Electrode assembly and battery cell

Abstract

The application discloses an electrode assembly and a battery cell, and relates to the technical field of batteries, wherein the electrode assembly comprises a first electrode assembly, a second electrode assembly, a first connecting structure and a second connecting structure, the first electrode assembly is provided with a first positive electrode tab and a first negative electrode tab, the second electrode assembly is provided with a second positive electrode tab and a second negative electrode tab, the first electrode assembly is connected with the second positive electrode tab through the first connecting structure, the first electrode assembly is connected with the second negative electrode tab through the second connecting structure, and the first electrode assembly and the second electrode assembly are arranged in a laminated mode; the technical scheme provided by the embodiment of the application connects every adjacent first electrode assembly and second electrode assembly, and makes them arranged in a laminated mode, so that a plurality of first electrode assemblies and second electrode assemblies share a group of electrode tabs, thereby greatly reducing the thickness of the electrode tabs and ensuring that the first electrode assemblies and the second electrode assemblies are not limited by the maximum value of the thickness design of the electrode tabs when the number of the first electrode assemblies and the second electrode assemblies increases.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to an electrode assembly and a battery cell. Background Technology

[0002] Stacked batteries are a type of battery structure manufactured using a stacking process. Their core feature is the alternating stacking of positive electrode sheets, negative electrode sheets, and separators to form a multi-layered electrode structure, also known as a stacked core. Compared to traditional wound batteries, stacked batteries offer more uniform current distribution, higher energy density, and better mechanical stability, making them particularly suitable for high-rate charge / discharge and high-capacity applications. The stacking process effectively reduces internal polarization, improving cycle life and safety. Furthermore, stacked batteries offer greater structural flexibility, allowing for customized electrode sizes and the number of layers to meet diverse market demands.

[0003] Generally speaking, to improve the energy storage capacity of stacked batteries, the number of stacked cells in each stack is increased. As the number of stacked cells increases, the overall thickness also increases, which leads to an increase in the number of tabs in each stack. The tabs need to be designed to be very long in order to achieve welding after being brought together. Utility Model Content

[0004] Several embodiments in this application propose an electrode assembly and a battery cell designed to shorten the tab length and double the design constraints on the thickness dimensions of the stacked cells.

[0005] An electrode assembly proposed in one embodiment of this application includes:

[0006] A first electrode assembly, the first electrode assembly having a first positive electrode tab and a first negative electrode tab;

[0007] The second electrode assembly has a second positive electrode tab and a second negative electrode tab;

[0008] A first connection structure, wherein the first electrode assembly is connected to the second positive electrode tab via the first connection structure; and

[0009] The second connection structure is used to connect the first electrode assembly to the second negative electrode tab.

[0010] The first electrode assembly and the second electrode assembly are stacked.

[0011] In one embodiment, the first connection structure is disposed at the end of the first electrode assembly that is away from the first positive electrode tab, and the second connection structure is disposed at the end of the first electrode assembly that is away from the first negative electrode tab, with the first connection structure and the second connection structure being spaced apart.

[0012] In one embodiment, the first connection structure is a first auxiliary electrode tab, and the second connection structure is a second auxiliary electrode tab, wherein the first auxiliary electrode tab and the second auxiliary electrode tab are respectively connected to the second positive electrode tab and the second negative electrode tab.

[0013] In one embodiment, the first connection structure includes a first auxiliary electrode tab and a first connecting piece, wherein the first auxiliary electrode tab is connected to the second positive electrode tab via the first connecting piece; and / or

[0014] The second connection structure includes a second auxiliary electrode tab and a second connecting piece, wherein the second auxiliary electrode tab is connected to the second negative electrode tab via the second connecting piece.

[0015] In one embodiment, the first auxiliary electrode tab and the first connecting piece are welded together; and / or

[0016] The second auxiliary electrode lug and the second connecting piece are welded together.

[0017] In one embodiment, the first electrode assembly includes a positive electrode sheet, a separator, and a negative electrode sheet stacked sequentially. Each positive electrode sheet is provided with a first positive electrode tab, and multiple first positive electrode tabs are stacked. Each negative electrode sheet is provided with a first negative electrode tab, and multiple first negative electrode tabs are stacked.

[0018] In one embodiment, the first positive electrode tab and the first negative electrode tab are offset in a plane parallel to the first positive electrode tab and the first negative electrode tab.

[0019] In one embodiment, the separator includes a plurality of straight segments disposed along the stacking direction of the positive electrode and the negative electrode and a transition segment connecting two adjacent straight segments, wherein the straight segments are at least partially disposed between the positive electrode and the negative electrode.

[0020] One embodiment of this application also proposes a battery cell, comprising:

[0021] The shell has a receiving cavity;

[0022] The electrode includes a positive electrode and a negative electrode that penetrate the housing;

[0023] At least one electrode assembly as described above is housed in the receiving cavity.

[0024] In one embodiment, the first positive electrode tab of each electrode assembly is connected to the positive electrode post, and the first negative electrode tab is connected to the negative electrode post.

[0025] In the various embodiments provided in this application, the first electrode assembly and the second electrode assembly are connected and stacked, allowing multiple first and second electrode assemblies to share a single set of tabs. This significantly reduces the thickness of the tabs, eliminating the need to extend their length and facilitating easy assembly and welding. Specifically, the electrode assembly includes a first electrode assembly, a second electrode assembly, a first connecting structure, and a second connecting structure. The first and second electrode assemblies each include a positive electrode sheet, a separator, and a negative electrode sheet stacked sequentially. Both the first and second electrode assemblies share a first positive tab and a first negative tab for current input and output, thereby reducing the number of tabs required and avoiding the problem of difficult assembly and welding due to large tab thickness. This also ensures that even with an increased number of electrode assemblies, the maximum tab thickness is not a limitation, thus improving the energy storage capacity of the electrode assembly. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments or prior art of this application, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0027] Figure 1 A schematic diagram of the structure of an embodiment of the electrode assembly provided in this application in its unfolded state;

[0028] Figure 2 for Figure 1 Schematic diagram of the middle electrode assembly in its folded state;

[0029] Figure 3 This is a schematic diagram of another embodiment of the electrode assembly provided in this application;

[0030] Figure 4 for Figure 1 A planar schematic diagram of the positive and negative electrode plates of the first electrode assembly;

[0031] Figure 5 for Figure 1 An exploded structural diagram of an embodiment of the first electrode assembly;

[0032] Figure 6 This is a schematic diagram of the structure of a single battery cell provided in this application.

[0033] Explanation of icon numbers:

[0034] 100. Electrode assembly; 1. First electrode assembly; 11. First positive electrode tab; 12. First negative electrode tab; 13. Positive electrode plate; 14. Negative electrode plate; 2. Second electrode assembly; 21. Second positive electrode tab; 22. Second negative electrode tab; 3. First connecting structure; 31. First auxiliary electrode plate; 32. First connecting piece; 4. Second connecting structure; 41. Second auxiliary electrode plate; 42. Second connecting piece; 5. Diaphragm; 51. Straight section; 52. Transition section; 6. Third electrode assembly; 7. Fourth electrode assembly;

[0035] 200. Battery cell; 211. Positive terminal; 212. Negative terminal; 220. Casing. Detailed Implementation

[0036] The technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of several embodiments. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0037] It should be noted that if multiple embodiments of this application involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0038] Furthermore, if multiple embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text implies three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0039] Generally speaking, to improve the energy storage capacity of stacked batteries, the number of stacks in each electrode assembly is increased. As the number of internal stacks increases, the overall thickness also increases, which leads to an increase in the number of tabs in each electrode assembly. The tabs need to be designed to be very long in order to achieve welding after being brought together.

[0040] To address the aforementioned problems, this application proposes an electrode assembly 100 to solve the technical issues described above.

[0041] Please see Figure 1 In one embodiment of this application, the electrode assembly 100 includes a first electrode assembly, a second electrode assembly, a first connection structure, and a second connection structure. The first electrode assembly has a first positive electrode tab and a first negative electrode tab, and the second electrode assembly has a second positive electrode tab and a second negative electrode tab. The first electrode assembly is connected to the second positive electrode tab through the first connection structure, and the first electrode assembly is connected to the second negative electrode tab through the second connection structure. The first electrode assembly and the second electrode assembly are stacked.

[0042] It is understood that the electrode assembly 100 proposed in this application is applicable to stacked batteries, and the aforementioned first electrode assembly 1 or second electrode assembly 2 is the smallest energy storage unit in a stacked battery formed by stacking multiple electrode sheets. A stacked battery is a battery manufactured using a stacking process, and its structure mainly consists of a positive electrode 13, a negative electrode 14, a separator 5, and an electrolyte. In a stacked battery, the positive electrode 13 and negative electrode 14 are typically made of metal foil, such as aluminum foil and copper foil, as current collectors, while the active material is coated onto these foils. The separator 5 is made of materials such as polyolefins, which have good chemical stability and mechanical strength, preventing short circuits. During the manufacturing process, the positive electrode 13, separator 5, and negative electrode 14 are stacked sequentially; for details, please refer to further documentation. Figure 5 The separator 5 serves to isolate the positive and negative electrodes and prevent short circuits, while allowing lithium ions to pass through to complete the electrochemical reaction. During the stacking process, the separator 5 can be employed as follows: Figure 5 The Z-shaped folding method shown alternatingly stacks the positive and negative electrode sheets 14 to form a stable stacked core structure. This arrangement not only ensures the ion conduction path inside the battery but also enhances battery safety through the microporous structure of the separator 5, such as limiting current and preventing thermal runaway in case of overheating or overcharging. The separator 5, positive electrode sheet 13, separator 5, and negative electrode sheet 14, stacked sequentially, constitute the smallest energy storage unit (hereinafter referred to as electrode assembly 100). The first electrode assembly 1 and the second electrode assembly 2, or the first electrode assembly 1, the second electrode assembly 2, ... and the nth electrode assembly array arrangement constitute the aforementioned electrode assembly 100. Subsequently, the stacked electrode assembly 100 is installed into the casing 220 of the battery cell 200, and electrolyte is injected. After sealing, formation, and other processes, the stacked battery is finally manufactured. The electrode assembly 100 described above can provide a larger electrode surface area and reduce the number of tabs, which helps to improve the energy density and charge / discharge efficiency of the battery.

[0043] Generally speaking, the internal structure of an electrode assembly is arranged according to a certain pattern. Taking the first electrode assembly 1 as an example, the first electrode assembly 1 contains multiple positive electrode plates 13, multiple negative electrode plates 14, and a separator 5. Each positive electrode plate 13 requires a positive electrode tab 21 to realize the input and output of current. It can be seen that, assuming that the thickness of each positive electrode plate 13 and each negative electrode plate 14 is L1, and the thickness of a separator 5 is L2, taking the first electrode assembly 1 composed of separator 5, positive electrode plate 13, separator 5 and negative electrode plate 14 stacked in sequence as an example, its theoretical thickness value should be 2(L1+L2). Furthermore, if the thickness of a single electrode tab (including positive electrode tab 21 and negative electrode tab 22) is L3, and since the positive electrode tab 21 and negative electrode tab 22 are staggered in space and are located on the same plane, then the theoretical thickness value of the electrode tab in the first electrode assembly 1 should be L3. Similarly, based on this embodiment, if the first electrode assembly 1 contains n energy storage units as described above, then the theoretical thickness of the first electrode assembly 1 should be 2(L1+L2). n, the theoretical thickness of the tab in the first electrode assembly 1 should be n L3.

[0044] When the technical solution proposed in this application is adopted, each pair of adjacent first electrode components 1 and second electrode components 2 are connected in series. The current only needs to be input and output in any one of the electrode components. Taking two first electrode components 1 containing n energy storage units as described above as an example, its energy storage capacity is equivalent to that of a first electrode component 1 containing 2n energy storage units as described above. However, since the first electrode components 1 and second electrode components 2 share a set of tabs, the theoretical thickness of the tabs in the electrode component 100 should be n. L3, not 2n L3. It can be seen that when adopting the technical solution proposed in this application, the thickness of the electrode tab can be greatly reduced while ensuring the same energy storage capacity. Therefore, it is not necessary to design the electrode tab to be very long, nor is there a problem of the electrode tab being difficult to gather and weld together.

[0045] Furthermore, based on the above extension, the number of electrode assemblies can be further increased by connecting two or more stacked cores in series, thereby increasing the battery's energy storage capacity exponentially. Since the first electrode assembly 1, the second electrode assembly 2, and so on up to the nth electrode assembly are connected in series, only one set of tabs is needed for current introduction and output, allowing multiple stacked cores to share the same set of tabs. This application does not limit the number of electrode assemblies 100 connected in series and can make adaptive adjustments according to actual energy storage needs. In addition, in battery embodiments with multiple electrode assemblies 100, the multiple electrode assemblies 100 can be arranged by winding or by sequential folding. This application does not limit this. In one embodiment of this application, the multiple electrode assemblies 100 are arranged by sequential reciprocating folding. For details, please refer to further explanation. Figure 4 , Figure 4 The provided embodiment includes a first electrode assembly 1, a second electrode assembly 2, a third electrode assembly 6, and a fourth electrode assembly 7. These four electrode assemblies are connected sequentially and folded back and forth, their structural principle being similar to that of a folding fan, folding in a Z-shape. A separator 5 is placed between adjacent electrode assemblies 100 to prevent short circuits caused by contact between electrode sheets. When multiple electrode assemblies 100 are folded, their overall shape is square, making fuller use of the internal space of the battery cell housing 220. Compared to a wound design, the stacked first electrode assembly 1 and second electrode assembly 2 do not have the curvature at the corners of the winding, fully utilizing the corner space of the battery, thus achieving higher energy density with the same cell volume. Furthermore, the stacked first electrode assembly 1 and second electrode assembly 2 ensure that the bending moment of each tab is the same, avoiding stress concentration problems.

[0046] In the various embodiments provided in this application, the first electrode assembly 1 and the second electrode assembly 2 are connected and stacked, so that multiple first electrode assemblies 1 and second electrode assemblies 2 share a set of tabs. This greatly reduces the thickness of the tabs and allows for easy convergence and welding without extending the length of the tabs. Specifically, the electrode assembly includes a first electrode assembly 1, a second electrode assembly 2, a first connecting structure 3, and a second connecting structure 4. The first electrode assembly 1 and the second electrode assembly 2 respectively include a positive electrode sheet 13, a diaphragm 5, and a negative electrode sheet 14 stacked sequentially. The first electrode assembly 1 and the second electrode assembly 2 in the electrode assembly share a first positive electrode tab 11 and a first negative electrode tab 12 to realize current input and output, thereby reducing the number of tabs required and avoiding the problem of difficulty in convergence and welding due to large tab thickness. It also ensures that when the number of electrode assemblies increases, it is not limited by the maximum design value of the tab thickness, thereby improving the energy storage capacity of the electrode assembly.

[0047] In the technical solution of this application, in order to achieve electrical connection between adjacent first electrode assembly 1 and second electrode assembly 2, the first electrode assembly 1 is provided with a first auxiliary electrode tab 31 and a second auxiliary electrode tab 32. For details, please refer to further details. Figure 1 or Figure 2 Taking a battery cell 200 with two electrode assemblies, a first electrode assembly 1 and a second electrode assembly 2, as an example, the first electrode assembly 1 has a first auxiliary electrode tab 31 and a second auxiliary electrode tab 32 on the side adjacent to the second electrode assembly 2. Correspondingly, the second electrode assembly 2 has a second positive electrode tab 21 and a second negative electrode tab 22. The first auxiliary electrode tab 31 is connected to the second positive electrode tab 21, and the second auxiliary electrode tab 32 is connected to the second negative electrode tab 22, thereby realizing the series connection of the first electrode assembly 1 and the second electrode assembly 2. The first positive electrode tab 11 and the first negative electrode tab 22 are used to lead out. The negative electrode tab 12 can be located on the first electrode assembly 1 or the second electrode assembly 2. The tab is used for the input and output of current between the two first electrode assemblies 1 and the second electrode assembly 2. For example, if the tab is located on the first electrode assembly 1 and the second electrode assembly 2, then when the battery is charging, the external current is input to the first electrode assembly 1 from the first positive electrode tab 11 and the first negative electrode tab 12, and is transmitted to the second electrode assembly 2 through the first connection structure 3 and the second connection structure 4 between the first electrode assembly 1 and the second electrode assembly 2; otherwise, external discharge is realized.

[0048] In this application, the choice of materials for the electrode tabs is widely applicable, and can include metallic aluminum, nickel-plated copper, or other metallic materials with excellent conductivity. This application does not impose specific limitations on these materials. In one embodiment of this application, the positive electrode tab is made of metallic aluminum, while the negative electrode tab is made of nickel-plated copper. Due to its excellent conductivity, metallic aluminum can significantly reduce the internal resistance of the battery, thereby improving the battery's energy transfer efficiency. Simultaneously, aluminum has a low density, which helps reduce the overall weight of the battery. Under the same volume or weight constraints, more electrode material can be accommodated, thus increasing the battery's energy density. The nickel-plated copper used for the negative electrode tab benefits from copper's high conductivity and good mechanical properties, meeting the battery's performance requirements under high-current charge and discharge conditions, ensuring stable current transmission and electrode structure stability. The nickel plating further enhances the material's corrosion resistance, effectively resisting the chemical corrosion environment that the battery may encounter during use, while also improving welding performance, ensuring a firm connection between the electrode tab and other battery components. This material combination not only ensures the stability and reliability of the battery during use but also effectively extends the battery's lifespan, providing a guarantee for the long-term stable operation of the battery.

[0049] It is understood that, since the final state of this electrode assembly 100 is a folded state, the total length of the first connecting structure 3 and the second connecting structure 4 located at the end of the first electrode assembly 1 near the second electrode assembly 2, after being connected to the second positive electrode tab 21 and the second negative electrode tab 22 of the second electrode assembly 2, must satisfy the requirement that when the first electrode assembly 1 and the second electrode assembly 2 are in the folded state, the tabs of the same polarity on the first electrode assembly 1 and the second electrode assembly 2 can contact the other tab, thereby achieving electrical connection. It should be noted that adjacent tabs of the same polarity can be electrically connected by overlapping or by means of an external conductive structure. This application does not limit this. In one embodiment of this application, the first auxiliary electrode 31 of the first electrode assembly 1 is connected to the second positive electrode tab 21 of the second electrode assembly 2 through the first connecting piece 32. Correspondingly, the second auxiliary electrode 41 of the first electrode assembly 1 is connected to the second negative electrode tab 22 of the second electrode assembly 2 through the second connecting piece 42. For details, please refer to further... Figure 1 and Figure 2 Taking the two tabs connected by the first connecting piece 32 as an example, the first auxiliary electrode 31 and the second positive electrode 22 are fixed to both sides of the first connecting piece 32 by ultrasonic welding. A high-energy-density laser beam is used to locally heat the tabs and the first connecting piece 32, achieving rapid melting and a strong metallurgical bond. Typically, the tabs are first ultrasonically pre-welded to form a single unit with the first connecting piece 32, and then laser welding is used to firmly connect the tabs to the first connecting piece 32. Laser welding allows for precise control of welding parameters, such as pulse width and frequency, to adapt to tabs of different materials and thicknesses, ensuring consistent and stable welding quality. This process not only improves welding efficiency but also significantly reduces battery performance problems caused by welding defects. Because the first connecting piece 32 has a certain thickness, welding the two tabs to it is easier, avoiding direct welding of the first auxiliary electrode 31 and the second positive electrode 22, which would complicate the process.

[0050] In this application, the materials of the first connecting piece 32 and the second connecting piece 42 can be any conductive metal material with a certain structural strength; no specific limitations are imposed. In one embodiment of this application, the material of the connecting piece matches the material of the electrode tab to ensure consistency and reliability of the welding process. Specifically, the first connecting piece 32 used to connect the first electrode tab 31 is made of aluminum, while the second connecting piece 42 used to connect the second electrode tab 41 is made of copper. This ensures that the connecting pieces and the corresponding electrodes maintain consistent material properties, thereby achieving better metallurgical bonding during the welding process and ensuring the conductivity and mechanical strength of the welded area. This design not only improves the overall structural stability of the battery but also optimizes its electrical performance, providing crucial assurance for efficient battery operation and long-term reliability.

[0051] It is understood that the first electrode assembly 1 or the second electrode assembly 2 may also include multiple energy storage units composed of positive electrode plates 13, separators 5, and negative electrode plates 14 arranged in a certain pattern. The separator 5 includes multiple straight sections 51 arranged along the stacking direction of the positive electrode plates 13 and the negative electrode plates 14, and transition sections 52 connecting adjacent straight sections 51. The straight sections 51 are at least partially located between the positive electrode plates 13 and the negative electrode plates 14. For details, please refer to further reading. Figure 5 When the thickness of a single electrode assembly increases, the number of the first electrode assembly 1 or the second electrode assembly 2 in the electrode assembly 100 should be reduced to ensure the rationality of the structural layout.

[0052] This application also proposes a battery cell 200, which includes a housing 220, terminals, and an electrode assembly 100 as described above. The housing 220 forms a receiving cavity in which the electrode assembly 100 is housed. The terminals include a positive terminal 211 and a negative terminal 212, both of which penetrate the housing 220. The electrode assembly 100 is electrically connected to the positive terminal 211 and the negative terminal 212 via a positive tab 21 and a negative tab 22, respectively, to achieve electrical connection with an external circuit. For details, please refer to further description. Figure 1 , Figure 6 The battery cell 200 may include one or more electrode assemblies 100. In the embodiments provided in this application, the battery cell 200 includes two electrode assemblies 100, which are arranged side by side and electrically connected to each other. The specific structure of the electrode assembly 100 is as described in the above embodiments. Since the battery cell 200 adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0053] The above description is merely an exemplary embodiment of this application and does not limit the patent scope of this application. Any equivalent structural transformations made based on the technical concept of this application and the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. An electrode assembly, characterized in that, include: A first electrode assembly (1) having a first positive electrode tab (11) and a first negative electrode tab (12); The second electrode assembly (2) has a second positive electrode tab (21) and a second negative electrode tab (22); The first connection structure (3) is used to connect the first electrode assembly (1) to the second positive electrode tab (21). as well as The second connection structure (4) is used to connect the first electrode assembly (1) to the second negative electrode tab (22). The first electrode assembly (1) and the second electrode assembly (2) are stacked.

2. The electrode assembly as described in claim 1, characterized in that, The first connection structure (3) is located at the end of the first electrode assembly (1) and away from the first positive electrode tab (11), and the second connection structure (4) is located at the end of the first electrode assembly (1) and away from the first negative electrode tab (12). The first connection structure (3) and the second connection structure (4) are arranged at intervals.

3. The electrode assembly as described in claim 2, characterized in that, The first connection structure (3) is a first auxiliary electrode tab, and the second connection structure (4) is a second auxiliary electrode tab. The first auxiliary electrode tab and the second auxiliary electrode tab are respectively connected to the second positive electrode tab (21) and the second negative electrode tab (22).

4. The electrode assembly as described in claim 2, characterized in that, The first connection structure (3) includes a first auxiliary electrode tab and a first connecting piece (32), wherein the first auxiliary electrode tab is connected to the second positive electrode tab (21) through the first connecting piece (32); and / or The second connection structure (4) includes a second auxiliary electrode tab and a second connecting piece (42), and the second auxiliary electrode tab is connected to the second negative electrode tab (22) through the second connecting piece (42).

5. The electrode assembly as described in claim 4, characterized in that, The first auxiliary electrode lug and the first connecting piece (32) are welded together; and / or The second auxiliary electrode lug and the second connecting piece (42) are welded together.

6. The electrode assembly as described in any one of claims 1 to 5, characterized in that, The first electrode assembly (1) includes a positive electrode (13), a separator (5) and a negative electrode (14) stacked sequentially. Each positive electrode (13) is provided with a first positive electrode tab (11), and multiple first positive electrode tabs (11) are stacked. Each negative electrode (14) is provided with a first negative electrode tab (12), and multiple first negative electrode tabs (12) are stacked.

7. The electrode assembly as claimed in claim 6, characterized in that, The first positive electrode tab (11) and the first negative electrode tab (12) are offset in a plane parallel to the first positive electrode tab (11) and the first negative electrode tab (12).

8. The electrode assembly as claimed in claim 6, characterized in that, The diaphragm (5) includes a plurality of straight segments (51) arranged along the stacking direction of the positive electrode (13) and the negative electrode (14) and a transition segment (52) connecting two adjacent straight segments (51), wherein the straight segments (51) are at least partially disposed between the positive electrode (13) and the negative electrode (14).

9. A single battery cell, characterized in that, include: The housing (220) has a receiving cavity; The terminals include a positive terminal (211) and a negative terminal (212) that penetrate the housing (220); At least one electrode assembly as claimed in any one of claims 1 to 8 is housed in the receiving cavity.

10. The battery cell as described in claim 9, characterized in that, The first positive electrode tab (11) of each electrode assembly is connected to the positive electrode post (211), and the first negative electrode tab (12) is connected to the negative electrode post (212).

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