Secondary battery and electronic device

Abstract

The invention provides a secondary battery and an electronic device. The secondary battery comprises an electrode assembly, a packaging bag, a first tab, a second tab, first tab glue and a first supporting piece. The packaging bag comprises a main body part and a top sealing part, and the electrode assembly is arranged in the main body part. The top sealing part comprises a first surface and a second surface in the thickness direction of the top sealing part. One end of the first tab is connected with the electrode assembly, and the other end of the first tab extends out of the top sealing part. One end of the second tab is connected with the electrode assembly, and the other end of the second tab extends out of the top sealing part. And the second tab and the first tab are arranged at an interval along the first direction. The first tab glue at least wraps the surface of the part, located in the top sealing part, of the first tab. The first supporting piece is adhered to the first surface, the first supporting piece is located between the first tab glue and the second tab along the first direction, the distance between the first supporting piece and the first tab glue is L1, and L1 is greater than 0mm, so that the hot box test passing rate of the secondary battery is improved, and the safety performance of the secondary battery is further improved.

Description

Technical Field

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

[0002] The packaging bag of soft-pack batteries is usually made of aluminum-plastic film or steel-plastic film. When the battery is in a high-temperature environment, the internal pressure of the packaging bag increases and swells. The top seal of the existing packaging bag is difficult to open in time to release the pressure, resulting in reduced safety performance of the battery. Summary of the invention

[0003] In view of the above situation, the present application provides a secondary battery, which is beneficial to improving safety performance.

[0004] An embodiment of the present application provides a secondary battery, the secondary battery comprising an electrode assembly, a packaging bag, a first pole ear, a second pole ear, a first pole ear glue and a first support member. The packaging bag comprises a main body and a top seal portion connected to the main body, and the electrode assembly is arranged in the main body. Along the thickness direction of the top seal portion, the top seal portion comprises a first surface and a second surface arranged opposite to each other. One end of the first pole ear is electrically connected to the electrode assembly, and the other end of the first pole ear extends out of the packaging bag from the top seal portion. One end of the second pole ear is electrically connected to the electrode assembly, and the other end of the second pole ear extends out of the packaging bag from the top seal portion. The second pole ear is spaced apart from the first pole ear along the first direction. The first pole ear glue at least wraps the surface of the portion of the first pole ear located in the top seal portion. The first support member is bonded to the first surface, and along the first direction, the first support member is located between the first pole ear glue and the second pole ear, and the spacing between the first support member and the first pole ear glue is L1, L1>0mm.

[0005] In the above-mentioned secondary battery, the first support member is arranged at a position where the top seal part is prone to deformation, and L1>0mm, so that the first support member and the first pole ear glue are arranged at intervals along the first direction. Under the support of the first support member, the structural strength of the position where the top seal part is connected to the first support member is better than the structural strength of the position where the top seal part is located between the first support member and the first pole ear glue. When the internal pressure of the packaging bag increases and bulges, the position of the top seal part located between the first support member and the first pole ear glue is prone to form a first stress concentration area. The first stress concentration area can be promptly opened and depressurized under the action of stress, thereby improving the safety performance of the secondary battery.

[0006] In some embodiments of the present application, the secondary battery also includes a second pole ear glue, which at least wraps the surface of the second pole ear located in the top seal portion to improve the packaging strength between the second pole ear and the top seal portion and reduce the risk of short circuit caused by contact between the second pole ear and the metal layer in the packaging film.

[0007] In some embodiments of the present application, along the thickness direction of the top seal portion, the first support member and the second pole ear glue at least partially overlap to reduce the risk of stress dispersion in other areas of the top seal portion between the first pole ear glue and the second pole ear glue, which is beneficial for the first stress concentration area to be able to be promptly opened and depressurized under the action of stress, thereby improving the safety performance of the secondary battery.

[0008] In some embodiments of the present application, 1mm≤L1≤8mm is used to increase the pressure relief speed and optimize the stress distribution, which is conducive to promoting the opening of the top seal when the electrochemical device expands due to heat, thereby improving the hot box test pass rate of the electrochemical device and being able to adapt to the installation tolerance between the first support member and the first electrode ear glue.

[0009] In some embodiments of the present application, 2mm≤L1≤6mm to further increase the pressure relief speed and better optimize the stress distribution, so that a more preferred pressure relief area can be obtained. During the hot box test, the probability of the top seal being broken can be further increased, thereby improving the safety and reliability of the electrochemical device.

[0010] In some embodiments of the present application, 2mm≤L1≤4mm, so as to further improve the pressure relief speed and obtain a more rational stress distribution. During the hot box test, the probability of the top seal being broken can be further improved, thereby further improving the safety and reliability of the electrochemical device.

[0011] In some embodiments of the present application, along the first direction, the distance between the first pole ear glue and the second pole ear glue is W1, 10mm≤W1≤60mm, so as to reduce the risk of interference between the first pole ear glue and the second pole ear glue, and facilitate the position of the first pole ear and the second pole ear to adapt to the protection plate. The length of the first support member is W2, 0.3W1≤W2<W1, so that the force-bearing area of ​​the top seal portion located between the first support member and the first pole ear glue is less than or equal to the force-bearing area of ​​the first support member, so as to facilitate the formation of a first stress concentration area at the top seal portion located between the first support member and the first pole ear glue.

[0012] In some embodiments of the present application, 0.5W1≤W2≤0.9W1, which further optimizes the first stress concentration area, improves stress distribution, and better improves the hot box test pass rate.

[0013] In some embodiments of the present application, the top seal portion includes a first side edge, and along the first direction, the first side edge is located on a side of the first pole ear away from the second pole ear. The secondary battery also includes a second support member, and the second support member is bonded to the first surface. Along the first direction, the second support member is located between the first pole ear glue and the first side edge. Under the support of the second support member, the structural strength of the portion where the top seal portion is connected to the second support member is better than the structural strength of the portion where the top seal portion is located between the first support member and the first pole ear glue, so as to reduce the risk of stress dispersion in the area where the top seal portion is located outside the first pole ear glue or the second pole ear glue, which is beneficial to enable the first stress concentration area to be promptly opened and depressurized under the action of stress, thereby improving the safety performance of the secondary battery.

[0014] In some embodiments of the present application, along the thickness direction of the top seal portion, the second support member and the first ear glue at least partially overlap, and along the first direction, the distance between the second support member and the first side edge is L3, L3 ≥ 2mm, so that the second support member and the first side edge are spaced apart along the first direction, reducing the risk of interference between the second support member and the side seal portion of the packaging bag.

[0015] In some embodiments of the present application, along the extending direction of the top seal portion, the width of the first surface is H1, the width of the first support member is H2, and 0.8H1≤H2≤H1, so as to improve the structural strength of the first support member and reduce the space waste caused by the first support member protruding from the first surface.

[0016] In some embodiments of the present application, the main body includes a top wall. The top seal portion is connected to the top wall, and the top wall includes a first top surface connected to the first surface. Along the thickness direction of the top seal portion, the thickness of the first support member is D1, and along the thickness direction of the main body, the width of the first top surface is D2, 1mm≤D1≤D2, so as to improve the structural strength of the first support member and reduce the space waste caused by the first support member being too thick and protruding from the top wall.

[0017] In some embodiments of the present application, the first support member comprises a polymer, and the polymer material comprises nitrocellulose and acrylic resin. Nitrocellulose can form a uniform and strong film at the coating position, protecting the coating position while providing a basis for the adhesion of other substances in the polymer, so that the remaining substances can be firmly adsorbed at the coating position. Acrylic resin can enhance the hardness of the coating position, thereby improving the structural strength of the first support member.

[0018] In some embodiments of the present application, the weight percentage of nitrocellulose in the first support member is P1, 10%≤P1≤20%, so as to improve the adsorption of the film and facilitate the dissolution of nitrocellulose in the solvent. The weight percentage of acrylic resin in the first support member is P2, 5%≤P2≤15%, so as to improve the hardness of the film and facilitate the dissolution of acrylic resin in the solvent.

[0019] In some embodiments of the present application, the first support member is a sheet-like structure.

[0020] In some embodiments of the present application, the first support member includes a polymer sheet, and the polymer sheet includes at least one of polyethylene, polypropylene, and polystyrene.

[0021] In some embodiments of the present application, the first support member includes a metal sheet, and the metal sheet includes at least one of an aluminum sheet, a stainless steel sheet, a copper sheet, or a nickel sheet.

[0022] In some embodiments of the present application, the first tab glue includes at least one of polypropylene, polyethylene, and polyethylene terephthalate; the second tab glue includes at least one of polypropylene, polyethylene, and polyethylene terephthalate.

[0023] In some embodiments of the present application, the secondary battery further includes a third support member, the third support member is bonded to the second surface, and along the thickness direction of the top seal portion, the third support member overlaps with the first support member. Under the support of the first support member and the third support member, the structural strength of the portion of the top seal portion connecting the first support member and the third support member is further superior to the structural strength of the portion of the top seal portion located between the first support member and the first pole ear glue. When the internal pressure of the packaging bag increases and bulges, the portion of the top seal portion located between the first support member and the first pole ear glue is prone to form a first stress concentration area.

[0024] In some embodiments of the present application, the secondary battery also includes a fourth support member, which is arranged on a side of the top seal portion away from the main body along the extending direction of the top seal portion, and the fourth support member connects the first support member and the third support member to improve the connection stability between the first support member and the second support member on the top seal portion.

[0025] An embodiment of the present application further provides an electronic device, which includes any one of the secondary batteries in the above embodiments.

[0026] In the above-mentioned secondary battery and electronic device, the first support member is arranged at a position where the top seal is prone to deformation, L1>0mm, so that the first support member and the first pole ear glue are spaced apart along the first direction. Under the support of the first support member, the structural strength of the position where the top seal is connected to the first support member is better than the structural strength of the position where the top seal is located between the first support member and the first pole ear glue. When the internal pressure of the packaging bag increases and bulges, the position of the top seal between the first support member and the first pole ear glue is prone to form a first stress concentration area. The first stress concentration area can be promptly opened and depressurized under the action of stress, thereby improving the safety performance of the secondary battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of a first supporting member of a secondary battery in an embodiment of the present application.

[0028] Figure 2 yes Figure 1 Section view along section line Ⅱ-Ⅱ.

[0029] Figure 3 It is a schematic structural diagram of a second supporting member of a secondary battery in an embodiment of the present application.

[0030] Figure 4 yes Figure 3 Section view along section line IV-IV.

[0031] Figure 5 It is a schematic structural diagram of an embodiment of the present application in which the first supporting member of the secondary battery is a plastic sheet or a metal sheet.

[0032] Figure 6 It is a schematic structural diagram of a third supporting member of a secondary battery in an embodiment of the present application.

[0033] Figure 7 yes Figure 6 Section view along section line VI-VI.

[0034] Figure 8 It is a schematic structural diagram of a fourth supporting member of a secondary battery in an embodiment of the present application.

[0035] Fig. 9 yes Figure 8 Section view along section line VIII-VIII.

[0036] Fig.10 It is a schematic structural diagram of a first supporting member of a secondary battery in another embodiment of the present application.

[0037] Fig.11 It is a schematic diagram of the structure of an electronic device in one embodiment of the present application.

[0038] Main component symbols

[0039] Secondary batteries 100A, 100B

[0040] Electronic device 200

[0041] Electrode assembly 10

[0042] Packaging bag 20

[0043] Main body 21

[0044] Top wall 211

[0045] First top surface 211A

[0046] Top seal 22

[0047] First stress concentration region 22A

[0048] Second stress concentration region 22B

[0049] First surface 221

[0050] Second surface 222

[0051] First side 223

[0052] Second side 224

[0053] First tab 30

[0054] Second pole ear 40

[0055] First ear glue 50

[0056] First edge 51

[0057] Second edge 52

[0058] The first support member 60

[0059] Third Edge 61

[0060] Fourth Edge 62

[0061] Adhesive layer 65

[0062] Second ear glue 70

[0063] Fifth Edge 71

[0064] Sixth Edge 72

[0065] The second support member 80

[0066] The third support member 90

[0067] Seventh Edge 91

[0068] Eighth Edge 92

[0069] Fourth support member 95

[0070] First direction X

[0071] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0072] 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.

[0073] 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.

[0074] When a value is considered to be "equal" to another value, it means that the two are equal within a set deviation, and the set deviation range is within 5%. In other words, when at least one of the two values ​​fluctuates within the set deviation range, even if their values ​​are not equal, they are still judged to be approximately equal. When a value is considered to be in a ratio of "1:1" to another value, it means that the two are equal within a set deviation, and the set deviation range is within 5%. In other words, when at least one of the two values ​​fluctuates within the set deviation range, even if their values ​​are not equal, they are still judged to be equal in ratio.

[0075] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more related listed items. The term "overlap" used herein refers to the overlap of the projections of two parts or the overlap of the projections of two parts.

[0076] An embodiment of the present application provides a secondary battery, the secondary battery comprising an electrode assembly, a packaging bag, a first pole ear, a second pole ear, a first pole ear glue and a first support member. The packaging bag comprises a main body and a top seal portion connected to the main body, and the electrode assembly is arranged in the main body. Along the thickness direction of the top seal portion, the top seal portion comprises a first surface and a second surface arranged opposite to each other. One end of the first pole ear is electrically connected to the electrode assembly, and the other end of the first pole ear extends out of the packaging bag from the top seal portion. One end of the second pole ear is electrically connected to the electrode assembly, and the other end of the second pole ear extends out of the packaging bag from the top seal portion. The second pole ear is spaced apart from the first pole ear along the first direction. The first pole ear glue at least wraps the surface of the portion of the first pole ear located in the top seal portion. The first support member is bonded to the first surface, and along the first direction, the first support member is located between the first pole ear glue and the second pole ear, and the spacing between the first support member and the first pole ear glue is L1, L1>0mm.

[0077] In the above-mentioned secondary battery, the first support member is arranged at a position where the top seal part is prone to deformation, and L1>0mm, so that the first support member and the first pole ear glue are arranged at intervals along the first direction. Under the support of the first support member, the structural strength of the position where the top seal part is connected to the first support member is better than the structural strength of the position where the top seal part is located between the first support member and the first pole ear glue. When the internal pressure of the packaging bag increases and bulges, the position of the top seal part located between the first support member and the first pole ear glue is prone to form a first stress concentration area. The first stress concentration area can be promptly opened and depressurized under the action of stress, thereby improving the safety performance of the secondary battery.

[0078] The embodiments of the present application are further described below in conjunction with the accompanying drawings.

[0079] Example 1

[0080] See also Figure 1 One embodiment of the present application provides a secondary battery 100A. The secondary battery 100A refers to a battery that can be used continuously by activating active materials through charging after discharge.

[0081] The secondary battery 100A includes an electrode assembly 10, a packaging bag 20, a first electrode tab 30, a second electrode tab 40, a first electrode tab glue 50 and a first support 60. The electrode assembly 10 is formed by winding or stacking a positive electrode sheet, a separator and a negative electrode sheet arranged in sequence. The electrode assembly 10 is used to convert chemical energy into electrical energy.

[0082] The packaging bag 20 includes a main body 21 and a top seal 22 connected to the main body 21. Specifically, the packaging bag 20 is made of a packaging film, the main body 21 refers to the part of the packaging film where the punching holes are set, and the top seal 22 refers to the part where the packaging film overlaps and joins. The electrode assembly 10 is arranged in the main body 21, and the top seal 22 is used to seal the main body 21 at the position corresponding to the head of the secondary battery 100A, that is, the position where the first pole tab 30 and the second pole tab 40 extend. Along the thickness direction of the top seal 22, the top seal 22 includes a first surface 221 and a second surface 222 arranged opposite to each other.

[0083] Specifically, the main body 21 includes a top wall 211, and the top sealing portion 22 is connected to the top wall 211. The top sealing portion 22 extends in a direction perpendicular to the top wall 211, or the top sealing portion 22 is bent toward the top wall 211. This application takes the way that the top sealing portion 22 extends in a direction perpendicular to the top wall 211 as an example for description.

[0084] One end of the first electrode tab 30 is electrically connected to the electrode assembly 10, and the other end of the first electrode tab 30 extends from the top seal portion 22 to the outside of the packaging bag 20. One end of the second electrode tab 40 is electrically connected to the electrode assembly 10, and the other end of the second electrode tab 40 extends from the top seal portion 22 to the outside of the packaging bag 20. The second electrode tab 40 is spaced apart from the first electrode tab 30 along the first direction X. The polarity of the first electrode tab 30 is opposite to that of the second electrode tab 40, and the first electrode tab 30 and the second electrode tab 40 are configured to be connected to an external circuit to form a complete current loop.

[0085] The first pole ear glue 50 at least wraps a portion of the surface of the first pole ear 30 located in the top seal portion 22 to improve the packaging strength between the first pole ear 30 and the top seal portion 22, and reduce the risk of short circuit caused by the first pole ear 30 contacting the metal layer in the packaging film. The first pole ear glue 50 includes a first edge 51 and a second edge 52 arranged relatively along the first direction X. When viewed along the thickness direction of the top seal portion 22, the first edge 51 and the second edge 52 are located on the outside of the first pole ear 30, and the first edge 51 is farther away from the second pole ear 40 than the second edge 52.

[0086] Optionally, the first tab glue 50 includes at least one of polypropylene, polyethylene, and polyethylene terephthalate.

[0087] Please also read Figure 1 and Figure 2 When the internal pressure of the packaging bag 20 increases and bulges, the portion of the top seal 22 between the first pole tab 30 and the second pole tab 40 is more likely to deform than other portions of the top seal 22. The first support member 60 is bonded to the first surface 221. Along the first direction X, the first support member 60 is located between the first pole tab glue 50 and the second pole tab 40, so that the first support member 60 is disposed at a portion of the top seal 22 that is likely to deform. The first support member 60 includes a third edge 61 and a fourth edge 62 that are disposed opposite to each other along the first direction X, and the third edge 61 is farther away from the second pole tab 40 than the fourth edge 62.

[0088] The spacing between the first support member 60 and the first pole ear glue 50 is L1, L1>0mm, so that the first support member 60 and the first pole ear glue 50 are spaced apart along the first direction X. Under the support of the first support member 60, the structural strength of the portion where the top seal 22 connects to the first support member 60 is better than the structural strength of the portion where the top seal 22 is located between the first support member 60 and the first pole ear glue 50. When the internal pressure of the packaging bag 20 increases and bulges, the portion where the top seal 22 is located between the first support member 60 and the first pole ear glue 50 is prone to form a first stress concentration area 22A. The first stress concentration area 22A can be promptly opened and depressurized under the action of stress, thereby improving the safety performance of the secondary battery 100A.

[0089] Optionally, L1 may be 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 6 mm, 8 mm, and any other value within the range of L1>0 mm.

[0090] It should be noted that L1 is measured in the following manner: observing along the thickness direction of the top seal portion 22, selecting three measuring points in a direction perpendicular to the first direction X, measuring the spacing value between the second edge 52 and the third edge 61 along the first direction X at each measuring point, and calculating the average value of the multiple spacing values, which is L1.

[0091] In the above-mentioned secondary battery 100A, the first support member 60 is arranged at a position where the top seal 22 is prone to deformation. L1>0mm, so that the first support member 60 and the first pole ear glue 50 are spaced apart along the first direction X. Under the support of the first support member 60, the structural strength of the portion where the top seal 22 is connected to the first support member 60 is better than the structural strength of the portion where the top seal 22 is located between the first support member 60 and the first pole ear glue 50. When the internal pressure of the packaging bag 20 increases and bulges, the portion of the top seal 22 located between the first support member 60 and the first pole ear glue 50 is prone to form a first stress concentration area 22A. The first stress concentration area 22A can be promptly opened and depressurized under the action of stress, thereby improving the safety performance of the secondary battery 100A.

[0092] In some embodiments, 1mm≤L1≤8mm can increase the pressure relief speed and optimize the stress distribution, which is conducive to promoting the opening of the top seal when the electrochemical device expands due to heat, thereby improving the hot box test pass rate of the electrochemical device and being able to adapt to the installation tolerance between the first support member 60 and the first electrode ear glue 50.

[0093] Furthermore, 2mm≤L1≤6mm can further increase the pressure relief speed and better optimize the stress distribution, so that a more preferred pressure relief area can be obtained. During the hot box test, the probability of the top seal being broken can be further increased, thereby improving the safety and reliability of the electrochemical device.

[0094] Furthermore, 2mm≤L1≤4mm can further improve the pressure relief speed and obtain a more rational stress distribution. During the hot box test, the probability of the top seal being broken can be further improved, thereby further improving the safety and reliability of the electrochemical device.

[0095] Please continue reading Figure 1In some embodiments, the secondary battery 100A further includes a second pole ear glue 70, which at least wraps the surface of the portion of the second pole ear 40 located in the top seal portion 22, so as to improve the packaging strength between the second pole ear 40 and the top seal portion 22, and reduce the risk of short circuit caused by the second pole ear 40 contacting the metal layer in the packaging film. The second pole ear glue 70 includes a fifth edge 71 and a sixth edge 72 arranged relatively along the first direction X. When viewed along the thickness direction of the top seal portion 22, the fifth edge 71 and the sixth edge 72 are located outside the second pole ear 40, and the fifth edge 71 is closer to the first pole ear 30 than the sixth edge 72.

[0096] Optionally, the second tab glue 70 includes at least one of polypropylene, polyethylene, and polyethylene terephthalate.

[0097] In some embodiments, along the thickness direction of the top seal portion 22, the first support member 60 and the second pole ear glue 70 at least partially overlap, so as to reduce the risk of stress dispersion in other areas of the top seal portion 22 between the first pole ear glue 50 and the second pole ear glue 70, which is conducive to timely opening and pressure relief of the first stress concentration area 22A under the action of stress, thereby improving the safety performance of the secondary battery 100A. Specifically, along the thickness direction of the top seal portion 22, the fourth edge 62 and the fifth edge 71 at least partially overlap, so as to reduce the space waste caused by the excessive overlap area of ​​the first support member 60 and the second pole ear glue 70 in the thickness direction of the top seal portion 22, and improve the space utilization rate of the first support member 60 in the top seal portion 22.

[0098] In some embodiments, along the first direction X, the distance between the first pole ear glue 50 and the second pole ear glue 70 is W1, 10mm≤W1≤60mm, so as to reduce the risk of interference between the first pole ear glue 50 and the second pole ear glue 70 and facilitate the position of the first pole ear 30 and the second pole ear 40 to adapt to the protective plate.

[0099] Optionally, W1 may be 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm, or any other value within the range of 10 mm ≤ W1 ≤ 60 mm.

[0100] In some embodiments, along the first direction X, the length of the first support member 60 is W2, 0.3W1≤W2<W1, so that the force-bearing area of ​​the top sealing portion 22 located between the first support member 60 and the first pole ear glue 50 is less than or equal to the force-bearing area of ​​the first support member 60, so as to form a first stress concentration area 22A at the position where the top sealing portion 22 is located between the first support member 60 and the first pole ear glue 50.

[0101] Furthermore, 0.5W1≤W2≤0.9W1, which further optimizes the first stress concentration area 22A, improves stress distribution, and better improves the hot box test pass rate.

[0102] Optionally, W2 may be one of 0.3W1, 0.5W1, 0.6W1, 0.7W1, 0.8W1, 0.9W1 and any other value in the range of 0.3W1≤W2<W1.

[0103] Please also read Figure 3 and Figure 4 In some embodiments, along the first direction X, the top seal portion 22 includes a first side edge 223 and a second side edge 224 that are oppositely arranged, the first side edge 223 is located on a side of the first pole tab 30 away from the second pole tab 40 , and the second side edge 224 is located on a side of the second pole tab 40 away from the first pole tab 30 .

[0104] The secondary battery 100A further includes a second support member 80, which is bonded to the first surface 221. Optionally, along the first direction X, the second support member 80 is located between the first pole ear glue 50 and the first side 223, or the second support member 80 is located between the second pole ear glue 70 and the second side 224, or the second support member 80 is located between the first pole ear glue 50 and the first side 223 and between the second pole ear glue 70 and the second side 224.

[0105] Under the support of the second support member 80, the structural strength of the portion where the top seal 22 is connected to the second support member 80 is better than the structural strength of the portion where the top seal 22 is located between the first support member 60 and the first pole ear glue 50, so as to reduce the risk of stress dispersion in the area where the top seal 22 is located outside the first pole ear glue 50 or the second pole ear glue 70, which is beneficial for the first stress concentration area 22A to be able to be promptly opened and depressurized under the action of stress, thereby improving the safety performance of the secondary battery 100A.

[0106] Please continue reading Figure 3 and Figure 4 In some embodiments, along the first direction X, the second support member 80 is located between the first pole ear glue 50 and the first side 223. Along the thickness direction of the top seal portion 22, the second support member 80 at least partially overlaps with the first pole ear glue 50. Specifically, along the thickness direction of the top seal portion 22, the first edge 51 and the edge of the second support member 80 facing the first pole ear 30 at least partially overlap, so as to reduce the space waste caused by the excessive overlap area between the second support member 80 and the first pole ear glue 50 in the thickness direction of the top seal portion 22, and improve the space utilization rate of the second support member 80 in the top seal portion 22.

[0107] Along the first direction X, the distance between the second support member 80 and the first side edge 223 is L3, L3 ≥ 2mm, so that the second support member 80 and the first side edge 223 are spaced apart along the first direction X, reducing the risk of interference between the second support member 80 and the side sealing portion of the packaging bag 20. Specifically, the side sealing portion is connected to both sides of the main body 21 along the first direction X, and the first side edge 223 and the second side edge 224 are respectively connected to one side sealing portion.

[0108] Optionally, L3 may be 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, or any other value within the range of L3>2 mm.

[0109] It should be noted that L3 is measured in the following manner: observing along the thickness direction of the top seal portion 22, selecting three measuring points in a direction perpendicular to the first direction X, measuring the spacing value along the first direction X between the first side edge 223 and the edge of the second support member 80 toward the first side edge 223 at each measuring point, and calculating the average value of the multiple spacing values, which is L3.

[0110] Please continue reading Figure 3 In some embodiments, along the first direction X, the second support member 80 is located between the second pole ear glue 70 and the second side edge 224. Along the thickness direction of the top seal portion 22, the second support member 80 at least partially overlaps with the second pole ear glue 70. Specifically, along the thickness direction of the top seal portion 22, the sixth edge 72 and the edge of the second support member 80 facing the second pole ear 40 at least partially overlap, so as to reduce the space waste caused by the excessive overlap area between the second support member 80 and the second pole ear glue 70 in the thickness direction of the top seal portion 22, and improve the space utilization rate of the second support member 80 in the top seal portion 22.

[0111] Along the first direction X, the distance between the second support member 80 and the second side edge 224 is L4, L4 ≥ 2 mm, so that the second support member 80 and the second side edge 224 are spaced apart along the first direction X, reducing the risk of interference between the second support member 80 and the side sealing portion of the packaging bag 20.

[0112] Optionally, L4 may be 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, or any other value within the range of L4>2 mm.

[0113] It should be noted that L4 is measured in the following manner: observing along the thickness direction of the top seal portion 22, selecting three measuring points in a direction perpendicular to the first direction X, measuring the spacing value along the first direction X between the second side 224 and the edge of the second support member 80 toward the second side 224 at each measuring point, and calculating the average value of the multiple spacing values, which is L4.

[0114] Please refer again Figure 1In some embodiments, along the extending direction of the top seal portion 22, the width of the first surface 221 is H1, the width of the first support member 60 is H2, and 0.8H1≤H2≤H1, so as to improve the structural strength of the first support member 60 and reduce the risk of interference between the first support member 60 and the top wall 211.

[0115] Optionally, H2 may be any value within the range of 0.8H1, 0.85H1, 0.9H1, 0.95H1, or 0.8H1≤H2≤H1.

[0116] In some embodiments, along the first direction X, the first support member 60 overlaps with the second support member 80 , which is beneficial for making the structural strength of the portion where the top seal portion 22 connects to the first support member 60 substantially the same as the structural strength of the portion where the top seal portion 22 connects to the second support member 80 .

[0117] Please refer again Figure 2 In some embodiments, the top wall 211 includes a first top surface 211A connected to the first surface 221. The thickness of the first support member 60 along the thickness direction of the top seal portion 22 is D1, and the width of the first top surface 211A along the thickness direction of the main body 21 is D2, 1mm≤D1≤D2, so as to improve the structural strength of the first support member 60 and reduce the space waste caused by the first support member 60 protruding from the top wall 211 due to its excessive thickness.

[0118] In some embodiments, the first support member 60 is formed by coating a coating material on the first surface 221 and then curing it to improve the connection stability between the first support member 60 and the first surface 221, reduce the risk of interference between the first support member 60 and the top seal portion 22, and help reduce production costs.

[0119] The first support member 60 includes a polymer, and the polymer material includes nitrocellulose and acrylic resin. Nitrocellulose can form a uniform and strong film at the coating position, protecting the coating position while providing a base for the other substances in the polymer to adhere to, so that the other substances can be firmly adsorbed at the coating position. Acrylic resin can enhance the hardness of the coating position, thereby improving the structural strength of the first support member 60.

[0120] In some embodiments, the weight percentage of nitrocellulose in the first support member 60 is P1, 10%≤P1≤20%. When P1 is too small (less than 10%), the formed film is not firm and the film adsorption is poor. When P1 is too large (greater than 20%), it is not conducive to the dissolution of nitrocellulose in the solvent. By limiting 10%≤P1≤20%, the adsorption of the film is improved and the dissolution of nitrocellulose in the solvent is facilitated.

[0121] In some embodiments, the weight percentage of the acrylic resin in the first support member 60 is P2, 5%≤P2≤15%. When P2 is too small (less than 2%), the formed film is likely to have insufficient hardness. When P2 is too large (greater than 15%), it is not conducive to the dissolution of the acrylic resin in the solvent. By limiting 5%≤P2≤15%, the hardness of the film is increased, and it is conducive to the dissolution of the acrylic resin in the solvent.

[0122] In some embodiments, the coating material comprises a film former, a resin, a solvent and a plasticizer. The film former comprises nitrocellulose, and the weight percentage of nitrocellulose in the coating material is 10% to 20%. The resin comprises an acrylic resin, and the weight percentage of the acrylic resin in the coating material is 2% to 15%. The solvent comprises ethyl acetate, toluene and butanol, and the weight percentage of ethyl acetate in the coating material is 10% to 20%, the weight percentage of toluene in the coating material is 30% to 35%, and the weight percentage of butanol in the coating material is 5% to 8%. The plasticizer comprises acetyl tributyl citrate and butyl hexanoate, and the weight percentage of acetyl tributyl citrate in the coating material is 3% to 8%, and the weight percentage of butyl hexanoate in the coating material is 10% to 15%.

[0123] See also Figure 5 In some embodiments, the first support member 60 is a sheet-like structure, which can also support the top seal portion 22. Specifically, the first support member 60 is bonded to the top seal portion 22 through the bonding layer 65.

[0124] Optionally, the first support member comprises a polymer sheet, and the polymer sheet comprises at least one of polyethylene, polypropylene, and polystyrene.

[0125] Optionally, the first support member includes a metal sheet, and the metal sheet includes at least one of an aluminum sheet, a stainless steel sheet, a copper sheet or a nickel sheet.

[0126] Optionally, the bonding layer 65 includes at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene. By selecting different material types and / or mass ratios to adjust the bonding strength of the bonding layer 65, the peeling strength between the first support member 60 and the top seal portion 22 is adjusted.

[0127] Please also read Figure 6 and Figure 7In some embodiments, the secondary battery 100A further includes a third support member 90, which is bonded to the second surface 222, and overlaps with the first support member 60 along the thickness direction of the top seal portion 22. Specifically, the third support member 90 includes a seventh edge 91 and an eighth edge 92 that are arranged opposite to each other along the first direction X, and along the thickness direction of the top seal portion 22, the seventh edge 91 overlaps with the third edge 61, and the eighth edge 92 overlaps with the fourth edge 62.

[0128] Under the support of the first support member 60 and the third support member 90, the structural strength of the portion where the top seal 22 connects the first support member 60 and the third support member 90 is further superior to the structural strength of the portion where the top seal 22 is located between the first support member 60 and the first tab glue 50. When the internal pressure of the packaging bag 20 increases and bulges, the portion where the top seal 22 is located between the first support member 60 and the first tab glue 50 is prone to form a first stress concentration area 22A.

[0129] Please also read Figure 8 and Fig. 9 In some embodiments, the secondary battery 100A further includes a fourth support member 95, which is disposed on a side of the top seal portion 22 away from the main body portion 21 along the extending direction of the top seal portion 22, and the fourth support member 95 connects the first support member 60 and the third support member 80 to improve the connection stability of the first support member 60 and the second support member 80 on the top seal portion 22.

[0130] Optionally, the fourth support member 95 , the first support member 60 and the third support member 80 are integrally provided.

[0131] It can be understood that the materials of the first support member 60 , the second support member 80 and the third support member 90 can be the same, so as to simplify the production process.

[0132] Example 2

[0133] See also Fig.10 One embodiment of the present application further provides a secondary battery 100B. The difference between the secondary battery 100B and the secondary battery 100A is that:

[0134] Along the first direction X, the first support member 60 is located between the first pole ear glue 50 and the second pole ear glue 70, and the spacing between the first support member 60 and the second pole ear glue 70 is L2, L2>0mm, that is, the first support member 60 and the second pole ear glue 70 are arranged at intervals along the first direction X to adapt to the installation tolerance between the first support member 60 and the second pole ear glue 60. Under the support of the first support member 60, the structural strength of the portion where the top seal 22 connects to the first support member 60 is better than the structural strength of the portion where the top seal 22 is located between the first support member 60 and the second pole ear glue 70. When the internal pressure of the packaging bag 20 increases and bulges, the portion of the top seal 22 located between the first support member 60 and the second pole ear glue 70 is prone to form a second stress concentration area 22B. The second stress concentration area 22B and the first stress concentration area 22A can be opened and depressurized in time under the action of stress, thereby improving the safety performance of the secondary battery 100B.

[0135] Optionally, L2 may be 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, or any other value within the range of L2>0 mm.

[0136] It should be noted that L2 is measured in the following manner: observing along the thickness direction of the top seal portion 22, selecting three measuring points in a direction perpendicular to the first direction X, measuring the spacing value between the fifth edge 71 and the fourth edge 62 along the first direction X at each measuring point, and calculating the average value of the multiple spacing values, which is L1.

[0137] Except for the above differences, the parameters of the secondary battery 100B are substantially the same as those of the secondary battery 100A, and reference may be made to the description of the secondary battery 100A.

[0138] See also Fig.11 In some embodiments, an embodiment of the present application further provides an electronic device 200. The electronic device 200 includes the secondary battery (100A, 100B) in any of the above embodiments. The electronic device 200 can be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, etc.

[0139] The specific implementation of the secondary battery in the examples and comparative examples is described below.

[0140] 1. Secondary battery hot box test:

[0141] First, the secondary battery to be tested is pretreated. The pretreatment conditions are as follows: after standing for 60 minutes at a test temperature of 20℃ (±5℃), discharge to 3.0V with a constant current of 0.7C and stand for 10 minutes; then charge to 4.5V with a constant current of 0.5C, and charge to 0.02C with a constant voltage. After the pretreatment is completed, the temperature sensing line is placed close to the surface of the secondary battery. The secondary battery is then placed vertically in a hot box for hot box testing, in which the temperature in the hot box is raised to 130±2℃ at 5±2℃ / min and maintained for 60 minutes. During the test, if the secondary battery does not burn or explode, it means that the hot box test has passed, otherwise, the hot box test has failed. 100 secondary batteries were tested, and the number of cells that passed the test was X, and the test pass rate was X / 100.

[0142] Embodiment 1:

[0143] A secondary battery with an initial thickness of 5.9 mm, a length of 100 mm, and a width of 50 mm at 50% SOC is assembled as follows:

[0144] (1) Preparation of negative electrode sheet: Mix the negative electrode active materials artificial graphite, conductive carbon black (Super P), and styrene-butadiene rubber (SBR) in a weight ratio of 96:1.5:2.5, add deionized water as a solvent, prepare a slurry with a weight percentage of 50wt%, and stir evenly. The slurry is evenly coated on one surface of the copper foil, and then dried at 110°C to obtain a negative electrode sheet coated with a negative electrode active material layer on one side. When preparing a double-sided coated negative electrode sheet, repeat the above steps on the other surface of the negative electrode sheet to obtain a negative electrode sheet coated with a negative electrode active material layer on both sides. Then the coated electrode sheet is cold pressed to a thickness of 105μm, cut and die-cut out the negative electrode tab on the copper foil at the edge of the negative electrode sheet, and the material of the negative electrode tab is copper.

[0145] (2) Preparation of positive electrode sheet: The positive electrode active materials lithium cobalt oxide (LiCoO2), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) are mixed in a weight ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP) is added as a solvent to prepare a slurry with a solid content of 75wt%, and stirred evenly. The slurry is evenly coated on one surface of the aluminum foil, and then dried at 90°C to obtain a positive electrode sheet coated with positive electrode active materials on one side. When preparing a double-sided coated positive electrode sheet, repeat the above coating steps on the other surface of the aluminum foil. The coated electrode sheet is then cold pressed to a thickness of 95μm, cut and die-cut out the positive electrode tab on the aluminum foil at the edge of the positive electrode sheet, and the material of the positive electrode tab is aluminum.

[0146] (3) Preparation of electrolyte: In a dry argon atmosphere, ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) were first mixed in a mass ratio of EC:EMC:DEC=30:50:20 to form a basic organic solvent, and then lithium salt lithium hexafluorophosphate (LiPF6) was added to the basic organic solvent to dissolve and mix evenly to obtain an electrolyte with a lithium salt concentration of 1.15 mol / L.

[0147] (4) Preparation of the diaphragm: A three-layer diaphragm is used, which includes a stacked adhesive layer, a substrate layer and an adhesive layer. The first substrate layer is made of polyethylene (PE), the adhesive in the adhesive layer is PVDF, and the adhesive layer also contains inorganic particles of boehmite.

[0148] (5) Preparation of electrode assembly: The positive electrode sheet, separator and negative electrode sheet are wound together.

[0149] (6) Electrode assembly: Place the aluminum-plastic film with holes punched and formed in an assembly fixture, with the holes facing upward, place the electrode assembly in the holes, and apply external force to press it. Then, cover the electrode assembly with another aluminum-plastic film with holes punched and formed, with the holes facing downward, and heat-seal the four sides of the two aluminum-plastic films by hot pressing to obtain an assembled electrode assembly.

[0150] (7) Liquid injection packaging: The assembled electrode assembly is injected with electrolyte, and after vacuum packaging, static standing, hot pressing, shaping and other processes, a secondary battery is produced.

[0151] (8) Nitrocellulose, acrylic resin, acetyl tributyl citrate, ethyl acetate, butyl hexanoate, butanol, and toluene are mixed in a weight ratio of 15:9:5:20:14:6:31 to form a coating material, and stirred evenly, and the coating material is evenly coated on the surface of the top seal portion, and then naturally air-dried to form a first support member. When preparing the second support member and / or the third support member, the above coating steps are repeated on the surface of the top seal portion.

[0152] Comparative Example 1: The top sealing portion is not provided with the first supporting member. It should be noted that the parameters of Comparative Example 1 are the same as those of Example 1 except that the first supporting member is not provided.

[0153] Comparative Example 2: The top seal portion is provided with a first support member, L1 = 0 mm. It should be noted that, in Comparative Example 2, other parameters are the same as those of Example 1 except that the size of the first support member is different.

[0154] Table 1 (Except for the parameters mentioned in Table 1, all other parameters of Examples 2-5 are the same as those of Example 1.)

[0155] Serial number <![CDATA[L1(mm)]]> Hot box test pass rate (%) Comparative Example 1 / 0 Comparative Example 2 / 13 Example 1 2 95 Example 2 1 84 Example 3 4 96 Example 4 6 90 Example 5 8 87

[0156] Note: “ / ” in Table 1 means that the parameter is not included.

[0157] It can be seen from Comparative Example 1-2 and Example 1-5 that the passing rate of the hot box test of the secondary battery can be improved by locating the first support member between the first pole ear glue and the second pole ear along the first direction and L1>0mm.

[0158] It can be seen from Examples 1-5 that by limiting 1mm≤L1≤8mm, the pass rate of the secondary battery hot box test can be improved. Further, it can be seen from Examples 1-4 that by limiting 2mm≤L1≤6mm, the pass rate of the secondary battery hot box test can be further improved. It can be seen from Examples 1-3 that by limiting 2mm≤L1≤4mm, the pass rate of the secondary battery hot box test can be further and better improved.

[0159] Table 2

[0160] (Except for the parameters mentioned in Table 2, all other parameters of Examples 6-17 are the same as those of Example 1, W1=20 mm)

[0161]

[0162] It can be seen from Examples 1, 6-8 that by 0.3W1≤W2<W1, the pass rate of the hot box test of the secondary battery can be improved. It can be seen from Examples 1, 7, and 8 that by 0.5W1≤W2≤0.9W1, the pass rate of the hot box test of the secondary battery can be further improved.

[0163] It can be seen from Examples 1, 9-11 that the passing rate of the secondary battery hot box test can be improved by 0.8H1≤H2≤H1. It should be noted that when H2>H1, the first support member is likely to interfere with the top wall, so an example of H2>H1 is not provided.

[0164] From Examples 1, 12-14, it can be seen that by P1, 10%≤P1≤20%, the passing rate of the secondary battery hot box test can be improved. It should be noted that when P1>20%, it is not conducive to the dissolution of nitrocellulose in the solvent, so no example with P1>20% is set.

[0165] From Examples 1, 15-17, it can be seen that by 5%≤P2≤15%, the passing rate of the secondary battery hot box test can be improved. When P2>15%, it should be noted that it is not conducive to the dissolution of acrylic resin in the solvent, so no example with P2>15% is set.

[0166] In addition, those skilled in the art may also make other changes within the spirit of the present application. Of course, these changes made according to the spirit of the present application should be included in the scope disclosed in the present application.

Claims

1. A secondary battery, characterized in that: The secondary battery comprises: Electrode assembly; A packaging bag, the packaging bag comprising a main body and a top seal portion connected to the main body, the electrode assembly is arranged in the main body, and along the thickness direction of the top seal portion, the top seal portion comprises a first surface and a second surface arranged opposite to each other; a first electrode tab, one end of which is electrically connected to the electrode assembly, and the other end of which extends out of the packaging bag from the top seal portion; a second electrode tab, one end of which is electrically connected to the electrode assembly, the other end of which extends out of the packaging bag from the top seal portion, and the second electrode tab is spaced apart from the first electrode tab along a first direction; A first electrode ear glue, wherein the first electrode ear glue at least wraps the surface of a portion of the first electrode ear located in the top seal portion; A first support member is bonded to the first surface; along the first direction, the first support member is located between the first pole tab glue and the second pole tab, and the distance between the first support member and the first pole tab glue is L1, L1>0mm.

2. The secondary battery according to claim 1, wherein: The secondary battery further includes a second electrode tab glue, and the second electrode tab glue at least wraps the surface of a portion of the second electrode tab located in the top seal portion.

3. The secondary battery according to claim 2, characterized in that: Along the thickness direction of the top seal portion, the first support member and the second tab glue at least partially overlap.

4. The secondary battery according to any one of claims 1 to 3, characterized in that: 1mm≤L1≤8mm.

5. The secondary battery according to claim 4, characterized in that: 2mm≤L1≤6mm.

6. The secondary battery according to claim 5, characterized in that: 2mm≤L1≤4mm.

7. The secondary battery according to claim 2, characterized in that: Along the first direction, the distance between the first tab glue and the second tab glue is W1, the length of the first support member is W2, 0.3W1≤W2<W1, 10mm≤W1≤60mm.

8. The secondary battery according to claim 7, characterized in that 0.5W1≤W2≤0.9W1.

9. The secondary battery according to claim 1, wherein: The top seal portion includes a first side edge, and along the first direction, the first side edge is located on a side of the first pole ear away from the second pole ear; The secondary battery further includes a second support member, which is bonded to the first surface. Along the first direction, the second support member is located between the first electrode tab glue and the first side.

10. The secondary battery according to claim 9, characterized in that Along the thickness direction of the top seal portion, the second support member and the first tab glue at least partially overlap, and along the first direction, the distance between the second support member and the first side edge is L3, and L3≥2mm.

11. The secondary battery according to claim 1, wherein Along the extending direction of the top sealing portion, the width of the first surface is H1, the width of the first support member is H2, and 0.8H1≤H2≤H1.

12. The secondary battery according to claim 1, wherein: The main body portion includes a top wall, the top sealing portion is connected to the top wall, and the top wall includes a first top surface connected to the first surface; Along the thickness direction of the top seal portion, the thickness of the first support member is D1, and along the thickness direction of the main body portion, the width of the first top surface is D2, 1mm≤D1≤D2.

13. The secondary battery according to claim 1, wherein: The first supporting member comprises a polymer, and materials of the polymer include nitrocellulose and acrylic resin.

14. The secondary battery according to claim 13, characterized in that: The weight percentage of the nitrocellulose in the first support member is P1, 10%≤P1≤20%; the weight percentage of the acrylic resin in the first support member is P2, 5%≤P2≤15%.

15. The secondary battery according to claim 1, wherein: The first supporting member is a sheet-like structure.

16. The secondary battery according to claim 15, characterized in that: The first support member includes a polymer sheet, and the polymer sheet includes at least one of polyethylene, polypropylene, and polystyrene.

17. The secondary battery according to claim 15, characterized in that: The first support member includes a metal sheet, and the metal sheet includes at least one of an aluminum sheet, a stainless steel sheet, a copper sheet or a nickel sheet.

18. The secondary battery according to claim 2, characterized in that: The first tab glue includes at least one of polypropylene, polyethylene, and polyethylene terephthalate; the second tab glue includes at least one of polypropylene, polyethylene, and polyethylene terephthalate.

19. The secondary battery according to claim 1, wherein: The secondary battery further includes a third support member, the third support member is adhered to the second surface, and along a thickness direction of the top seal portion, the third support member overlaps with the first support member.

20. The secondary battery according to claim 19, wherein: The secondary battery further includes a fourth support member, which is disposed on a side of the top sealing portion away from the main body portion along an extending direction of the top sealing portion, and connects the first support member and the third support member.

21. An electronic device, characterized in that: The electronic device includes the secondary battery according to any one of claims 1 to 20.

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