Secondary battery and electronic device

Abstract

The invention provides a secondary battery and an electronic device, the secondary battery comprises an electrode assembly and a shell, the shell comprises a first packaging part and a second packaging part, and the first packaging part and the second packaging part are oppositely arranged and enclose to accommodate the electrode assembly; the electrode assembly comprises an electrode plate, the electrode plate comprises a current collector, and a plurality of protruding tabs are arranged on one side of the current collector; the plurality of tabs are at least partially overlapped and folded in the thickness direction of the battery to form a connecting part, the connecting part comprises a first connecting section, a bent section and a second connecting section, the bent section is connected with the first connecting section and the second connecting section, and the bent section is bent in the thickness direction of the secondary battery and is close to the first packaging part; the secondary battery further comprises an adapter, the adapter is connected with the second connecting section, and part of the adapter extends out of the shell; electrode assembly fixing glue is arranged between the electrode assembly and the first packaging part and used for bonding the electrode assembly and the first packaging part. And the safety performance and the energy density of the secondary battery can be improved.

Description

Technical Field

[0001] This application relates to the field of electrochemical technologies, and particularly to a secondary battery and an electronic device. Background Art

[0002] During the production and long-term use of secondary batteries, drop safety is a crucial issue. When a multi-layer electrode assembly drops, the electrode assembly may be displaced or deformed, which may cause damage to the internal structure of the electrode assembly, electrolyte leakage, short circuit, or even fire and explosion. Summary of the Invention

[0003] The purpose of this application is to provide a secondary battery and an electronic device to reduce the risk of displacement or deformation of the electrode assembly during a drop. The specific technical solutions are as follows:

[0004] In a first aspect of this application, a secondary battery is provided, including an electrode assembly and a housing. The housing includes a first packaging portion and a second packaging portion. The first packaging portion and the second packaging portion are oppositely arranged and enclose to accommodate the electrode assembly. The electrode assembly includes electrode plates. The electrode plates include current collectors, and one side of the current collector has a plurality of protruding tabs. Along the thickness direction of the battery, at least a part of the plurality of tabs overlap and converge to form a connection portion. The connection portion includes a first connection segment, a bending segment, and a second connection segment. The bending segment connects the first connection segment and the second connection segment. The bending segment is bent along a first direction and is close to the first packaging portion. The first direction is the thickness direction of the secondary battery. The secondary battery further includes an adapter, and the adapter is connected to the second connection segment, and a part of the adapter extends out of the housing. An electrode assembly fixing glue is provided between the electrode assembly and the first packaging portion to bond the electrode assembly and the first packaging portion. The bending segment is the bent part of the connection portion, and the electrode assembly fixing glue connects the first packaging portion and the electrode assembly. By providing the electrode assembly fixing glue, the thickness of the electrode assembly fixing glue is small, which can connect the electrode assembly and the housing more firmly on the premise of ensuring the energy density, reduce the internal displacement and deformation during a drop, and improve the overall structural stability of the battery cell. When the secondary battery drops, the electrode assembly drives the connection portion to move synchronously, which can reduce the relative displacement between the tabs and the electrode assembly, thereby reducing the risk of the tabs being squeezed, improving the force on the tabs. At the same time, after the tabs converge and pass through the first connection segment, they are bent, increasing the distance between the tabs and the bending segment, which can reduce the risk of stress concentration at the bending segment of the connection portion, thereby reducing the risk of the tabs breaking at the bending portion, and is beneficial to improving the safety performance of the secondary battery.

[0005] In an embodiment of the present application, a device fixing glue is provided on the outer side of the housing for fixing the secondary battery to the device, and the device fixing glue is provided on the outer side of the second packaging portion. The electrode assembly fixing glue is provided on the inner side of the first packaging portion, and the electrode assembly fixing glue and the device fixing glue are provided on different sides of the housing. The electrode assembly fixing glue connects the first packaging portion and the electrode assembly for fixing between the housing and the electrode assembly, and the device fixing glue connects the housing and the device for fixing between the housing and the device. The electrode assembly fixing glue and the device fixing glue are respectively located on both sides of the housing. In this way, when the secondary battery drops, the interaction force between the electrode assembly and the housing will not be affected by the mutual tearing between the housing and the device. That is to say, the mutual tearing force between the housing and the device will not be transmitted to the electrode assembly fixing glue through the housing. Therefore, through the above arrangement, it is beneficial to reduce the risk of damage to the electrode tab connected to the electrode assembly fixing glue due to concentrated force during the drop of the secondary battery, thereby being beneficial to improving the safety performance of the secondary battery.

[0006] In an embodiment of the present application, the adapter includes a first section and a second section. The first section is connected to the second connecting section, and the included angle between the first section and the second section is 60° - 150°. The adapter is welded to the second connecting section, which can increase the mechanical strength at the connection between the connecting portion and the adapter, make the connection between the connecting portion and the adapter more tight, and reduce the risk of separation between the adapter and the connecting portion when the electrode assembly drops.

[0007] In an embodiment of the present application, the first connecting section is a straight section. A bend is formed between the first section and the second section of the adapter, and this bend, together with the first connecting section and the bent section, forms a bend similar to a "T" shape. This "T" - shaped bend structure has a buffering effect when the electrode assembly drops, can reduce the force on the tab, and is beneficial to reducing the risk of tab fracture. Therefore, through the above arrangement, it is beneficial to improve the safety performance of the secondary battery.

[0008] In an embodiment of the present application, the adapter includes a third section, a fourth section, a fifth section, and a sixth section. The fourth section connects the third section and the fifth section. The third section and the fifth section are spaced apart along the second direction, which is the length direction of the electrode assembly. The fifth section connects the sixth section, and a part of the sixth section extends out of the housing. The third section is welded to the second connecting section. Welding the adapter to the connecting portion can increase the mechanical strength of the connection between the connecting portion and the connecting portion, making the connection between the connecting portion and the adapter tighter, and reducing the risk of separation between the adapter and the connecting portion when the electrode assembly drops. A first bend is formed between the third section and the fourth section of the adapter, a first bend is formed between the fourth section and the fifth section, and a first bend is formed between the fifth section and the sixth section. Moreover, the bend between the third section and the fourth section and the first connecting section, the second connecting section, and the bent section of the connecting portion can also jointly form a bend similar to a "W" shape. The above-mentioned multiple bends provide a better buffering effect when the electrode assembly drops, can reduce the force on the tab, and thus help reduce the risk of tab fracture. Therefore, through the above settings, it is beneficial to improve the safety performance of the secondary battery.

[0009] In an embodiment of the present application, a protective glue is provided at the welding position between the second connecting section and the adapter. The protective glue covers the welding position between the second connecting section and the adapter. The protective glue wraps at least one circle around the outer periphery of the welding position, so that the burrs generated by welding can be effectively wrapped by the protective glue. During the subsequent dropping process of the secondary battery, even if the welding position contacts the housing, it is not easy to pierce the housing, which can reduce the risk of the welding position piercing the housing. In addition, the protective glue has an insulating effect and can also reduce the risk of short circuit between the welding position and the electrode assembly. Moreover, the protective glue can make the connection between the connecting portion and the adapter tighter, reducing the risk of separation between the adapter and the connecting portion when the electrode assembly drops. Therefore, the above settings are beneficial to improve the safety performance of the secondary battery.

[0010] In an embodiment of the present application, the distance between the bent section and the electrode assembly is 30%-60% of the dimension in the length direction of the electrode assembly. Through the above settings, a buffering space can be provided for the electrode assembly when the secondary battery drops, enabling the connecting portion to move together with the electrode assembly, thereby reducing the relative displacement between the tab and the electrode assembly, reducing the risk of the tab being pressed, and improving the force on the tab when the electrode assembly drops, which is beneficial to reducing the risk of tab fracture. Therefore, through the above settings, it is beneficial to improve the safety performance of the secondary battery.

[0011] In an embodiment of the present application, the fixing glue for the electrode assembly includes one of SIS glue and double-sided tape. SIS glue is a thermoplastic elastomer and can be used as a hot melt pressure-sensitive adhesive. The double-sided tape has adhesive layers coated on both sides of the substrate layer. The present application has no special restrictions on the double-sided tape as long as it can achieve the purpose of the present application. Under the same bonding force, the above materials have a smaller thickness, which is beneficial to improving the energy density of the secondary battery.

[0012] In an embodiment of the present application, the thickness of the fixing glue for the electrode assembly is 12 μm - 35 μm.

[0013] In an embodiment of the present application, along the first direction, the minimum distance between the outer contour of the orthographic projection of the fixing glue for the electrode assembly and the outer contour of the orthographic projection of the multi-layer electrode sheet is 5 mm - 40 mm. The present application does not particularly limit the shape of the outer contour of the orthographic projection of the fixing glue for the electrode assembly along the first direction, as long as the purpose of the present application can be achieved.

[0014] By controlling the thickness of the fixing glue for the electrode assembly and the minimum distance between the outer contour of the orthographic projection of the fixing glue for the electrode assembly and the outer contour of the orthographic projection of the multi-layer electrode sheet within the scope of the present application, the adhesion of the fixing glue for the electrode assembly can be improved, so that the connecting part can move together with the electrode assembly when the secondary battery drops, thereby reducing the relative displacement between the tab and the electrode assembly, reducing the risk of the tab being pressed, improving the force on the tab when the electrode assembly drops, and being beneficial to reducing the risk of the tab breaking. Therefore, through the above settings, it is beneficial to improve the safety performance of the secondary battery.

[0015] The second aspect of the present application provides an electronic device, which includes the secondary battery in any of the above embodiments. Thus, the electronic device provided by the present application has good safety performance.

[0016] Advantages of the present application:

[0017] The present application provides a secondary battery and an electronic device. The secondary battery includes an electrode assembly and a housing. The housing includes a first packaging portion and a second packaging portion. The first packaging portion and the second packaging portion are disposed opposite to each other and enclose to accommodate the electrode assembly. The electrode assembly includes electrode tabs. The electrode tabs include current collectors. One side of the current collector has a plurality of protruding tabs. Along the thickness direction of the battery, at least a part of the plurality of tabs overlap and converge to form a connection portion. The connection portion includes a first connection segment, a bent segment, and a second connection segment. The bent segment connects the first connection segment and the second connection segment. The bent segment is bent along a first direction and is close to the first packaging portion. The first direction is the thickness direction of the secondary battery. The secondary battery further includes an adapter. The adapter is connected to the second connection segment, and a part of the adapter extends out of the housing. An electrode assembly fixing adhesive is disposed between the electrode assembly and the first packaging portion for bonding the electrode assembly to the first packaging portion. The bent segment is the bent part of the connection portion. The electrode assembly fixing adhesive connects the first packaging portion and the electrode assembly. By providing the electrode assembly fixing adhesive, the thickness of the electrode assembly fixing adhesive is small, and the electrode assembly can be more firmly connected to the housing on the premise of ensuring the energy density, reducing the internal displacement and deformation during dropping, and improving the overall structural stability of the battery cell. When the secondary battery drops, the electrode assembly drives the connection portion to move synchronously, which can reduce the relative displacement between the tabs and the electrode assembly, thereby reducing the risk of the tabs being squeezed, improving the force on the tabs. At the same time, after the tabs converge and pass through the first connection segment, they are bent, increasing the distance between the tabs and the bent segment, which can reduce the risk of stress concentration at the bent segment of the connection portion, thereby reducing the risk of the tabs breaking at the bent portion, and is beneficial to improving the safety performance of the secondary battery.

[0018] Of course, it is not necessary for any product or method implementing the present application to achieve all the above advantages simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application, and those of ordinary skill in the art can also obtain other embodiments according to these drawings.

[0020] Figure 1 Schematic diagram of the structure of a secondary battery in an implementation scheme of the present application;

[0021] Figure 2 For Figure 1 A-A cross-sectional view of

[0022] Figure 3 For Figure 2 Partial view E of

[0023] Figure 4 For Figure 2Cross-sectional view taken along line B-B;

[0024] Figure 5 Schematic structural diagram of an electrode assembly of a secondary battery in another embodiment of the present application;

[0025] Figure 6 is Figure 5 Partial view F of.

[0026] Reference numerals are as follows:

[0027] Housing 10; First packaging portion 11; Second packaging portion 12; Electrode assembly 20; Connection portion 21; First connection section 211; Second connection section 212; Bent section 213; Tab 22; Electrode tab 24; Current collector 241; Electrode assembly fixing glue 30; Equipment fixing glue 40; Adapter 50; First section 51; Second section 52; Third section 53; Fourth section 54; Fifth section 55; Sixth section 56; Protective glue 60. Detailed implementation manners

[0028] Next, the technical solutions in the present application will be clearly and completely described in conjunction with the embodiments of the present application and the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those skilled in the art based on the present application belong to the scope of protection of the present application.

[0029] The purpose of the present application is to provide a secondary battery and an electronic device to reduce the risk of displacement or deformation of the electrode assembly during a drop. The specific technical solutions are as follows:

[0030] The first aspect of the present application provides a secondary battery. As Figure 2 shown, the secondary battery includes an electrode assembly 20 and a housing 10. The housing 10 includes a first packaging portion 11 and a second packaging portion 12. The first packaging portion 11 and the second packaging portion 12 are oppositely arranged and enclose to accommodate the electrode assembly 20. The electrode assembly 20 includes an electrode tab 24. The electrode tab 24 includes a current collector 241. One side of the current collector 241 has a plurality of protruding tabs 22. Along the thickness direction (X direction) of the battery, at least a part of the plurality of tabs 22 overlap and converge to form a connection portion 21. As Figure 3As shown, the connection portion 21 includes a first connection segment 211 and a second connection segment 212, and a bending segment 213 connects the first connection segment 211 and the second connection segment 212. The first connection segment 211 is the portion from the starting point of the overlapping portion of the plurality of tabs 22 to the starting point of the bending segment 213; the bending segment 213 is bent along the first direction (X direction) and is close to the first packaging portion 11, and the first direction (X direction) is the thickness direction (X direction) of the secondary battery; the secondary battery also includes a transition piece 50, the transition piece 50 is connected to the second connection segment 212, and part of the transition piece 50 extends out of the housing 10; an electrode assembly fixing glue 30 is provided between the electrode assembly 20 and the first packaging portion 11, for bonding the electrode assembly 20 to the first packaging portion 11. The bending segment 213 is the bending portion of the connection portion 21, and the electrode assembly fixing glue 30 connects the first packaging portion 11 and the electrode assembly 20. By setting the electrode assembly fixing glue, the thickness of the electrode assembly fixing glue is small, and the electrode assembly can be connected to the shell more firmly under the premise of ensuring energy density, reducing internal displacement and deformation during falling, and improving the overall structural stability of the battery cell. When the secondary battery falls, the electrode assembly drives the connection part to move synchronously, which can reduce the relative displacement between the pole ear and the electrode assembly, thereby reducing the risk of the pole ear being squeezed and improving the force on the pole ear. At the same time, after the pole ear is folded, it passes through the first connecting section and then bends, which increases the distance between the pole ear and the bending section, which can reduce the risk of stress concentration in the connecting part in the bending section, thereby reducing the risk of the pole ear breaking in the bending section, which is beneficial to improving the safety performance of the secondary battery.

[0031] In one embodiment of the present application, Figure 1 As shown, a device fixing glue 40 is disposed on the outside of the housing 10 for fixing the secondary battery on the device, and the device fixing glue 40 is disposed on the outside of the second packaging portion 12. Figure 2As shown, the electrode assembly fixing glue 30 is disposed inside the first packaging portion 11. The electrode assembly fixing glue 30 and the device fixing glue 40 are disposed on different sides of the housing 10. The electrode assembly fixing glue 30 connects the first packaging portion 11 and the electrode assembly 20 and is used for fixing between the housing 10 and the electrode assembly 20. The device fixing glue 40 connects between the housing 10 and the device and is used for fixing between the housing 10 and the device. The electrode assembly fixing glue 30 and the device fixing glue 40 are respectively located on two sides of the housing 10. In this way, when the secondary battery drops, the interaction force between the electrode assembly 20 and the housing 10 will not be affected by the mutual tearing between the housing 10 and the device. That is to say, the mutual tearing force between the housing 10 and the device will not be transmitted to the electrode assembly fixing glue 30 through the housing 10. Therefore, through the above arrangement, it is beneficial to reduce the risk of damage to the electrode tab connected to the electrode assembly fixing glue due to concentrated stress when the secondary battery drops, thereby being beneficial to improving the safety performance of the secondary battery. There is no particular limitation on the above device in this application, as long as the purpose of this application can be achieved. There is no particular limitation on the device fixing glue in this application, as long as the purpose of this application can be achieved. For example, it can be selected from easy-pull glue and double-sided glue.

[0032] In an embodiment of the present application, as Figure 3 shown, the adapter 50 includes a first section 51 and a second section 52. The first section 51 is welded to the second connection section 212. The included angle R between the first section 51 and the second section 52 is 60° - 150°. For example, the included angle between the first section and the second section can be 60°, 70°, 80°, 90°, 100°, 110°, 120°, 130°, 140°, 150° or a range composed of any two of these values. The adapter 50 is welded to the second connection section 212, which can increase the mechanical strength of the connection between the connection portion 21 and the adapter 50, make the connection between the connection portion 21 and the adapter 50 more tight, and reduce the risk of separation between the adapter and the connection portion when the electrode assembly drops.

[0033] In an embodiment of the present application, as Figure 3 shown, the first connection section 211 is a straight section. A bend is formed between the first section 51 and the second section 52 of the adapter 50. This bend, together with the first connection section 211 and the bent section 213, forms a bend similar to a "T" shape. This "T" - shaped bend structure has a buffering effect when the electrode assembly drops, can reduce the force on the tab, and is beneficial to reducing the risk of tab fracture. Therefore, through the above arrangement, it is beneficial to improve the safety performance of the secondary battery.

[0034] In an embodiment of the present application, as Figure 6As shown, the adapter 50 includes a third section 53, a fourth section 54, a fifth section 55, and a sixth section 56. The fourth section 54 connects the third section 53 and the fifth section 55. The third section 53 and the fifth section 55 are spaced apart in the second direction (Y direction). The fifth section 55 connects the sixth section 56, and a part of the sixth section 56 extends out of the housing 10. The third section 53 is welded to the second connecting section 212. The adapter 50 is welded to the connecting portion 21, which can increase the mechanical strength at the connection between the connecting portion and the adapter, making the connection between the connecting portion and the adapter tighter, and reducing the risk of separation between the adapter and the connecting portion when the electrode assembly drops. A first bend is formed between the third section 53 and the fourth section 54 of the adapter 50, a first bend is formed between the fourth section 54 and the fifth section 55, and a first bend is formed between the fifth section 55 and the sixth section 56. Moreover, the bend between the third section 53 and the fourth section 54 and the first connecting section 211, the second connecting section 212, and the bent section 213 of the connecting portion 21 can also jointly form a bend similar to the "W" shape. The above-mentioned multiple bends provide a better buffering effect when the electrode assembly drops, can reduce the force on the tab, and thus is beneficial to reducing the risk of tab breakage. Therefore, through the above settings, it is beneficial to improve the safety performance of the secondary battery.

[0035] In an embodiment of the present application, as Figure 2 and Figure 5 shown, a protective glue 60 is provided at the welding position between the second connecting section 212 and the adapter 50. The protective glue 60 covers the welding position between the second connecting section 212 and the adapter 50. The protective glue wraps at least one circle around the periphery of the welding position, so that the burrs generated by welding can be effectively wrapped by the protective glue. During the subsequent dropping process of the secondary battery, even if the welding position contacts the housing, it is not easy to pierce the housing, which can reduce the risk of the welding position piercing the housing. Moreover, the protective glue has an insulating effect and can also reduce the risk of short circuit when the welding position contacts the electrode assembly. In addition, the protective glue can make the connection between the connecting portion and the adapter tighter, reducing the risk of separation between the adapter and the connecting portion when the electrode assembly drops. Therefore, the above settings are beneficial to improving the safety performance of the secondary battery.

[0036] In an embodiment of the present application, the distance between the bent section and the electrode assembly is 30%-60% of the dimension in the length direction of the electrode assembly. For example, the ratio of the distance between the bent section and the electrode assembly to the dimension in the length direction of the electrode assembly can be 30%, 40%, 50%, 60%, or a range composed of any two of these values. As Figure 2As shown, the distance between the bent section 213 and the electrode assembly 20 is as shown by d in the figure, and the dimension of the electrode assembly 20 in the length direction (Y direction) is as shown by L in the figure. Through the above settings, a buffer space can be provided for the electrode assembly when the secondary battery drops, enabling the connecting part to move together with the electrode assembly, thereby reducing the relative displacement between the tab and the electrode assembly, reducing the risk of the tab being pressed, improving the force on the tab when the electrode assembly drops, and being conducive to reducing the risk of the tab breaking. Therefore, through the above settings, it is beneficial to improve the safety performance of the secondary battery.

[0037] In an embodiment of the present application, the electrode assembly fixing glue includes one of SIS glue and double-sided glue. SIS glue is a thermoplastic elastomer and can be used as a hot melt pressure-sensitive adhesive. The double-sided glue has glue layers coated on both sides of the base material layer. The present application has no special restrictions on the double-sided glue as long as the purpose of the present application can be achieved. Under the condition of the same bonding force, the thickness of the above materials is smaller, which is beneficial to improving the energy density of the secondary battery.

[0038] In an embodiment of the present application, the thickness of the electrode assembly fixing glue is 12μm - 35μm. For example, the thickness of the electrode assembly fixing glue can be 12μm, 15μm, 20μm, 25μm, 30μm, 35μm, or a range composed of any two of these values.

[0039] In an embodiment of the present application, along the first direction, the minimum distance between the outer contour of the orthographic projection of the electrode assembly fixing glue and the outer contour of the orthographic projection of the multi-layer electrode plates is 5mm - 40mm. For example, the minimum distance between the outer contour of the orthographic projection of the electrode assembly fixing glue and the outer contour of the orthographic projection of the multi-layer electrode plates can be 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, or a range composed of any two of these values. The present application has no special restrictions on the shape of the outer contour of the orthographic projection of the electrode assembly fixing glue along the first direction as long as the purpose of the present application can be achieved. Exemplarily, taking the outer contour of the orthographic projection of the electrode assembly fixing glue along the first direction as a rectangle as an example, as Figure 4 shown, the distances between the outer contour of the electrode assembly fixing glue 30 and the outer contour of the orthographic projection of the multi-layer electrode plates 24 are A1, A2, A3, and A4.

[0040] By controlling the thickness of the electrode assembly fixing glue and the minimum distance between the outer contour of the orthographic projection of the electrode assembly fixing glue and the outer contour of the orthographic projection of the multi-layer electrode plates within the scope of the present application, the bonding force of the electrode assembly fixing glue can be improved, enabling the connecting part to move together with the electrode assembly when the secondary battery drops, thereby reducing the relative displacement between the tab and the electrode assembly, reducing the risk of the tab being pressed, improving the force on the tab when the electrode assembly drops, and being conducive to reducing the risk of the tab breaking. Therefore, through the above settings, it is beneficial to improve the safety performance of the secondary battery.

[0041] The present application has no particular limitation on the secondary battery, and it can be any secondary battery known in the art. For example, it can be a lithium-ion battery.

[0042] The present application has no particular limitation on the electrode assembly, and it can be any electrode assembly known in the art. For example, it can be a laminated or wound electrode assembly.

[0043] The housing is used to accommodate the positive electrode plate, the separator, the negative electrode plate, and the electrolyte, as well as other components known in the field of secondary batteries. The present application does not limit the above-mentioned other components. The present application has no particular limitation on the housing, and it can be a housing known in the art as long as the purpose of the present application can be achieved. For example, the housing can be a hard-shell housing or a flexible housing. The material of the hard-shell housing can be metal, and the present application does not limit the type of metal. Any known metal hard-shell housing in the art can be used as long as the purpose of the present application can be achieved. The flexible housing can be a metal plastic film, such as an aluminum plastic film, a steel plastic film, etc.

[0044] The preparation process of the secondary battery of the present application has no particular limitation. For example, the preparation process of the secondary battery can include but is not limited to the following steps: stacking the positive electrode plate, the separator, and the negative electrode plate in sequence, and winding, folding, etc. as needed to obtain a wound-structured electrode assembly; bonding the electrode assembly fixing glue to the electrode assembly; placing the electrode assembly into the housing; bonding the electrode assembly fixing glue to the first packaging part; injecting the electrolyte into the housing and sealing it to obtain the secondary battery. Or, stacking the positive electrode plate, the separator, and the negative electrode plate in sequence, and then fixing the four corners of the entire laminated structure with tape to obtain a laminated-structured electrode assembly; bonding the electrode assembly fixing glue to the electrode assembly; placing the electrode assembly into the housing; bonding the electrode assembly fixing glue to the first packaging part; injecting the electrolyte into the housing and sealing it to obtain the secondary battery. In addition, an overcurrent protection element, a guide plate, etc. can also be placed in the housing as needed to prevent the pressure inside the secondary battery from rising and overcharging / discharging.

[0045] The second aspect of the present application provides an electronic device, which includes the secondary battery in any of the above embodiments. Therefore, the electronic device provided by the present application has good safety performance.

[0046] The electronic device of the present application is not particularly limited, and it can be any electronic device known in the prior art. For example, the electronic device may include, but is not limited to, a laptop computer, a pen-input computer, a mobile computer, an e-book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a headset stereo, a video recorder, an LCD TV, a portable cleaner, a portable CD player, a minidisc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, an automobile, a motorcycle, a moped, a bicycle, a lighting fixture, a toy, a game console, a clock, a power tool, a flash, a camera, a large household battery, and a lithium-ion capacitor.

[0047] Examples

[0048] Hereinafter, examples and comparative examples are given to more specifically illustrate the embodiments of the present application. Various tests and evaluations are carried out according to the following methods. In addition, unless otherwise specified, "parts" and "%" are based on mass.

[0049] Test methods and equipment:

[0050] Measurement of the tab breakage ratio and the case breakage ratio:

[0051] Taking a mobile phone as an example. The secondary battery is connected to the mobile phone through a device fixing adhesive. Drop tests are carried out on the six sides of the mobile phone and the four corners on the side close to the secondary battery at a height of 1.5 m from the smooth concrete surface. 100 secondary batteries are tested, and the number of secondary batteries with tab breakage and the number of secondary batteries with case breakage after 10 tests and 20 tests at each position are respectively recorded. The tab breakage ratio and the seal breakage ratio for 10 tests and 20 tests are respectively calculated:

[0052] Tab breakage ratio = Number of secondary batteries with tab breakage / Total number

[0053] Case breakage ratio = Number of secondary batteries with case breakage / Total number.

[0054] Example 1

[0055] <Preparation of the positive electrode tab>

[0056] The cathode active material LiCoO2, the conductive agent Super P, and the binder polyvinylidene fluoride are mixed at a mass ratio of 97.9:0.9:1.2. N-methylpyrrolidone (NMP) is added as a solvent to prepare a slurry with a solid content of 75 wt%. After vacuum stirring evenly, the cathode slurry is obtained. The cathode slurry is uniformly coated on one surface of a cathode current collector aluminum foil with a thickness of 10 μm and dried at 120 °C to obtain a cathode plate with a single-sided coated cathode material layer. The coating weight of the cathode material layer is 267.8 mg / 1540 mm 2 . Then, the above steps are repeated on the other surface of the aluminum foil to obtain a cathode plate with a double-sided coated cathode material layer. After drying at 120 °C, it is cold-pressed, and then the tab is formed by cutting to obtain a cathode plate with a specification of 74 mm × 867 mm for use. Among them, the thickness of the single-sided cathode material layer is 42 μm.

[0057] <Preparation of Anode Plate>

[0058] The anode active material artificial graphite, the binder styrene-butadiene rubber, and the conductive agent acetylene black are mixed at a mass ratio of 97.4:1.4:1.2. Deionized water is added as a solvent to prepare a slurry with a solid content of 45 wt%. After vacuum stirring evenly, the anode slurry is obtained. The anode slurry is uniformly coated on one surface of an anode current collector copper foil with a thickness of 6 μm and dried at 120 °C to obtain an anode plate with a single-sided coated anode material layer. The coating weight of the anode material layer is 142 mg / 1540 mm 2 . Then, the above steps are repeated on the other surface of the copper foil to obtain an anode plate with a double-sided coated anode material layer. After drying at 120 °C, it is cold-pressed, and then the tab is formed by cutting to obtain an anode plate with a specification of 78 mm × 875 mm for use. Among them, the thickness of the single-sided anode material layer is 54.5 μm.

[0059] <Preparation of Electrolyte>

[0060] In an environment with a water content of less than 10 ppm, dimethyl carbonate, diethyl carbonate, and ethylene carbonate are mixed at a mass ratio of 1:1:1 to obtain an organic solvent. Then, the electrolyte salt LiPF6 is added to the organic solvent and mixed evenly to obtain the electrolyte. Among them, based on the mass of the electrolyte, the mass percentage of the electrolyte salt is 12.5%, and the rest is the organic solvent.

[0061] <Separator>

[0062] A porous polyethylene film with a thickness of 7 μm (provided by Celgard) is used as the separator.

[0063] <Preparation of Lithium-Ion Battery>

[0064] Stack the prepared positive electrode sheet, separator, and negative electrode sheet in sequence, with the separator in the middle of the positive electrode sheet and the negative electrode sheet to play an isolation role. After winding, gather and weld the tabs of multiple positive electrode sheets to form a positive connection part, and gather and weld the tabs of multiple negative electrode sheets to form a negative connection part to obtain an electrode assembly. Place the electrode assembly into an aluminum-plastic film packaging bag, use an electrode assembly fixing adhesive to connect the electrode assembly and the first packaging part, and make the bent parts of the positive connection part and the negative connection part close to the first packaging part. Connect adapter parts to the positive connection part and the negative connection part respectively, and remove moisture at 80°C, then inject the prepared electrolyte. After processes such as vacuum packaging, standing, formation, degassing, and trimming, a lithium-ion battery is obtained. Among them, the upper limit voltage of formation is 4.15V, the formation temperature is 70°C, and the formation standing time is 2h. Paste equipment fixing adhesive on the outside of the second packaging part.

[0065] Example 2

[0066] Except for setting the equipment fixing adhesive on the outside of the first packaging part, the rest is the same as in Example 1.

[0067] Comparative Example 1

[0068] Except for not setting the electrode assembly fixing adhesive, the rest is the same as in Example 1.

[0069] The performance parameters of each example and comparative example are shown in Table 1.

[0070] Table 1

[0071]

[0072] It can be seen from Example 1, Example 2, and Comparative Example 1 that by setting an electrode assembly fixing adhesive in the inner side of the first packaging part of the housing to connect the electrode assembly and the first packaging part, and making the bent segments of the connection parts formed by gathering and shaping the tabs of the electrode sheets close to the first packaging part, the risk of tab breakage and housing damage caused by displacement or deformation of the electrode assembly during dropping can be reduced. In Comparative Example 1, the electrode assembly fixing adhesive is not set, and in Example 2, both the electrode assembly fixing adhesive and the equipment fixing adhesive are set on the first packaging part. At this time, the tab breakage ratio and housing damage ratio of Comparative Example 1 are relatively high; while the tab breakage ratio and housing damage ratio of Example 1 and Example 2 are relatively low, and the lithium-ion battery has good safety performance.

[0073] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included within the scope of protection of the present application.

Claims

1. A secondary battery, comprising an electrode assembly and a housing, characterized in that, The shell comprises a first packaging portion and a second packaging portion, wherein the first packaging portion and the second packaging portion are arranged opposite to each other and enclosed to accommodate the electrode assembly; The electrode assembly includes an electrode plate, the electrode plate includes a current collector, and one side of the current collector has a plurality of protruding tabs; Along the thickness direction of the battery, the plurality of tabs at least partially overlap and gather to form a connecting portion, the connecting portion comprising a first connecting segment, a bending segment and a second connecting segment, the bending segment connecting the first connecting segment and the second connecting segment, the bending segment bending along a first direction and close to the first packaging portion, the first direction being the thickness direction of the secondary battery; The secondary battery further includes a connecting piece, the connecting piece is connected to the second connecting section, and a part of the connecting piece extends out of the housing; An electrode assembly fixing glue is provided between the electrode assembly and the first packaging portion, for bonding the electrode assembly to the first packaging portion.

2. The secondary battery according to claim 1, wherein The outer side of the shell is provided with a device fixing glue for fixing the secondary battery on the device, and the device fixing glue is provided on the outer side of the second packaging part.

3. The secondary battery according to claim 1, characterized in that, The adapter comprises a first section and a second section, the first section is welded to the second connecting section, the second section extends out of the shell, and an angle between the first section and the second section is 60°-150°.

4. The secondary battery according to claim 3, characterized in that, The first connecting section is a straight section.

5. The secondary battery according to claim 1, characterized in that, The adapter includes a third section, a fourth section, a fifth section and a sixth section, the fourth section connects the third section and the fifth section, the third section and the fifth section are spaced apart along a second direction, the second direction is the length direction of the electrode assembly, the fifth section connects the sixth section, and part of the sixth section extends out of the shell; the third section is welded to the second connecting section.

6. The secondary battery according to any one of claims 3 to 5, characterized in that, Protective glue is provided at the welding position between the second connecting section and the adapter.

7. The secondary battery according to claim 1, wherein The distance between the bending section and the electrode assembly is 30%-60% of the length dimension of the electrode assembly.

8. The secondary battery according to claim 1, characterized in that, The electrode assembly fixing glue includes one of SIS glue and double-sided glue.

9. The secondary battery according to claim 1, characterized in that, The electrode assembly fixing glue has a thickness of 12 μm-35 μm.

10. The secondary battery according to claim 1, wherein, Along the first direction, the minimum distance between the outer contour of the orthographic projection of the electrode assembly fixing glue and the outer contour of the orthographic projection of the multi-layer electrode plate is 5mm-40mm. 11 . An electronic device comprising the secondary battery according to claim 1 .

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