Secondary battery, electric equipment and preparation method of secondary battery

Abstract

The invention discloses a secondary battery, electric equipment and a preparation method of the secondary battery. The secondary battery comprises an electrode assembly, a first tab bundle and a first adapter, the first tab bundle comprises a plurality of first tabs, the plurality of first tabs are stacked to form the first tab bundle, the first tab bundle comprises a first part, a second part and a tab bending part, and the first part is connected with the first pole piece. The first adapter comprises a first connecting part, an adapter bending part, a second connecting part and a third connecting part which are connected in sequence, the first connecting part is connected to the second part and located on the side, away from the electrode assembly in the second direction, of the second part, and the adapter bending part is connected with the first connecting part and the second connecting part; the third connecting part is connected with the second connecting part, an included angle is formed between the third connecting part and the second connecting part, and the transfer bending part and the tab bending part are located on the same side of the electrode assembly in the first direction. The thickness of the secondary battery can be reduced, and the possibility that the packaging bag is damaged can be reduced.

Description

Technical Field

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

[0002] At present, multi-tab secondary batteries usually gather the tabs into a tab bundle, then weld the tab bundle to the adapter, and the adapter extends out of the packaging bag to connect to an external device. Fig. 9 As shown, a portion of the adapter 02 is connected to the side of the tab bundle facing the electrode assembly. During the preparation process, a portion of the welding mark of the tab bundle 01 and the adapter 02 needs to be reserved at both ends of the welding mark to facilitate the operation of the welding head and absorb processing errors. After the tab bundle 01 and the adapter 02 are bent, the reserved portion extends along the thickness direction of the secondary battery, thereby occupying space in the thickness direction of the secondary battery, making it difficult to further reduce the thickness of the secondary battery. Summary of the invention

[0003] In view of the above situation, it is necessary to provide a secondary battery that can reduce the space occupied by the tab bundle and the adapter in the thickness direction of the secondary battery while reducing the possibility of damage to the packaging bag.

[0004] The first aspect of an embodiment of the present application provides a secondary battery, which includes a packaging bag, an electrode assembly, a first pole lug bundle and a first adapter. The electrode assembly includes a first pole piece, a second pole piece and a separator, which are stacked, and the separator is located between the first pole piece and the second pole piece; the polarities of the first pole piece and the second pole piece are opposite. The first pole lug bundle is accommodated in the packaging bag, and the first pole lug bundle includes a plurality of first pole lugs, and the plurality of first pole lugs are stacked to form a first pole lug bundle, the first pole lug is connected to the first pole piece, and the end of the first pole lug connected to the first pole piece is arranged along the first direction, and the first direction is the thickness direction of the electrode assembly; the first pole lug bundle includes a first part, a second part and a pole lug bending part, the first part is connected to the first pole piece, the pole lug bending part connects the first part and the second part, the first part and the second part are arranged relative to each other along the second direction, and the second direction is perpendicular to the first direction. The first adapter includes a first connection part, a transfer bending part, a second connection part and a third connection part which are connected in sequence, the first connection part is connected to the second part, and the first connection part is located on the side of the second part away from the electrode assembly along the second direction, the transfer bending part connects the first connection part and the second connection part, the first connection part and the second connection part are arranged opposite to each other along the second direction, the third connection part is connected to the second connection part and is arranged at an angle to the second connection part, the transfer bending part and the pole ear bending part are located on the same side of the electrode assembly along the first direction, the third connection part and the transfer bending part are arranged opposite to each other along the first direction, and the third connection part extends out of the packaging bag.

[0005] In this secondary battery, the first connecting part is connected to the second part, the first connecting part and the second connecting part are arranged opposite to each other along the second direction, the third connecting part is connected to the second connecting part and is arranged at an angle to the second connecting part, the transition bending part and the pole ear bending part are located on the same side of the electrode assembly along the first direction, and the third connecting part and the transition bending part are arranged opposite to each other along the first direction. During its preparation process, the parts reserved for welding at the ends of the first connecting part and the second part can be cut off, which is beneficial to reducing the overall space occupied by the first pole ear bundle and the first adapter in the first direction, and further beneficial to thinning the thickness of the secondary battery; and, when the secondary battery falls, the first adapter can release part of the stress through the opening and closing deformation between the first connecting part and the second connecting part to reduce its pulling on the packaging bag, which is beneficial to reducing the possibility of damage to the packaging bag.

[0006] In one or more embodiments of the present application, the second part includes a first end away from the bending portion of the pole ear and a second end connected to the bending portion of the pole ear. The second part is welded to the first connecting portion and forms a first weld mark. Along the extension direction of the second part, the distance between the first weld mark and the first end is S, 0≤S≤0.4mm.

[0007] In the solution of the present application, the portion reserved for welding can be cut off, and the distance between the weld mark and the end of the second portion can be made smaller, so that the size occupied by the second portion is smaller, and the thickness of the secondary battery can be further reduced.

[0008] In one or more embodiments of the present application, the second part is welded to the first connection part to form a first weld mark, and along the length direction of the second part, the width of the first weld mark is W, 0.2mm≤W≤0.85mm. When W≥0.2mm is set, the width of the first weld mark is not too small, which is conducive to improving the stability of the connection between the first connection part and the second part; when W≤0.85mm is set, the width of the first weld mark is not too large, and accordingly, the length of the second part is not too long, which is conducive to reducing the space occupied by the first tab bundle in the first direction, thereby facilitating the thickness reduction of the secondary battery.

[0009] In one or more embodiments of the present application, the second portion is welded to the first connecting portion to form a first weld mark. Along the length direction of the second portion, the distance between the first weld mark and the bent portion of the tab is D 1 , 0.1mm≤D 1 ≤0.5mm. Setting D 1 ≥0.1mm, the distance between the first weld mark and the bent part of the tab is not too small, which is conducive to reducing the requirements for processing accuracy; set D 1 ≤0.5mm, the distance between the first weld mark and the bent portion of the tab is not too large, which is beneficial to reducing the length of the second portion, thereby facilitating thinning the thickness of the secondary battery.

[0010] In one or more embodiments of the present application, the second portion is welded to the first connecting portion to form a first weld mark, and along the extension direction of the first adapter, the length from the first weld mark to the third connecting portion is L 1 , 0.8mm≤L 1 ≤5.8mm. Set L 1 ≥0.8mm, the length from the first weld mark to the third connection part is not too short, which is conducive to reserving an appropriate length for the bending of the first adapter; set L 1 ≤5.8mm, the length from the first weld mark to the third connecting portion is not too long, which is beneficial to reducing the space occupied by the first adapter in the first direction after being bent, thereby helping to reduce the thickness of the secondary battery.

[0011] In one or more embodiments of the present application, the length of the second portion is L, 0.5mm≤L≤10mm. When L≥0.5mm, the length of the second portion is not too small, and the length of the second portion that can be used to connect with the first connecting portion is not too small, which is beneficial to improving the connection stability between the second portion and the first connecting portion; when L≤10mm, the length of the transition bending portion is not too long, which is beneficial to reducing the thickness of the secondary battery.

[0012] In one or more embodiments of the present application, 0.5 mm≤L≤5.5 mm. Setting L≤5.5 mm is beneficial to further reduce the space occupied by the second part in the first direction.

[0013] In one or more embodiments of the present application, the thickness of the secondary battery is T, 2.0 mm ≤ T ≤ 6 mm.

[0014] In one or more embodiments of the present application, the second portion includes a first end away from the bent portion of the pole ear and a second end connected to the bent portion of the pole ear, and along the first direction, the first end and the third connecting portion are located on the same side of the electrode assembly; the first connecting portion includes a third end, and along the first direction, the first end and the third end are located on the same side of the electrode assembly. Along the length direction of the second portion, the distance between the first ends of any two first pole ears is D 2 , 0≤D 2 ≤0.2mm; along the length direction of the second portion, the distance between the third end and the first end of any first pole ear is D 3 , 0≤D 3 In this way, it is beneficial to improve the flatness of the ends of the first electrode tab and the first connecting portion, reduce the space occupied by the uneven ends, and is beneficial to reduce the thickness of the secondary battery.

[0015] In one or more embodiments of the present application, along the second direction, the projections of the first tab and the first adapter are located within the projection range of the electrode assembly, which is beneficial to reducing the influence of the first tab bundle and the first adapter on the thickness of the secondary battery.

[0016] In one or more embodiments of the present application, there is a first gap between the first part and the second part. The secondary battery includes a filler, which is arranged in the first gap to separate the first part and the second part, and the filler is made of a flexible material. When the secondary battery falls, the filler can act as a buffer between the first part and the second part, which is conducive to reducing the risk of damage to the first tab bundle.

[0017] In one or more embodiments of the present application, the filling piece is formed by curing the glue.

[0018] In one or more embodiments of the present application, the filling piece is adhesive tape, and the adhesive tape bonds the first part and the second part.

[0019] In one or more embodiments of the present application, the packaging bag includes a first protective layer, a metal layer, and a second protective layer which are stacked, the metal layer is sandwiched between the first protective layer and the second protective layer, and the first protective layer faces the inside of the packaging bag. The electrode assembly and the first tab bundle are contained in the packaging bag, and part of the third connection portion extends out of the packaging bag. The secondary battery includes a first adhesive layer, the first adhesive layer adheres to the third connection portion and the first protective layer, and along the first direction, the first adhesive layer is located on the side of the third connection portion away from the second portion. The secondary battery includes a first adhesive, the first adhesive adheres to the first adhesive layer and the electrode assembly, and the first adhesive extends along the second direction. The provision of the first adhesive is conducive to reducing the possibility of burrs on the first adapter piercing the first protective layer, thereby helping to reduce corrosion of the packaging bag; and the provision of the first adhesive can also reduce the pulling of the first adapter on the first tab bundle when the battery cell falls, thereby reducing the possibility of the first tab breaking.

[0020] In one or more embodiments of the present application, the secondary battery further includes a second adhesive layer, the second adhesive layer is bonded to the first adhesive layer, the third connecting portion and the first protective layer, and the second adhesive layer is arranged opposite to the first adhesive layer along the thickness direction of the third connecting portion. The secondary battery further includes a second adhesive member, the second adhesive member is bonded to the second adhesive layer, the second connecting portion, the bending portion of the pole ear and the surface of the electrode assembly. The second adhesive layer is provided to further reduce the possibility of burrs on the first adapter piercing the first protective layer, thereby reducing corrosion of the packaging bag.

[0021] A second aspect of the embodiments of the present application provides an electrical device, characterized in that it includes a secondary battery as described in any of the aforementioned embodiments.

[0022] A third aspect of an embodiment of the present application provides a method for preparing a secondary battery, the method comprising the following steps: Take an electrode assembly, the electrode assembly is connected to a plurality of first pole tabs, the first pole tabs are arranged along a first direction, the first direction is the thickness direction of the electrode assembly, and the first pole tabs extend along a second direction, the second direction is perpendicular to the first direction; Take a first adapter and place the first adapter on one side of the electrode assembly along a first direction, so that along the first direction, a projection of a portion of the first electrode tab overlaps with a projection of the first electrode tab; Applying a force to the first adapter and the first pole tab so that a portion of the first adapter and the first pole tab are gathered together along a first direction to form a stacked structure; along the first direction, the first adapter is located on a side of the first pole tab facing the outside of the electrode assembly, and a projection of the first adapter overlaps with the electrode assembly; welding or bonding the first adapter to the first pole tab; and the stacked portion of the first adapter and the first pole tab extends along a second direction; Cutting the stacked portion of the first adapter and the first tab to reduce the length thereof along the second direction; The first tab and the first adapter are bent so that the welded or bonded portion of the first adapter and the first tab extends in the first direction, and a portion of the first adapter not connected to the first tab extends in the first direction and a portion extends in the second direction.

[0023] In the preparation method of this secondary battery, during the connection process between the first adapter and the first pole lug bundle, the first adapter is located on the side of the first pole lug facing the outside of the electrode assembly, so that the first adapter does not need to avoid the pressing knife. After the first adapter and the first pole lug bundle are bent, it is beneficial to reduce the space occupied by the first adapter and the first pole lug bundle in the first direction; and, cutting the stacked part of the first adapter and the first pole lug is beneficial to further reduce the space occupied by the first adapter and the first pole lug bundle in the first direction, thereby facilitating the thinning of the thickness of the secondary battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic structural diagram of a secondary battery in one embodiment of the present application.

[0025] Figure 2 yes Figure 1 Schematic diagram of the cross-sectional structure at II-II.

[0026] Figure 3 yes Figure 2 Enlarged view of point A in the middle.

[0027] Figure 4 yes Figure 1 Schematic diagram of the cross-sectional structure at IV-IV in the figure.

[0028] Figure 5 It is a schematic diagram of the structure of an electrical device in an embodiment of the present application.

[0029] Figure 6 It is a schematic diagram of the structure of a secondary battery during the preparation process in one embodiment of the present application.

[0030] Figure 7 It is a schematic diagram of the structure of a secondary battery during the preparation process in one embodiment of the present application.

[0031] Figure 8 It is a schematic diagram of the structure of a secondary battery during the preparation process in one embodiment of the present application.

[0032] Fig. 9 It is a partial structural schematic diagram of a secondary battery in the prior art.

[0033] Main component symbols 100, secondary battery; 10, packaging bag; 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 adapter; 31, first connecting portion; 311, third end; 31a, first weld print ; 32, transition bending portion; 33, second connecting portion; 34, third connecting portion; 40, first pole ear bundle; 41, first part; 42, second part; 43, pole ear bending portion; 401, first pole ear; 4011, first end; 50, filling member; 61, first glue layer; 62, second glue layer; 71, first adhesive member; 72, second adhesive member; 80, second transition member; 90, second pole ear bundle; 91, second pole ear; 1000, electrical equipment; X, first direction; Y, second direction.

[0034] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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".

[0040] 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.

[0041] The first aspect of an embodiment of the present application provides a secondary battery, which includes a packaging bag, an electrode assembly, a first pole lug bundle and a first adapter. The electrode assembly includes a first pole piece, a second pole piece and a separator, which are stacked, and the separator is located between the first pole piece and the second pole piece; the polarities of the first pole piece and the second pole piece are opposite. The first pole lug bundle is accommodated in the packaging bag, and the first pole lug bundle includes a plurality of first pole lugs, and the plurality of first pole lugs are stacked to form a first pole lug bundle, the first pole lug is connected to the first pole piece, and the end of the first pole lug connected to the first pole piece is arranged along the first direction, and the first direction is the thickness direction of the electrode assembly; the first pole lug bundle includes a first part, a second part and a pole lug bending part, the first part is connected to the first pole piece, the pole lug bending part connects the first part and the second part, the first part and the second part are arranged relative to each other along the second direction, and the second direction is perpendicular to the first direction. The first adapter includes a first connection part, a transfer bending part, a second connection part and a third connection part which are connected in sequence, the first connection part is connected to the second part, and the first connection part is located on the side of the second part away from the electrode assembly along the second direction, the transfer bending part connects the first connection part and the second connection part, the first connection part and the second connection part are arranged opposite to each other along the second direction, the third connection part is connected to the second connection part and is arranged at an angle to the second connection part, the transfer bending part and the pole ear bending part are located on the same side of the electrode assembly along the first direction, the third connection part and the transfer bending part are arranged opposite to each other along the first direction, and the third connection part extends out of the packaging bag.

[0042] Since it is necessary to reserve space in the width direction of the welding head and the welding seat during the welding process to prevent the welding head and the welding seat from falling directly on the foil due to errors, in this secondary battery, the first connecting part connects to the second part, the first connecting part and the second connecting part are arranged relatively to each other along the second direction, the third connecting part connects to the second connecting part and is arranged at an angle to the second connecting part, the transition bending part and the pole ear bending part are located on the same side of the electrode assembly along the first direction, and the third connecting part and the transition bending part are arranged relatively to each other along the first direction. During its preparation process, the part reserved for welding at the end of the first connecting part and the second part can be cut off to reduce the length of this part, which is beneficial to reducing the space occupied by the first pole ear bundle and the first adapter as a whole in the first direction, and further beneficial to thinning the thickness of the secondary battery; and when the secondary battery falls, the first adapter can release part of the stress through the opening and closing deformation between the first connecting part and the second connecting part to reduce its pulling on the packaging bag, which is beneficial to reducing the possibility of damage to the packaging bag.

[0043] The embodiments of the present application are further described below in conjunction with the accompanying drawings.

[0044] like Figure 1 and Figure 2As shown, the first aspect of the embodiment of the present application provides a secondary battery 100, which includes a packaging bag 10, an electrode assembly 20, a first adapter 30 and a second adapter 80. The electrode assembly 20 is contained in the packaging bag 10 and is used to store and release electrical energy. The first adapter 30 and the second adapter 80 are both connected to the electrode assembly 20, and part of the first adapter 30 and part of the second adapter 80 extend out of the packaging bag 10. The polarities of the first adapter 30 and the second adapter 80 are opposite. The first adapter 30 and the second adapter 80 are used to electrically connect the secondary battery 100 to an external device to form a passage.

[0045] 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 which are stacked, and the separator 23 is located between the first electrode sheet 21 and the second electrode sheet 22. The first electrode sheet 21 and the second electrode sheet 22 have opposite polarities. In other words, 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.

[0046] 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.

[0047] 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.

[0048] In some embodiments, the positive electrode current collector 2011 is a composite current collector.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] In some embodiments, the negative electrode current collector 2021 is a composite current collector.

[0053] 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.

[0054] In some embodiments, the isolation film 23 is one of a polyethylene film, a polypropylene film, a polyester film, or a polyimide film.

[0055] 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.

[0056] 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.

[0057] In some embodiments, the secondary battery 100 includes an electrolyte, and the electrolyte is contained in the packaging bag 10 .

[0058] 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.

[0059] 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.

[0060] In some embodiments, Figure 2As shown, the secondary battery 100 includes a first pole tab bundle 40, which is accommodated in the packaging bag 10, and the first adapter 30 is connected to the first pole tab bundle 40. Specifically, the first pole tab bundle 40 includes a plurality of first pole tabs 401, which are stacked to form the first pole tab bundle 40, the first pole tabs 401 are connected to the first pole sheet 21, and the ends of the first pole tabs 401 connected to the first pole sheet 21 are arranged along the first direction X, and the first direction X is the thickness direction of the electrode assembly 20; the first pole tab bundle 40 includes a first portion 41, a second portion 42 and a pole tab bending portion 43, the first portion 41 is connected to the first pole sheet 21, the pole tab bending portion 43 connects the first portion 41 and the second portion 42, the first portion 41 and the second portion 42 are arranged opposite to each other along the second direction Y, and the second direction Y is perpendicular to the first direction X. The first adapter 30 includes a first connection portion 31, a transfer bending portion 32, a second connection portion 33 and a third connection portion 34 which are connected in sequence. The first connection portion 31 is connected to the second portion 42, and the first connection portion 31 is located on the side of the second portion 42 away from the electrode assembly 20 along the second direction Y. The transfer bending portion 32 connects the first connection portion 31 and the second connection portion 33. The first connection portion 31 and the second connection portion 33 are arranged opposite to each other along the second direction Y. The third connection portion 34 connects the second connection portion 33 and is arranged at an angle to the second connection portion 33. The transfer bending portion 32 and the pole ear bending portion 43 are located on the same side of the electrode assembly 20 along the first direction X. The third connection portion 34 and the transfer bending portion 32 are arranged opposite to each other along the first direction X, and the third connection portion extends out of the packaging bag.

[0061] In this secondary battery 100, the first connection portion 31 is connected to the second portion 42, the first connection portion 31 and the second connection portion 33 are arranged opposite to each other along the second direction Y, the third connection portion 34 is connected to the second connection portion 33, and is arranged at an angle with the second connection portion 33, the transition bending portion 32 and the pole ear bending portion 43 are located on the same side of the electrode assembly 20 along the first direction X, and the third connection portion 34 and the transition bending portion 32 are arranged opposite to each other along the first direction X. During its preparation process, the portion reserved for welding at the end of the first connection portion 31 and the second portion 42 can be cut off, which is beneficial to reducing the space occupied by the first pole ear bundle 40 and the first adapter 30 as a whole in the first direction X, and further beneficial to reducing the thickness of the secondary battery 100; and, when the secondary battery 100 falls, the first adapter 30 can release part of the stress through the opening and closing deformation between the first connection portion 32 and the second connection portion 33, so as to reduce its pulling on the packaging bag 10, thereby beneficial to reducing the possibility of damage to the packaging bag 10.

[0062] It should be noted that even though the solution provided in the embodiment of the present application is initially designed for a structure in which the first connection part 31 and the second part 42 are connected by welding, this solution is also applicable to a structure in which the first connection part 31 and the second part 42 are connected by other methods such as conductive adhesive bonding.

[0063] In some embodiments, the second part 42 includes a first end 4011 away from the pole ear bending portion 43 and a second end connected to the pole ear bending portion 43. The second part 42 is welded to the first connecting portion 31 and forms a first weld mark 31a. Along the extension direction of the second part 42, the distance between the first weld mark 31a and the first end 4011 is S, 0≤S≤0.4mm.

[0064] In the solution of the present application, the portion reserved for welding can be cut off, and the distance between the first weld mark 31a and the first end 4011 of the second portion 42 can be made smaller, so that the size occupied by the second portion 42 is smaller, and the thickness of the secondary battery can be further reduced.

[0065] Exemplarily, S may be 0 mm, 0.1 mm, 0.2 mm, or 0.3 mm.

[0066] In some embodiments, Figure 3 As shown, the second portion 42 is welded to the first connection portion 31 to form a first weld mark 31a. Along the length direction of the second portion 42, the width of the first weld mark 31a is W, 0.2mm≤W≤0.85mm. When W≥0.2mm, the width of the first weld mark 31a is not too small, which is beneficial to improving the stability of the connection between the first connection portion 31 and the second portion 42; when W≤0.85mm, the width of the first weld mark 31a is not too large, and accordingly, the length of the second portion 42 is not too long, which is beneficial to reducing the space occupied by the first tab bundle 40 in the first direction X, thereby facilitating the thickness reduction of the secondary battery 100.

[0067] In some embodiments, Figure 3 As shown, the second portion 42 is welded to the first connecting portion 31 to form a first weld mark 31a. Along the length direction of the second portion 42, the distance between the first weld mark 31a and the tab bending portion 43 is D 1 , 0.1mm≤D 1 ≤0.5mm. Setting D 1 ≥0.1mm, the distance between the first weld mark 31a and the bent portion 43 of the tab is not too small, which is conducive to reducing the requirements for processing accuracy; setting D 1 ≤0.5mm, the distance between the first weld mark 31a and the tab bending portion 43 is not too large, which is beneficial to reducing the length of the second portion 42, thereby facilitating the thickness reduction of the secondary battery 100. 1When measuring, the inflection point between the second portion 42 and the tab bending portion 43 located at the innermost side of the U-shaped structure of the first tab bundle 40 is used as an endpoint of the measurement.

[0068] In some embodiments, the second portion 42 is welded to the first connection portion 31 to form a first weld mark 31a. Along the extension direction of the first adapter 30, the length from the first weld mark 31a to the third connection portion 34 is L. 1 , 0.8mm≤L 1 ≤5.8mm. Set L 1 ≥0.8mm, the length from the first weld mark 31a to the third connecting portion 34 is not too short, which is conducive to reserving an appropriate length for the bending of the first adapter 30; setting L 1 ≤5.8 mm, the length from the first weld mark 31 a to the third connecting portion 34 is not too long, which is beneficial to reducing the space occupied by the first adapter 30 in the first direction X after being bent, thereby facilitating reducing the thickness of the secondary battery 100 .

[0069] In some embodiments, Figure 3 As shown, the length of the second portion 42 is L, 0.5mm≤L≤10mm. When L≥0.5mm, the length of the second portion 42 is not too small, and the length of the second portion 42 that can be used to connect with the first connecting portion 31 is not too small, which is beneficial to improving the connection stability between the second portion 42 and the first connecting portion 31; when L≤10mm, the length of the transition bending portion 32 is not too long, which is beneficial to reducing the thickness of the secondary battery 100. When measuring L, the inflection point located at the innermost side of the U-shaped structure of the first tab bundle 40 between the second portion 42 and the tab bending portion 43 is used as one of the measurement endpoints.

[0070] In some embodiments, 0.5 mm≤L≤5.5 mm. Setting L≤5.5 mm is beneficial to further reduce the space occupied by the second portion 42 in the first direction X.

[0071] In some embodiments, the thickness of the secondary battery is T, 2.0 mm ≤ T ≤ 6 mm.

[0072] Illustratively, the thickness T of the secondary battery may be 2.0 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3.0 mm, 4.0 mm, 5.0 mm, or 6.0 mm.

[0073] In some embodiments, Figure 3As shown, the second portion 42 includes a first end 4011 away from the tab bending portion 43 and a second end connected to the tab bending portion 43. Along the first direction X, the first end 4011 and the third connecting portion 34 are located on the same side of the electrode assembly 20. The first connecting portion 31 includes a third end 311. Along the first direction X, the first end 4011 and the third end 311 are located on the same side of the electrode assembly 20. Along the length direction of the second portion 42, the distance between the first ends 4011 of any two first tabs 401 is D 2 , 0≤D 2 ≤0.2mm; along the length direction of the second portion 42, the distance between the third end 311 and any one of the first ends 4011 of the first tab 401 is D 3 , 0≤D 3 ≤0.2mm. This is beneficial to improving the flatness of the ends of the first electrode tab 401 and the first connecting portion 31, reducing the space occupied by the uneven ends, and is beneficial to reducing the thickness of the secondary battery 100.

[0074] In some embodiments, along the second direction Y, the projections of the first tabs 401 and the first adapter 30 are located within the projection range of the electrode assembly 20 . This helps reduce the impact of the first tab bundle 40 and the first adapter 30 on the thickness of the secondary battery 100 .

[0075] In some embodiments, Figure 2 As shown, there is a first gap between the first part 41 and the second part 42; the secondary battery 100 includes a filler 50, which is arranged in the first gap to separate the first part 41 and the second part 42, and the filler 50 is made of a flexible material. When the secondary battery 100 falls, the filler 50 can play a buffering role between the first part 41 and the second part 42, which is conducive to reducing the risk of damage to the first tab bundle 40.

[0076] In some embodiments, the filling member 50 is formed by curing glue.

[0077] In some embodiments, the filling piece 50 is adhesive tape, and the adhesive tape bonds the first portion 41 and the second portion 42 .

[0078] In some embodiments, Figure 2 As shown, the secondary battery 100 includes a packaging bag 10 , which includes a first protective layer 11 , a metal layer 12 , and a second protective layer 13 stacked together. 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 packaging bag 10 .

[0079] 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, and polyphenylene oxide. By using the aforementioned materials, the first protective layer 11 is difficult to be dissolved or swelled by the electrolyte, which helps to reduce the risk of corrosion of the metal layer 12 adjacent to the first protective layer 11.

[0080] In some embodiments, the material of the metal layer 12 includes but is not limited to aluminum foil and austenite-ferrite duplex stainless steel foil. By using the aforementioned materials, the metal layer 12 can not only improve the structural strength of the packaging bag 10, but also react with oxygen in the air to form a dense oxide film, thereby reducing the risk of water vapor penetrating into the containing cavity.

[0081] 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, and polyphenylene oxide. By using the aforementioned materials, the second protective layer 13 can reduce the risk of air infiltration into the containing cavity and improve the deformation ability of the packaging bag 10.

[0082] In some embodiments, Figure 2 As shown, the electrode assembly 20 and the first tab bundle 40 are accommodated in the packaging bag 10, and part of the third connection part 34 extends out of the packaging bag 10. The secondary battery 100 includes a first adhesive layer 61, the first adhesive layer 61 adheres the third connection part 34 and the first protective layer 11, and along the first direction X, the first adhesive layer 61 is located on the side of the third connection part 34 away from the second part 42. The secondary battery 100 includes a first adhesive 71, the first adhesive 71 adheres the first adhesive layer 61 and the electrode assembly 20, and the first adhesive 71 extends along the second direction Y. The provision of the first adhesive 71 is conducive to reducing the possibility of the burrs on the first adapter 30 piercing the first protective layer 11, thereby helping to reduce the corrosion of the packaging bag 10; and the provision of the first adhesive 71 can also reduce the pulling of the first adapter 30 on the first tab bundle 40 when the battery cell falls, reducing the possibility of the first tab 401 breaking.

[0083] In some embodiments, Figure 2 As shown, the secondary battery 100 further includes a second adhesive layer 62, which is bonded to the first adhesive layer 61, the third connection portion 34 and the first protective layer 11, and the second adhesive layer 62 is arranged opposite to the first adhesive layer 61 along the thickness direction of the third connection portion 34. The secondary battery 100 further includes a second adhesive member 72, which is bonded to the second adhesive layer 62, the second connection portion 33, the tab bending portion 43 and the surface of the electrode assembly 20. The second adhesive layer 62 is provided to further reduce the possibility that the burrs on the first adapter 30 pierce the first protective layer 11, thereby reducing the corrosion of the packaging bag 10.

[0084] In some embodiments, Figure 4 As shown, the secondary battery 100 includes a second pole tab bundle 90, the second pole tab bundle 90 includes a plurality of second pole tabs 91, the second pole tabs 91 are connected to the second pole sheet 22, the second pole tabs 91 are gathered to form the second pole tab bundle 90, and the second pole tab bundle 90 is connected to the second adapter 80. The connection structure of the second pole tab bundle 90 and the second adapter 80 can refer to the connection structure of the first pole tab bundle 40 and the first adapter 30, and will not be repeated here.

[0085] like Figure 5 As shown, a second aspect of an embodiment of the present application provides an electric device 1000 , which includes a secondary battery 100 as described in any of the above embodiments.

[0086] In some embodiments, the electric device 1000 includes but is not limited to a mobile phone, a laptop computer, an electric toy, and an electric tool.

[0087] like Figures 6 to 8 As shown, a third aspect of the embodiment of the present application provides a method for preparing a secondary battery 100, the method comprising the following steps: Take an electrode assembly 20, the electrode assembly 20 is connected with a plurality of first pole tabs 401, the first pole tabs 401 are arranged along a first direction X, the first direction X is the thickness direction of the electrode assembly 20, and the first pole tabs 401 extend along a second direction Y, and the second direction Y is perpendicular to the first direction X; Take a first adapter 30 and place the first adapter 30 on one side of the electrode assembly 20 along the first direction X, so that along the first direction X, a projection of a portion of the first electrode tab 401 overlaps with a projection of the first electrode tab 401; Applying a force to the first adapter 30 and the first pole tab 401, so that a portion of the first adapter 30 and the first pole tab 401 are collapsed along the first direction X and form a stacked structure; along the first direction X, the first adapter 30 is located on a side of the first pole tab 401 facing the outside of the electrode assembly 20, and a projection of the first adapter 30 overlaps with the electrode assembly 20; welding or bonding the first adapter 30 and the first pole tab 401; the stacked portion of the first adapter 30 and the first pole tab 401 extends along the second direction Y; Cutting the stacked portion of the first adapter 30 and the first tab 401 to reduce the length thereof along the second direction Y; The first pole tab 401 and the first adapter 30 are bent so that the welded or bonded portion of the first adapter 30 and the first pole tab 401 extends along the first direction X, and a portion of the first adapter 30 not connected to the first pole tab 401 extends along the first direction X and a portion thereof extends along the second direction Y.

[0088] In the preparation method of this secondary battery 100, during the connection process between the first adapter 30 and the first pole lug bundle 40, the first adapter 30 is located on the side of the first pole lug 401 facing the outside of the electrode assembly 20, so that the first adapter 30 does not need to avoid the pressing knife. After the first adapter 30 and the first pole lug bundle 40 are bent, it is beneficial to reduce the space occupied by the first adapter 30 and the first pole lug bundle 40 in the first direction X; and, cutting the stacked part of the first adapter 30 and the first pole lug 401 is beneficial to further reduce the space occupied by the first adapter 30 and the first pole lug bundle 40 in the first direction X, thereby facilitating the thinning of the thickness of the secondary battery 100.

[0089] 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 spirit 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: Packaging bags; an electrode assembly, contained in the packaging bag, the electrode assembly comprising a first electrode sheet, a second electrode sheet and a separator, the separator being located between the first electrode sheet and the second electrode sheet; the first electrode sheet and the second electrode sheet have opposite polarities; a first electrode tab bundle, contained in the packaging bag, the first electrode tab bundle comprising a plurality of first electrode tabs, the plurality of first electrode tabs being stacked to form the first electrode tab bundle, the first electrode tab being connected to the first electrode sheet, and the ends of the first electrode tabs connected to the first electrode sheet being arranged along a first direction, the first direction being the thickness direction of the electrode assembly; the first electrode tab bundle comprising a first portion, a second portion and an electrode tab bending portion, the first portion being connected to the first electrode sheet, the electrode tab bending portion connecting the first portion and the second portion, the first portion and the second portion being arranged opposite to each other along a second direction, the second direction being perpendicular to the first direction; The first adapter comprises a first connection part, a transfer bending part, a second connection part and a third connection part which are connected in sequence, the first connection part is connected to the second part, and the first connection part is located on the side of the second part away from the electrode assembly along the second direction, the transfer bending part connects the first connection part and the second connection part, the first connection part and the second connection part are arranged opposite to each other along the second direction, the third connection part connects the second connection part and is arranged at an angle to the second connection part, the transfer bending part and the pole ear bending part are located on the same side of the electrode assembly along the first direction, the third connection part and the transfer bending part are arranged opposite to each other along the first direction, and the third connection part extends out of the packaging bag.

2. The secondary battery according to claim 1, wherein: The second part includes a first end away from the bending portion of the pole ear and a second end connected to the bending portion of the pole ear. The second part is welded to the first connecting portion and forms a first weld mark. Along the extension direction of the second part, the distance between the first weld mark and the first end is S, 0≤S≤0.4mm.

3. The secondary battery according to claim 1, wherein: The second portion is welded to the first connecting portion to form a first weld mark. Along the length direction of the second portion, the width of the first weld mark is W, and 0.2 mm≤W≤0.85 mm.

4. The secondary battery according to claim 1, wherein: The second portion is welded to the first connecting portion to form a first weld mark. Along the length direction of the second portion, the distance between the first weld mark and the bent portion of the tab is D1, and 0.1 mm ≤ D1 ≤ 0.5 mm.

5. The secondary battery according to claim 1, wherein: The second portion is welded to the first connection portion to form a first weld mark. Along the extension direction of the first adapter, the length from the first weld mark to the third connection portion is L1, and 0.8 mm≤L1≤5.8 mm.

6. The secondary battery according to claim 1, wherein: The length of the second portion is L, 0.5 mm ≤ L ≤ 10 mm.

7. The secondary battery according to claim 6, characterized in that: 0.5mm≤L≤5.5mm.

8. The secondary battery according to claim 7, wherein: The thickness of the secondary battery is T, 2.0 mm ≤ T ≤ 6 mm.

9. The secondary battery according to claim 1, wherein: The second portion includes a first end away from the tab bending portion and a second end connected to the tab bending portion, and along the first direction, the first end and the third connecting portion are located on the same side of the electrode assembly; The first connecting portion includes a third end, and along the first direction, the first end and the third end are located on the same side of the electrode assembly; Along the length direction of the second portion, the distance between the first ends of any two of the first tabs is D2, 0≤D2≤0.2 mm; Along the length direction of the second portion, a distance between the third end and the first end of any one of the first electrode tabs is D3, and 0≤D3≤0.2 mm.

10. The secondary battery according to any one of claims 1 to 9, characterized in that: Along the second direction, projections of the first electrode tab and the first adapter are located within the projection range of the electrode assembly.

11. The secondary battery according to claim 1, wherein A first gap is defined between the first portion and the second portion; The secondary battery includes a filling member, the filling member is disposed in the first gap to separate the first portion and the second portion, and the filling member is made of a flexible material.

12. The secondary battery according to claim 11, wherein: The filling piece is formed by curing the glue; or, The filling piece is adhesive tape, and the adhesive tape bonds the first part and the second part.

13. The secondary battery according to claim 1, wherein: The packaging bag comprises a first protective layer, a metal layer and a second protective layer which are stacked, 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 packaging bag; The electrode assembly and the first electrode tab bundle are accommodated in the packaging bag, and part of the third connecting portion extends out of the packaging bag; The secondary battery comprises a first adhesive layer, the first adhesive layer is bonded to the third connection portion and the first protective layer, and along the first direction, the first adhesive layer is located on a side of the third connection portion away from the second portion; The secondary battery includes a first adhesive member, the first adhesive member adheres the first adhesive layer and the electrode assembly, and the first adhesive member extends along the second direction.

14. The secondary battery according to claim 13, characterized in that: The secondary battery further includes a second adhesive layer, the second adhesive layer is bonded to the first adhesive layer, the third connecting portion and the first protective layer, and along the thickness direction of the third connecting portion, the second adhesive layer is arranged opposite to the first adhesive layer; The secondary battery further includes a second adhesive member, which is bonded to the second adhesive layer, the second connecting portion, the tab bending portion, and the surface of the electrode assembly.

15. An electrical equipment, characterized in that: Comprising the secondary battery according to any one of claims 1 to 14.

16. A method for preparing a secondary battery, characterized in that: The following steps are involved: Take an electrode assembly, the electrode assembly is connected with a plurality of first pole tabs, the first pole tabs are arranged along a first direction, the first direction is the thickness direction of the electrode assembly, and the first pole tabs extend along a second direction, the second direction is perpendicular to the first direction; Taking a first adapter, placing the first adapter on one side of the electrode assembly along the first direction, wherein a projection of a portion of the first electrode tab overlaps with a projection of the first electrode tab along the first direction; Applying a force to the first adapter and the first tab so that a portion of the first adapter and the first tab are collapsed along the first direction to form a stacked structure; Along the first direction, the first adapter is located on a side of the first electrode tab facing the outside of the electrode assembly, and a projection of the first adapter overlaps with the electrode assembly; Welding or bonding the first adapter to the first tab; the stacked portion of the first adapter and the first tab extends along the second direction; cutting a portion where the first adapter and the first tab are stacked to reduce a length thereof along the second direction; The first pole tab and the first adapter are bent so that the welded or bonded portion of the first adapter and the first pole tab extends along the first direction, and a portion of the first adapter not connected to the first pole tab extends partly along the first direction and partly along the second direction.

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