Battery cell, battery, and electric device

Abstract

The present application relates to a battery cell including a jelly-roll, the jelly-roll being a cylindrical structure formed by winding a positive electrode tab, a first separator, a negative electrode tab, and a second separator, the positive electrode tab including a positive electrode main portion and a plurality of positive electrode tab portions protruding from an end surface of the positive electrode main portion and spaced apart from each other, the negative electrode tab including a negative electrode main portion and a plurality of negative electrode tab portions protruding from an end surface of the negative electrode main portion and spaced apart from each other. The jelly-roll has opposite first and second end portions in an axial direction thereof, the first end portion has at least two positive electrode tab groups formed thereon, and the second end portion has at least two negative electrode tab groups formed thereon. Each of the positive electrode tab groups includes a plurality of positive electrode tab portions arranged in a radial direction of the first end portion, and the respective positive electrode tab groups are equally spaced apart in a circumferential direction of the first end portion. Each of the negative electrode tab groups includes a plurality of negative electrode tab portions arranged in a radial direction of the second end portion, and the respective negative electrode tab groups are equally spaced apart in a circumferential direction of the second end portion.

Description

Technical Field

[0001] This invention relates to a battery cell, a battery, and an electrical device. Background Technology

[0002] The wound cylindrical battery is a widely used cell structure in the lithium-ion battery field. It typically consists of an electrode assembly (positive electrode, negative electrode, and separator) wound together to form the cell body, which is then assembled into a cylindrical casing and subjected to processes such as electrolyte filling and sealing to produce the finished battery. Due to its compact structure, high energy density, and mature manufacturing process, this type of battery is widely used in many fields, including new energy vehicles. However, existing cylindrical batteries suffer from problems such as high internal resistance and poor electrolyte permeability, requiring further improvement. Summary of the Invention

[0003] In view of this, it is necessary to propose an improved battery cell in order to solve at least one of the technical problems mentioned above and / or other unmentioned technical problems.

[0004] According to a first aspect of the present invention, a battery cell is provided, the battery cell comprising a core, the core being a cylindrical structure formed by winding stacked positive electrode sheets, a first separator, a negative electrode sheet, and a second separator, the positive electrode sheet comprising a positive electrode body portion and a plurality of positive electrode tabs protruding from the end face of the positive electrode body portion and spaced apart from each other, the negative electrode sheet comprising a negative electrode body portion and a plurality of negative electrode tabs protruding from the end face of the negative electrode body portion and spaced apart from each other, wherein the core has opposing first end and second end portions along its axial direction, at least two positive electrode tab groups are formed on the first end portion, and at least two negative electrode tab groups are formed on the second end portion, each positive electrode tab group comprising a plurality of positive electrode tabs arranged in a radial direction along the first end portion, and each positive electrode tab group being equally spaced along the circumferential direction of the first end portion, and each negative electrode tab group comprising a plurality of negative electrode tabs arranged in a radial direction along the second end portion, and each negative electrode tab group being equally spaced along the circumferential direction of the second end portion.

[0005] According to an optional embodiment of the present invention, the positive electrode tab group and the negative electrode tab group are aligned with each other in the axial direction of the winding core.

[0006] According to an optional embodiment of the present invention, the number of positive electrode tabs is the same as the number of negative electrode tabs.

[0007] According to an optional embodiment of the invention, all positive electrode tabs and / or all negative electrode tabs have the same geometric features.

[0008] According to an optional embodiment of the present invention, two positive electrode tabs spaced 180 degrees apart in the circumferential direction are formed on the first end, or three positive electrode tabs spaced 120 degrees apart in the circumferential direction are formed.

[0009] According to an optional embodiment of the present invention, two negative electrode tabs spaced 180 degrees apart in the circumferential direction are formed on the second end, or three negative electrode tabs spaced 120 degrees apart in the circumferential direction are formed.

[0010] According to an optional embodiment of the present invention, the battery cell further includes a housing for accommodating the winding core and a top cover disposed at the open end of the housing. The top cover is provided with a terminal post. The positive electrode tab is electrically connected to the housing through a positive electrode busbar, and the negative electrode tab is electrically connected to the terminal post through a negative electrode busbar, such that the housing constitutes the positive output terminal of the battery cell, and the terminal post constitutes the negative output terminal of the battery cell.

[0011] According to an optional embodiment of the present invention, the positive busbar has the same number of branch ends as the positive electrode tab group to achieve a one-to-one electrical connection, and the negative busbar has the same number of branch ends as the negative electrode tab group to achieve a one-to-one electrical connection. Preferably, the positive busbar and the negative busbar have the same number of branch ends.

[0012] According to an optional embodiment of the present invention, the negative electrode busbar has a through hole at the junction of each branch end, and the through hole is aligned axially with the central hole channel of the winding core.

[0013] According to an optional embodiment of the present invention, the positive electrode tab is bent toward the first end of the winding core to form a positive electrode welding portion for welding connection with the positive electrode busbar, and the negative electrode tab is bent toward the second end of the winding core to form a negative electrode welding portion for welding connection with the negative electrode busbar.

[0014] According to a second aspect of the invention, a battery is provided, comprising any of the battery cells according to the invention.

[0015] According to a third aspect of the invention, an electrical device is provided, comprising a battery according to the invention.

[0016] Through certain embodiments of the present invention, a battery cell with a multi-electrode group split design is provided, which can combine the advantages of existing monopolar and all-electrode designs while avoiding their respective disadvantages, thereby achieving lower internal resistance, better electrolyte permeability and consistency.

[0017] It is worth noting that the advantages and beneficial effects of the present invention are not limited to those mentioned above. Those skilled in the art can understand other unmentioned advantages and beneficial effects of the present invention through the following specific embodiments and claims. Attached Figure Description

[0018] The invention will now be described in more detail with reference to the accompanying drawings, which will provide a better understanding of the principles, features, and advantages of the invention. In the drawings, Figure 1 A schematic diagram illustrating the structure of an example of an existing battery cell is shown. Figure 2 A schematic diagram illustrating the structure of another existing battery cell example is shown. Figure 3 An exploded view schematically illustrates an exemplary electrode assembly for forming the core of a battery cell according to the present invention; Figure 4 A schematic diagram of the unfolded positive or negative electrode sheet used to form the core of a battery cell according to the present invention is shown. Figure 5 A perspective view and an end view of the core of an exemplary battery cell according to the present invention are schematically shown; Figure 6 A perspective view and an end view of the core of another exemplary battery cell according to the present invention are schematically shown; Figure 7 A schematic cross-sectional view of a battery cell according to the present invention is shown; Figure 8 The schematic diagram illustrates the structural diagrams of exemplary positive and negative electrode busbars of a battery cell according to the present invention; and Figure 9 The diagram schematically illustrates the structure of another exemplary positive and negative busbars of a battery cell according to the present invention. Detailed Implementation

[0019] To make the technical problems to be solved, the technical solutions, and the beneficial technical effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and exemplary embodiments. It should be understood that the specific embodiments described herein are only for explaining the principles of the invention and are not intended to limit the scope of protection of the invention.

[0020] Figure 1 A schematic structural diagram of an example of a conventional battery cell is shown, wherein (a) is a cross-sectional view of the conventional battery cell 800, (b) is an unfolded view of the positive or negative electrode sheet in the battery cell 800, (c) is a structural view of the core 81 of the battery cell 800 before the bent tab 82, and (d) is an end view of the core 81. Figure 1As shown, in this conventional battery cell 800, the positive electrode 811 and negative electrode 812 used to wind and form the core 81 each include a main body 83 and a plurality of tabs 82 protruding from the end face of the main body and spaced apart from each other. After the electrode assembly is wound into the core 81, at the end of the core 81, the plurality of tabs 82 are arranged radially to form a tab group 820, as shown in (c) and (d). Then, each tab 82 is bent toward the inner end face of the core 81 (i.e., the face formed by the inner edge of the main body 83) to form a welded part for welding. Thus, the manufacturing of the core 81 can be completed. The core 81 can then be inserted into the housing and electrolyte injected into it. The core 81 of this conventional battery cell 800 includes only one tab group 820 at the end, and therefore can be called a single tab design. Because it has only one tab group 820, the area blocked after the tab is bent is small, so there are many liquid injection channels and good electrolyte permeability. However, due to the long electron transport path, the internal resistance of the structure is large and the conductivity is poor.

[0021] Figure 2 A schematic diagram illustrating the structure of another existing battery cell example is shown, with the views, components, and reference numerals corresponding to... Figure 1 Correspondingly, in this battery cell 900, the positive electrode 911 and negative electrode 912 used to wind and form the core 91 each include more densely distributed tabs 92, such that after being wound into the core 91, the tabs 92, after bending, essentially cover almost the entire end of the core, as shown in (c) and (d). This is generally referred to as a full tab design. Due to the large number of tabs, the electron transport path is significantly shortened, resulting in low internal resistance and good conductivity. However, the large shielding area leads to fewer electrolyte injection channels, making it difficult for the electrolyte to completely penetrate into the electrode through the tabs tightly covering the ends, thus affecting the battery's capacity, lifespan, and safety.

[0022] Figures 3-9 Structural views of various components of a battery cell according to the present invention are shown schematically. An exemplary battery cell 100 according to the present invention includes a core 10. For example... Figure 3 and Figure 5 As shown, the core 10 is a cylindrical structure formed by winding together a positive electrode 1, a first diaphragm 3, a negative electrode 2, and a second diaphragm 4.

[0023] The first separator 3 is sandwiched between the positive electrode 1 and the negative electrode 2 to achieve insulation between the positive and negative electrodes while allowing lithium ions to pass through. The first separator 3 and the second separator 4 are located on opposite sides of the negative electrode 2, respectively. The second separator 4 provides insulation protection to the outside of the negative electrode 2. The first separator 3 and the second separator 4 can have the same structure.

[0024] The positive electrode 1 serves as the delithiation end of the battery. Its main body 11 is composed of a positive current collector (e.g., aluminum foil) and a coated positive active material layer (e.g., ternary materials, lithium iron phosphate, etc.). A portion of the active material layer is left uncoated to form a positive electrode tab 12, which is used for subsequent welding to the positive electrode busbar to conduct current. The negative electrode 2 serves as the lithium insertion end of the battery. Its main body 21 is composed of a negative current collector (e.g., copper foil) and a coated negative active material layer (e.g., graphite, silicon carbide, etc.). Similarly, a portion of the active material layer is left uncoated to form a negative electrode tab 22, which is used for subsequent welding to the negative electrode busbar to conduct current. Therefore, the positive electrode 1 includes a positive electrode main body 11 and a plurality of positive electrode tabs 12 protruding from the end face of the positive electrode main body 11 and spaced apart from each other. The negative electrode 2 includes a negative electrode main body 21 and a plurality of negative electrode tabs 22 protruding from the end face of the negative electrode main body 21 and spaced apart from each other.

[0025] The stacked positive electrode 1, first separator 3, negative electrode 2, and second separator 4 can be arranged in sequence to form an electrode assembly, and wound to form a cylindrical core 10. (Reference) Figure 5 and Figure 6 The core 10 has opposing first and second ends along its axial direction A. At least two positive electrode tab groups 120 are formed on the first end, and at least two negative electrode tab groups 220 are formed on the second end. Each positive electrode tab group 120 includes a plurality of positive electrode tab portions 12 arranged along the radial direction R of the first end, and the positive electrode tab groups 120 are equally spaced along the circumferential direction C of the first end. Similarly, each negative electrode tab group 220 includes a plurality of negative electrode tab portions 22 arranged along the radial direction R of the second end, and the negative electrode tab groups 220 are equally spaced along the circumferential direction C of the second end.

[0026] In this way, multiple tab groups spaced apart from each other can be formed on each end of the core 10, thereby combining the advantages of the single tab design and the full tab design and avoiding their respective disadvantages. This allows the formed battery cell 100 to have lower internal resistance and better electrolyte wetting effect, optimize battery self-discharge rate, solve low voltage problem and open circuit voltage (OCV) discrete failure problem, improve yield and overall equipment efficiency, shorten the electrolyte filling process cycle and reduce the investment cost of electrolyte filling equipment.

[0027] In the first end, each turn of the electrode assembly may include one tab from each tab group. The same applies to the second end. Alternatively, the initial and final turns may consist solely of winding the diaphragm without positive and negative electrodes or tabs.

[0028] Preferably, the positive electrode tab group 120 and the negative electrode tab group 220 can be aligned with each other accordingly along the axial direction A of the core 10. This allows for the simple manufacture, assembly, and winding of the positive and negative electrode sheets, for example, by stacking the positive electrode sheet 1, the first diaphragm 3, and the negative electrode sheet 2 and the second diaphragm 4 so that the positive electrode tab 12 and the negative electrode tab 22 are aligned along the height direction, and then wound along the length direction.

[0029] Preferably, the number of positive electrode tabs 120 and negative electrode tabs 220 is the same. Figure 5 A perspective view and an end view of the core of an exemplary battery cell according to the present invention are schematically shown. In this embodiment, two positive electrode tabs 120 spaced 180 degrees apart from each other in the circumferential direction C are formed on a first end of the core 10, and two negative electrode tabs 220 spaced 180 degrees apart from each other in the circumferential direction C are formed on a second end. Figure 6 A perspective view and an end view of the core 10 of another exemplary battery cell according to the present invention are schematically shown. In this embodiment, three positive electrode tabs 120 spaced 120 apart from each other in the circumferential direction C are formed on a first end of the core 10, and three negative electrode tabs 220 spaced 120 apart from each other in the circumferential direction C are formed on a second end.

[0030] like Figure 4 As shown, to achieve radial arrangement of the tabs within each tab group, the spacing between adjacent tabs gradually increases from the starting end of the winding to the ending end within the electrode sheet. Therefore, the positive and negative tab groups are preferably two or three each, which ensures the spacing between adjacent tabs in the positive or negative electrode sheet from a manufacturability perspective. In some possible embodiments, there may also be more than three positive or negative tab groups.

[0031] Preferably, all positive electrode tabs 12 and / or all negative electrode tabs 22 have the same geometric features. Figure 4 In the exemplary electrode shown, the electrode tab is rectangular in shape. However, in some other embodiments, the electrode tab can also be square, parallelogram, or trapezoidal, etc. Adjusting the shape of the electrode tab can also facilitate its bending.

[0032] Figure 7 A schematic cross-sectional view of a battery cell according to the present invention is shown. Figure 7As shown, the battery cell 100 also includes a housing 20 for accommodating the winding core 10 and a top cover 30 disposed at the open end of the housing 20. The top cover 30 is provided with a terminal post 31. In particular, unlike the prior art, the positive electrode tab 12 is electrically connected to the housing 20 through a positive electrode busbar, and the negative electrode tab 22 is electrically connected to the terminal post 31 through a negative electrode busbar, so that the housing 20 constitutes the positive output terminal of the battery cell 100, and the terminal post 31 constitutes the negative output terminal of the battery cell 100.

[0033] Figure 8 and Figure 9 The structural diagrams of two different exemplary positive and negative busbars are shown respectively. Figure 8 The positive and negative busbars shown are particularly suitable for Figure 5 The shown core 10, Figure 9 The positive and negative busbars shown are particularly suitable for Figure 6 The core 10 shown is an example. Specifically, the positive electrode busbar 40 has the same number of branch ends as the positive electrode tab group 120 to achieve a one-to-one electrical connection, and the negative electrode busbar 50 has the same number of branch ends as the negative electrode tab group 220 to achieve a one-to-one electrical connection. Preferably, the number of positive and negative electrode tab groups is the same, and correspondingly, the positive electrode busbar 40 and the negative electrode busbar 50 have the same number of branch ends. Therefore, the positive electrode busbar 40 and the negative electrode busbar 50 can be formed into a generally strip shape when each has two branch ends, and into a generally trident shape when each has three branch ends.

[0034] During manufacturing, the positive electrode tab 12 can be bent toward the first end of the core 10 to form a positive electrode welding part, and then welded to the positive electrode busbar 40. After that, the positive electrode busbar 40 is welded to the bottom of the housing 20 away from the opening end. Thus, the positive electrode busbar 40 is preferably a symmetrical structure (axisymmetric structure or centrosymmetric structure) and is solid at the center without a through hole, thereby ensuring the strength of the welded connection with the housing.

[0035] For the negative electrode, the negative electrode tab 22 can be bent towards the second end of the winding core 10 to form a negative electrode welding part, and then it can be welded to the negative electrode busbar 50. The negative electrode busbar 50 can be assembled (e.g., welded) together with the top cover 30 and its terminal post 31 to form a shape such as Figure 8 or Figure 9The assembly structure shown in (b) is then used, and the negative electrode busbar 50 of the assembly structure is welded to the negative electrode welding area of ​​the core 10. After the connection between the core 10 and the negative electrode busbar 50 is completed, the top cover 30 can be rotated 180 degrees toward the core 10 or the housing 20, thereby fastening it to the opening end of the housing 20 and sealing it. For this purpose, one branch end of the negative electrode busbar 50 can be longer than the other branch ends, thus acting as a flipping part. The top cover 30 can have a pre-reserved liquid injection port, and electrolyte can be injected into the inside of the housing 20 after sealing, and then sealed after the liquid injection is completed. The injected electrolyte can be as follows: Figure 7 The arrows in the diagram schematically show the way and direction in which the material penetrates into the electrode.

[0036] Preferably, such as Figure 8 and Figure 9 As shown in (b), the negative electrode busbar 50 may have through holes 51 at the junction of each branch end, and the through holes 51 are aligned with the center hole channel 14 of the core 10 along the axial direction A. Due to the winding process, the core 10 has the following characteristics: Figure 6 and Figure 7 The central hole channel 14 shown extends along the axial direction A of the core 10. This central hole channel 14 serves as an important electrolyte injection channel. Providing a through hole 51 in the negative electrode manifold 50 and aligning it with the central hole channel 14 facilitates the opening or extension of the electrolyte injection channel, providing more wetting paths for the core 10. This allows the electrolyte to flow through the negative electrode manifold and penetrate into the central hole channel 14 and the gaps between the turns of the electrode assembly below the negative electrode manifold. This improves the electrolyte wetting effect and enhances the consistency of the battery cells.

[0037] Other embodiments of the present invention relate to a battery comprising any of the aforementioned battery cells 100 and a corresponding electrical device comprising said battery. Here, the battery comprises a plurality of battery cells 100 according to the present invention electrically connected together in series and / or parallel, and is integrally housed within a battery casing. The electrical device is an electrical device that uses the battery according to the present invention as a power source, including but not limited to vehicles and other transportation vehicles, mobile devices such as mobile phones.

[0038] Although specific embodiments of the invention have been described in detail herein, they are given for illustrative purposes only and should not be construed as limiting the scope of the invention. Various substitutions, alterations, and modifications can be conceived without departing from the spirit and scope of the invention.

Claims

1. A battery cell (100), the battery cell (100) comprising a core (10), the core (10) being a cylindrical structure formed by winding stacked positive electrode plates (1), a first separator (3), a negative electrode plate (2), and a second separator (4). The positive electrode plate (1) includes a positive electrode body portion (11) and a plurality of positive electrode tabs (12) that protrude from the end face of the positive electrode body portion (11) and are spaced apart from each other. The negative electrode plate (2) includes a negative electrode body portion (21) and a plurality of negative electrode tabs (22) that protrude from the end face of the negative electrode body portion (21) and are spaced apart from each other. in, The core (10) has a first end and a second end opposite to each other along its axial direction (A), at least two positive electrode tabs (120) are formed on the first end, and at least two negative electrode tabs (220) are formed on the second end. Each positive electrode tab group (120) includes a plurality of positive electrode tab portions (12) arranged in a radial direction (R) along the first end, and the various positive electrode tab groups (120) are equally spaced apart in a circumferential direction (C) along the first end. Each negative electrode tab group (220) includes a plurality of negative electrode tab portions (22) arranged in a radial direction (R) along the second end, and each negative electrode tab group (220) is equally spaced apart in a circumferential direction (C) along the second end.

2. The battery cell (100) according to claim 1, characterized in that, The positive electrode tab group (120) and the negative electrode tab group (220) are aligned with each other in the axial direction (A) of the core (1).

3. The battery cell (100) according to claim 1 or 2, characterized in that, The number of positive electrode tabs (120) is the same as the number of negative electrode tabs (220); and / or All positive electrode tabs (12) and / or all negative electrode tabs (22) have the same geometric features.

4. The battery cell (100) according to any one of claims 1-3, characterized in that, Two positive electrode tabs (120) spaced 180 degrees apart in the circumferential direction (C) are formed on the first end, or three positive electrode tabs (120) spaced 120 degrees apart in the circumferential direction (C) are formed; and / or Two negative electrode tabs (220) are formed on the second end, spaced 180 degrees apart from each other in the circumferential direction (C), or three negative electrode tabs (220) are formed, spaced 120 degrees apart from each other in the circumferential direction (C).

5. The battery cell (100) according to any one of claims 1-4, characterized in that, The battery cell (100) further includes a housing (20) for accommodating the winding core (10) and a top cover (30) provided at the open end of the housing (20). The top cover (30) is provided with a terminal post (31). The positive electrode tab (12) is electrically connected to the housing (20) through a positive electrode busbar (40), and the negative electrode tab (22) is electrically connected to the terminal post (31) through a negative electrode busbar (50), so that the housing (20) constitutes the positive output terminal of the battery cell (100), and the terminal post (31) constitutes the negative output terminal of the battery cell (100).

6. The battery cell (100) according to claim 5, characterized in that, The positive electrode busbar (40) has the same number of branch ends as the positive electrode tab group (120) to achieve a one-to-one electrical connection, and the negative electrode busbar (50) has the same number of branch ends as the negative electrode tab group (220) to achieve a one-to-one electrical connection. Preferably, the positive electrode busbar (40) and the negative electrode busbar (50) have the same number of branch ends.

7. The battery cell (100) according to claim 5 or 6, characterized in that, The negative electrode busbar (50) has a through hole (51) at the junction of each branch end, and the through hole (51) is aligned with the central hole channel (14) of the core (10) in the axial direction (A).

8. The battery cell (100) according to any one of claims 5-7, characterized in that, The positive electrode tab (12) is bent toward the first end of the core (10) to form a positive electrode welding part for welding connection with the positive electrode busbar (40), and the negative electrode tab (22) is bent toward the second end of the core (10) to form a negative electrode welding part for welding connection with the negative electrode busbar (50).

9. A battery comprising a battery cell (100) according to any one of claims 1-8.

10. An electrical appliance comprising the battery according to claim 9.

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