Secondary battery and electric device

Abstract

The present application relates to the technical field of energy storage, and in particular to a secondary battery and an electric device. The secondary battery comprises a housing, an electrode assembly, a tab assembly, and an adapter, wherein the housing is provided with an accommodating cavity; the electrode assembly is accommodated in the accommodating cavity; and the tab assembly is connected to the electrode assembly. The adapter is bent, and has a bending vertex in the thickness direction of the electrode assembly. One end of the adapter is connected to the tab assembly and has a connection area, the other end of the adapter is connected to the housing and has a fixing area, the maximum length between the bending vertex and the connection area in the thickness direction of the electrode assembly is a, and the maximum length between the bending vertex and the fixing area in the thickness direction of the electrode assembly is defined as b, satisfying b-a > 0, so as to facilitate an improvement in the safety of the secondary battery.

Description

Secondary batteries and electrical equipment Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to a secondary battery and electrical equipment. Background Technology

[0002] In recent years, rechargeable batteries have been widely used in small devices such as portable electronic devices, as well as medium and large devices such as battery packs or energy storage in hybrid and electric vehicles. With the rapid development of various commercial products, the requirements for the safety performance of rechargeable batteries are becoming increasingly stringent.

[0003] For steel-cased rechargeable batteries, multi-tab cells tend to accumulate at the bottom of the casing during installation. Excessive compression of the tabs leads to greater stress at the base of the tabs, making them prone to breakage. To address this issue, it is indeed necessary to provide an improved rechargeable battery. Summary of the Invention

[0004] In view of this, this application provides a secondary battery and an electrical device that can improve the problem of easy breakage at the base of the electrode tab.

[0005] In a first aspect, embodiments of this application provide a secondary battery, including a housing, an electrode assembly, a tab assembly, and an adapter. The housing has a cavity, the electrode assembly is housed within the cavity, and the tab assembly is connected to the electrode assembly. The adapter is bent, and has a bending apex along the thickness direction of the electrode assembly. One end of the adapter is connected to the tab assembly and has a connection area, while the other end of the adapter is connected to the housing and has a fixing area. The maximum length of the bending apex and the connection area along the thickness direction of the electrode assembly is 'a', and the maximum length of the bending apex and the fixing area along the thickness direction of the electrode assembly is 'b', satisfying 'ba > 0'.

[0006] Along the thickness direction of the electrode assembly, the maximum length of the bending vertex and the fixed area along the thickness direction of the electrode assembly is greater than the maximum length of the bending vertex and the connecting area along the thickness direction of the electrode assembly. This allows the adapter to pull the tab assembly to move within the housing space during the insertion process, thereby improving the problem of breakage at the root of the tab due to accumulation and compression, and enhancing the safety of the secondary battery.

[0007] In the above embodiments, the thickness of the cavity along the thickness direction of the electrode assembly is H, satisfying ba < 0.5H.

[0008] Along the thickness direction of the electrode assembly, the difference between the maximum length of the bending vertex and the fixed area along the thickness direction of the electrode assembly and the maximum length of the bending vertex and the connecting area along the thickness direction of the electrode assembly is less than half the thickness of the electrode assembly. This helps to reduce the height of the bending vertex, thereby improving the fact that the bending vertex of the adapter extends beyond the upper surface of the electrode assembly and contacts the housing along the thickness direction of the electrode assembly.

[0009] In one or more of the above embodiments, the adapter includes a connecting part and a fixing part, the bending vertex is located between the connecting part and the fixing part, the connecting part is connected to the tab assembly, the fixing part is connected to the housing, and both the connecting part and the fixing part are elastic.

[0010] During the insertion of the electrode assembly into the casing, the fixing part is connected to the casing. Since the fixing part is elastic, and the connecting part is connected to the tab assembly and is also elastic, the fixing part and the connecting part have an elastic force that pulls the connecting part and the tab assembly. This facilitates the automatic assembly of the tab assembly, improves the problem of breakage caused by accumulation and compression at the root of the tab, and helps to improve the safety of the secondary battery.

[0011] In one or more of the above embodiments, the housing includes a bottom shell and a side shell, the side shell is surrounded and sealed to the bottom shell, and there is an insertion space between the electrode assembly and the side shell, the electrode assembly is housed in the insertion space.

[0012] The side shell surrounds and seals the bottom shell. Before the electrode assembly is inserted into the shell, the tab assembly and adapter can be accommodated in the shell space, thereby providing storage space for the electrode assembly and improving the convenience of inserting the electrode assembly into the shell.

[0013] In one or more of the above embodiments, along the thickness direction of the electrode assembly, the minimum length of the fixed region and the bottom shell along the thickness direction of the electrode assembly is c, satisfying 0 < c < 0.3H.

[0014] Along the thickness direction of the electrode assembly, the minimum length of the fixing area and the bottom shell along the thickness direction of the electrode assembly is controlled between 0 and 0.3 times the thickness of the electrode assembly, which helps to leave welding positions for the fixing part and improves the convenience of welding.

[0015] In one or more of the above embodiments, 0.1H < c < 0.3H is satisfied.

[0016] Along the thickness direction of the electrode assembly, the minimum length of the fixing area and the bottom shell along the thickness direction of the electrode assembly is controlled between 0.1H and 0.3 times the thickness of the electrode assembly. This helps to leave more welding positions for the fixing part and further improves the convenience of welding.

[0017] In one or more of the above embodiments, the electrode assembly includes a first electrode, a diaphragm, and a second electrode. The diaphragm is disposed between the first electrode and the second electrode. The first electrode and the second electrode have opposite polarities. The first electrode, the second electrode, and the diaphragm are stacked and wound to form a wound structure. The first electrode includes a first current collector and a first active material layer. The first current collector includes a first main body region and a plurality of first empty foil regions disposed on the side of the first main body region. The surface of the first main body region is provided with the first active material layer, and the surface of the first empty foil regions is not provided with the first active material layer. The first empty foil regions of the plurality of first electrodes are wound and stacked along the thickness direction of the electrode assembly to form an electrode tab assembly.

[0018] The first electrode, the second electrode, and the diaphragm are stacked and wound to form a wound structure. The first empty foil areas of multiple first electrodes are wound and stacked along the thickness direction of the electrode assembly to form an electrode tab assembly, thereby improving the current carrying capacity of the electrode assembly.

[0019] In one or more of the above embodiments, the electrode assembly includes a plurality of first electrodes, a plurality of second electrodes, and a separator disposed between the first electrodes and the second electrodes, wherein the first electrodes and the second electrodes have opposite polarities, and the first electrodes, the separator, and the second electrodes are stacked to form a stacked structure; the first electrodes include a first current collector and a first active material layer, the first current collector includes a first body region and a first empty foil region, the surface of the first body region is provided with the first active material layer, and the surface of the first empty foil region is not provided with the first active material layer, and the first empty foil regions of the plurality of first electrodes are stacked along the thickness direction of the electrode assembly to form an electrode tab assembly.

[0020] The first electrode, the diaphragm, and the second electrode are stacked to form a stacked structure. The first empty foil areas of multiple first electrodes are wound and stacked along the thickness direction of the electrode assembly to form an electrode tab assembly, thereby improving the current carrying capacity of the electrode assembly.

[0021] In one or more of the above embodiments, insulating elements are provided on the surface of the fixed area facing the tab assembly and on the surface of the bottom shell facing the tab assembly.

[0022] By providing an insulating element on the surface of the fixed area facing the tab assembly, and providing an insulating element on the surface of the bottom shell facing the tab assembly, the tab assembly is separated from the fixed area and the bottom shell, thereby improving the problem of wear on the tabs after the tab assembly comes into contact with the fixed area and the bottom shell, and enhancing the safety of the tab assembly.

[0023] Secondly, embodiments of this application provide an electrical device including the secondary battery described in one or more of the above embodiments. Attached Figure Description

[0024] Figure 1 is a schematic diagram of the overall structure of the secondary battery in one embodiment of this application.

[0025] Figure 2 is a schematic diagram of the exploded structure of a secondary battery in one embodiment of this application.

[0026] Figure 3 is a cross-sectional structural diagram of a secondary battery in one embodiment of this application.

[0027] Figure 4 is a cross-sectional view of the secondary battery before it is installed in the casing in one embodiment of this application.

[0028] Figure 5 is a cross-sectional structural diagram of the secondary battery in another embodiment of this application.

[0029] Figure 6 is a schematic diagram of the structure of the electrical equipment in another embodiment of this application.

[0030] Key Component Symbols Explanation: 001 Secondary Battery 100 Casing 110 Cavity 120 Bottom Casing 130 Side Casing 131 Terminal Post 140 Housing Space 150 Cover Plate 200 Electrode Assembly 210 First Electrode 220 Separator 230 Second Electrode 300 Tab Assembly 310 Positive Tab Assembly 320 Negative Tab Assembly 400 Adapter 410 Bending Point 420 Connection Area 430 Fixing Area 440 Connection Part 450 Fixing Part 500 Insulating Component 002 Electrical Equipment Detailed Implementation

[0031] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0032] It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or may also have an intervening component. When a component is considered to be "placed" on another component, it can be directly placed on the other component or may also have an intervening component. The terms "top," "bottom," and similar expressions used in this article are for illustrative purposes only.

[0033] Unless otherwise stated, the term "multiple" as used herein refers to two or more.

[0034] The terms “first”, “second”, etc., are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implying the quantity, specific order, or primary and secondary relationship of the indicated technical features.

[0035] The term "perpendicular" is used to describe the ideal state between two components. In actual production or use, two components may exist in a state that is approximately perpendicular.

[0036] The term "parallel" is used to describe the ideal state between two components. In actual production or use, two components can exist in a state that is approximately parallel.

[0037] It should be noted that when a parameter is greater than, equal to or less than a certain endpoint value, it should be understood that the endpoint value is allowed to have a tolerance of ±5%.

[0038] It should be understood that the dimensions and thicknesses of the components shown in the accompanying drawings are for better understanding and more convenient description, and this application is not limited to the dimensions and thicknesses shown in the accompanying drawings.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0040] This application provides a secondary battery that can improve the problem of breakage at the base of the electrode tab due to accumulation and compression during the electrode assembly insertion process.

[0041] An embodiment of this application provides a secondary battery, including a housing, an electrode assembly, a tab assembly, and an adapter. The housing has a cavity, the electrode assembly is housed within the cavity, and the tab assembly is connected to the electrode assembly. The adapter is bent, and has a bend vertex along the thickness direction of the electrode assembly. One end of the adapter is connected to the tab assembly and has a connection area, while the other end of the adapter is connected to the housing and has a fixing area. The maximum length of the bend vertex and the connection area along the thickness direction of the electrode assembly is 'a', and the maximum length of the bend vertex and the fixing area along the thickness direction of the electrode assembly is 'b', satisfying 'ba > 0'.

[0042] Along the thickness direction of the electrode assembly, the maximum length of the bending vertex and the fixed area along the thickness direction of the electrode assembly is greater than the maximum length of the bending vertex and the connecting area along the thickness direction of the electrode assembly. This allows the adapter to pull the tab assembly to move within the housing space during the insertion process, thereby improving the problem of breakage at the root of the tab due to accumulation and compression, and enhancing the safety of the secondary battery.

[0043] Some embodiments of this application will now be described with reference to the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0044] Please refer to Figures 1 and 2. An embodiment of this application provides a secondary battery 001, which includes a housing 100 and an electrode assembly 200. The housing 100 has a cavity 110, and the electrode assembly 200 is housed in the cavity 110.

[0045] In some embodiments, the housing 100 includes a bottom shell 120 and a side shell 130, with a cavity 110 formed between the bottom shell 120 and the side shell 130.

[0046] In some embodiments, the housing 100 is a rigid outer shell. As an exemplary example, the bottom shell 120 and the side shell 130 are both metal shells made of at least one of steel alloy, nickel alloy, and copper alloy.

[0047] In some embodiments, the bottom shell 120 and the side shell 130 are both made of stainless steel or stainless steel.

[0048] In some embodiments, the bottom shell 120 and the side shell 130 are made of different materials.

[0049] In some embodiments, the secondary battery 001 includes a tab assembly 300 and an adapter 400, the tab assembly 300 being connected to the electrode assembly 200, and the adapter 400 being connected to the tab assembly 300 and the side shell 130.

[0050] In some embodiments, a pole post 131 is provided on the side shell 130, and an adapter 400 connects the tab assembly 300 and the pole post 131.

[0051] In some embodiments, the tab assembly 300 includes a positive tab assembly 310 and a negative tab assembly 320. Two adapters 400 are provided, one adapter 400 connecting the positive tab assembly 310 and the pole post 131, and the other adapter 400 connecting the negative tab assembly 320 and the side shell 130.

[0052] In some embodiments, the electrode assembly 200 includes a first electrode 210, a diaphragm 220, and a second electrode 230. The diaphragm 220 is disposed between the first electrode 210 and the second electrode 230. The first electrode 210 and the second electrode 230 have opposite polarities. The first electrode 210, the second electrode 230, and the diaphragm 220 are stacked and wound to form a wound structure. The first electrode 210 includes a first current collector and a first active material layer. The first current collector includes a first main body region and a plurality of first empty foil regions disposed on the side of the first main body region. The surface of the first main body region is provided with the first active material layer, and the surface of the first empty foil regions is not provided with the first active material layer. After the first empty foil regions of the plurality of first electrodes 210 are wound, they are stacked along the thickness direction of the electrode assembly 200 to form an electrode tab assembly 300, thereby improving the current carrying capacity of the electrode assembly 200.

[0053] In some embodiments, the electrode assembly 200 includes a plurality of first electrodes 210, a plurality of second electrodes 230 stacked along the thickness direction, and a separator 220 disposed between the first electrodes 210 and the second electrodes 230. The first electrodes 210 and the second electrodes 230 have opposite polarities. The first electrodes 210, the separator 220, and the second electrodes 230 are stacked to form a stacked structure. The first electrodes 210 include a first current collector and a first active material layer. The first current collector includes a first body region and a first empty foil region. The surface of the first body region is provided with the first active material layer, and the surface of the first empty foil region is not provided with the first active material layer. The first empty foil regions of the plurality of first electrodes 210 are stacked along the thickness direction of the electrode assembly 200 to form an electrode tab assembly 300, thereby improving the current carrying capacity of the electrode assembly 200.

[0054] The following provides a detailed explanation of the connection method between one of the adapters 400 and the negative electrode tab assembly 320.

[0055] Referring to Figures 3 and 4, in some embodiments, the adapter 400 is bent and has a bend vertex 410 along the thickness direction of the electrode assembly 200.

[0056] One end of the adapter 400 is connected to the tab assembly 300 and has a connection area 420. The other end of the adapter 400 is connected to the housing 100 and has a fixing area 430. The maximum length of the bending vertex 410 and the connection area 420 along the thickness direction of the electrode assembly 200 is 'a', and the maximum length of the bending vertex 410 and the fixing area 430 along the thickness direction of the electrode assembly 200 is 'b', satisfying 'a > 0'. The maximum length of the bending vertex 410 and the fixing area 430 along the thickness direction of the electrode assembly 200 is greater than the maximum length of the bending vertex 410 and the connection area 420 along the thickness direction of the electrode assembly 200. This allows the adapter 400 to pull the tab assembly 300 within the housing space 140 during the insertion of the electrode assembly 200 into the housing, thereby improving the problem of breakage at the root of the tab due to accumulation and compression, and enhancing the safety of the secondary battery 001.

[0057] In some embodiments, the connection area 420 is the weld mark formed by welding one end of the adapter 400 to the tab assembly 300, and the fixing area 430 is the weld mark formed by welding the other end of the adapter 400 to the housing 100.

[0058] In some embodiments, the housing 100 further includes a cover plate 150 disposed on the side of the side housing 130 away from the bottom housing 120. Along the thickness direction of the electrode assembly 200, the thickness of the cavity 110 is H, satisfying ba < 0.5H. Along the thickness direction of the electrode assembly 200, the difference between the maximum length of the bending vertex 410 and the maximum length of the fixing region 430 along the thickness direction of the electrode assembly 200 and the maximum length of the bending vertex 410 and the connecting region 420 along the thickness direction of the electrode assembly 200 is less than half the thickness of the electrode assembly 200. This facilitates reducing the height of the bending vertex 410, thereby improving the connection of the adapter 400 so that the bending vertex 410 extends beyond the upper surface of the electrode assembly 200 and contacts the cover plate 150 along the thickness direction of the electrode assembly 200.

[0059] In some embodiments, the adapter 400 includes a connecting portion 440 and a fixing portion 450, with a bending vertex 410 located between the connecting portion 440 and the fixing portion 450.

[0060] The connecting part 440 is connected to the tab assembly 300, and the fixing part 450 is connected to the side shell 130. Both the connecting part 440 and the fixing part 450 are elastic. During the insertion of the electrode assembly 200 into the shell, the fixing part 450 is connected to the shell 100. Since the fixing part 450 is elastic, and the connecting part 440 is connected to the tab assembly 300 and is also elastic, the fixing part 450 and the connecting part 440 have an elastic force that pulls the connecting part 440 and the tab assembly 300. This facilitates the automatic assembly of the tab assembly 300, improves the problem of breakage caused by accumulation and compression at the root of the tab, and helps to improve the safety of the secondary battery 001.

[0061] Referring to Figures 3 and 4, in some embodiments, the side shell 130 surrounds and seals the bottom shell 120, and an insertion space 140 is provided between the electrode assembly 200 and the side shell 130, within which the electrode assembly 200 is housed. Before the electrode assembly 200 is inserted into the shell, the tab assembly 300 and the adapter 400 can be housed within the insertion space 140, thereby providing accommodating space for the electrode assembly 200 and improving the ease of insertion.

[0062] In some embodiments, along the thickness direction of the electrode assembly 200, the minimum length of the fixing region 430 and the bottom shell 120 along the thickness direction of the electrode assembly 200 is c, satisfying 0 < c < 0.3H. Controlling the minimum length of the fixing region 430 and the bottom shell 120 along the thickness direction of the electrode assembly 200 to between 0 and 0.3 times the thickness of the electrode assembly 200 facilitates providing a welding position for the fixing part 450 and improves welding convenience.

[0063] In other embodiments, the minimum length c of the fixing region 430 and the bottom shell 120 along the thickness direction of the electrode assembly 200 satisfies 0.1H < c < 0.3H. The minimum length of the fixing region 430 and the bottom shell 120 along the thickness direction of the electrode assembly 200 is controlled between 0.1H and 0.3 times the thickness of the electrode assembly 200, which helps to leave more welding positions for the fixing part 450 and further improves the convenience of welding.

[0064] Preferably, the minimum length c of the fixed region 430 and the bottom shell 120 along the thickness direction of the electrode assembly 200 satisfies 0.15H < c < 0.25H.

[0065] In some embodiments, the thickness H of the cavity 110 is 5 mm, and 0.75 mm < c < 1.25 mm.

[0066] In some embodiments, the minimum length c of the fixed region 430 and the bottom shell 120 along the thickness direction of the electrode assembly 200 is any one of 0.75, 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.1, 1.15, 1.2, and 1.25.

[0067] Referring to Figure 5, in some embodiments, an insulating member 500 is provided on the surface of the fixed area 430 facing the tab assembly 300, thereby separating the tab assembly 300 from the fixed area 430, improving the problem of wear on the tab after the tab assembly 300 comes into contact with the fixed area 430, and improving the safety of the tab assembly 300.

[0068] An insulating element 500 is provided on the surface of the bottom shell 120 facing the tab assembly 300, thereby separating the tab assembly 300 from the bottom shell 120, improving the problem of wear on the tabs after the tab assembly 300 comes into contact with the bottom shell 120, and improving the safety of the tab assembly 300.

[0069] Please refer to Figure 6. An embodiment of this application provides an electrical device 002, which includes the secondary battery 001 in the above embodiments.

[0070] To verify the impact of the structure of the adapter 400 on the charge and discharge performance of the secondary battery 001, the following experiments were conducted:

[0071] Vibration and shock test: 20 secondary batteries (001) were used for each comparative and example test group. Each secondary battery (001) was placed in a 25°C environment and left to stand for 30 minutes. The secondary battery (001) to be tested was fixed on a platform, and a 25g, 15ms half-sine wave impact waveform was applied to the secondary battery (001) using a vibration testing machine. The impact was performed 3 times along the head direction of the cell, and observed for 2 hours. The test was considered passed if the cells' tabless broke.

[0072] The following describes the specific implementation of the secondary battery 001 in the embodiments and comparative examples, using a winding structure as an example.

[0073] (1) Preparation of the anode electrode: Artificial graphite, conductive carbon black (Super P), and styrene-butadiene rubber (SBR) were mixed in a weight ratio of 96:1.5:2.5. Deionized water was added as a solvent to prepare an anode active material slurry with a weight percentage of 70 wt%, which was then stirred evenly. A 10 μm thick copper foil was used as the anode current collector. The anode active material slurry was uniformly coated onto one surface of the anode current collector along its thickness direction using a slot coater, leaving an empty foil area without an anode active material layer at one end of the anode current collector's width direction. The foil was dried at 110°C to obtain an anode electrode substrate with a single-sided anode active material layer. The above steps were then repeated on the other side of the anode current collector along its thickness direction, leaving an empty foil area without an anode active material layer at one end of the anode current collector's width direction, to obtain an anode electrode substrate with a double-sided anode active material layer, wherein the compaction of the anode active material layer was 1.70 g / cm³. 3 A single anode sheet is obtained by punching the anode electrode substrate using a mold and a die-cutting blade. The empty foil areas without an anode active material layer form anode tabs. Therefore, the anode tabs are assembled to form an anode tab assembly 300.

[0074] (2) Preparation of cathode electrode: Lithium cobalt oxide (LiCoO2), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) were mixed in a weight ratio of 97.5:1.0:1.5. N-methylpyrrolidone (NMP) was added as a solvent to prepare a cathode active material slurry with a solid content of 75 wt%, and the mixture was stirred evenly for later use. A 10 μm thick aluminum foil was used as the cathode current collector. The above cathode active material slurry was uniformly coated on one surface of the cathode current collector along its thickness direction using a slot coater. An empty foil area without a cathode active material layer was reserved at one end of the cathode current collector in the width direction. The foil was dried at 90°C to obtain a cathode electrode substrate with a cathode active material layer coated on one side. The above steps were then repeated on the other side of the cathode current collector along its thickness direction, with an empty foil area without a cathode active material layer reserved at one end of the cathode current collector in the width direction, to obtain a cathode electrode substrate with cathode active material layers coated on both sides. A single cathode electrode is obtained by punching the cathode electrode substrate using a mold and a die-cutting blade. The empty foil areas where no cathode active material layer is set form cathode tabs. Therefore, the cathode tabs are assembled to form a cathode tab assembly 300.

[0075] (3) Preparation of electrolyte: In a dry argon atmosphere, ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) are first mixed in a mass ratio of EC:EMC:DEC = 30:50:20 to form a basic organic solvent. Then, lithium salt lithium hexafluorophosphate (LiPF6) is added to the basic organic solvent to dissolve and mix evenly to obtain an electrolyte with a lithium salt concentration of 1.15 mol / L and an electrolyte conductivity of 8.0 S / m.

[0076] (4) Preparation of diaphragm 220: The diaphragm 220 adopts a three-layer structure with a thickness of 5 μm, which includes a first adhesive layer, a first substrate layer and a second adhesive layer stacked together. The first substrate layer is made of polyethylene (PE), and both the first adhesive layer and the second adhesive layer contain a first adhesive and boehmite.

[0077] (5) Electrode assembly 200 preparation: A first electrode 210, a diaphragm 220 and a second electrode 230 are stacked along the first direction X to form a winding layer, and the winding layer is then wound to form a winding structure, wherein the first electrode 210 is set to 17 layers and the second electrode 230 is set to 18 layers.

[0078] (6) Assembly of electrode assembly 200: First, one end of the adapter 400 is welded to the anode tab assembly 300 to form a connection area 420. Then, the other end of the adapter 400 is welded to the side shell 130 to form a fixing area 430. Finally, the electrode assembly 200 is housed between the bottom shell 120 and the side shell 130, and the cover plate 150 is welded to the side shell 130 to form a sealed shell 100. The secondary battery 001 has a length of 60 mm, a width of 45 mm, and a thickness of 5.2 mm. The thickness H of the cavity 110 is 5 mm, and the thickness of the electrode assembly 200 is 4.8 mm. The maximum length a of the bending vertex 410 and the connecting area 420 along the thickness direction of the electrode assembly 200 is 2.45 mm, the maximum length b of the bending vertex 410 and the fixing area 430 along the thickness direction of the electrode assembly 200 is 2.95 mm, and the minimum length c of the fixing area 430 and the bottom shell 120 along the thickness direction of the electrode assembly 200 is 0.5 mm.

[0079] (7) Electrolyte injection and encapsulation: Electrolyte is injected into the assembled electrode assembly 200, and after vacuum encapsulation, standing, hot pressing formation, shaping and other processes, the secondary battery 001 is obtained.

[0080] Comparative Example 1: The difference from Example 1 is that the maximum length a of the bending vertex 410 and the connecting area 420 along the thickness direction of the electrode assembly 200 is 2.7 mm, and the maximum length b of the bending vertex 410 and the fixing area 430 along the thickness direction of the electrode assembly 200 is 2.7 mm.

[0081] Example 2: The difference from Example 1 is that the maximum length a of the bending vertex 410 and the connecting area 420 along the thickness direction of the electrode assembly 200 is 2.2 mm, and the maximum length b of the bending vertex 410 and the fixing area 430 along the thickness direction of the electrode assembly 200 is 3.2 mm.

[0082] Example 3: The difference from Example 1 is that the maximum length a of the bending vertex 410 and the connecting area 420 along the thickness direction of the electrode assembly 200 is 1.7 mm, and the maximum length b of the bending vertex 410 and the fixing area 430 along the thickness direction of the electrode assembly 200 is 3.7 mm.

[0083] Example 4: The difference from Example 1 is that the maximum length a of the bending vertex 410 and the connecting area 420 along the thickness direction of the electrode assembly 200 is 1.5 mm, and the maximum length b of the bending vertex 410 and the fixing area 430 along the thickness direction of the electrode assembly 200 is 3.9 mm.

[0084] Example 5: The difference from Example 1 is that the maximum length a of the bending vertex 410 and the connecting area 420 along the thickness direction of the electrode assembly 200 is 1.2 mm, and the maximum length b of the bending vertex 410 and the fixing area 430 along the thickness direction of the electrode assembly 200 is 4.2 mm.

[0085] Example 6: The difference from Example 1 is that the minimum length c of the fixed area 430 and the bottom shell 120 along the thickness direction of the electrode assembly 200 is 0.3 mm.

[0086] Example 7: The difference from Example 1 is that the minimum length c of the fixed area 430 and the bottom shell 120 along the thickness direction of the electrode assembly 200 is 0.3 mm.

[0087] The main parameter controls and test results for each embodiment and comparative example are shown in Table 1:

[0088] Table 1

[0089] Analysis of Table 1 shows that Embodiments 1 to 7, which meet the features of this application, can effectively improve the safety of the secondary battery 001.

[0090] In Comparative Example 1, along the thickness direction of the electrode assembly 200, the maximum length a of the bending vertex 410 and the connecting region 420 along the thickness direction of the electrode assembly 200 is the same as the maximum length b of the bending vertex 410 and the fixing region 430 along the thickness direction of the electrode assembly 200. As a result, during the process of inserting the electrode assembly 200 into the housing, the tab assembly 300 accumulates in the housing space 140, causing the secondary battery 001 to break.

[0091] In Example 1, compared to Comparative Example 1, the difference between the maximum length a of the bending vertex 410 and the connecting area 420 along the thickness direction of the electrode assembly 200 and the maximum length b of the bending vertex 410 and the fixed area 430 along the thickness direction of the electrode assembly 200 is 0.5 mm, so that the adapter 400 can pull the tab assembly 300 to move within the housing space 140. The number of tests passed is increased, the problem of breakage at the root of the tab due to accumulation and compression is improved, and the safety of the secondary battery 001 is improved.

[0092] In Example 2, compared to Example 1, the difference between the maximum length a of the bending vertex 410 and the connecting area 420 along the thickness direction of the electrode assembly 200 and the maximum length b of the bending vertex 410 and the fixed area 430 along the thickness direction of the electrode assembly 200 is increased from 0.5 mm to 1 mm, so that the distance that the adapter 400 pulls the tab assembly 300 to move within the housing space 140 is increased, and the number of tests passed is increased.

[0093] In Example 3, compared to Example 2, the difference between the maximum length a of the bending vertex 410 and the connecting area 420 along the thickness direction of the electrode assembly 200 and the maximum length b of the bending vertex 410 and the fixed area 430 along the thickness direction of the electrode assembly 200 is increased from 1 mm to 2 mm, so that the distance that the adapter 400 pulls the tab assembly 300 to move within the housing space 140 is further increased, and the number of tests passed is increased.

[0094] In Example 4, compared to Example 3, the difference between the maximum length a of the bending vertex 410 and the connecting area 420 along the thickness direction of the electrode assembly 200 and the maximum length b of the bending vertex 410 and the fixed area 430 along the thickness direction of the electrode assembly 200 is increased from 2 mm to 2.4 mm, so that the distance that the adapter 400 pulls the tab assembly 300 to move within the housing space 140 is further increased, and the number of tests passed is increased.

[0095] In Example 5, compared to Example 4, the difference between the maximum length a of the bending vertex 410 and the connecting region 420 along the thickness direction of the electrode assembly 200 and the maximum length b of the bending vertex 410 and the fixed region 430 along the thickness direction of the electrode assembly 200 is increased from 2.5 mm to 3 mm, and the number of tests passed is increased to a certain extent compared to Comparative Example 1.

[0096] As shown in Table 1, satisfying ba < 0.5H can reduce the interference between the adapter 400 and the cover plate 150 during the insertion of the electrode assembly 200 into the casing, thereby further improving the safety of the secondary battery 001.

[0097] As can be seen from Table 1, compared with Examples 6 and 7, Example 1 can further improve the safety of the secondary battery 001 by controlling the minimum length c of the fixed area 430 and the bottom shell 120 along the thickness direction of the electrode assembly 200 to between 0.75 mm and 1.25 mm.

[0098] Furthermore, those skilled in the art should recognize that the above embodiments are merely illustrative of this application and are not intended to limit the scope of this application. Any appropriate changes and modifications made to the above embodiments within the substantive scope of this application fall within the scope of this disclosure.

[0099] Furthermore, those skilled in the art can make various other corresponding changes and modifications based on the technical concept of this application, and all such changes and modifications should fall within the protection scope of the claims of this application.

Claims

1. A secondary battery, characterized in that, include: A housing having a cavity; An electrode assembly, wherein the electrode assembly is housed within the cavity; A tab assembly, wherein the tab assembly is connected to the electrode assembly; An adapter is provided, wherein the adapter is bent along the thickness direction of the electrode assembly, and the adapter has a bend vertex; one end of the adapter is connected to the tab assembly and has a connection area, and the other end of the adapter is connected to the housing and has a fixing area; the maximum length of the bend vertex and the connection area along the thickness direction of the electrode assembly is a, and the maximum length of the bend vertex and the fixing area along the thickness direction of the electrode assembly is b, satisfying ba > 0.

2. The secondary battery as described in claim 1, characterized in that, Along the thickness direction of the electrode assembly, the thickness of the cavity is H, satisfying ba < 0.5H.

3. The secondary battery as described in claim 1 or 2, characterized in that, The adapter includes a connecting part and a fixing part, the bending vertex is located between the connecting part and the fixing part, the connecting part is connected to the tab assembly, the fixing part is connected to the housing, and both the connecting part and the fixing part are elastic.

4. The secondary battery as described in claim 1, characterized in that, The housing includes a bottom shell and a side shell. The side shell surrounds and is sealed to the bottom shell. There is an insertion space between the electrode assembly and the side shell, and the electrode assembly is housed in the insertion space.

5. The secondary battery as described in claim 4, characterized in that, Along the thickness direction of the electrode assembly, the minimum length of the fixed region and the bottom shell along the thickness direction of the electrode assembly is c, satisfying 0 < c < 0.3H.

6. The secondary battery as described in claim 5, characterized in that, It satisfies 0.1H < c < 0.3H.

7. The secondary battery as described in claim 1, characterized in that, The electrode assembly includes a first electrode, a diaphragm, and a second electrode. The diaphragm is disposed between the first and second electrodes. The first and second electrodes have opposite polarities. The first electrode, the second electrode, and the diaphragm are stacked and wound to form a wound structure. The first electrode includes a first current collector and a first active material layer. The first current collector includes a first main body region and a plurality of first empty foil regions disposed on the side of the first main body region. The first active material layer is disposed on the surface of the first main body region, and the first active material layer is not disposed on the surface of the first empty foil regions. The first empty foil regions of the plurality of first electrodes are wound and stacked along the thickness direction of the electrode assembly to form the tab assembly.

8. The secondary battery as described in claim 1, characterized in that, The electrode assembly includes a plurality of first electrodes, a plurality of second electrodes, and a separator disposed between the first electrodes and the second electrodes, all stacked along the thickness direction. The first electrodes and the second electrodes have opposite polarities. The first electrodes, the separator, and the second electrodes are stacked to form a stacked structure. The first electrode includes a first current collector and a first active material layer. The first current collector includes a first body region and a first empty foil region. The first active material layer is disposed on the surface of the first body region, and the first active material layer is not disposed on the surface of the first empty foil region. The first empty foil regions of the plurality of first electrodes are stacked along the thickness direction of the electrode assembly to form the tab assembly.

9. The secondary battery as described in claim 6, characterized in that, Insulating elements are provided on the surface of the fixed area facing the tab assembly and on the surface of the bottom shell facing the tab assembly.

10. An electrical appliance, characterized in that, Includes the secondary battery as described in any one of claims 1 to 9.

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