Secondary battery and electric device

Abstract

The invention discloses a secondary battery and electric equipment. The secondary battery comprises a shell, an electrode assembly, a first tab bundle and a first adapter tab, the electrode assembly comprises a first pole piece, an isolating membrane and a second pole piece which are arranged in a stacked mode, the first pole lug bundle is contained in the shell and comprises a plurality of first pole lugs, the first pole lugs are connected with the first pole piece, the ends, connected with the first pole piece, of the first pole lugs are arranged in the first direction, and the first direction is the thickness direction of the electrode assembly. The plurality of first tabs are arranged in a stacked manner. The first transfer tab is connected with the shell, a part of the first transfer tab extends out of the shell, a part of each first tab is connected with the first transfer tab to form a first welding part, and a part of each first tab is connected with the first transfer tab to form a second welding part. And the second welding part is arranged, so that the performance of the secondary battery can be maintained under the condition that partial position of the first tab is broken.

Description

Technical Field

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

[0002] At present, the tabs of multi-tab secondary batteries are usually gathered into tab bundles, which are then connected to adapter tabs, which are connected to the shell, and a portion of the adapter tabs extends out of the shell. When the secondary battery is impacted or dropped, the electrode assembly and the tab bundle move relative to the shell, causing a pull between the tab bundle and the adapter tab, which can easily cause some tabs to break and disconnect from the adapter tab. For a multi-tab laminated structure secondary battery, the tab breakage will result in the inability to release the capacity of the pole piece connected to the tab, thereby causing the capacity of the secondary battery to decrease. For a multi-tab wound structure secondary battery, the tab breakage will increase the internal resistance of the secondary battery. Summary of the invention

[0003] In view of the above situation, it is necessary to provide a secondary battery that reduces the possibility of performance damage of the secondary battery after falling.

[0004] The first aspect of the embodiment of the present application provides a secondary battery, which includes a housing, an electrode assembly, a first pole tab bundle and a first adapter pole tab. The electrode assembly includes a first pole piece, a second pole piece and a separator, the first pole piece and the second pole piece have opposite polarities, the first pole piece, the separator and the second pole piece are stacked, and the electrode assembly is accommodated in the housing. The first pole tab bundle is accommodated in the housing, the first pole tab bundle includes a plurality of first pole tabs, the plurality of first pole tabs are all connected to the first pole piece, the ends of the plurality of first pole tabs connected to the first pole piece are arranged along the first direction, the first direction is the thickness direction of the electrode assembly, the plurality of first pole tabs are stacked, and the first pole tab bundle is located on one side of the electrode assembly along the second direction. The first adapter pole tab is connected to the housing, and part of the first adapter pole tab extends out of the housing. Along the third direction, the width of the first pole tab bundle is greater than the width of the first adapter pole tab, a part of each first pole tab is connected to the first adapter pole tab and forms a first welding portion, a part of each first pole tab is connected to form a second welding portion, and the first welding portion and the second welding portion are arranged along the third direction; the first direction, the second direction and the third direction are perpendicular to each other.

[0005] In the prior art, the first pole tab is gathered along the first direction to form a first pole tab bundle, and only a portion of the first pole tab bundle is connected to the first adapter pole tab at the position of the first welding portion. When the secondary battery is dropped or impacted, the portion of the first pole tab that is not connected to the first adapter pole tab is pushed and pulled by the first adapter pole tab and is repeatedly deformed, thereby causing a break. In other words, along the second direction, the position where the first pole tab bundle is broken is between the electrode assembly and the first welding portion. In the secondary battery provided by the present application, the width of the first pole lug bundle along the third direction is greater than the width of the first adapter pole lug, and the first pole lugs are also connected by the second welding portion. Compared with the prior art, even if the first pole lug is damaged, it is more likely to be partially torn rather than broken as a whole. The reason is that, on the one hand, the part of the first pole lug bundle wider than the first adapter pole lug is pushed and pulled by the first adapter pole lug to a lesser extent than other parts, and is more likely to keep the structure intact. On the other hand, the second welding portion can hinder the expansion of the crack on the first pole lug. Therefore, when the secondary battery is impacted or dropped, even if the first pole lug is partially broken at the aforementioned position, the first pole piece connected to the broken first pole lug can still be connected to the first adapter pole lug through the second welding portion, thereby maintaining the conductive effect. For a secondary battery with a laminated structure, the connection between the first pole lug and the first adapter pole lug is conducive to connecting all the first pole pieces to the circuit, thereby facilitating the full release of the capacity of the secondary battery; for a secondary battery with a winding structure, the connection between the first pole lug and the first adapter pole lug is conducive to shortening the moving path of electrons, thereby facilitating reducing the internal resistance of the secondary battery. Since the first adapter pole lug is led out along the second direction and is subjected to greater force in the extending direction, the first pole lug bundle is more likely to break in the second direction. If the first welding portion and the second welding portion are arranged along the second direction, the second welding portion and the first welding portion are also easily broken. Therefore, arranging the first welding portion and the second welding portion along the third direction can further ensure that even if the first welding portion is broken around, the first pole piece connected to the broken first pole lug can still be connected to the first adapter pole lug through the second welding portion. In addition, the extension of the first welding portion and the second welding portion along the second direction will cause the first pole lug bundle to need to reserve a longer length, affecting the energy density of the battery. In summary, the second welding portion is provided to help maintain the performance of the secondary battery when part of the first pole lug is broken.

[0006] In one or more embodiments of the present application, part of the first welding portion overlaps part of the second welding portion, and along the third direction, the width of the region where the first welding portion and the second welding portion overlap is D 1 , 0≤D 1≤0.5mm. The partial overlap of the first welding part and the second welding part is conducive to reducing the space occupied by the first welding part and the second welding part in the third direction, so as to reduce the width of the secondary battery along the third direction as needed. However, the welding process has a certain influence on the strength of the first electrode ear, and the overlap of the first welding part and the second welding part will aggravate this influence. Therefore, setting D 1 ≤0.5mm, the overlapping portion of the first welding portion and the second welding portion is not too large, which is beneficial to reducing the influence of the welding process on the structural strength of the first electrode.

[0007] In one or more embodiments of the present application, the first welding portion and the second welding portion are spaced apart along the third direction, and along the third direction, the distance between the first welding portion and the second welding portion is D 2 , 0<D 2 ≤1mm. The first welding part and the second welding part are arranged at intervals to prevent the first pole ear from having its structural strength affected by undergoing two weldings. However, the first welding part and the second welding part are arranged at intervals to increase the space occupied by the first pole ear in the third direction. Therefore, 0<D 2 ≤1mm, the distance between the first welding portion and the second welding portion is not too large, and the width of the first electrode tab is not too large, which is beneficial to reducing the restriction of the width of the first electrode tab on the width of the electrode assembly.

[0008] In one or more embodiments of the present application, along the extension direction of the first tab bundle, the length of the first welding portion is L 1 , 1.5mm≤L 1 ≤11mm. Set L 1 ≥1.5mm, the length of the first welding portion is not too short, which is conducive to improving the stability of the welding structure of the first tab bundle and the first transfer tab; setting L 1 ≤11mm, the length of the first welding portion is not too long, which is beneficial to reducing the area of ​​the first electrode ear that is welded and reducing the impact of the welding process on the structural strength of the first electrode ear.

[0009] In one or more embodiments of the present application, the first tab bundle is disposed on one side of the electrode assembly along the second direction, and along the third direction, the width of the first welding portion is W 1 , 3mm≤W 1 ≤5mm, the first direction, the second direction and the third direction are perpendicular to each other. Set W 1 ≥3mm, the width of the first welding portion is not too small, which is conducive to improving the stability of the welding structure of the first tab bundle and the first transfer tab; setting W 1 ≤5mm, the width of the first welding portion is not too large, which is beneficial to reducing the area of ​​the first electrode tab to be welded and reducing the influence of the welding process on the structural strength of the first electrode tab.

[0010] In one or more embodiments of the present application, along the extension direction of the first tab bundle, the length of the second welding portion is L 2 , 1.5mm≤L 2 ≤11mm. Set L 2 ≥1.5mm, the length of the second welding portion is not too short, which is beneficial to improve the stability of the welding structure between the first tabs; setting L 2 ≤11mm, the length of the second welding portion is not too long, which is beneficial to reducing the area of ​​the first electrode ear that is welded and reducing the impact of the welding process on the structural strength of the first electrode ear.

[0011] In one or more embodiments of the present application, the first electrode tab bundle is arranged on one side of the electrode assembly along the second direction, and along the third direction, the width of the second welding portion is W 2 , 3mm≤W 2 ≤5mm, the first direction, the second direction and the third direction are perpendicular to each other. Set W 2 ≥3mm, the width of the second welding portion is not too small, which is beneficial to improve the stability of the welding structure between the first tabs; setting W 2 ≤5mm, the width of the second welding portion is not too large, which is beneficial to reducing the area of ​​the first electrode tab to be welded and reducing the influence of the welding process on the structural strength of the first electrode tab.

[0012] In one or more embodiments of the present application, the length of the first tab bundle is L 3 , 8mm≤L 3 ≤10mm. Set L 3 ≥8mm, the length of the first tab bundle is not too short, which is conducive to reducing the difficulty of welding the first tab bundle and the first transfer tab; setting L 3 ≤10mm, the length of the first tab bundle is not too long, which is beneficial to reducing the space occupied by the first tab bundle in the shell.

[0013] In one or more embodiments of the present application, the width of the first tab bundle is W 3 , 6mm≤W 3 ≤8mm. Set W 3 ≥6mm, the width of the first tab bundle is not too small, which is beneficial to improve the current carrying capacity of the first tab bundle; setting W 3 ≤8mm, the width of the first electrode tab bundle is not too large, which is beneficial to reducing the restriction of the width of the first electrode tab bundle on the width of the electrode assembly.

[0014] In one or more embodiments of the present application, a portion of each first pole tab is connected to form a third welding portion, and along the third direction, the first welding portion, the second welding portion and the third welding portion are arranged in sequence. Since the first pole tabs are also connected through the third welding portion, when the secondary battery is impacted or dropped, even if a portion of the first pole tab is broken and disconnected from the first adapter pole tab at the first welding portion and the second welding portion, the broken first pole tab can still be connected to the first adapter pole tab through the third welding portion, thereby maintaining the conductive function.

[0015] In one or more embodiments of the present application, the shell includes a first protective layer, a metal layer, and a second protective layer, the metal layer is sandwiched between the first protective layer and the second protective layer, and the first protective layer faces the interior of the shell. The secondary battery includes a first adhesive, the first adhesive adheres the first tab bundle and the first adapter tab, and the first adhesive covers the surface of the first tab bundle and the first adapter tab located inside the shell. In this way, it is helpful to reduce the possibility of the first protective layer being punctured by burrs on the first tab bundle and the first adapter tab, thereby reducing the possibility of corrosion of the shell.

[0016] In one or more embodiments of the present application, the secondary battery further includes a second pole lug bundle and a second adapter pole lug. The second pole lug bundle is accommodated in the shell, and the second pole lug bundle includes a plurality of second pole lugs, and the plurality of second pole lugs are all connected to the second pole piece, and the ends of the plurality of second pole lugs connected to the second pole piece are arranged along the first direction; the plurality of second pole lugs are stacked, and the second pole lug bundle is located on one side of the electrode assembly along the second direction. The second adapter pole lug is connected to the shell, and part of the second adapter pole lug extends out of the shell, and along the third direction, the width of the second pole lug bundle is greater than the width of the second adapter pole lug; part of each second pole lug is connected to the second adapter pole lug to form a fourth welding portion, and part of each second pole lug is connected to form a fifth welding portion, and the fourth welding portion and the fifth welding portion are arranged along the third direction. Since the second pole tabs are connected not only through the fourth welding part but also through the fifth welding part, and the second pole tab bundle is connected to the second adapter pole tab through the fourth welding part, when the secondary battery is impacted or dropped, even if part of the second pole tab is broken and disconnected from the second adapter pole tab at the fourth welding part, the broken second pole tab can still be connected to the second adapter pole tab through the fifth welding part, thereby maintaining the conductive function. Therefore, the fifth welding part is provided to help maintain the performance of the secondary battery when part of the second pole tab is broken.

[0017] A second aspect of the embodiments of the present application provides an electrical device, which includes a secondary battery as described in any of the above embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall structure of a secondary battery in one embodiment of the present application.

[0019] Figure 2 yes Figure 1 Schematic diagram of the cross-sectional structure at II-II.

[0020] Figure 3 It is a partial structural schematic diagram of a secondary battery in one embodiment of the present application.

[0021] Figure 4 It is a partial structural schematic diagram of a secondary battery in one embodiment of the present application.

[0022] Figure 5 It is a partial structural schematic diagram of a secondary battery in one embodiment of the present application.

[0023] Figure 6 It is a partial structural schematic diagram of a secondary battery in one embodiment of the present application.

[0024] Figure 7 yes Figure 1 Schematic diagram of the cross-sectional structure at VII-VII.

[0025] Figure 8 It is a schematic diagram of the structure of an electrical device in an embodiment of the present application.

[0026] Main component symbols 100, secondary battery; 10, housing; 11, first protective layer; 12, metal layer; 13, second protective layer; 20, electrode assembly; 21, first pole piece; 22, second pole piece; 23, separator; 201, positive pole piece; 2011, positive electrode current collector; 2012, positive electrode active material layer; 202, negative pole piece; 2021, negative electrode current collector; 2022, negative electrode active material layer; 30, first pole lug bundle; 31, first pole lug; 301, first welding portion; 3011, first welding point; 302, second welding part; 3021, second welding point; 303, third welding part; 3031, third welding point; 40, first transfer tab; 50, first adhesive; 51, first glue part; 52, second glue part; 60, second tab bundle; 61, second tab; 601, fourth welding part; 602, fifth welding part; 70, second transfer tab; 1000, electrical equipment; X, first direction; Y, second direction; Z, third direction.

[0027] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0028] 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.

[0029] 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 arranged element at the same time. When an element is considered to be "set" on another element, it may be directly set on the other element or there may be a centrally arranged element at the same time. In this application, unless otherwise clearly specified and limited, the term "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0031] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0032] In the description of the embodiments of the present application, the term "perpendicular" is used to describe an ideal state between two components. In actual production or use, there may be a state that is approximately perpendicular between the two components. The two components described as "perpendicular" may not be absolutely straight lines or planes, but may be roughly straight lines or planes. From a macroscopic point of view, if the overall extension direction is a straight line or a plane, the components can be considered to be "straight lines" or "planes".

[0033] Reference to "embodiment" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. The various embodiments in the present application may be combined with each other in the absence of conflict.

[0034] The embodiment of the present application provides a secondary battery, which includes a housing, an electrode assembly, a first pole tab bundle and a first adapter pole tab. The electrode assembly includes a first pole piece, a second pole piece and a separator, the first pole piece and the second pole piece have opposite polarities, the first pole piece, the separator and the second pole piece are stacked, and the electrode assembly is accommodated in the housing. The first pole tab bundle is accommodated in the housing, the first pole tab bundle includes a plurality of first pole tabs, the plurality of first pole tabs are all connected to the first pole piece, the ends of the plurality of first pole tabs connected to the first pole piece are arranged along the first direction, the first direction is the thickness direction of the electrode assembly, the plurality of first pole tabs are stacked, and the first pole tab bundle is located on one side of the electrode assembly along the second direction. The first adapter pole tab is connected to the housing, and part of the first adapter pole tab extends out of the housing. Along the third direction, the width of the first pole tab bundle is greater than the width of the first adapter pole tab, part of each first pole tab is connected to the first adapter pole tab and forms a first welding portion, part of each first pole tab is connected to form a second welding portion, and the first welding portion and the second welding portion are arranged along the third direction; the first direction, the second direction and the third direction are perpendicular to each other.

[0035] In the prior art, the first pole tab is gathered along the first direction to form a first pole tab bundle, and only a portion of the first pole tab bundle is connected to the first adapter pole tab at the position of the first welding portion. When the secondary battery is dropped or impacted, the portion of the first pole tab that is not connected to the first adapter pole tab is pushed and pulled by the first adapter pole tab and is repeatedly deformed, thereby causing a break. In other words, along the second direction, the position where the first pole tab bundle is broken is between the electrode assembly and the first welding portion. In the secondary battery provided in the present application, the width of the first pole lug bundle along the third direction is greater than the width of the first adapter pole lug, and the first pole lugs are also connected by a second welding portion. Compared with the prior art, even if the first pole lug is damaged, it is more likely to be locally torn rather than completely broken. The reason is that, on the one hand, the part of the first pole lug bundle wider than the first adapter pole lug is less pushed and pulled by the first adapter pole lug than other parts, and is more likely to keep the structure intact. On the other hand, the second welding portion can hinder the expansion of the crack on the first pole lug. Therefore, when the secondary battery is impacted or falls, even if the first pole lug is partially broken at the aforementioned position, the first pole sheet connected to the broken first pole lug can still be connected to the first adapter pole lug through the second welding portion, thereby maintaining the conductive function. For a secondary battery with a laminated structure, the first pole tab and the first adapter pole tab are connected to each other, which is conducive to the full release of the capacity of the secondary battery; since the first adapter pole tab is led out along the second direction, the force in the extending direction is large, and the first pole tab bundle is more likely to break in the second direction. If the first welding part and the second welding part are arranged along the second direction, the second welding part and the first welding part are also easy to break. Therefore, the first welding part and the second welding part are arranged along the third direction, which can further ensure that even if the first welding part is broken around, the first pole tab connected to the broken first pole tab can still be connected to the first adapter pole tab through the second welding part, and the first welding part and the second welding part extend along the second direction, which will cause the first pole tab bundle to reserve a longer length, affecting the energy density. For a secondary battery with a winding structure, the first pole tab and the first adapter pole tab are connected to each other, which is conducive to shortening the moving path of electrons, thereby reducing the internal resistance of the secondary battery. In summary, the second welding part is provided to maintain the performance of the secondary battery when part of the first pole tab is broken.

[0036] In the accompanying drawings, the thickness direction of the secondary battery 100 is taken as the first direction X, the direction in which the first adapter tab 40 extends out of the housing is taken as the second direction Y, and the direction perpendicular to the first direction X and the second direction Y is taken as the third direction Z, thereby establishing a spatial rectangular coordinate system.

[0037] like Figure 1 and Figure 2As shown, an embodiment of the present application provides a secondary battery 100, which includes a housing 10 and an electrode assembly 20, wherein the electrode assembly 20 is accommodated in the housing 10, and the electrode assembly 20 is used to store and release electrical energy. The secondary battery 100 also includes a first adapter tab 40 and a second adapter tab 70, both of which are electrically connected to the electrode assembly 20, and the first adapter tab 40 and the second adapter tab 70 are used to electrically connect the secondary battery 100 to an external device. The external device includes, but is not limited to, a charging device, an electrical device 1000, and a testing device.

[0038] In some embodiments, the housing 10 is a flexible packaging bag, such as an aluminum-plastic film. In other embodiments, the housing 10 is a hard shell, such as a plastic shell, or a metal shell including at least one of a steel alloy, an aluminum alloy, and a copper alloy.

[0039] In some embodiments, Figure 2 As shown, the electrode assembly 20 includes a first electrode sheet 21, a second electrode sheet 22 and a separator 23, and the first electrode sheet 21, the separator 23 and the second electrode sheet 22 are stacked. Specifically, the separator 23 is disposed between adjacent first electrode sheets 21 and second electrode sheets 22 to insulate the first electrode sheets 21 and the second electrode sheets 22. The polarities of the first electrode sheet 21 and the second electrode sheet 22 are opposite, and specifically, one of the first electrode sheet 21 and the second electrode sheet 22 is a positive electrode sheet 201, and the other is a negative electrode sheet 202.

[0040] In some embodiments, Figure 2 As shown, the positive electrode sheet 201 includes a positive electrode current collector 2011 and a positive electrode active material layer 2012 which are stacked.

[0041] In some embodiments, the positive electrode current collector 2011 is a metal foil. As an illustrative example, the positive electrode current collector 2011 can be a metal foil including at least one of aluminum, nickel, tantalum, and titanium, such as aluminum foil.

[0042] In some embodiments, the positive electrode current collector 2011 is a composite current collector.

[0043] In some embodiments, the positive active material layer 2012 includes a positive active material. As an illustrative example, the positive active material 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.

[0044] In some embodiments, Figure 2 As shown, the negative electrode sheet 202 includes a negative electrode current collector 2021 and a negative electrode active material layer 2022 which are stacked.

[0045] In some embodiments, the negative electrode current collector 2021 is a metal foil. As an illustrative example, the negative electrode current collector 2021 can be a metal foil including at least one of copper, nickel, tantalum, and titanium, such as copper foil.

[0046] In some embodiments, the negative electrode current collector 2021 is a composite current collector.

[0047] In some embodiments, the negative electrode active material layer 2022 includes a negative electrode active material. As an illustrative example, the negative electrode active material includes at least one of graphite, hard carbon, soft carbon, silicon, silicon-oxygen material, and silicon-carbon material.

[0048] In some embodiments, the isolation film 23 is one of a polyethylene film, a polypropylene film, a polyester film, or a polyimide film.

[0049] In some embodiments, the first electrode sheet 21 , the isolation film 23 , and the second electrode sheet 22 are stacked and wound to form a winding structure. In other words, the electrode assembly 20 is a winding structure.

[0050] In some embodiments, a plurality of first electrode sheets 21 , isolation films 23 , and a plurality of second electrode sheets 22 are alternately stacked to form a laminated structure; in other words, the electrode assembly 20 is a laminated structure.

[0051] In some embodiments, the secondary battery 100 includes an electrolyte, and the electrolyte is contained in the housing 10 .

[0052] In some embodiments, the electrolyte includes an electrolyte salt. The electrolyte salt includes at least one of an organic lithium salt or an inorganic lithium salt.

[0053] In some embodiments, the electrolyte salt is not limited to lithium hexafluorophosphate (LiPF 6 ), bis(trifluoromethanesulfonyl)imide lithium LiN (CF 3 SO 2 ) 2 (LiTFSI), lithium bis(fluorosulfonyl)imide Li(N(SO 2 F) 2 )(LiFSI), lithium hexafluorocesium oxide (LiCsF 6 ), lithium perchlorate (LiClO 4 ) or lithium trifluoromethanesulfonate (LiCF 3 SO 3 ) at least one of.

[0054] In some embodiments, Figure 2As shown, the secondary battery 100 includes a first pole tab bundle 30, which is accommodated in the housing 10 and connected to the first adapter pole tab 40. The first pole tab bundle 30 includes a plurality of first pole tabs 31, each of which is connected to the first pole sheet 21, and the ends of the plurality of first pole tabs 31 connected to the first pole sheet 21 are arranged along a first direction X, and the first direction X is the thickness direction of the electrode assembly 20; the plurality of first pole tabs 31 are stacked, and the first pole tab 30 bundle is located on one side of the electrode assembly 20 along the second direction Y. Specifically, for the electrode assembly 20 with a wound structure, multiple first pole ears 31 are connected to the same first pole piece 21, and the multiple first pole ears 31 are arranged at intervals along the length direction of the first pole piece 21. The provision of multiple first pole ears 31 is beneficial to shortening the movement path of electrons, thereby reducing the internal resistance of the first pole piece 21; for the electrode assembly 20 with a stacked structure, multiple first pole pieces 21 are provided, and each first pole piece 21 is connected to a first pole ear 31, so that each first pole piece 21 can work normally.

[0055] In some embodiments, taking the first electrode sheet 21 as the positive electrode sheet 201 as an example, during the preparation of the first electrode sheet 21, the surface of the positive electrode current collector 2011 in the thickness direction is only partially covered by the positive electrode active material layer 2012, and the uncovered surface is the positive electrode empty foil area, and the first electrode tab 31 is obtained by cutting the positive electrode empty foil area. To avoid confusion of concepts, in the embodiments of the present application, after cutting out the first electrode tab 31, the first electrode tab 31 is regarded as a structure different from the positive electrode current collector 2011, even if the two are different parts of the same metal foil.

[0056] Figures 3 to 6 A schematic diagram of the connection structure of an electrode assembly 20, a first electrode tab bundle 30, a first transition electrode tab 40, a second electrode tab bundle 60 and a second transition electrode tab 70 in one embodiment of the present application is shown.

[0057] In some embodiments, Figure 2 and Figure 3 As shown, the secondary battery 100 further includes a first adapter tab 40, the first adapter tab 40 is connected to the housing 10, and part of the first adapter tab 40 extends out of the housing 10; along the third direction, the width of the first tab bundle 30 is greater than the width of the first adapter tab, a part of each first tab 31 is connected to the first adapter tab 40 to form a first welding portion 301, and a part of each first tab 31 is connected to form a second welding portion 302, and the first welding portion 301 and the second welding portion 302 are arranged along the third direction. Among them, the first tab 31 and the first adapter tab 40 can be connected by welding to form the first welding portion 301; the first tabs 31 can be connected by welding to form the second welding portion 302.

[0058] In the secondary battery 100 provided in the present application, the width of the first pole lug bundle 30 along the third direction Z is greater than the width of the first adapter pole lug 40, and the first pole lugs 31 are also connected by the second welding portion 302. Compared with the prior art, even if the first pole lug 31 is damaged, it is more likely to be partially torn rather than broken as a whole. The reason is that, on the one hand, the part of the first pole lug bundle 30 that is wider than the first adapter pole lug 40 is pushed and pulled by the first adapter pole lug 40 to a lesser extent than other parts, and is more likely to keep the structure intact. On the other hand, the second welding portion 302 can hinder the expansion of the cracks on the first pole lug 31. Therefore, when the secondary battery 100 is impacted or dropped, even if the first pole lug 31 is partially broken, the first pole sheet 21 connected to the broken first pole lug 31 can still be connected to the first adapter pole lug 40 through the second welding portion 302, thereby maintaining the conductive function. For the secondary battery 100 with a laminated structure, the first pole tab 31 and the first adapter pole tab 40 remain connected, which is conducive to connecting all the first pole sheets 21 to the circuit, thereby facilitating the full release of the capacity of the secondary battery 100; for the secondary battery 100 with a wound structure, the first pole tab 31 and the first adapter pole tab 40 remain connected, which is conducive to shortening the moving path of electrons, thereby facilitating reducing the internal resistance of the secondary battery 100. In summary, the second welding portion 302 is provided to maintain the performance of the secondary battery 100 when a portion of the first pole tab 31 is broken.

[0059] On the other hand, since the first adapter pole ear 40 is led out along the second direction and is subjected to greater force in the extending direction, the first pole ear bundle 30 is more likely to break in the second direction Y. If the first welding portion 301 and the second welding portion 302 are arranged along the second direction Y, the second welding portion 302 and the first welding portion 301 are also prone to break. Therefore, arranging the first welding portion 301 and the second welding portion 302 along the third direction Z can further ensure that even if the first welding portion 301 is broken, the first pole piece 21 connected to the broken first pole ear 31 can still be connected to the first adapter pole ear 40 through the second welding portion 302. In addition, the extension of the first weld print portion 301 and the second weld print portion 302 along the second direction Y will result in the need to reserve a longer length for the first pole ear 31 bundle, affecting the energy density of the battery.

[0060] In the embodiments of the present application, Figure 3As shown, part of each first pole ear 31 and the first adapter pole ear 40 are welded to form a first welding portion 301, and part of each first pole ear 31 is welded to form a second welding portion 302. During the welding process of the first adapter pole ear 40 and the first pole ear bundle 30, a plurality of first welding points 3011 are formed, and the area where the plurality of first welding points 3011 are located is the first welding portion 301. During the welding process between the plurality of first pole ears 31, a plurality of second welding points 3021 are formed, and the area where the plurality of second welding points 3021 are located is the second welding portion 302. Figure 3 The first welding part 301 and the second welding part 302 are indicated by dotted lines. That is, the area formed by the outermost periphery of all the first welding points 3011 is the first welding part 301, and the area formed by the outermost periphery of all the second welding points 3021 is the second welding part 302. Since there is a certain distribution regularity between the first welding points 3011 and the second welding points 3021, there is also a certain distribution regularity between the first welding points 3011 and the second welding points 3021. By observing the distribution regularity of the first welding points 3011 and the second welding points 3021, the first welding points 3011 and the second welding points 3021 can be distinguished, thereby distinguishing the first welding part 301 and the second welding part 302. It should be supplemented that the distinction between the first welding point 3011 and the second welding point 3021 can also be distinguished by the cross-sectional structure of the first welding point 3011 and the second welding point 3021. The first welding point 3011 is formed by the welding of part of the first pole tab 31 and part of the first transfer pole tab 40, while the second welding point 3021 is only formed by the welding of the first pole tab 31. It should be supplemented that part of the first welding point 3011 may be fused with part of the second welding point 3021 .

[0061] In some embodiments, Figure 2 As shown, the first tab bundle 30 is bent into a U-shape to reduce the occupation of the head space of the secondary battery 100 by the first tab bundle 30 , thereby facilitating the improvement of the energy density of the secondary battery 100 .

[0062] In some embodiments, Figure 4 As shown, part of the first welding portion 301 overlaps part of the second welding portion 302, and along the third direction Z, the width of the overlapping area of ​​the first welding portion 301 and the second welding portion 302 is D 1 , 0≤D 1 ≤0.5mm. The first welding part 301 and the second welding part 302 partially overlap, which is beneficial to reduce the space occupied by the first welding part 301 and the second welding part 302 in the third direction Z, so as to reduce the width of the secondary battery 100 along the third direction Z as needed. However, the welding process has a certain influence on the strength of the first electrode tab 31, and the overlap of the first welding part 301 and the second welding part 302 will aggravate this influence. Therefore, setting D 1≤0.5mm, the overlapping portion of the first welding portion 301 and the second welding portion 302 is not too large, which is conducive to reducing the impact of the welding process on the structural strength of the first electrode tab 31. Here, the width of the overlapping portion of the first welding portion 301 and the second welding portion 302 refers to the maximum distance between the first welding point 3011 and the second welding point 3021, which are the farthest apart in the overlapping portion of the first welding portion 301 and the second welding portion 302, along the third direction Z. It should be supplemented that the maximum distance refers to the size of the welding point included in the measurement result.

[0063] In some embodiments, D 1 The value is one of 0.1 mm, 0.2 mm, 0.3 mm and 0.4 mm.

[0064] In some embodiments, Figure 3 As shown, the first welding portion 301 is separated from the second welding portion 302, and along the third direction Z, the distance between the first welding portion 301 and the second welding portion 302 is D 2 , 0<D 2 ≤1mm. The first welding portion 301 and the second welding portion 302 are arranged at intervals to prevent the first pole tab 31 from having its structural strength affected by undergoing two weldings. However, the first welding portion 301 and the second welding portion 302 are arranged at intervals to increase the space occupied by the first pole tab 31 in the third direction Z. Therefore, 0<D 2 ≤1mm, the distance between the first welding part 301 and the second welding part 302 is not too large, and the width of the first pole tab 31 is not too large, which is conducive to reducing the restriction of the width of the first pole tab 31 on the width of the electrode assembly 20. Here, the distance between the first welding part 301 and the second welding part 302 refers to the minimum distance between the first welding point 3011 and the second welding point 3021 that are closest to each other in the first welding part 301 and the second welding part 302 along the third direction Z. It should be supplemented that the minimum distance refers to not including the size of the welding point in the measurement result.

[0065] In some embodiments, D 2 The value is one of 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm and 0.9 mm.

[0066] In some embodiments, Figure 3 As shown, along the extension direction of the first tab bundle 30, the length of the first welding portion 301 is L 1 , 1.5mm≤L 1 ≤11mm. Set L 1 ≥1.5mm, the length of the first welding portion 301 is not too short, which is beneficial to improve the stability of the welding structure of the first tab bundle 30 and the first transfer tab 40; setting L1 ≤11mm, the length of the first welding portion 301 is not too long, which is conducive to reducing the area of ​​the first pole tab 31 to be welded and reducing the impact of the welding process on the structural strength of the first pole tab 31. Here, the extension direction of the first pole tab bundle 30 corresponds to the length direction of the first pole tab bundle 30 in the flattened state. The length of the first welding portion 301 refers to the maximum distance between the two first welding points 3011 in the first welding portion 301 that are farthest apart along the extension direction of the first pole tab bundle 30.

[0067] In some embodiments, L 1 The value is one of 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm and 10mm.

[0068] In some embodiments, Figure 3 As shown, the first electrode tab bundle 30 is arranged on one side of the electrode assembly 20 along the second direction Y, and along the third direction Z, the width of the first welding portion 301 is W 1 , 3mm≤W 1 ≤5mm. Set W 1 ≥3mm, the width of the first welding portion 301 is not too small, which is beneficial to improve the stability of the welding structure of the first tab bundle 30 and the first transfer tab 40; setting W 1 ≤5mm, the width of the first welding portion 301 is not too large, which is conducive to reducing the area of ​​the first pole tab 31 to be welded and reducing the impact of the welding process on the structural strength of the first pole tab 31. The width of the first welding portion 301 refers to the maximum distance between the two first welding points 3011 in the first welding portion 301 that are farthest apart along the third direction Z.

[0069] In some embodiments, W 1 The value is one of 3.2mm, 3.4mm, 3.6mm, 3.8mm, 4.0mm, 4.2mm, 4.4mm, 4.6mm and 4.8mm.

[0070] In some embodiments, Figure 3 As shown, along the extension direction of the first tab bundle 30, the length of the second welding portion 302 is L 2 , 1.5mm≤L 2 ≤11mm. Set L 2 ≥1.5mm, the length of the second welding portion 302 is not too short, which is beneficial to improve the stability of the welding structure between the first tabs 31; setting L 2≤11mm, the length of the second welding portion 302 is not too long, which is beneficial to reduce the area of ​​the first pole tab 31 to be welded, and reduce the impact of the welding process on the structural strength of the first pole tab 31. The length of the second welding portion 302 refers to the maximum distance between the two first welding points 3011 in the second welding portion 302 that are farthest apart along the extension direction of the first pole tab bundle 30.

[0071] In some embodiments, L 2 The value is one of 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm and 10mm.

[0072] In some embodiments, Figure 3 As shown, the first electrode tab bundle 30 is disposed on one side of the electrode assembly 20 along the second direction Y, and along the third direction Z, the width of the second welding portion 302 is W. 2 , 3mm≤W 2 ≤5mm. Set W 2 ≥3mm, the width of the second welding portion 302 is not too small, which is beneficial to improve the stability of the welding structure between the first tabs 31; setting W 2 ≤5mm, the width of the second welding portion 302 is not too large, which is beneficial to reduce the area of ​​the first pole tab 31 to be welded and reduce the impact of the welding process on the structural strength of the first pole tab 31. The width of the second welding portion 302 refers to the maximum distance between the two first welding points 3011 in the second welding portion 302 that are farthest apart along the third direction Z.

[0073] In some embodiments, W 2 The value is one of 3.2mm, 3.4mm, 3.6mm, 3.8mm, 4.0mm, 4.2mm, 4.4mm, 4.6mm and 4.8mm.

[0074] In some embodiments, Figure 3 As shown, the length of the first tab bundle 30 is L 3 , 8mm≤L 3 ≤10mm. When L3≥8mm is set, the length of the first tab bundle 30 is not too short, which is conducive to reducing the difficulty of welding the first tab bundle 30 and the first transfer tab 40; when L 3 ≤10 mm, the length of the first tab bundle 30 is not too long, which is beneficial to reducing the space occupied by the first tab bundle 30 in the shell 10.

[0075] In some embodiments, L 3 The value is one of 8.2mm, 8.4mm, 8.6mm, 8.8mm, 9.0mm, 9.2mm, 9.4mm, 9.6mm and 9.8mm.

[0076] In some embodiments, Figure 3 As shown, the width of the first tab bundle 30 is W 3 , 6mm≤W 3 ≤8mm. Set W 3 ≥6mm, the width of the first tab bundle 30 is not too small, which is beneficial to improve the current carrying capacity of the first tab bundle 30; setting W 3 ≤8mm, the width of the first electrode tab bundle 30 is not too large, which is beneficial to reducing the restriction of the width of the first electrode tab bundle 30 on the width of the electrode assembly 20.

[0077] In some embodiments, W 3 The value is one of 6.2mm, 6.4mm, 6.6mm, 6.8mm, 7.0mm, 7.2mm, 7.4mm, 7.6mm and 7.8mm.

[0078] In some embodiments, Figure 5 As shown, a portion of each first pole tab 31 is connected to form a third welding portion 303, and the first welding portion 301, the second welding portion 302 and the third welding portion 303 are arranged along the third direction Z. Since the first pole tabs 31 are also connected through the third welding portion 303, when the secondary battery 100 is impacted or dropped, even if a portion of the first pole tab 31 is broken and disconnected from the first adapter pole tab 40 at the first welding portion 301 and the second welding portion 302, the broken first pole tab 31 can still be connected to the first adapter pole tab 40 through the third welding portion 303, thereby maintaining the conductive function.

[0079] It should be noted that a plurality of third welding points 3031 will be formed during the welding process between the plurality of first electrode tabs 31 , and the area where the plurality of third welding points 3031 are located is the third welding portion 303 . Figure 5 The third welding portion 303 is indicated by a dotted line.

[0080] In some embodiments, Figure 2 As shown, the housing 10 includes a first protective layer 11, a metal layer 12 and a second protective layer 13, the metal layer 12 is sandwiched between the first protective layer 11 and the second protective layer 13, and the first protective layer 11 faces the inside of the housing 10. The secondary battery 100 includes a first adhesive 50, the first adhesive 50 adheres the first tab bundle 30 and the first adapter tab 40, and the first adhesive 50 covers the surfaces of the first tab bundle 30 and the first adapter tab 40 located inside the housing 10. In this way, it is helpful to reduce the possibility of the first protective layer 11 being punctured by the burrs on the first tab bundle 30 and the first adapter tab 40, thereby reducing the possibility of corrosion of the housing 10.

[0081] In some embodiments, the material of the first protective layer 11 includes, but is not limited to, polyethylene, polypropylene, polycarbonate, polyamide, polyethylene terephthalate, acrylonitrile-butadiene-styrene copolymer, polyoxymethylene, polyphenylene oxide, etc. By using the aforementioned materials, the first protective layer 11 is difficult to be dissolved or swelled by the electrolyte, which is beneficial to reduce the risk of corrosion of the metal layer 12.

[0082] In some embodiments, the material of the metal layer 12 includes but is not limited to aluminum foil, austenite-ferrite duplex stainless steel foil, etc. In this way, the metal layer 12 can react with oxygen to form a dense oxide film, thereby reducing the risk of moisture penetrating into the housing 10 .

[0083] In some embodiments, the material of the second protective layer 13 includes, but is not limited to, polyamide, polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, acrylonitrile-butadiene-styrene copolymer, polyoxymethylene, polyphenylene oxide, and the like.

[0084] In some embodiments, Figure 2 and Figure 6 As shown, the first adhesive component 50 includes a first adhesive portion 51 and a second adhesive portion 52. Along the first direction X, the first adhesive portion 51 and the second adhesive portion 52 are respectively located on opposite sides of the first pole tab bundle 30 and the first transition pole tab 40. The first adhesive portion 51 is bonded to the second adhesive portion 52. The first adhesive portion 51 and the first adhesive portion 51 together cover the surfaces of the first pole tab bundle 30 and the first transition pole tab 40 located inside the shell 10.

[0085] In some embodiments, Figure 7As shown, the secondary battery 100 includes a second pole tab bundle 60, which is accommodated in the housing 10, and the second pole tab bundle 60 includes a plurality of second pole tabs 61, and the plurality of second pole tabs 61 are all connected to the second pole sheet 22, and the ends of the plurality of second pole tabs 61 connected to the second pole sheet 22 are arranged along the first direction X, and the plurality of second pole tabs 61 are stacked, and the second pole tab bundle 60 is located on one side of the electrode assembly 20 along the second direction Y. The second transfer pole tab 70 is connected to the housing 10, and part of the second transfer pole tab 70 extends out of the housing 10, and along the third direction Z, the width of the second pole tab bundle 60 is greater than the width of the second transfer pole tab 70; a part of each second pole tab 61 is connected to the second transfer pole tab 70 to form a fourth welding portion 601, and a part of each second pole tab 61 is connected to form a fifth welding portion 602, and the fourth welding portion 601 and the fifth welding portion 602 are arranged along the third direction Z. Since the second pole tabs 61 are connected not only through the fourth welding portion 601 but also through the fifth welding portion 602, and the second pole tab bundle 60 is connected to the second adapter pole tab 70 through the fourth welding portion 601, when the secondary battery 100 is impacted or dropped, even if a portion of the second pole tab 61 is broken and disconnected from the second adapter pole tab 70 at the fourth welding portion 601, the broken second pole tab 61 can still be connected to the second adapter pole tab 70 through the fifth welding portion 602, thereby maintaining the conductive function. Therefore, the fifth welding portion 602 is provided to help maintain the performance of the secondary battery 100 when a portion of the second pole tab 61 is broken. Since the second adapter pole ear 70 is led out along the second direction and is subjected to greater force in the extending direction, the second pole ear bundle 60 is more likely to break in the second direction Y. If the fourth welding part 601 and the fifth welding part 602 are arranged along the second direction Y, the fifth welding part 602 and the fourth welding part 601 are also prone to break. Therefore, arranging the fourth welding part 601 and the fifth welding part 602 along the third direction can further ensure that the fourth welding part 601 is broken around the pole piece, and the pole piece connected to the broken second pole ear 61 can still be connected to the second adapter pole ear 70 through the fifth welding part 602. In addition, the extension of the fourth welding part 601 and the fifth welding part 602 along the second direction Y will cause the second pole ear bundle 60 to need to reserve a longer length, affecting the energy density.

[0086] like Figure 8 As shown, an embodiment of the present application further provides an electric device 1000 , which includes a secondary battery 100 as described in any of the above embodiments.

[0087] In some embodiments, the power-consuming device 1000 includes but is not limited to mobile phones, laptop computers, power tools, power toys, and electronic cigarettes.

[0088] The present application is further described below through specific embodiments.

[0089] Peel force test between multiple layers of tabs: Cut the tab bundle with scissors and cut it into 10mm×20mm samples. Use double-sided tape to stick the sample on a stainless steel plate. Use a 180° peel force test method to test the adhesion of the upper and lower parts of the tab bundle (divided into two parts along the thickness direction). The test speed is 300mm / min and the test length is 40mm.

[0090] Table 1 It can be seen from the above table that the larger the length and width of the welding part, the greater the peeling force between the tabs. The length of the first welding part or the second welding part is greater than 1.5mm, and the width of the first welding part or the second welding part is greater than 3mm to meet the peeling force requirements between the tabs. If the length or width is too large, it will occupy the space inside the battery cell and affect the energy density.

[0091] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present application and are not intended to be limiting of the present application. As long as they are within the spirit and scope of the present application, appropriate changes and modifications to the above embodiments are within the scope of the present application.

Claims

1. A secondary battery, characterized in that: include: case; An electrode assembly, comprising a first electrode piece, a second electrode piece and a separator, wherein the first electrode piece and the second electrode piece have opposite polarities, and the first electrode piece, the separator and the second electrode piece are stacked; the electrode assembly is accommodated in the housing; a first pole tab bundle, accommodated in the housing, the first pole tab bundle comprising a plurality of first pole tabs, the plurality of first pole tabs are all connected to the first pole sheet, ends of the plurality of first pole tabs connected to the first pole sheet are arranged along a first direction, the first direction being a thickness direction of the electrode assembly; the plurality of first pole tabs are stacked; the first pole tab bundle is located at one side of the electrode assembly along a second direction; A first transfer tab, wherein the first transfer tab is connected to the housing, and a portion of the first transfer tab extends out of the housing; Along the third direction, the width of the first pole lug bundle is greater than the width of the first transfer pole lug, a portion of each of the first pole lugs is connected to the first transfer pole lug to form a first welding portion, a portion of each of the first pole lugs is connected to form a second welding portion, and the first welding portion and the second welding portion are arranged along the third direction; the first direction, the second direction and the third direction are perpendicular to each other.

2. The secondary battery according to claim 1, wherein: A portion of the first welding portion overlaps a portion of the second welding portion, and along the third direction, a width of an overlapping region of the first welding portion and the second welding portion is D1, 0≤D1≤0.5 mm.

3. The secondary battery according to claim 1, wherein: The first welding portion and the second welding portion are spaced apart along the third direction. Along the third direction, a distance between the first welding portion and the second welding portion is D2, where 0<D2≤1 mm.

4. The secondary battery according to claim 1, wherein: Along the extension direction of the first tab bundle, the length of the first welding portion is L1, 1.5 mm ≤ L1 ≤ 11 mm; and / or The first electrode tab bundle is arranged on one side of the electrode assembly along the second direction. Along the third direction, the width of the first welding portion is W1, 3mm≤W1≤5mm, and the first direction, the second direction and the third direction are perpendicular to each other.

5. The secondary battery according to claim 1, wherein: Along the extension direction of the first tab bundle, the length of the second welding portion is L2, 1.5 mm ≤ L2 ≤ 11 mm; and / or The first electrode tab bundle is arranged on one side of the electrode assembly along the second direction. Along the third direction, the width of the second welding portion is W2, 3mm≤W2≤5mm, and the first direction, the second direction and the third direction are perpendicular to each other.

6. The secondary battery according to claim 1, wherein: The length of the first tab bundle is L3, 8mm≤L3≤10mm; and / or The width of the first tab bundle is W3, 6mm≤W3≤10mm.

7. The secondary battery according to any one of claims 1 to 6, characterized in that: Parts of each of the first electrode tabs are connected to form a third welding portion, and the first welding portion, the second welding portion and the third welding portion are arranged along the third direction.

8. The secondary battery according to claim 1, wherein: The shell comprises a first protective layer, a metal layer and a second protective layer, the metal layer is sandwiched between the first protective layer and the second protective layer, and the first protective layer faces the interior of the shell; The secondary battery includes a first adhesive member, the first adhesive member adheres the first tab bundle and the first adapter tab, and the first adhesive member covers surfaces of the first tab bundle and the first adapter tab located inside the housing.

9. The secondary battery according to claim 1, wherein: include: a second pole tab bundle, accommodated in the housing, the second pole tab bundle comprising a plurality of second pole tabs, the plurality of second pole tabs are all connected to the second pole piece, and ends of the plurality of second pole tabs connected to the second pole piece are arranged along the first direction; the plurality of second pole tabs are stacked; the second pole tab bundle is located at one side of the electrode assembly along the second direction; A second transfer tab, the second transfer tab is connected to the housing, and a portion of the second transfer tab extends out of the housing; Along the third direction, the width of the second pole tab bundle is greater than the width of the second transfer pole tab, a portion of each second pole tab is connected to the second transfer pole tab to form a fourth welding portion, a portion of each second pole tab is connected to form a fifth welding portion, and the fourth welding portion and the fifth welding portion are arranged along the third direction.

10. An electrical device, characterized in that: The invention comprises the secondary battery as claimed in any one of claims 1 to 9.

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