Secondary battery and battery pack

Abstract

The embodiment of the utility model discloses a secondary battery and a battery pack, and the secondary battery comprises a battery cell, a molded part and a protective layer. The battery cell comprises a battery cell main body and a tab bundle. And the tab bundle is connected to one end of the battery cell main body in the first direction. And a welding printing area formed by welding is arranged on the surface of one side of the tab bundle. At least part of the forming piece is arranged on one side, facing the battery cell main body, of the welding printing area and is provided with a forming hole; the forming hole penetrates through the forming part along the first direction; and the protective layer is filled in the forming hole, is connected with the tab bundle and covers the welding printing area. In the embodiment of the invention, the protective layer is formed through the forming piece, so that the protective layer covers the welding and printing area of the tab bundle, and the probability that welding residues on the tab bundle are separated from the tab bundle can be reduced.

Description

Technical Field

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

[0002] In secondary batteries, the lug bundle is welded to the pole. During the welding process, a large amount of dust, debris, welding slag and other fine metal particles are generated. These fine metal particles cannot be completely removed by the dust removal mechanism in the welding equipment. The remaining fine metal particles may enter the battery cell during the use of the secondary battery, causing safety hazards such as short circuit in the secondary battery. Utility Model Content

[0003] The embodiments of the present application provide a secondary battery, which reduces the probability of welding residues on a tab bundle being separated from the tab bundle.

[0004] In order to solve the above technical problems, the embodiments of the present application disclose the following technical solutions:

[0005] On the one hand, a secondary battery is provided, the secondary battery has a first direction, and the secondary battery includes a battery cell, a molded part, and a protective layer. The battery cell includes a battery cell body and a tab bundle, the tab bundle is connected to one end of the battery cell body in the first direction, and one side surface of the tab bundle has a weld mark area formed by welding. At least part of the molded part is arranged on a side of the weld mark area facing the battery cell body and is provided with a molded hole, and the molded hole penetrates the molded part along the first direction. The protective layer fills the molded hole, is connected to the tab bundle, and covers the weld mark area.

[0006] In addition to one or more of the features disclosed above, or as an alternative, the secondary battery further comprises a pole. The weld print area comprises a first sub-weld print area and a second sub-weld print area, each pole lug bundle comprises a plurality of pole lugs of the same polarity and stacked, the plurality of pole lugs of the same polarity are welded and connected to each other to form a first sub-weld print area, the pole lug bundle is welded and connected to the pole to form a second sub-weld print area, the first sub-weld print area and the second sub-weld print area are respectively located on the surface of the pole lug bundle facing away from the pole, and the second sub-weld print area is located in the first sub-weld print area.

[0007] In addition to or as an alternative to one or more of the features disclosed above, the weld print area is located within the orthographic projection of the hole wall of the formed hole on the surface where the weld print area is located.

[0008] In addition to or as an alternative to one or more of the features disclosed above, in the first direction, a distance between an edge of the forming hole of the forming part and a surface where the weld print area is located is less than or equal to 0.5 mm.

[0009] In addition to or as an alternative to one or more of the features disclosed above, the secondary battery further includes a cover body, and the molded piece is fixedly connected to the cover body.

[0010] In addition to one or more of the features disclosed above, or as an alternative, the cover body has a hook, the molded part has a molded portion and a fixed portion connected to each other, the molded portion is arranged on the side of the weld print area facing the battery body and is provided with a molded hole, the fixed portion has a snap-on opening, the hook is passed through the snap-on opening, and is snap-fitted with the fixed portion.

[0011] In addition to one or more of the features disclosed above, or as an alternative, the secondary battery also includes a pole. The pole lug bundle includes a first part, a second part, and a third part. The first part is welded to the pole, and the first part has a weld print area. The second part is connected to one end of the battery body in the first direction, and the first part and the second part are located on opposite sides of the molded part in the first direction. The third part is wrapped around a predetermined edge of the molded part and is connected to the first part and the second part, respectively. Among them, the predetermined edge of the molded part is located outside the welding connection area between the first part and the pole.

[0012] In addition to one or more of the features disclosed above, or as an alternative, the secondary battery further includes a pole. The number of battery cells is at least two, and in the two battery cells, the pole tab bundles of the same polarity are respectively welded to the same pole, and the weld print areas of the pole tab bundles of the same polarity are respectively arranged toward the battery cell body, and the side facing the battery cell body is the predetermined side. At least part of the molded parts are respectively arranged on the predetermined side. The number of molding holes is at least two, each molding hole corresponds to the weld print area one by one, and the two molding holes are arranged at intervals. The number of protective layers is at least two, each protective layer fills a molding hole and covers the weld print area of ​​the corresponding pole tab bundle.

[0013] In addition to one or more of the features disclosed above, or as an alternative, the secondary battery further includes a pole. The number of battery cells is at least two, and in the two battery cells, the pole lug bundles of the same polarity are respectively welded to the same pole, and the weld marks of the pole lug bundles of the same polarity are respectively arranged toward the battery cell body, and the side facing the battery cell body is the predetermined side. At least part of the molded part is arranged on the predetermined side. The number of molded holes is one. The number of protective layers is one, and one protective layer covers the weld marks of the two pole lug bundles of the same polarity respectively.

[0014] In addition to one or more of the features disclosed above, or as an alternative, the secondary battery has an intersecting second direction and a third direction, and the two battery cells are distributed in the second direction. In the two battery cells, the weld marks of the two tab bundles welded to the same pole are arranged at intervals in the second direction. Each tab bundle has a cutting edge, and the cutting edge is located between the weld marks of the two tab bundles along the second direction. The cutting edge has a main body section and a protruding section distributed along the third direction, and the main body section is arranged relative to the weld mark area. The formed hole includes a hole body and a notch, the notch is connected to a side edge of the hole body in the third direction, the portion of the protective layer corresponding to the notch covers the protruding section, and the portion of the protective layer corresponding to the hole body covers the weld mark area and the main body section.

[0015] In addition to one or more of the features disclosed above, or as an alternative, the secondary battery also has a third direction. The secondary battery also includes a cover and two poles, the poles are arranged on the cover, the two poles are arranged at intervals in the third direction, and the pole lug bundle is located between the cover and the battery body in the first direction. The molded part includes a molding part and an anti-overflow part, the molding part is arranged on the side of the weld print area facing the battery body and is provided with a molding hole, the anti-overflow part is connected to the molding part, the anti-overflow part is located on one side of the pole lug bundle in the third direction, and protrudes from the surface of the pole lug bundle facing the cover in the first direction.

[0016] On the other hand, a battery pack is also provided, the battery pack includes a box body and a secondary battery. The box body has a cavity. The secondary battery is accommodated in the cavity of the box body, and the secondary battery is any of the above-mentioned secondary batteries.

[0017] One of the above technical solutions has the following advantages or beneficial effects:

[0018] The protective layer is connected to the tab bundle and covers the welding mark area of ​​the tab bundle, which can fix the welding residue, reduce the probability of the welding residue detaching from the tab bundle, and even avoid the welding residue detaching from the tab bundle, thereby reducing the safety hazards of the secondary battery caused by welding residue. In addition, since the protective layer is filled in the forming hole of the molded part, on the one hand, the shape and position of the protective layer are more controllable, reducing the risk of the protective layer interfering with or affecting other components in the secondary battery. On the other hand, the protective layer can fix the molded part to the tab bundle, improving the positional firmness of the molded part. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The technical solution and other beneficial effects of the present application will be made apparent by describing in detail the specific implementation methods of the present application in conjunction with the accompanying drawings.

[0020] Figure 1 is a three-dimensional exploded view of a secondary battery in an embodiment of the present application;

[0021] Figure 2 yes Figure 1A schematic cross-sectional structure diagram of a secondary battery shown;

[0022] Figure 3 yes Figure 2 In the EE section view, the molded parts are omitted;

[0023] Figure 4 yes Figure 2 An enlarged view of a partial view in FIG.

[0024] Figure 5 yes Figure 1 A schematic diagram of the three-dimensional structure of a molded part in the secondary battery shown;

[0025] Figure 6 Is manufacturing Figure 1 The schematic diagram of the secondary battery process after the electrode bundle and the electrode column are welded;

[0026] Figure 7 Is manufacturing Figure 1 A schematic diagram of a secondary battery process after forming a protective layer in a forming hole;

[0027] Figure 8 yes Figure 7 Left view of

[0028] Fig. 9 yes Figure 7 An enlarged view of the partial view A in the figure, showing the weld mark area and the pole;

[0029] Fig.10 yes Figure 7 Middle BB section view;

[0030] Fig.11 is a cross-sectional schematic diagram of a protective layer covering welding residues on a tab bundle in an embodiment;

[0031] Fig.12 yes Fig. 9 An enlarged view of the partial view C in FIG.

[0032] Fig.13 is a schematic diagram of the three-dimensional structure of a molded part in a secondary battery of another embodiment of the present application;

[0033] Fig.14 Is adopted Fig.13 A schematic diagram of a molded protective layer of the molded part shown;

[0034] Fig.15 is a schematic diagram of the three-dimensional structure of a molded part in a secondary battery of another embodiment of the present application;

[0035] Fig.16 Is adopted Fig.15 A schematic diagram of a molded protective layer of the molded part shown;

[0036] Fig.17 is a schematic diagram of the three-dimensional structure of a molded part in a secondary battery of another embodiment of the present application;

[0037] Fig.18 is a schematic diagram of the three-dimensional structure of a molded part in a secondary battery of another embodiment of the present application;

[0038] Fig.19 yes Fig. 9 In the DD cross-sectional view, the molded part has an overflow prevention portion.

[0039] Description of reference numerals:

[0040] 10-housing; 101-opening; 102-accommodating cavity; 20-cover; 210-top cover sheet; 220-lower insulating member; 221-hooking hook; 30-pole; 40-cell; 410-cell body; 420-ear bundle; 421-first part; 422-second part; 423-third part; 425-cutting edge; 4251-main section; 4252-protruding section; 427-first surface; 428-second surface ;426-weld print area;4261-first sub-weld print area;4262-second sub-weld print area;4263-welding residue;50-molded part;510-molding part;511-molding hole;5111-hole body;5112-notch;512-predetermined edge;520-fixing part;521-clamping opening;530-anti-overflow part;60-protective layer;70-gap;Z-first direction;X-second direction;Y-third direction. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and beneficial effects of this application more clear, the following further describes this application in detail in conjunction with the accompanying drawings and specific implementation methods. It should be understood that the specific implementation methods described in this specification are only for explaining this application, not for limiting this application.

[0042] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" refers to two or more, unless otherwise clearly and specifically defined.

[0043] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "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 a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0044] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0045] In the production process of existing new energy power batteries, ultrasonic welding and laser welding are usually used to electrically connect the tab bundle to the pole. Ultrasonic welding generates high-frequency vibrations through ultrasonic generators and transducers, which drive rapid friction between the surfaces of the welded parts, so that the surfaces of the welded parts are in close contact to achieve atomic bonding, thereby forming a weld. Laser welding is a method of welding that uses a high-energy-density laser beam as a heat source to bombard the welded parts with heat. At present, a large amount of fine metal particles such as dust, debris, and welding slag will be generated during ultrasonic welding and laser welding. These fine metal particles cannot be completely removed by the dust removal mechanism in the welding equipment. The remaining fine metal particles may enter the battery cell during the use of the secondary battery, resulting in safety hazards such as short circuits in the secondary battery.

[0046] In the embodiment of the present application, a protective layer is attached to the weld mark area of ​​the tab bundle to reduce the probability of welding residues on the tab bundle detaching from the tab bundle, thereby reducing the safety hazards of the secondary battery caused by welding residues.

[0047] Weld residues are residual materials produced during the welding process and are commonly found at weld joints and around welds. These residues can include slag, dust, chips, oxides, metal fragments, etc. Slag is a solid residue formed by molten metal during the cooling process, which may adhere to the surface of the weld or solidify inside the weld. Oxides are usually formed in the reaction of oxygen with molten metal, and they adhere to the metal surface around the weld. Metal fragments may be produced by welding materials or explosive reactions, and they may be ejected during the welding process and adhere to the area near the weld.

[0048] See also Figures 1 to 4 . Figure 1 It is a three-dimensional exploded view of the secondary battery in the embodiment of the present application. Figure 2 yes Figure 1 The cross-sectional structure diagram of the secondary battery shown is shown, with the housing 10 omitted. Figure 3 yes Figure 2 EE cross-sectional view in. Figure 4 yes Figure 2 To show the weld print area 426, Figure 3 The molded part 50 is omitted.

[0049] For the convenience of description, the following definition is made: the secondary battery has a first direction Z, a second direction X, and a third direction Y, any two of which intersect. Specifically, any two of the first direction Z, the second direction X, and the third direction Y are perpendicular to each other. Figure 1 The secondary battery shown is a square battery, the first direction Z may also be referred to as a height direction, the second direction X may also be referred to as a thickness direction, and the third direction Y may also be referred to as a length direction.

[0050] The secondary battery includes a housing 10 , a cover 20 , a pole 30 , a battery cell 40 , a molded part 50 and a protective layer 60 .

[0051] The housing 10 has an opening 101 at one end in the first direction Z. The housing 10 is made of, for example, aluminum alloy. The housing 10 is substantially in the shape of a cuboid.

[0052] The cover body 20 covers the opening 101 of the shell 10, and is surrounded by the shell 10 to form a closed accommodating cavity 102. Specifically, the cover body 20 includes a top cover sheet 210 and a lower insulating member 220. The top cover sheet 210 and the shell 10 are surrounded to form a closed accommodating cavity 102. The lower insulating member 220 is located in the accommodating cavity 102 and is fixedly connected to the top cover sheet 210. The lower insulating member 220 can prevent the battery cell 40 from contacting the top cover sheet 210 and thus preventing the two from being electrically conductive. The material of the top cover sheet 210 is, for example, aluminum alloy. The material of the lower insulating member 220 is, for example, insulating plastic.

[0053] There are two poles 30. Each pole 30 is disposed through the cover 20, with a portion located in the accommodating cavity 102 and the other portion located outside the accommodating cavity 102. The two poles 30 are spaced apart in the third direction Y. The two poles 30 have different polarities. One pole 30 is the positive pole of the secondary battery, and the other pole 30 is the negative pole of the secondary battery.

[0054] The battery cell 40 is accommodated in the accommodating cavity 102. The battery cell 40 includes a battery cell body 410 and two tab bundles 420. The tab bundle 420 is connected to one end of the battery cell body 410 in the first direction Z. The battery cell body 410 is formed by winding a stacked positive electrode sheet, a separator and a negative electrode sheet, and is extruded into a flat plate. In one example, the battery cell body 410 is a flat structure similar to a rectangular parallelepiped. The polarities of the two tab bundles 420 are different. One tab bundle 420 is a positive tab bundle, and is connected to the positive electrode sheet in the battery cell body 410. The other tab bundle 420 is a negative tab bundle, and is connected to the negative electrode sheet in the battery cell body 410. The positive tab bundle 420 is welded to the positive pole column 30. The negative tab bundle 420 is welded to the negative pole column 30.

[0055] Figure 1 In the illustrated embodiment, the number of the battery cells 40 is two, and the battery cell bodies 410 of the two battery cells 40 are stacked in the second direction X. The pole tab bundles 420 of the same polarity in the two battery cells 40 are respectively welded to the same pole 30. Specifically, the pole tab bundles 420 of the positive poles in the two battery cells 40 are respectively welded to the pole 30 of the positive pole. The pole tab bundles 420 of the negative poles in the two battery cells 40 are respectively welded to the pole 30 of the negative pole.

[0056] In other embodiments, the number of the battery cells 40 may also be one, three, or more than four.

[0057] The specific structure of the secondary battery is not limited to Figure 1 As shown, for example, in some other embodiments, the housing 10 has an opening 101 at both ends in the first direction Z. Correspondingly, there are two covers 20, which are respectively provided at both ends of the housing 10 in the first direction Z, so as to form a receiving cavity 102 with the housing 10. One pole 30 is provided on one cover 20, and another pole 30 is provided on another cover 20. The two tab bundles 420 in each battery cell 40 are respectively provided at both ends of the battery cell body 410 in the first direction Z.

[0058] In the following, Figure 1 As an example of the secondary battery shown in FIG. 1 , it is described how to reduce the welding residue 4263 on the tab bundle 420 by using the protective layer 60 (see FIG. 1 ). Fig.11 )The probability of escaping from the tab bundle 420.

[0059] One side surface of the tab bundle 420 has a weld mark area 426 formed by welding.

[0060] Specifically, the tab bundle 420 has a first surface 427 and a second surface 428 that are opposite to each other. The pole 30 has an end surface located in the accommodating cavity 102 in the first direction Z. The tab bundle 420 is attached to the end surface of the pole 30 by welding through the first surface 427. The first surface 427 faces the pole 30, and the second surface 428 faces away from the pole 30. The weld mark area 426 is located on the second surface 428 of the tab bundle 420.

[0061] The weld print area 426 includes a first sub-weld print area 4261 and a second sub-weld print area 4262. The first sub-weld print area 4261 and the second sub-weld print area 4262 are respectively located on the second surface 428. The second sub-weld print area 4262 is located in the first sub-weld print area 4261.

[0062] Each tab bundle 420 includes a plurality of tabs with the same polarity and stacked, and the plurality of tabs are all or partially welded to each other, that is, two adjacent tabs with the same polarity are welded to form a tab bundle 420, and a first sub-weld area 4261 is formed on the first surface 427 or the second surface 428. The welding connection between the plurality of tabs includes, but is not limited to, ultrasonic welding, laser welding, and resistance welding.

[0063] The tab bundle 420 is welded to the pole 30 to form a second sub-weld area 4262. The tab bundle 420 and the pole 30 are welded to each other in a manner including, but not limited to, ultrasonic welding, laser welding, and resistance welding.

[0064] In some other embodiments (not shown), the weld print area 426 may also include only the first sub-weld print area 4261 or the second sub-weld print area 4262. That is, according to actual needs, the first sub-weld print area 4261 or the second sub-weld print area 4262 is selectively protected (attached with a protective layer 60).

[0065] In some other embodiments (not shown), the first sub-weld print area 4261 and the second sub-weld print area 4262 in the weld print area 426 may also partially intersect or be separated from each other.

[0066] The molded part 50 is used to form a protective layer 60 on the weld print area 426. Figure 1 In the secondary battery shown, there are two molded parts 50. One molded part 50 is provided corresponding to the positive electrode column 30, and is used to form a protective layer 60 on the welded areas 426 of the two positive electrode tab bundles 420. Another molded part 50 is provided corresponding to the negative electrode column 30, and is used to form a protective layer 60 on the welded areas 426 of the two negative electrode tab bundles 420.

[0067] Please also read Figure 5 . Figure 5 yes Figure 1 A schematic diagram of the three-dimensional structure of the molded part 50 in the secondary battery is shown.

[0068] The molded member 50 is fixedly connected to the cover 20. At least a portion of the molded member 50 is disposed on a side of the weld print area 426 facing the battery body 410 and is provided with a molded hole 511. The molded hole 511 penetrates the molded member 50 along the first direction Z. The protective layer 60 is filled in the molded hole 511, connected to the tab bundle 420 and covers the weld print area 426.

[0069] The secondary battery has at least two battery cells 40. In the two battery cells 40, the tab bundles 420 of the same polarity are respectively welded to the same pole 30. The weld print areas 426 of the tab bundles 420 of the same polarity are respectively arranged toward the battery cell body 410, and the side facing the battery cell body 410 is the predetermined side S (see Figure 2 ). At least part of the molded part 50 is respectively arranged on the predetermined side S. The number of the molded holes 511 is at least two, each molded hole 511 corresponds to the weld print area 426 one by one, and the two molded holes 511 are arranged at intervals. The number of the protective layers 60 is at least two, each protective layer 60 fills a molded hole 511 and covers the weld print area 426 of the corresponding tab bundle 420.

[0070] Specifically, in the secondary battery as shown in FIG1 , the molded member 50 includes a molded portion 510 and a fixing portion 520 connected to each other. The molded portion 510 is generally in the shape of a plate. The molded portion 510 is disposed on the side of the weld print area 426 facing the battery body 410, that is, disposed on the predetermined side S. The molded portion 510 has two molded holes 511. The molded member 50 is fixedly connected to the cover 20 through the fixing portion 520. The specific method of fixed connection is described in detail below.

[0071] By fixing the forming portion 510 to the cover body 20 , the position of the forming hole 511 can be more accurately set, thereby making the setting position of the protection layer 60 more accurate.

[0072] In some embodiments, the protective layer 60 is a glue-like substance, for example, a polymer glue, a hot melt glue, a polymer glue, a solvent-based glue or a water-based glue. The protective layer 60 can be filled into the forming hole 511 by scraping, spraying, dispensing or gluing. After the protective layer 60 is cured, it is bonded to the second surface 428 of the tab bundle 420 and to the inner wall surface of the forming hole 511 by its own bonding properties.

[0073] In other embodiments, the protective layer 60 is rubber or plastic. The protective layer 60 is melted by heat and filled into the forming hole 511 , and after being cooled and solidified, it is bonded to the second surface 428 of the tab bundle 420 and the inner wall of the forming hole 511 .

[0074] See also Figures 6 to 10 . Figure 6 Is manufacturing Figure 1 The schematic diagram of the secondary battery process is shown after the electrode tab bundle 420 and the electrode column 30 are welded. Figure 7 Is manufacturing Figure 1 The schematic diagram shows the process of forming the protective layer 60 in the forming hole 511 in the secondary battery process. Figure 8 yes Figure 7 Left view of . Fig. 9 yes Figure 7 The enlarged view of the partial view A in FIG. 1 shows the weld mark area 426 and the pole 30. Fig.10 yes Figure 7 BB section view. Figures 6 to 10 introduce Figure 1 The manufacturing process of the secondary battery is shown.

[0075] In a scenario of assembling a secondary battery, the assembly steps are as follows:

[0076] The tabs of each battery cell 40 are welded into an integrated structure to obtain a tab bundle 420. Specifically, a portion or all of the tabs with the same polarity in the same battery cell 40 are connected by ultrasonic welding to obtain a tab bundle 420. The second surface 428 of the tab bundle 420 forms a first sub-weld area 4261.

[0077] like Figure 6 The battery cell 40 and the cover 20 are arranged in the posture shown, and each tab bundle 420 is welded to the corresponding pole 30. The second surface 428 of the tab bundle 420 forms a second sub-weld area 4262. Specifically, the tab bundle 420 of the positive electrode of each battery cell 40 is welded to the pole 30 of the positive electrode, and the tab bundle 420 of the negative electrode of each battery cell 40 is welded to the pole 30 of the negative electrode.

[0078] The molded member 50 is fixed to the cover 20 . Specifically, one molded member 50 is disposed at the positive electrode post 30 , and another molded member 50 is disposed at the negative electrode post 30 .

[0079] The flowable protective layer 60 is filled in each molding hole 511 of each molding part 50 , and the protective layer 60 is cured.

[0080] Cell closing operation: the cell bodies 410 of the two cell bodies 40 are respectively turned over by 90° so that the cell bodies 410 of the two cell bodies 40 are stacked.

[0081] Inserting operation: inserting two battery cells 40 into the housing 10 .

[0082] The cover body 20 is connected to the housing 10 so that the cover body 20 closes the opening 101 of the housing 10. Specifically, the top cover sheet 210 in the cover body 20 can be connected to the housing 10 by welding.

[0083] In the embodiment of the present application, the protective layer 60 is connected to the tab bundle 420 and covers the weld mark area 426 of the tab bundle 420. The protective layer 60 can fix the welding residue 4263, reduce the probability of the welding residue 4263 detaching from the tab bundle 420, and even avoid the welding residue 4263 detaching from the tab bundle 420, thereby reducing the safety hazards of the secondary battery caused by the welding residue 4263.

[0084] The molded part 50 is fixed to the cover body 20 , so that the position of the protection layer 60 is more accurate and the fixation is more reliable.

[0085] Before molding, the protective layer 60 has fluidity. If the molding member 50 is not provided, the protective layer 60 may flow onto the cover 20, which may cause the protective layer 60 to block the explosion-proof valve or the injection hole on the cover 20. By providing the molding member 50, the protective layer 60 is filled in the molding hole 511 of the molding member 50, and the shape of the protective layer 60 is more controllable, reducing the risk of the protective layer 60 interfering with or affecting the spatial placement of other components in the secondary battery.

[0086] The protective layer 60 can fix the molded part 50 to the tab bundle 420 , thereby improving the positional firmness of the molded part 50 .

[0087] See also Fig. 9 In some embodiments, the weld mark area 426 is located within the orthographic projection of the hole wall of the forming hole 511 on the surface where the weld mark area 426 is located, that is, the area enclosed by the surface area formed by the weld mark area 426 and the orthographic projection of the hole wall of the forming hole 511 on the surface where the weld mark area 426 is located, and the surface area is smaller than or equal to the area enclosed by the orthographic projection.

[0088] Specifically, in Figure 1 In the secondary battery shown, at the pole 30 of the positive electrode, the forming holes 511 of the forming member 50 correspond to the tab bundles 420 one by one, and each forming hole 511 is directly opposite to the second surface 428 of the corresponding tab bundle 420. In the process of filling the protective layer 60, the protective layer 60 will not overflow from the gap between the two tab bundles 420 in the second direction X toward the side of the cover 20.

[0089] Specifically, the shape of the molded hole 511 matches the shape of the weld print area 426. Figure 1 In the secondary battery shown, the weld print area 426 and the molded hole 511 are both rectangular in shape.

[0090] See also Figure 4 In the process of filling the protective layer 60, the protective layer 60 with fluidity may overflow from the gap between the forming part 510 and the second surface 428 of the tab bundle 420. In order to reduce the overflow of the protective layer 60, the following definition is also made. For the convenience of description, the distance between the edge of the forming hole 511 of the molded part 50 and the surface where the weld print area 426 is located is defined as the assembly gap value L.

[0091] In some embodiments, in the first direction Z, the assembly clearance value L is less than or equal to 0.5 mm. Figure 4 In the embodiment, the molded part 50 abuts against the tab bundle 420 in the first direction Z, so that the assembly gap value L is 0 mm.

[0092] In order to verify the influence of the assembly clearance value L on overflow, the following test was performed.

[0093] In the following tests, the following Figure 1 The secondary battery shown in FIG. In different embodiments, the assembly gap value L has different values. After the protective layer 60 is cured, Figure 7 In the state shown, it is observed whether there is any overflow of the protective layer 60 .

[0094] The test results of each embodiment are shown in the following table.

[0095] Table 1:

[0096]

[0097] As can be seen from Table 1, in the embodiments where polyolefin is used as the material of the protective layer 60 and the viscosity of the protective layer 60 before curing is 1500 MPa·s or 2600 MPa·s, when the assembly gap value L is less than or equal to 0.5 mm, there is no overflow, and when the assembly gap value L is greater than 0.5 mm, there is overflow. Similarly, in the embodiments where epoxy resin is used as the material of the protective layer 60 and the viscosity of the protective layer 60 before curing is 1500 MPa·s or 2600 MPa·s, when the assembly gap value L is less than or equal to 0.5 mm, there is no overflow, and when the assembly gap value L is greater than 0.5 mm, there is overflow.

[0098] In summary, when the assembly clearance value L is less than or equal to 0.5 mm, it is beneficial to reduce the overflow of the protective layer 60 .

[0099] In one inspection scenario, the finished secondary battery can be filled with glue and sliced, and then the assembly gap value L can be inspected using a measuring projector.

[0100] In the case where the molded member 50 is fixedly connected to the cover body 20 , in order to ensure that the molded member 50 can be smoothly assembled to the cover body 20 and the assembly gap value L is controllable, the following limitations are also made.

[0101] See also Figure 4 . In some embodiments, after the tab bundle 420 is welded to the end face of the pole 30 and before the molded part 50 is assembled, the thickness dimension of the tab bundle 420 in the first direction Z is L1 mm. In the first direction Z, the distance between the end face of the pole 30 and the surface of the cover 20 facing the battery cell 40 is L2 mm. In the first direction Z, the distance between the surface of the molded part 510 facing the weld print area 426 and the surface of the cover 20 facing the battery cell 40 is L3 mm. Satisfies: 0.9*(L1+L2)≤L3≤1.1*(L1+L2).

[0102] In one detection scenario, a vernier caliper may be used to detect L1, L2, and L3.

[0103] See also Fig.11 . Fig.11 FIG. 4 is a cross-sectional schematic diagram of a protective layer 60 covering welding residues 4263 on a tab bundle 420 in an embodiment.

[0104] In some embodiments, the tab bundle 420 has a protruding welding residue 4263 in the welding mark area 426. The welding residue 4263 is embedded in the protective layer 60. The thickness dimension of the protective layer 60 in the first direction Z is greater than the protruding height of the welding residue 4263 in the first direction Z.

[0105] In this way, the welding residue 4263 can be prevented from contacting the rest of the tab bundle 420 or the battery cell body 410 , thereby preventing the welding residue 4263 from damaging the rest of the tab bundle 420 or the battery cell body 410 .

[0106] In some embodiments, when the forming portion 510 abuts against the tab bundle 420 , the depth dimension of the forming hole 511 in the first direction Z is H mm, and the thickness dimension of the protective layer 60 in the first direction Z is h mm, satisfying: 0.05≤h≤H.

[0107] Typically, the protruding height of the welding residue 4263 in the first direction Z is less than 0.05 mm. By the above definition, the protective layer 60 can completely cover the welding residue 4263 , and the protective layer 60 will not overflow the forming hole 511 in the first direction Z during the filling process of the protective layer 60 .

[0108] See also Fig. 9 and Fig.12 . Fig.12 yes Fig. 9 An enlarged view of detail view C in FIG.

[0109] In order to fix the molded member 50 to the cover body 20, the following structure may be adopted.

[0110] The cover 20 has a hook 221. Specifically, the lower insulating member 220 has a hook 221 on the side facing the accommodating cavity 102. The fixing portion 520 has a snap-fit ​​opening 521. The snap-fit ​​opening 521 penetrates the fixing portion 520 in the first direction Z. The hook 221 is inserted into the snap-fit ​​opening 521 and snap-fits with the fixing portion 520.

[0111] When fixing the molded piece 50 to the cover body 20, the molded piece 50 is pressed toward one side of the cover body 20, so that the hook 221 and / or the fixing portion 520 are elastically deformed to pass through the snap-fit ​​opening 521, and the snap-fit ​​is achieved after the hook 221 and / or the fixing portion 520 are elastically restored.

[0112] To achieve stable connection, the molded part 50 has a plurality of fixing parts 520, which are spaced around the molded part 510. Correspondingly, the cover body 20 has a plurality of hooks 221. The fixing parts 520 correspond to the hooks 221 one by one, and each hook 221 is engaged with the corresponding fixing part 520.

[0113] In other embodiments, the positions of the hook 221 and the fixing portion 520 may also be swapped, that is, the molded part 50 has the hook 221 and the cover body 20 has the fixing portion 520 .

[0114] In other embodiments, the fixing portion 520 may also be a slot disposed on the forming portion 510. The hook 221 is engaged with the forming portion 510 through the slot.

[0115] The above-mentioned snap-fitting structure can improve the efficiency of assembling the molded part 50 .

[0116] In order to fix the molded part 50 to the cover body 20, in addition to the snap-fitting method, bolt fastening or adhesive connection can also be used.

[0117] See also Figure 2 In addition to being used for forming the protective layer 60, the molded part 50 also has the function of assisting in bending the tab bundle 420 during the process of assembling the secondary battery (core assembly operation).

[0118] Specifically, the tab bundle 420 includes a first portion 421, a second portion 422, and a third portion 423. The first portion 421 is welded to the pole 30, and the first portion 421 has a weld mark area 426. The second portion 422 is connected to one end of the cell body 410 in the first direction Z, and the first portion 421 and the second portion 422 are located on opposite sides of the molded member 50 in the first direction Z. The third portion 423 is arranged around a predetermined edge 512 of the molded member 50, and is connected to the first portion 421 and the second portion 422, respectively. Among them, the predetermined edge 512 of the molded member 50 is located outside the welded connection area between the first portion 421 and the pole 30.

[0119] After the tab bundle 420 is welded to the pole 30, the tab bundle 420 is bent at the predetermined edge 512 during the process of flipping the two battery cell bodies 410 by 90 degrees. Therefore, the molded part 50 can also replace the U-shaped glue to bend and shape the tab bundle 420.

[0120] See also Fig.13 and Fig.14 . Fig.13 It is a schematic diagram of the three-dimensional structure of a molded part 50 in a secondary battery according to another embodiment of the present application. Fig.14 Is adopted Fig.13 The molded part 50 is shown as a schematic diagram of a molded protective layer 60 .

[0121] To improve the efficiency of forming the protective layer 60 , in some embodiments, one forming hole 511 may also correspond to the weld print areas 426 of multiple tab bundles 420 .

[0122] Specifically, the number of the battery cells 40 is at least two, and in the two battery cells 40, the tab bundles 420 of the same polarity are respectively welded to the same pole 30, and the weld print areas 426 of the tab bundles 420 of the same polarity are respectively arranged toward the battery cell body 410, and the side facing the battery cell body 410 is the predetermined side S. At least part of the molded part 50 is arranged on the predetermined side S. The number of the molded hole 511 is one. The number of the protective layer 60 is one, and one protective layer 60 covers the weld print areas 426 of the two tab bundles 420 of the same polarity.

[0123] like Fig.13 and Fig.14 As shown, the two tab bundles 420 are respectively welded to the same pole 30. After the molded part 50 is fixed to the cover 20, a protective layer 60 is filled in the molded hole 511, and the protective layer 60 can cover the weld marks 426 of the two tab bundles 420 respectively.

[0124] Each of the tab bundles 420 has a cutting edge 425, and the cutting edge 425 is located between the weld print areas 426 of the two tab bundles 420 along the second direction X. The cutting edge 425 has a main section 4251 and a protruding section 4252 distributed along the third direction Y, and the main section 4251 is arranged opposite to the weld print area 426. The cutting edge 425 may have defects such as cutting burrs. Fig.13 In the embodiment of the molded part 50 shown, the protective layer 60 can also cover the main body section 4251 of the cut edge 425 of each tab bundle 420 , thereby reducing the probability of burrs on the main body section 4251 detaching from the tab bundle 420 .

[0125] Furthermore, in order to enable the protective layer 60 to also cover the protruding section 4252, the following improvements are made.

[0126] See also Fig.15 and Fig.16 . Fig.15 It is a schematic diagram of the three-dimensional structure of a molded part 50 in a secondary battery according to another embodiment of the present application. Fig.16 Is adopted Fig.15 The molded part 50 is shown as a schematic diagram of a molded protective layer 60 .

[0127] In the two battery cells 40, the weld print areas 426 of the two tab bundles 420 welded to the same pole 30 are arranged at intervals in the second direction X. The formed hole 511 includes a hole body 5111 and a notch 5112, and the notch 5112 is connected to a side edge of the hole body 5111 in the third direction Y. The portion of the protective layer 60 corresponding to the notch 5112 covers the protruding section 4252, and the portion of the protective layer 60 corresponding to the hole body 5111 covers the weld print area 426 and the main section 4251.

[0128] Specifically, since the cutting edge 425 has protruding sections 4252 on both sides of the third direction Y, correspondingly, the forming hole 511 has notches 5112 on both side edges of the third direction Y. In other embodiments, the forming hole 511 may have only one notch 5112 as required.

[0129] See also Figures 17 to 19 . Fig.17 It is a schematic diagram of the three-dimensional structure of a molded part 50 in a secondary battery according to another embodiment of the present application. Fig.18 It is a schematic diagram of the three-dimensional structure of a molded part 50 in a secondary battery according to another embodiment of the present application. Fig.17 and Fig.18 The molded parts 50 shown in the drawings each have an overflow prevention portion 530 . Fig.19 yes Fig. 9 In the DD cross-sectional view in FIG. 1 , the molded part 50 has an overflow prevention portion 530 .

[0130] like Fig.19 As shown, the tab bundle 420 is located between the cover 20 and the battery body 410 in the first direction Z. There is a gap 70 between the tab bundle 420 and the cover 20 in the first direction Z. When the protective layer 60 is formed, the protective layer 60 with fluidity may overflow into the gap 70 and overflow from the gap 70 in the third direction Y again.

[0131] In order to reduce the protective layer 60 in the gap 70 from further overflowing in the third direction Y, the molded part 50 further has an overflow prevention portion 530 .

[0132] Specifically, the overflow prevention portion 530 is connected to the forming portion 510. The overflow prevention portion 530 is located at one side of the tab bundle 420 in the third direction Y, and protrudes from the surface of the tab bundle 420 facing the cover 20 in the first direction Z.

[0133] The number of the overflow prevention parts 530 can be set according to actual needs. For example, the overflow prevention part 530 is provided at one end of the forming part 510 in the third direction Y, or the overflow prevention parts 530 are provided at both ends of the forming part 510 in the third direction Y.

[0134] In addition, the present application also provides a battery pack. The battery pack includes a box and a secondary battery. The box has a cavity. The secondary battery is accommodated in the cavity of the box. The secondary battery can be any of the secondary batteries in the above embodiments.

[0135] In summary, in the embodiments of the secondary battery and the battery pack of the present application, the protective layer is formed by forming a molded part so that the protective layer covers the weld mark area of ​​the tab bundle, which can reduce the probability of welding residues on the tab bundle detaching from the tab bundle.

[0136] The introduction provided in the above steps is only used to help understand the structure and core ideas of the present application. For ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A secondary battery, characterized in that: The secondary battery has a first direction, and the secondary battery includes: A battery cell, the battery cell comprising a battery cell body and a tab bundle, the tab bundle being connected to one end of the battery cell body in the first direction, and a side surface of the tab bundle having a weld mark area formed by welding; a molded part, at least a portion of which is disposed on a side of the weld print area facing the battery core body and is provided with a molded hole, the molded hole penetrating the molded part along the first direction; and The protective layer fills the forming hole, is connected to the tab bundle and covers the weld print area.

2. The secondary battery according to claim 1, characterized in that: Also includes: Pole; Wherein, the weld print area includes a first sub-weld print area and a second sub-weld print area, each of the pole lug bundles includes a plurality of pole lugs with the same polarity and arranged in a stacked manner, the plurality of pole lugs with the same polarity are welded and connected to each other to form the first sub-weld print area, the pole lug bundle is welded and connected to the pole to form the second sub-weld print area, the first sub-weld print area and the second sub-weld print area are respectively located on the surface of the pole lug bundle facing away from the pole, and the second sub-weld print area is located in the first sub-weld print area.

3. The secondary battery according to claim 1, characterized in that: The weld print area is located within the orthographic projection of the hole wall of the forming hole on the surface where the weld print area is located.

4. The secondary battery according to claim 1, characterized in that: In the first direction, the distance between the edge of the forming hole of the forming member and the surface where the weld print area is located is less than or equal to 0.5 mm.

5. The secondary battery according to claim 1, characterized in that: The secondary battery further includes a cover body, and the molded part is fixedly connected to the cover body.

6. The secondary battery according to claim 5, characterized in that: The cover body has a hook, and the molded part has a molded part and a fixed part connected to each other. The molded part is arranged on the side of the weld print area facing the battery body and is provided with the molded hole. The fixed part has a snap-on opening, and the hook is passed through the snap-on opening to snap-fit ​​with the fixed part.

7. The secondary battery according to claim 1, characterized in that: The secondary battery also includes a pole; The tab bundle comprises: A first part, connected to the pole by welding, the first part having the weld mark area; a second portion connected to one end of the battery cell body in the first direction, the first portion and the second portion being located at opposite sides of the molded part in the first direction; and a third portion, which is arranged around a predetermined edge of the molded part and is connected to the first portion and the second portion respectively; Wherein, the predetermined edge of the molded part is located outside a welding connection area between the first portion and the pole.

8. The secondary battery according to claim 3, characterized in that: The secondary battery also includes a pole; The number of the battery cells is at least two, and in the two battery cells, the tab bundles of the same polarity are respectively welded to the same pole, and the weld marks of the tab bundles of the same polarity are respectively arranged toward the battery cell body, and the side facing the battery cell body is the predetermined side; At least part of the molding part is arranged on the predetermined side, the number of the molding holes is at least two, each molding hole corresponds to the welding imprint area one by one, and the two molding holes are arranged at intervals; The number of the protective layers is at least two, and each protective layer fills one of the forming holes and covers the corresponding weld print area of ​​the tab bundle.

9. The secondary battery according to claim 1, characterized in that: The secondary battery also includes a pole; The number of the battery cells is at least two, and in the two battery cells, the tab bundles of the same polarity are respectively welded to the same pole, and the weld marks of the tab bundles of the same polarity are respectively arranged toward the battery cell body, and the side facing the battery cell body is the predetermined side; At least a portion of the molding is disposed on the predetermined side, and the number of the molding hole is one; The number of the protective layer is one, and the protective layer covers the weld print areas of the two tab bundles of the same polarity respectively.

10. The secondary battery according to claim 9, characterized in that: The secondary battery has a second direction and a third direction intersecting each other, and the two battery cells are distributed in the second direction; In the two battery cells, the weld print areas of the tab bundles of the same polarity are arranged at intervals in the second direction; Each of the tab bundles has a cutting edge, the cutting edge is located between the weld print areas of the two tab bundles along the second direction, the cutting edge has a main body section and a protruding section distributed along the third direction, and the main body section is arranged opposite to the weld print area; The forming hole includes a hole body and a notch, wherein the notch is connected to a side edge of the hole body in the third direction, a portion of the protective layer corresponding to the notch covers the protruding section, and a portion of the protective layer corresponding to the hole body covers the weld print area and the main section.

11. The secondary battery according to claim 1, characterized in that: The secondary battery also has a third orientation; The secondary battery further comprises a cover and two poles, wherein the poles are arranged on the cover, the two poles are arranged at intervals in the third direction, and the pole lug bundle is located between the cover and the battery body in the first direction; The molded part includes a molding part and an anti-overflow part. The molding part is arranged on the side of the weld print area facing the battery cell body and is provided with the molding hole. The anti-overflow part is connected to the molding part. The anti-overflow part is located on one side of the pole tab bundle in the third direction and protrudes from the surface of the pole tab bundle facing the cover body in the first direction.

12. A battery pack, characterized in that: include: A box body, wherein the box body has a cavity; A secondary battery is contained in the cavity of the box, and the secondary battery is the secondary battery according to any one of claims 1 to 11.

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