Electrode assembly and battery cell

Abstract

The utility model relates to the technical field of batteries, particularly provides an electrode assembly and a single battery, and aims to solve the technical problems that electrolyte is difficult to inject and the production efficiency is low after a full tab or a multi-tab of a cylindrical battery is flattened. Therefore, the electrode assembly comprises a tab, the tab is provided with a kneading area, and a liquid passing channel is arranged on a kneading plane of the kneading area so that electrolyte can enter the electrode assembly. By arranging the liquid passing channel for the electrolyte to flow on the kneading plane of the electrode assembly, the speed of the electrolyte entering the electrode assembly and the standing efficiency after liquid injection are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and specifically provides an electrode assembly and a battery monomer. Background Art

[0002] Lithium-ion batteries have outstanding advantages such as high energy density, low environmental pollution, high power density, long service life, wide adaptability, and small self-discharge coefficient. They are one of the most widely used batteries in the world today and an important part of the development of new energy.

[0003] With the continuous upgrading of market demand, cylindrical batteries have developed from 18650 and 21700 to the larger and more energy-dense 4680 series cylindrical batteries. Compared with 18650 and 21700 cylindrical cells, the 4680 cylindrical battery adopts a full-ear design, which effectively shortens the current path, promotes smoother movement of electrons inside the battery, reduces the internal resistance of the cell itself, and significantly reduces Joule heat loss. In addition, cylindrical batteries are made of stainless steel, which has higher mechanical strength and can effectively absorb the pressure caused by the expansion of the negative electrode, so they are more suitable for high-silicon and high-nickel systems.

[0004] However, large cylindrical batteries currently widely use the full-tab flattening method or the multi-tab folding method. Although this can reduce the internal resistance of the battery, the tabs block the gap at the end face of the core, especially for cells with the tabs flattened. This makes it difficult for the electrolyte to enter the core during injection, thereby reducing production efficiency. Utility Model Content

[0005] The utility model aims to solve the above technical problem, that is, to solve the technical problem that after the full pole ears or multiple pole ears of a cylindrical battery are flattened, electrolyte injection is difficult and production efficiency is low.

[0006] In a first aspect, the utility model provides an electrode assembly, including: a pole ear, the pole ear having a flattened area, and a liquid passage is provided on the flattened surface of the flattened area to allow electrolyte to enter the interior of the electrode assembly.

[0007] In the above technical solution, a liquid flow channel for circulating electrolyte is provided on the kneading surface of the electrode assembly. During liquid injection, the electrolyte can be accelerated to infiltrate into the interior of the electrode assembly through the liquid flow channel, thereby improving the efficiency of electrolyte injection and static placement.

[0008] In some embodiments, the depth of the liquid passage is less than or equal to the thickness of the tab.

[0009] In the above technical solution, the depth of the liquid channel is set to be less than or equal to the thickness of the electrode ear. In this way, when the kneaded surface of the electrode ear is processed to produce the liquid channel, adverse effects on the structure within the electrode assembly are prevented, such as the processing device piercing the diaphragm and causing a short circuit in the battery cell.

[0010] In some embodiments, the kneading surface has a welding portion, and the welding portion is spaced apart from the liquid passage.

[0011] In some embodiments, the minimum distance between the welding portion and the liquid passage is greater than or equal to 0.2 mm.

[0012] In the above technical solution, the kneaded surface of the pole ear has a welding portion welded to the current collecting component. In order to avoid the welding portion damaging the liquid channel during the subsequent welding process, or the presence of the liquid channel affecting the welding effect of the pole ear and the current collecting component, the welding portion and the liquid channel are spaced apart to optimize the solution to the above-mentioned problem; at the same time, if the minimum distance is set too small, it will not play a role in avoiding mutual interference. Therefore, the minimum distance between the welding portion and the liquid channel is set to be greater than or equal to 0.2 mm.

[0013] In some embodiments, the liquid passage is a circular gap, and the liquid passage is concentrically arranged with the welding portion.

[0014] In some embodiments, the shape of the liquid passage is linear, wavy or circular.

[0015] In some embodiments, the liquid passage is a plurality of slits, and the plurality of slits extend radially along the kneading plane.

[0016] In some embodiments, the plurality of gaps are evenly distributed along the circumference on the kneading plane.

[0017] In the above technical solution, multiple gaps are evenly distributed along the radial direction of the kneading plane or along the circumference of the kneading plane, which can increase the coverage of electrolyte infiltration, improve the rate of electrolyte entering the electrode assembly and the efficiency of liquid injection and standing, and reduce the difficulty of production.

[0018] In some embodiments, in the radial direction of the kneading plane, the length of the liquid passage is less than or equal to the diameter of the kneading plane.

[0019] In the above technical solution, the inventors found that when the length of the liquid passage is greater than the diameter of the kneading surface, the effect of the liquid passage will be affected.

[0020] In a second aspect, the utility model further provides a battery cell, comprising a shell and the above-mentioned electrode assembly, wherein the electrode assembly is arranged in the shell.

[0021] The advantages of the battery cell and the electrode assembly described above compared to the prior art are the same and will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only illustrate certain embodiments of the present application and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 is a schematic structural diagram of an electrode assembly provided by an embodiment of the utility model in a first state;

[0024] Figure 2 yes Figure 1 A cross-sectional view of an electrode assembly provided in an embodiment in a first state;

[0025] Figure 3 is a schematic structural diagram of an electrode assembly provided by an embodiment of the utility model in a second state;

[0026] Figure 4 It is a structural schematic diagram of a kneading plane of an electrode assembly provided by an embodiment of the utility model;

[0027] Figure 5 It is a structural schematic diagram of a kneading plane of an electrode assembly provided by another embodiment of the utility model;

[0028] Figure 6 It is a structural schematic diagram of a kneading plane of an electrode assembly provided in yet another embodiment of the utility model.

[0029] List of reference numerals:

[0030] 1. Electrode assembly; 2. Electrode ear; 3. Flattened area; 4. Non-flattened area; 5. Flattened surface; 6. Liquid passage; 7. Welding part. DETAILED DESCRIPTION

[0031] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0032] It should be noted that in the description of the present invention, the terms "inside", "outside", "top", "bottom" and other terms indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third", and "fourth" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0033] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installation", "setting" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0035] Existing large cylindrical batteries widely use the full-ear flattening method or the multi-ear folding method. Although the aforementioned method can reduce the internal resistance of the battery, the stacked arrangement of the ears after winding blocks the gap between the end faces of the winding core. When injecting liquid into the winding core, it undoubtedly increases the difficulty of electrolyte infiltration, thereby reducing production efficiency. In order to solve the aforementioned problem, existing manufacturers have found that after the full or multi-ear ears are flattened, there are areas of the ears that are not completely flattened, so impregnation gaps are set in the aforementioned areas that are not completely flattened. In this way, a path for the electrolyte to pass through is formed in the unflattened area of ​​the battery's ears, and the entire electrode assembly housed in the battery is evenly impregnated with electrolyte, thereby improving the battery's electrolyte impregnation. In view of the above scheme, the inventors found that in the actual working condition of flattening all or multiple tabs, there may be a risk of collapse of the tabs after flattening. The area of ​​the tabs that is not completely flattened is limited. The effect of setting an impregnation gap in the area of ​​the tabs that is not completely flattened is minimal. On the contrary, it will weaken the strength of the base of the tabs, further increasing the risk of tab breakage or collapse. Based on this, the inventors provide a technical solution that can solve the above technical problems. The specific embodiment of the electrode assembly 1 of the utility model is described in detail below in conjunction with the accompanying drawings:

[0036] Reference Figure 1 To Attachment Figure 3 , attached Figure 1 FIG. 1 is a schematic diagram of the structure of the electrode assembly 1 of the utility model in the first state, wherein the first state is the working condition after the electrode assembly 1 is wound and before the tab 2 is flattened; FIG. Figure 2 For attachment Figure 1 sectional view of Figure 3This is a schematic structural diagram of the electrode assembly 1 of the present utility model in the second state, and the second state is the working condition after the tab 2 is flattened. The electrode assembly 1 of the present utility model includes a tab 2, which is a component that is not coated with active material and is used to provide a transmission channel for current. The tab 2 has a flattened area 3 and an unflattened area 4. The flattened area 3 is a dense area formed after the tab 2 is flattened. The flattened area 3 has a flattened surface 5. Flattening the tab 2 is to reduce the volume of the electrode assembly 1 and facilitate the subsequent welding of the flattened surface 5. The unflattened area 4 is the area on the tab 2 that is not flattened and is arranged between the flattened area 3 and the main body of the electrode assembly 1.

[0037] Refer to the attached Figure 1 to the attached Figure 6 figures. There is a liquid passing channel 6 provided on the flattened surface 5 of the present utility model. Due to the setting of the liquid passing channel 6, the number of channels and the flow channel area for the electrolyte to flow into the interior of the electrode assembly 1 are increased, thereby improving the liquid injection and infiltration efficiency of the battery. In this embodiment, in the first direction (i.e., the X direction marked in the attached Figure 2 figures), the depth of the liquid passing channel 6 is less than or equal to the thickness of the tab 2. In this way, during the process of processing the liquid passing channel 6 on the flattened surface 5, it will not have an adverse effect on the separator through the tab 2, resulting in the serious consequence of battery short circuit. There is a welding part 7 on the flattened surface 5 of the present utility model. The welding part 7 is used to weld the tab 2 to the electrical connection part of the battery cell to transmit the current between the inside and outside of the battery cell. For example, laser penetration welding can be used. Specifically, the welding part 7 of the tab 2 and the electrical connection part are heated by laser radiation, and the surface heat diffuses to the inside through heat conduction. By controlling laser parameters such as the width, energy, peak power, and repetition frequency of the laser pulse, the laser penetrates the electrical connection part and melts the tab 2, so that the tab 2 is connected to the electrical connection part. Further, if laser penetration welding is used, the welding part 7 can be composed of multiple welding lines. There are no restrictions on the trajectory and the number of the welding lines. The trajectory of the welding lines can be a straight line, a spiral line, a sine curve, a cosine curve, or a curve composed of combinations of various parts. Since different trajectories and different numbers of the welding lines will affect the welding area of the welding part 7, the number of the welding lines needs to be selected accordingly according to the trajectory of the welding lines. Here, the present utility model does not make any restrictions. Furthermore, the welding part 7 and the liquid passing channel 6 are arranged at intervals. Preferably, the minimum distance between the welding part 7 and the liquid passing channel 6 is greater than or equal to 0.2 mm. The inventor found that when the distance between the welding part 7 and the liquid passing channel 6 is set less than 0.2 mm, when the tab 2 is welded to the electrical connection part, it will have an adverse effect on the liquid passing channel 6.

[0038] Refer to the attached Figure 1 to the attached Figure 6 figures. In this embodiment, the liquid passing channel 6 can be set as the linear slit shown in the attached Figure 4 figures, or can be set as the attached Figure 5The circular gap shown can also be set as an additional Figure 6 The wavy gap shown or other shapes. The present invention is not limited here. Further, in the case where the liquid passage 6 is set as a circular gap, the liquid passage 6 is concentrically arranged with the welding portion 7, and the liquid passage 6 can be set as an arc or circle with intervals, as long as it can be ensured that there is no mutual interference between welding and liquid passage, and it will not increase the difficulty of production and manufacturing. In addition, multiple circular gaps can be provided. Further, in the case where the liquid passage 6 is set as a linear gap or a wavy gap, the liquid passage 6 is a plurality of gaps and the plurality of gaps extend along the radial direction of the kneading plane 5. Preferably, the plurality of gaps are evenly distributed circumferentially on the kneading plane 5 to ensure that the electrolyte infiltration covers a wider range. In addition, the welding portion 7 can also extend radially along the kneading plane 5 and be evenly distributed circumferentially, as long as the welding area is large enough and does not affect the effect of electrolyte infiltration. The present invention is not limited here. In the present embodiment, in the second direction (i.e., the attached Figure 2 The Y direction marked in the figure is the radial direction of the kneading plane), the length of the liquid passage 6 is less than or equal to the diameter of the kneading plane 5. The inventors found that when the length of the liquid passage 6 is greater than the diameter of the kneading plane 5, the effect of the liquid passage 6 will be affected.

[0039] The utility model also provides a battery cell having the above-mentioned electrode assembly 1. In this embodiment, the battery cell may also include a shell, and the electrode assembly 1 is arranged in the shell. The beneficial effects of the battery cell are the same as the advantages of the electrode assembly 1 in this embodiment over the prior art, and will not be repeated here. In the utility model, the battery cell may include a lithium-ion secondary battery, a lithium-ion primary battery, a lithium-sulfur battery, a sodium-lithium-ion battery, a sodium-ion battery or a magnesium-ion battery, etc., and the embodiment of the utility model is not limited to this. The battery cell may be a cylinder, a flat body, a cuboid or other shapes, etc., and the embodiment of the utility model is not limited to this. The battery cell is generally divided into three types according to the packaging method: a cylindrical battery cell, a square battery cell and a soft-pack battery cell, and the embodiment of the utility model is not limited to this. So far, the technical scheme of the utility model has been described in conjunction with the preferred embodiments shown in the accompanying drawings, but it is easy for those skilled in the art to understand that the protection scope of the utility model is obviously not limited to these specific embodiments. Without departing from the principle of the utility model, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical schemes after these changes or substitutions will fall within the protection scope of the utility model.

Claims

1. An electrode assembly, characterized in that: include: The electrode tab has a flattened area, and a liquid passage is provided on the flattened surface of the flattened area to allow the electrolyte to enter the interior of the electrode assembly; The kneading plane further has a welding portion, the welding portion extends along the radial direction of the kneading plane and is evenly distributed along the circumferential direction, and the welding portion is spaced apart from the liquid passage; Wherein, the liquid passage is configured as a linear gap or a wavy gap, the liquid passage is configured with a plurality of gaps, and the plurality of gaps extend along the radial direction of the kneading plane and are evenly distributed along the circumferential direction on the kneading plane; Alternatively, the liquid passage is a circular gap, and the liquid passage is concentrically arranged with the welding portion.

2. The electrode assembly according to claim 1, characterized in that: The depth of the liquid passage is less than or equal to the thickness of the electrode tab.

3. The electrode assembly according to claim 1, characterized in that: The minimum distance between the welding portion and the liquid passage is greater than or equal to 0.2 mm.

4. A battery cell, characterized in that: include: case; The electrode assembly according to any one of claims 1 to 3; The electrode assembly is arranged in the shell.

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