Secondary battery and electric device
By using the first adhesive member to bond the first electrode sheet in the electrode assembly of the secondary battery, safety problems such as short circuit and corrosion of the secondary battery are solved, and higher safety and space utilization are achieved.
Patent Information
- Application Number
- CN202510360687.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-25
- Publication Date
- 2025-06-20
AI Technical Summary
Secondary batteries are prone to safety problems such as short circuits and corrosion during use, and safety is urgently needed.
By using the first adhesive member in the electrode assembly of the secondary battery, the first electrode sheet layer is bonded to ensure that the length of the adhesive member is at least half of the first edge and is flush with or beyond the first edge, reducing the direct contact of the first electrode sheet layer with the packaging bag, playing a buffering role and reducing the risk of short circuit.
It effectively reduces the risk of short circuit caused by breakage of the first pole sheet and burrs pierce the isolation film, improves the safety of the secondary battery, and optimizes the space utilization rate.
Smart Images
Figure CN120184416A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of energy storage, and particularly to a secondary battery and an electrical device. Background Art
[0002] With the continuous update and development of secondary battery technology, the application fields of secondary batteries are also expanding continuously. Subsequently, the safety issues of battery cells have attracted increasing public attention, and problems such as short circuits and corrosion of secondary batteries need to be solved urgently. Summary of the Invention
[0003] In view of this, it is necessary to provide a secondary battery and an electrical device, which are beneficial to improving the safety of the secondary battery.
[0004] An embodiment of this application provides a secondary battery, which includes an electrode assembly, a packaging bag, a first tab, and a first bonding member. The electrode assembly is a stacked structure. The packaging bag includes a main body portion and a top-sealing portion connecting the main body portion. The electrode assembly is disposed in the main body portion. The packaging bag includes a first side wall and a second side wall arranged along a first direction. The first direction is the thickness direction of the secondary battery. Along the first direction, the distance between the first side wall and the top-sealing portion is less than the distance between the second side wall and the top-sealing portion. The electrode assembly includes a first electrode plate, a second electrode plate, and a separator. The separator is located between the first electrode plate and the second electrode plate. The first electrode plate includes a first electrode plate layer. Along the first direction, the first electrode plate layer is located on the outermost layer of the electrode assembly and is opposite to the first side wall. The second electrode plate includes a second electrode plate layer adjacent to the first electrode plate layer. The second electrode plate layer is located on the second outermost layer of the electrode assembly. Along a second direction, the second electrode plate layer extends beyond the first electrode plate layer. The second direction is the direction in which the electrode assembly points to the top-sealing portion. The first tab is integrally provided with the first electrode plate. The first electrode plate layer includes a first edge. The first tab is connected to the first edge. The first bonding member connects the first electrode plate layer. Along a third direction, the length of the first bonding member is L1, and the length of the first edge is L2. 2L1≥L2. The first bonding member is flush with or extends beyond the first edge. The first direction, the second direction, and the third direction are perpendicular to each other in pairs. By bonding the first electrode plate layer with the first bonding member, the length of the first bonding member is at least half of the length of the first edge, and the first bonding member is flush with or extends beyond the first edge, reducing the direct contact between the first edge and the packaging bag, playing a certain buffering role here, reducing the risk of breakage of the first electrode plate layer and forming burrs to pierce the separator, resulting in short circuits, and improving the safety of the secondary battery.
[0005] In one or more of the above optional embodiments, the first pole piece layer has a first median line extending in the second direction, and in the first direction, the first adhesive member overlaps with the first median line. The unbonded part of the first edge without the first adhesive member is partitioned to reduce the continuously exposed part of the first edge, thereby reducing the contact between the continuously exposed part of the first edge and the packaging bag, further reducing the breakage of the first pole piece layer, and forming a risk that burrs pierce the separator to cause a short circuit, and improving the safety of the secondary battery.
[0006] In one or more of the above optional embodiments, a second adhesive member is further included. The second adhesive member bonds the electrode assembly and the second side wall. In the first direction, the orthographic projection of the first adhesive member does not overlap with the orthographic projection of the second adhesive member. Reducing the overlap between the first adhesive member and the second adhesive member in the first direction X reduces the occupied space and reduces the impact of the increased thickness of the secondary battery on the energy density.
[0007] In one or more of the above optional embodiments, the thickness d of the first adhesive member satisfies 10 μm ≤ d ≤ 50 μm. When controlling d ≥ 10 μm, the first adhesive member has a better buffering effect, and burrs are not easily pierced through the first adhesive member. When controlling d ≤ 50 μm, the space occupied by the thickness of the first adhesive member is reduced. By limiting 10 μm ≤ d ≤ 50 μm, the short-circuit risk is reduced, and the space utilization rate of the secondary battery is improved.
[0008] In one or more of the above optional embodiments, in the second direction, the first adhesive member extends beyond the first edge, and the width W2 by which the first adhesive member extends beyond the first edge satisfies 1 mm ≤ W2 ≤ 3 mm. When controlling W2 ≥ 1 mm, the width by which the first adhesive member extends beyond the first edge further reduces the direct contact between the first edge and the adhesive layer of the packaging bag, playing a better buffering role. When controlling W2 ≤ 3 mm, the width by which the first adhesive member extends beyond the first edge is controlled to reduce the overlap between the first adhesive member and the top sealing part, thereby avoiding the situation that the heat-sealed top sealing part is affected. By defining 1 mm ≤ W2 ≤ 3 mm, the direct contact between the first edge and the adhesive layer of the packaging bag is further reduced, playing a better buffering role, reducing the breakage of the first pole piece layer, forming a risk that burrs pierce the separator to cause a short circuit, and improving the safety of the secondary battery.
[0009] In one or more of the above optional embodiments, in the second direction, when controlling 2 mm ≤ W2 ≤ 3 mm, it is beneficial to better enable the first adhesive member to play a buffering role, further reducing the risk of breakage of the first pole piece layer and further improving the safety of the secondary battery.
[0010] In one or more of the above optional embodiments, in the third direction, L1 ≤ L2. Further reducing the direct contact between the first edge and the adhesive layer of the packaging bag, reducing the risk of breakage of the first pole piece layer piercing the separator to cause a short circuit, and improving the safety of the secondary battery.
[0011] In one or more of the above optional embodiments, the secondary battery further includes a second tab and a second adapter. The second tab is a negative tab, the second tab is connected to the second electrode plate, and the second tab is connected to the second adapter to form a second welding area. The first adhesive includes a second extension portion, and the dimension of the second extension portion along the third direction is less than L1. The second extension portion covers the second welding area. Usually, the thickness of the adhesive layer is set to be much larger than the protruding height of the burrs, reducing the occurrence of burrs piercing through the adhesive layer. By only providing the second extension portion, not only is the risk of burrs in the second welding area piercing through the separator film and contacting the first electrode plate, causing a short circuit risk, but also the bonding step is reduced, saving material costs.
[0012] In one or more of the above optional embodiments, the secondary battery further includes a first adapter. The first tab is connected to the first adapter to form a first welding area. The first adhesive includes a first extension portion, and the dimension of the first extension portion along the third direction is less than L1. The first extension portion covers the first welding area, reducing the risk of burrs in the first welding area piercing through the adhesive layer of the packaging bag, resulting in electrolyte corrosion of the metal layer and short circuit.
[0013] In one or more of the above optional embodiments, along the second direction, the width W1 of the first adhesive overlapping with the main body portion along the first direction satisfies 5 mm ≤ W1 ≤ 8 mm. When controlling W1 ≥ 5 mm, increasing the width of the first adhesive improves the adhesion between the first adhesive and the first electrode plate layer, reducing the occurrence of separation between the first adhesive and the first electrode plate layer. When controlling W1 ≤ 8 mm, controlling the width of the first adhesive reduces the overlap between the first adhesive and the second adhesive in the first direction, resulting in an increase in the space occupied by the secondary battery. By defining 5 mm ≤ W1 ≤ 8 mm, the adhesion between the first adhesive and the first electrode plate layer is ensured, improving the space utilization rate of the secondary battery.
[0014] In one or more of the above optional embodiments, the packaging bag includes an adhesive layer and a metal layer. The adhesive layer connects the metal layer, and the first adhesive is located on the side of the adhesive layer facing away from the metal layer.
[0015] In one or more of the above optional embodiments, the adhesive layer includes a polypropylene material and / or a polyethylene material. Both the polypropylene material and the polyethylene material have good chemical resistance, heat-sealing performance, and good flexibility, which is beneficial for the packaging bag to maintain stability in the battery working environment.
[0016] In one or more of the above optional embodiments, the first adhesive includes insulating adhesive tape. The insulating adhesive tape is relatively soft. When used as the first adhesive, it can better play a buffering and transition role, further reducing the risk of breakage of the first electrode plate layer.
[0017] The embodiments of the present application provide an electrical device including the secondary battery in any one of the above embodiments.
[0018] The secondary battery and the electrical device of the present application bond the first electrode sheet layer through the first adhesive. The length of the first adhesive is at least half of the length of the first edge, and the first adhesive is flush with or extends beyond the first edge, reducing the direct contact between the first edge and the adhesive layer, playing a certain buffering role here, reducing the breakage of the first electrode sheet layer, and reducing the risk of burrs piercing the separator to cause a short circuit, thereby improving the safety of the secondary battery. Description of the Drawings
[0019] Figure 1 Shows a schematic structural diagram of a secondary battery in some embodiments.
[0020] Figure 2 Shows a schematic cross-sectional view of the secondary battery along II-II in some embodiments.
[0021] Figure 3 Shows a schematic cross-sectional view of the secondary battery along III-III in some embodiments.
[0022] Figure 4 Shows a schematic cross-sectional view of the packaging bag in some embodiments.
[0023] Figure 5 Shows a schematic structural diagram of the first electrode sheet and the first electrode tab in some embodiments.
[0024] Figure 6 Shows a schematic structural diagram of the first electrode sheet, the first electrode tab and the first adhesive in some embodiments.
[0025] Figure 7 Shows a schematic structural diagram of the first electrode sheet, the first electrode tab and the first adhesive in some other embodiments.
[0026] Figure 8 Shows a schematic structural diagram of the first electrode sheet, the first electrode tab and the first adhesive in some further embodiments.
[0027] Figure 9 Shows a schematic structural diagram of the first electrode sheet, the first electrode tab and the first adhesive in some other embodiments.
[0028] Figure 10 Shows a schematic structural diagram of the first electrode sheet, the first electrode tab and the first adhesive in some other embodiments.
[0029] Figure 11 Shows a schematic structural diagram of a partial secondary battery in some embodiments.
[0030] Figure 12 Shows a schematic structural diagram of a partial secondary battery in some other embodiments.
[0031] Figure 13 The structural schematic diagram of the electrical equipment in some embodiments is shown.
[0032] Description of the main component symbols:
[0033] Secondary battery 100
[0034] Packaging bag 10
[0035] Adhesive layer 101
[0036] Metal layer 102
[0037] Outer layer 103
[0038] First adapter 104
[0039] Second adapter 105
[0040] Receiving space 110
[0041] First welding area 100a
[0042] Second welding area 100b
[0043] Main body part 10a
[0044] Top sealing part 10b
[0045] First side wall 11
[0046] Second side wall 12
[0047] Electrode assembly 20
[0048] First pole piece 21
[0049] First current collector 201
[0050] First active material layer 202
[0051] First pole piece layer 21a
[0052] First edge 211
[0053] First midline 212
[0054] First section 211a
[0055] Second section 211b
[0056] Second pole piece 22
[0057] Second current collector 203
[0058] Second active material layer 204
[0059] Second pole piece layer 22a
[0060] Separator film 23
[0061] First tab 30
[0062] First adhesive member 40
[0063] First extension portion 41
[0064] Second extension portion 42
[0065] Second adhesive member 50
[0066] Second tab 60
[0067] Electrical device 200
[0068] First direction X
[0069] Second direction Y
[0070] Third direction Z
[0071] The following specific embodiments will further illustrate the present application in conjunction with the above-mentioned drawings. Detailed implementation manners
[0072] The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments.
[0073] When a component is considered to be "provided on" another component, it can be directly provided on the other component or there may be an intermediate component at the same time. When a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intermediate component at the same time.
[0074] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the description of the present application in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "or / and" used herein includes any and all combinations of one or more of the related listed items.
[0075] It can be understood that the term "vertical" is used to describe the ideal state between two components. In the actual production or use state, there can be a state approximately vertical or equal between two components. For example, in combination with numerical description, vertical can refer to the included angle range between two straight lines being between 90° ± 10°, vertical can also refer to the dihedral angle range between two planes being between 90° ± 10°, and vertical can further refer to the included angle range between a straight line and a plane being between 90° ± 10°. The two components described as "vertical" may not be absolutely straight lines or planes, and can also be approximately straight lines or planes. From a macroscopic perspective, as long as the overall extension direction is a straight line or a plane, the components can be considered as "straight lines" or "planes".
[0076] Unless otherwise defined, the term "plurality" in this article, when used to describe the quantity of components, specifically refers to two or more of such components.
[0077] The following will, with reference to the accompanying drawings, elaborate on some embodiments of the present application. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.
[0078] Please refer to Figures 1 to 6 , an embodiment of the present application provides a secondary battery 100, including a packaging bag 10 and an electrode assembly 20, and the electrode assembly 20 is disposed inside the packaging bag 10.
[0079] In some embodiments, the packaging bag 10 includes a main body portion 10a and a top sealing portion 10b connecting the main body portion 10a. The electrode assembly 20 is disposed inside the main body portion 10a. The packaging bag 10 includes a first side wall 11 and a second side wall 12 arranged along a first direction X. Along the first direction X, the distance h1 between the first side wall 11 and the top sealing portion 10b is less than the distance h2 between the second side wall 12 and the top sealing portion 10b. The first direction X is the thickness direction of the secondary battery 100.
[0080] It can be understood that along the first direction X, the distance between the first side wall 11 and the top sealing portion 10b refers to the distance from the connection position of the top sealing portion 10b and the main body portion 10a to the first side wall 11. Along the first direction X, the distance between the second side wall 12 and the top sealing portion 10b refers to the distance from the connection position of the top sealing portion 10b and the main body portion 10a to the second side wall 12.
[0081] In some embodiments, the electrode assembly 20 has a laminated structure. The electrode assembly 20 includes a first electrode tab 21, a second electrode tab 22, and a separator 23, and the separator 23 is located between the first electrode tab 21 and the second electrode tab 22. The first electrode tab 21 includes a first electrode tab layer 21a, and along the first direction X, the first electrode tab layer 21a is located on the outermost layer of the electrode assembly 20 and faces the first side wall 11. The second electrode tab 22 includes a second electrode tab layer 22a adjacent to the first electrode tab layer 21a. The second electrode tab layer 22a is located on the second outermost layer of the electrode assembly 20. Along the second direction Y, the second electrode tab layer 22a extends beyond the first electrode tab layer 21a. The second direction Y is the direction in which the electrode assembly 20 points to the top sealing portion 10b, and the second direction Y is perpendicular to the first direction X.
[0082] In some embodiments, the secondary battery 100 includes a first tab 30, and the first tab 30 is integrally provided with the first electrode tab 21. The first electrode tab layer 21a includes a first edge 211, and the first tab 30 is connected to the first edge 211.
[0083] In some embodiments, the secondary battery 100 includes a first adhesive member 40. The first adhesive member 40 is connected to the first electrode tab layer 21a. Along the third direction Z, the length of the first adhesive member 40 is L1, and the length of the first edge 211 is L2. 2L1≥L2. The first adhesive member 40 is flush with or extends beyond the first edge 211. The first direction X, the second direction Y, and the third direction Z are perpendicular to each other in pairs.
[0084] Please refer to Figure 4 , in some embodiments, the packaging bag 10 includes an adhesive layer 101, a metal layer 102, and an outer layer 103 arranged in sequence along the first direction X. The adhesive layer 101 is adjacent to the electrode assembly 20, and the first adhesive member 40 is located on the side of the adhesive layer 101 facing away from the metal layer 102. The outer layer 103 can be a nylon layer or a composite layer of polyester resin (PET) and nylon, which functions to prevent pollution, corrosion, and external force damage. The metal layer 102 can include one of aluminum and steel, which functions to prevent water, provide a barrier, and form the packaging bag 10. The adhesive layer 101 is a heat-sealing layer. The adhesive layer 101 can include a polymer, and the polymer includes one of polypropylene and polyethylene, which is used to seal the packaging bag 10 and to separate the metal layer 102 from the electrode assembly 20, reducing the risk of electrolyte leakage in the packaging bag 10 corroding the metal layer 102.
[0085] During the use stage or the formation stage of the secondary battery 100, the first edge 211 of the first electrode tab layer 21a is in direct contact with the adhesive layer 101 and embeds into the adhesive layer 101 to form an indentation. As the extrusion deepens, it is easy to form a stacking layer on the side of the first electrode tab layer 21a facing the top sealing portion 10b. The stacking layer is located in the accommodation space 110 formed by the first electrode tab layer 21a and the second electrode tab layer 22a (such as Figure 3As shown, when the electrode assembly 20 expands, the stacked layer hinders the extension and stretching of the first electrode sheet layer 21a in the second direction Y, easily causing the first electrode sheet layer 21a to break and form burrs, which may pierce the separator 23, thereby leading to a short circuit. In the present application, the first electrode sheet layer 21a is bonded by the first bonding member 40. The length of the first bonding member 40 is at least half of the length of the first edge 211. The first bonding member 40 is flush with or extends beyond the first edge 211, reducing the direct contact between the first edge 211 and the bonding layer 101, playing a certain buffering role here, reducing the risk of the first electrode sheet layer 21a breaking to form burrs and the burrs piercing the separator 23 to cause a short circuit, and improving the safety of the secondary battery 100.
[0086] Please refer to Figure 2 , in some embodiments, the first electrode sheet 21 includes a first current collector 201 and a first active material layer 202 provided on the first current collector 201. Along the first direction X, on the side of the first current collector 201 of the outermost first electrode sheet 21 relative to the main body portion 10a, the first active material layer 202 is not provided. On both sides of the first current collector 201 of the first electrode sheet 21 located between the second electrode sheets 22, the first active material layer 202 is provided.
[0087] In some embodiments, on the side of the first current collector 201 of the first electrode sheet layer 21a facing the first side wall 11, the first active material layer 202 is not provided, and the first bonding member 40 is connected to the side of the first current collector 201 of the first electrode sheet layer 21a facing the first side wall 11, that is, the side where the first active material layer 202 is not provided on the first current collector 201 of the first electrode sheet layer 21a.
[0088] In some embodiments, the second electrode sheet 22 includes a second current collector 203 and a second active material layer 204 provided on the second current collector 203. Along the first direction X, on both sides of the second current collector 203, the second active material layer 204 is provided.
[0089] Please refer to Figure 5 , in some embodiments, the first tab 30 and the first electrode sheet 21 are integrally cut and formed. The first edge 211 includes a first section 211a and a second section 211b. Along the third direction Z, the length of the first section 211a is L 21 , the length of the second section 211b is L 22 , L2 = L 21 +L 22 .
[0090] Please refer to Figure 6, in some embodiments, when along the third direction Z, the length of the first adhesive member 40 is at least half of the length of the first edge 211 and less than the length of the first edge 211, the first adhesive member 40 is flush with or extends beyond the second segment 211b; or a part of the first adhesive member 40 is flush with the second segment 211b and the remaining part is flush with the first segment 211a; or a part of the first adhesive member 40 extends beyond the second segment 211b and the remaining part extends beyond the first segment 211a; or a part of the first adhesive member 40 is flush with the second segment 211b and the remaining part extends beyond the first segment 211a; or a part of the first adhesive member 40 extends beyond the second segment 211b and the remaining part is flush with the first segment 211a.
[0091] Please refer to Figure 7 , in some embodiments, when L1 is equal to L2, a part of the first adhesive member 40 is flush with the second segment 211b and the remaining part is flush with the first segment 211a; or a part of the first adhesive member 40 extends beyond the second segment 211b and the remaining part extends beyond the first segment 211a. Or a part of the first adhesive member 40 is flush with the second segment 211b and the remaining part extends beyond the first segment 211a; or a part of the first adhesive member 40 extends beyond the second segment 211b and the remaining part is flush with the first segment 211a.
[0092] Please refer to Figure 8 , in some embodiments, along the third direction Z, the length L1 of the first adhesive member 40 is equal to the length of the first electrode sheet layer 21a. Reducing the number of times of pasting the first adhesive member 40 is beneficial to improving the assembly efficiency.
[0093] Please refer to Figure 5 and Figure 6 , in some embodiments, the first electrode sheet layer 21a has a first median line 212 extending along the second direction Y. In the first direction X, the first adhesive member 40 overlaps with the first median line 212. By covering the middle position of the first electrode sheet layer 21a with the bonding position of the first adhesive member 40, the part of the first edge 211 that is not bonded with the first adhesive member 40 is partitioned, reducing the continuously exposed part of the first edge 211, and further reducing the contact between the continuously exposed part of the first edge 211 and the adhesive layer 101 of the packaging bag 10, further reducing the risk of the first electrode sheet layer 21a being broken and forming burrs to pierce the separator film 23 resulting in a short circuit, and improving the safety of the secondary battery 100.
[0094] Please refer to Figure 2, in some embodiments, the secondary battery 100 includes a second adhesive member 50. The second adhesive member 50 bonds the electrode assembly 20 and the second side wall 12, and fixes the position of the electrode assembly 20 within the packaging bag 10 through the second adhesive member 50. Along the first direction X, the orthographic projection of the first adhesive member 40 does not overlap with the orthographic projection of the second adhesive member 50, reducing the overlap of the first adhesive member 40 and the second adhesive member 50 in the first direction X, reducing the occupied space, and reducing the impact on the energy density caused by the increase in the thickness of the secondary battery 100.
[0095] Optionally, the second adhesive member 50 bonds the first current collector 201 of the other outermost first pole piece 21 opposite to the first pole piece layer 21a and the second side wall 12.
[0096] Please refer to Figures 6 to 8 , in some embodiments, along the second direction Y, the width W1 of the overlap of the first adhesive member 40 with the main body portion 10a along the first direction X is 5 mm ≤ W1 ≤ 8 mm. At this time, the first adhesive member 40 is flush with the first edge 211. When controlling W1 ≥ 5 mm, the width of the first adhesive member 40 is increased, the adhesion force between the first adhesive member 40 and the first pole piece layer 21a is enhanced, and the situation of the separation of the first adhesive member 40 from the first pole piece layer 21a is reduced. When controlling W1 ≤ 8 mm, the width of the first adhesive member 40 is controlled, and the overlap of the first adhesive member 40 and the second adhesive member 50 in the first direction X is reduced, resulting in an increase in the space occupied by the secondary battery 100. By defining 5 mm ≤ W1 ≤ 8 mm, the adhesion force between the first adhesive member 40 and the first pole piece layer 21a is ensured, and the space utilization rate of the secondary battery 100 is improved.
[0097] Optionally, W1 can be any one or any range composed of any two of 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm, and 8 mm.
[0098] Please refer to Figure 9 and Figure 10 , in some embodiments, along the second direction Y, the first adhesive member 40 extends beyond the first edge 211. The width W2 of the first adhesive member 40 extending beyond the first edge 211 is 1 mm ≤ W2 ≤ 3 mm. When controlling W2 ≥ 1 mm, the width of the first adhesive member 40 extending beyond the first edge 211 further reduces the direct contact between the first edge 211 and the adhesive layer 101, playing a better buffering role. When controlling W2 ≤ 3 mm, the width of the first adhesive member 40 extending beyond the first edge 211 is controlled, reducing the overlap between the first adhesive member 40 and the top sealing portion 10b, which may affect the hot pressing of the top sealing portion 10b. By defining 1 mm ≤ W2 ≤ 3 mm, the direct contact between the first edge 211 and the adhesive layer 101 is further reduced, playing a better buffering role, reducing the risk of the breakage of the first pole piece layer 21a and the formation of burrs piercing the separator 23 resulting in a short circuit, and improving the safety of the secondary battery 100.
[0099] In some embodiments, along the second direction Y, further when 2 mm ≤ W2 ≤ 3 mm is controlled, it is beneficial to better enable the first bonding member 40 to play a buffering role, further reduce the risk of breakage of the first electrode sheet layer 21a, and further improve the safety of the secondary battery 100.
[0100] Optionally, W1 can be any one of 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm or a range composed of any two of them.
[0101] Please refer to Figure 2 、 Figure 3 and Figure 11 , in some embodiments, the secondary battery 100 includes a first adapter 104. The first tab 30 is connected to the first adapter 104 to form a first welding area 100a. The first adapter 104 extends out of the secondary battery 100 from the top seal portion 10b for connecting to an electrical device. The first bonding member 40 includes a first extension portion 41. Along the third direction Z, the size of the first extension portion 41 is less than L1. The first extension portion 41 covers the first welding area 100a, reducing the risk that the burrs in the first welding area 100a pierce the bonding layer 101, resulting in the electrolyte corroding the metal layer 102 and causing a short circuit.
[0102] In some embodiments, along the third direction Z, the first extension portion 41 extends beyond the width W3 of the first tab 30, where 1 mm ≤ W3 ≤ 1.5 mm, which is beneficial for blocking the burrs at the edge of the first extension portion 41, reducing the short circuit risk, and reducing the space occupied by the first extension portion 41 along the third direction Z.
[0103] Optionally, W3 can be any one of 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm or a range composed of any two of them.
[0104] In some embodiments, the secondary battery 100 includes a second tab 60 and a second adapter 105. The second tab 60 is integrally formed with the second electrode sheet 22, and the second tab 60 extends out of the second electrode sheet 22. The second tab 60 is connected to the second adapter 105 to form a second welding area 100b. The second adapter 105 extends out of the secondary battery 100 from the top seal portion 10b for connecting to an electrical device. The first bonding member 40 includes a second extension portion 42. Along the third direction Z, the size of the second extension portion 42 is less than L1. The second extension portion 42 covers the second welding area 100b, reducing the risk that the burrs in the second welding area 100b pierce the separator 23 and contact the first electrode sheet 21, causing a short circuit.
[0105] In some embodiments, along the third direction Z, the second extension portion 42 extends beyond the width W4 of the second tab 60, where 1 mm ≤ W4 ≤ 1.5 mm. This is beneficial for blocking burrs at the edge of the second extension portion 42, reducing the risk of short circuit, and decreasing the space occupied by the second extension portion 42 along the third direction Z.
[0106] Optionally, W4 can be any one of 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm or a range composed of any two of them.
[0107] In some embodiments, the first tabs 30 of each first electrode tab 21 are stacked and then welded together, and then welded to the first adapter 104. Along the first direction X, the first welding area 100a is located on the side of the first tab 30 connected to the first electrode tab layer 21a facing the first sidewall 11, facilitating the bonding of the first extension portion 41 to the first welding area 100a. Optionally, the welding includes ultrasonic welding, laser welding, etc.
[0108] Please refer to Figure 12 , in some embodiments, the first electrode tab 21 is a positive electrode tab and the second electrode tab 22 is a negative electrode tab. The secondary battery 100 includes a second tab 60 and a second adapter 105. The second tab 60 is integrally formed with the second electrode tab 22 and extends out of the second electrode tab 22. The second tab 60 is connected to the second adapter 105 to form a second welding area 100b. The second adapter 105 extends out of the secondary battery 100 from the top seal portion 10b for connecting to an electrical device. The first bonding member 40 includes a second extension portion 42. Along the third direction Z, the size of the second extension portion 42 is less than L1, and the second extension portion 42 covers the second welding area 100b. Usually, the thickness of the adhesive layer 101 is set to be greater than the protruding height of the burrs, reducing the occurrence of burrs piercing through the adhesive layer 101. By only providing the second extension portion 42, not only is the risk of burrs at the second welding area 100b piercing through the separator 23 and contacting the first electrode tab 21, causing a short circuit risk, reduced, but also the bonding steps are reduced, saving material costs.
[0109] In some embodiments, the second tabs 60 of each second electrode tab 22 are stacked and then welded together, and then welded to the second adapter 105. Along the first direction X, the second welding area 100b is located on the side of the second tab 60 connected to the second electrode tab layer 22a facing the first sidewall 11. After the first bonding member 40 is connected to the first electrode tab layer 21a, while facilitating the bonding of the first extension portion 41 to the first welding area 100a, it further facilitates the bonding of the second extension portion 42 to the second welding area 100b. By one-time bonding, the bonding of the first bonding member 40 is achieved, which is beneficial for reducing the bonding steps and improving the assembly efficiency. Optionally, the welding includes ultrasonic welding, laser welding, etc.
[0110] In some embodiments, the thickness d of the first adhesive member 40 satisfies 10 μm ≤ d ≤ 50 μm. When d ≥ 10 μm is controlled, the first adhesive member 40 has a better buffering effect, and burrs are not easily pierced through the first adhesive member 40. When d ≤ 50 μm is controlled, the space occupied by the thickness of the first adhesive member 40 is reduced. By limiting 10 μm ≤ d ≤ 50 μm, the short-circuit risk is reduced, and the space utilization rate of the secondary battery 100 is improved.
[0111] Optionally, d can be any one of 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm or a range composed of any two of them.
[0112] In some embodiments, the first adhesive member 40 includes insulating adhesive paper. The insulating adhesive paper is relatively soft. When used as the first adhesive member, it can better play a buffering and transition role, and further reduce the risk of breakage of the first electrode sheet layer.
[0113] The present application will be further described below through specific embodiments.
[0114] Short-circuit test method: (1) Maintain the test temperature at 25 °C, and let the secondary battery 100 stand for 30 min; (2) Charge at a constant current of 2.5C to 4.25V, and then charge at a constant voltage to 2C; (3) Charge at a constant current of 2C to 4.35V, and then charge at a constant voltage to 1.5C; (4) Charge at a constant current of 1.5C to 4.3V, and then charge at a constant voltage to 1C; (5) Charge at a constant current of 1.0C to 4.53V, and then charge at a constant voltage to 0.025C; (6) Stand for 5 min, and discharge at a constant current of 1.0C to 3V; (7) Stand for 5 min; (8) Repeat steps 2 to 7 for 800 times.
[0115] Judgment criterion for passing the test: After the cycle is completed, the battery is charged at a constant current of 0.5C to 4.53V at 25 °C, and then charged at a constant voltage to 0.025C. After standing for 1 h, the test voltage V1 is measured, and after standing for another 24 h, the test voltage V2 is measured; if V1 - V2 > 0.5V, the battery is determined to be short-circuited; the number of tested batteries is 20, the number of short-circuited battery cells is Y, and the short-circuit incidence rate is Y / 20.
[0116] The preparation process of the secondary battery 100 in the embodiment includes the following steps:
[0117] Preparation of the positive electrode sheet: The positive electrode active material lithium cobaltate, the conductive agent conductive carbon black, and the binder polyvinylidene fluoride (PVDF) are dissolved in an N-methylpyrrolidone (NMP) solution in a weight ratio of 97.5:1:1.5 to form a positive electrode slurry. Aluminum foil is used as the positive electrode current collector, and the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing, and slitting, the positive electrode sheet is obtained.
[0118] Preparation of the negative electrode plate: Artificial graphite as the negative active material, sodium carboxymethyl cellulose (CMC) as the thickening agent, and styrene-butadiene rubber (SBR) as the binder are mixed in a weight ratio of 96:1.5:2.5. Deionized water is added and stirred evenly under the action of a vacuum mixer to obtain the negative electrode slurry. The negative electrode slurry is evenly coated on the negative current collector copper foil; dried, and then obtained the negative electrode plate after cold pressing, slicing, and slitting.
[0119] Preparation of the separator 23: The base material layer of the separator 23 is polyethylene (PE). Alumina ceramic layers are coated on both sides of the base material layer 231, and then polyvinylidene fluoride (PVDF) is coated on both sides coated with the ceramic layer, and dried.
[0120] Preparation of the electrolyte: In a dry argon atmosphere glove box, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a mass ratio of 3:5:2, and lithium salt LiPF6 is added. After mixing evenly, the electrolyte is obtained, wherein the mass percentage concentration of LiPF6 is 12.5%.
[0121] Preparation of the electrode assembly 20: The positive electrode plate, the separator, and the negative electrode plate are stacked. Multiple first tabs 30 are gathered to form a tab assembly and welded to the first adapter 104. Multiple second tabs 60 are gathered to form a tab assembly and welded to the second adapter 105. Polyimide adhesive tape is selected as the first adhesive 40, and the first adhesive 40 is adhered to the first electrode plate layer 21a, and the second adhesive 50 is adhered to another outermost first electrode plate 21.
[0122] Assembly of the electrode assembly 20: The formed aluminum-plastic film with a pit is placed in the assembly fixture with the pit surface facing up. The electrode assembly 20 is placed in the pit, and an external force is applied to press it tightly. The second adhesive 50 adheres to the second side wall 12. Then another formed aluminum-plastic film with a pit is covered on the electrode assembly 20 with the pit surface facing down, and the four sides of the two aluminum-plastic films are heat-sealed by hot pressing. Control the distance between the first side wall 11 and the top sealing part 10b to be less than the distance between the second side wall 12 and the top sealing part to obtain the assembled electrode assembly.
[0123] Liquid injection and encapsulation: The electrolyte is injected into the assembled electrode assembly, and after processes such as vacuum encapsulation, standing, hot pressing formation, and shaping, the secondary battery 100 is obtained.
[0124] In this application, 20 secondary batteries 100 are used as a group to test the secondary batteries 100.
[0125] It should be noted that except for the different parameters in the table, other parameters of Comparative Examples 1-2 are the same as those of Example 1.
[0126] Table 1 (Other parameters of Examples 1 to 11 are the same as those of Example 1 except for the parameters involved in Table 1)
[0127]
[0128] Note: In Table 1, "\ " means that the parameter is not included.
[0129] It can be known from Comparative Examples 1-2 and Examples 1-11 in Table 1 that when the first bonding member 40 is provided and the first bonding member 40 is flush with or extends beyond the first edge 211, it is beneficial to reduce the risk of the first electrode sheet layer 21a breaking and forming burrs to pierce the separator 23, resulting in short circuit, and improve the safety of the secondary battery 100.
[0130] It can be known from Comparative Example 2 and Examples 1-3 in Table 1 that when the length L1 of the first bonding member 40 is at least half of the length of the first edge 211, it is beneficial to reduce the risk of the first electrode sheet layer 21a breaking and piercing the separator 23, resulting in short circuit, and improve the safety of the secondary battery 100.
[0131] It can be known from Examples 4-7 in Table 1 that when the thickness d of the first bonding member 40 is 10μm ≤ d ≤ 50μm, the first bonding member 40 has a better buffering effect, and burrs are not easily pierced through the first bonding member 40, reducing the short circuit risk.
[0132] It can be known from Examples 8-11 in Table 1 that when the width W2 by which the first bonding member 40 extends beyond the first edge 211 is 1mm ≤ W2 ≤ 3mm, the direct contact between the first edge 211 and the adhesive layer 101 is further reduced, playing a better buffering role, reducing the risk of the first electrode sheet layer 21a breaking and forming burrs to pierce the separator 23, resulting in short circuit, and improving the safety of the secondary battery 100. Further, when 2mm ≤ W2 ≤ 3mm is controlled, it is beneficial to better enable the first bonding member 40 to play a buffering role, further reducing the risk of the first electrode sheet layer 21a breaking and further improving the safety of the secondary battery 100.
[0133] Please refer to Figure 13 , this application also provides an electrical device 200 using the above secondary battery 100. In one embodiment, the electrical device 200 of this application can be, but is not limited to, electronic devices, drones, backup power supplies, electric vehicles, electric motorcycles, electric assist bicycles, electric tools, large household battery modules, etc.
[0134] Those of ordinary skill in the art of this technology should recognize that the above embodiments are only used to illustrate this application, rather than to limit this application. As long as within the scope of the essential spirit of this application, appropriate changes and variations made to the above embodiments fall within the scope disclosed by this application.
Claims
1. A secondary battery, characterized in that: include: An electrode assembly, wherein the electrode assembly is a laminate structure; A packaging bag, comprising a main body and a top seal portion connected to the main body, wherein the electrode assembly is disposed on the main body, and wherein the packaging bag comprises a first side wall and a second side wall arranged along a first direction, wherein the first direction is a thickness direction of the secondary battery, and along the first direction, a distance between the first side wall and the top seal portion is smaller than a distance between the second side wall and the top seal portion; The electrode assembly comprises a first electrode sheet, a second electrode sheet and a separation film, wherein the separation film is located between the first electrode sheet and the second electrode sheet, the first electrode sheet comprises a first electrode sheet layer, and along the first direction, the first electrode sheet layer is located at the outermost layer of the electrode assembly and is opposite to the first side wall, the second electrode sheet comprises a second electrode sheet layer adjacent to the first electrode sheet layer, and the second electrode sheet layer is located at the second outer layer of the electrode assembly, and along the second direction, the second electrode sheet layer exceeds the first electrode sheet layer, and the second direction is the direction of the electrode assembly pointing to the top seal portion; a first pole ear, wherein the first pole ear is integrally arranged with the first pole piece, the first pole piece layer comprises a first edge, and the first pole ear is connected to the first edge; A first adhesive is connected to the first pole piece layer. Along the third direction, the length of the first adhesive is L1, the length of the first edge is L2, 2L1≥L2, the first adhesive is flush with the first edge or exceeds the first edge, and the first direction, the second direction, and the third direction are perpendicular to each other.
2. The secondary battery according to claim 1, wherein: The first pole piece layer has a first center line extending along the second direction, and in the first direction, the first adhesive component overlaps with the first center line.
3. The secondary battery according to claim 1, wherein: A second adhesive is also included, and the second adhesive is used to bond the electrode assembly and the second side wall. Along the first direction, the orthographic projection of the first adhesive does not overlap with the orthographic projection of the second adhesive.
4. The secondary battery according to claim 3, characterized in that: The thickness d of the first adhesive member is 10 μm≤d≤50 μm.
5. The secondary battery according to claim 4, characterized in that: Along the second direction, the first adhesive extends beyond the first edge, and the first adhesive extends beyond the first edge by a width W2, where 1 mm≤W2≤3 mm.
6. The secondary battery according to claim 5, characterized in that: 2mm≤W2≤3mm.
7. The secondary battery according to claim 1, wherein: Along the third direction, L1≤L2.
8. The secondary battery according to claim 1, wherein: The secondary battery further includes a second pole tab and a second adapter, the second pole tab is a negative pole tab, the second pole tab is connected to the second pole sheet, and the second pole tab is connected to the second adapter to form a second welding area; The first adhesive member includes a second extending portion, a size of the second extending portion along the third direction is smaller than L1, and the second extending portion covers the second welding area.
9. The secondary battery according to claim 8, characterized in that The secondary battery further includes a first adapter, and the first electrode tab is connected to the first adapter to form a first welding area; The first adhesive member includes a first extending portion, a size of the first extending portion along the third direction is smaller than L1, and the first extending portion covers the first welding area.
10. The secondary battery according to claim 1, wherein: Along the second direction, a width W1 of the first adhesive overlapping the main body along the first direction is 5 mm ≤ W1 ≤ 8 mm.
11. The secondary battery according to claim 1, wherein The packaging bag comprises an adhesive layer and a metal layer, the adhesive layer is connected to the metal layer, and the first adhesive component is located on a side of the adhesive layer away from the metal layer.
12. The secondary battery according to claim 11, wherein: The adhesive layer includes polypropylene material and / or polyethylene material.
13. The secondary battery according to any one of claims 1 to 12, characterized in that: The first adhesive member includes insulating tape.
14. An electrical device, characterized in that: Comprising the secondary battery according to any one of claims 1 to 13.