion disposed at two ends along its own extension direction, and along the thickness direction of the sealing member, the first fixing portion and the second fixing portion are stacked and disposed at the corner portion; the first fixing portion and the second fixing portion are fixedly connected.

2. The secondary battery according to claim 1, characterized in that: The seal also includes a third fixing portion, one end of which is connected to the first fixing portion, and the other end of which is connected to the second fixing portion; along the extension direction of the corner portion, the corner portion has a first boundary and a second boundary, and along the direction perpendicular to the first boundary and the direction perpendicular to the second boundary, the projections of the first fixing portion and the second fixing portion are both located within the projection range of the third fixing portion.

3. The secondary battery according to claim 1, characterized in that: When viewed along the first direction, the corner portion is in an arc shape; the first direction is parallel to the thickness direction of the shell.

4. The secondary battery according to claim 3, characterized in that: The secondary battery also includes a first pole ear, which is connected to the electrode assembly and extends out of the electrode assembly along a second direction; along a third direction, a projection of the corner portion at least partially overlaps with a projection of the first pole ear; the first direction, the second direction and the third direction are perpendicular to each other.

5. The secondary battery according to claim 4, characterized in that: The electrode assembly includes a first edge, and the first electrode tab extends out of the first edge along the second direction; along the second direction, the distance between the first edge and the shell is D, the radius of the corner portion is R, and 0.77 mm≤R≤D.

6. The secondary battery according to claim 3, characterized in that: Observed along the first direction, the length of the corner portion is L1, and the length of the second fixing portion is L2; ​​0.3 mm ≤ L2 < L1.

7. The secondary battery according to claim 6, characterized in that: The thickness of the sealing member is d0,14 μm≤d0≤300 μm.

8. The secondary battery according to claim 1, characterized in that: The sealing member includes a first adhesive layer and a metal layer, the first adhesive layer is bonded to the first shell and the second shell, and the metal layer is arranged on a side of the first adhesive layer away from the first shell and the second shell.

9. The secondary battery according to claim 8, characterized in that: The sealing member further includes a second adhesive layer, which is disposed on a side of the metal layer away from the first adhesive layer.

10. The secondary battery according to any one of claims 1 to 9, 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.

11. The secondary battery according to claim 10, characterized in that: The secondary battery further includes an insulating member. Along the first direction, a gap is formed between the first side wall and the second side wall. The insulating member is disposed in the gap and connects the first side wall and the second side wall.

12. The secondary battery according to claim 11, characterized in that: The insulating member and the sealing member are integrally formed.

13. An electrical equipment, characterized in that: The invention comprises the secondary battery according to any one of claims 1 to 12.

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