Pole piece, electrode assembly, and battery

Abstract

The application provides a pole piece, an electrode assembly and a battery, and relates to the technical field of batteries. The pole piece comprises a body and a tab, the body has a length direction and a width direction, and the tab is connected to one side of the body. The tab comprises a first connecting part and a second connecting part. In the width direction, the two sides of the first connecting part are connected to the body and the second connecting part respectively, and in the direction of the body towards the second connecting part, the width of the first connecting part in the length direction gradually decreases, so that ions can be more uniformly dispersed on the surface of the tab, the aggregation and congestion of ions in local areas are avoided, the transmission resistance is reduced, and the battery internal resistance is reduced.

Description

Technical Field

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

[0002] In the field of battery technology, the positive and negative electrodes of a battery are led out through tabs for charging and discharging. Traditional high-capacity batteries (capacity greater than 314Ah) generally use a stacked electrode structure. However, the tabs formed by die-cutting traditional electrodes are prone to ion aggregation and congestion during ion conduction, resulting in excessively high overall internal resistance of the battery. Utility Model Content

[0003] Embodiments of this application provide an electrode, an electrode assembly, and a battery to improve the technical problem of ion aggregation easily occurring on the tabs of the electrode.

[0004] In a first aspect, embodiments of this application provide an electrode sheet, comprising:

[0005] The body has a length direction and a width direction;

[0006] The tab is connected to one side of the main body;

[0007] The electrode includes a first connecting portion and a second connecting portion. Along the width direction, the two sides of the first connecting portion are respectively connected to the body and the second connecting portion. Along the direction from the body toward the second connecting portion, the width of the first connecting portion gradually decreases in the length direction.

[0008] Optionally, the maximum length of the second connecting portion in the length direction is not greater than the minimum length of the first connecting portion in the length direction.

[0009] Optionally, the first connecting part is trapezoidal in shape, the second connecting part is rectangular in shape, and the second connecting part is connected to the short side of the first connecting part.

[0010] Optionally, the first connecting portion includes a first side and a second side disposed opposite to each other along the length direction. The angle between the first side and the body is a first angle, and the opening of the first angle faces the second side. The angle between the second side and the body is a second angle, and the opening of the second angle faces the first side. The angle range of both the first angle and the second angle is 30° to 60°.

[0011] Optionally, the angles of the first included angle and the second included angle are equal, so that the first connecting part is in the shape of an isosceles trapezoid.

[0012] Optionally, the first side and the second connecting portion are connected on one side of the length direction to form a first rounded corner, and / or the second side and the second connecting portion are connected on the other side of the length direction to form a second rounded corner.

[0013] Optionally, the radian of the first rounded corner is equal to the radian of the second rounded corner.

[0014] Secondly, embodiments of this application provide an electrode assembly, including:

[0015] Multiple electrodes, the multiple electrodes including multiple positive electrodes and multiple negative electrodes, the multiple positive electrodes and multiple negative electrodes being stacked alternately;

[0016] Multiple insulating elements, each of which is disposed between an adjacent positive electrode and a negative electrode;

[0017] Multiple fasteners are provided on the sides of the multiple electrodes to bind the multiple electrodes and the multiple insulating elements.

[0018] Thirdly, embodiments of this application provide a battery, comprising:

[0019] At least one electrode assembly;

[0020] A cover plate is disposed on the electrode assembly and connected to the second connection portion of the electrode tab.

[0021] Optionally, the battery includes an even number of electrode assemblies, and the tabs of the even number of electrode assemblies are all connected to the same cover plate.

[0022] The beneficial effects of the embodiments of this application are as follows:

[0023] This application provides an electrode, an electrode assembly, and a battery. By dividing the electrode tab into two parts—a first connecting part and a second connecting part—the first connecting part is connected to the main body, and the second connecting part is connected to the side of the first connecting part away from the main body. This allows the second connecting part to function as a connecting tab in a conventional battery, enabling the electrode tab to connect to the cover plate without a connecting tab, improving the utilization of the battery's internal space, and allowing for a larger electrode assembly within the battery's internal space. Furthermore, the width of the first connecting part gradually decreases along the length direction from the main body towards the second connecting part, allowing ions to be more evenly dispersed on the electrode tab surface, avoiding ion aggregation and congestion in localized areas, thereby reducing transmission resistance and helping to lower the battery's internal resistance. In addition, the electrode tab structure with the width of the first connecting part gradually decreasing along the length direction from the main body towards the second connecting part has a smaller collision area compared to a traditional rectangular electrode tab, which can reduce the risk of the electrode tab folding or cracking to a certain extent. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a battery provided in an embodiment of this application;

[0025] Figure 2 This is a schematic diagram of another battery structure provided in an embodiment of this application;

[0026] Figure 3 This is a schematic diagram of the structure of an electrode assembly provided in an embodiment of this application;

[0027] Figure 4 This is a schematic diagram of the structure of an electrode sheet in an electrode assembly provided in an embodiment of this application;

[0028] Figure 5 This is a schematic diagram of the structure of another electrode in an electrode assembly provided in an embodiment of this application.

[0029] Explanation of reference numerals in the attached figures:

[0030] 1. Electrode assembly; 11. Electrode sheet; 111. Body; 112. Electrode tab; 113. First connecting part; 1131. First side; 1132. Second side; 114. Second connecting part; 12. Fixing member; 2. Cover plate; α1. First included angle; α2. Second included angle; α3. First rounded corner; α4. Second rounded corner;

[0031] X represents the length direction; Y represents the width direction. Detailed Implementation

[0032] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of this application. In addition, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application. In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in actual use or operation, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device.

[0033] Please see Figure 1 or Figure 2 This application provides a battery comprising at least one electrode assembly 1 and a cover plate 2, the cover plate 2 being disposed on the electrode assembly 1 and connected to the tabs 112 in the electrode assembly 1. Generally, to save on connection costs and internal battery space, multiple electrode assemblies 1 are connected to one cover plate 2.

[0034] In some embodiments, the battery includes an even number of electrode assemblies 1. The tabs 112 of the even number of electrode assemblies 1 are all connected to the same cover plate 2 to improve the integration of the multiple electrode assemblies 1. Exemplarily, the cover plate 2 is disposed above the multiple electrode assemblies 1, and then the tabs 112 of the electrode assemblies 1 are bent so that the multiple electrode assemblies 1 are all connected to the cover plate 2.

[0035] See one example. Figure 1 The electrode assembly 1 includes two electrodes arranged adjacent to each other. The cover plate 2 is located above the two electrode assemblies 1, and the tabs 112 of the two electrode assemblies 1 are bent to connect with the cover plate 2.

[0036] In another example, see Figure 2 The battery includes four electrode components 1, wherein every two electrode components 1 form a core pack group, and the two core pack groups are arranged adjacent to each other. Before being connected to the cover plate 2, the two electrode components 1 in a core pack group are pre-connected. The pre-connection method is welding, that is, welding the two electrode components 1 into a single unit to form a core pack group, and then connecting the two core pack groups to the cover plate 2 respectively. In other embodiments, the battery may also include more electrode components 1, and the connections between multiple electrode components 1 and between multiple electrode components 1 and the cover plate 2 are deduced from the above example and will not be repeated here.

[0037] In some embodiments, see Figure 3 The electrode assembly 1 includes multiple electrode plates 11, multiple insulating members, and multiple fixing members 12. The multiple electrode plates 11 further include multiple positive electrode plates 11 and multiple negative electrode plates 11. The multiple positive electrode plates 11 and multiple negative electrode plates 11 are alternately stacked. Each insulating member is disposed between a pair of adjacent positive electrode plates 11 and negative electrode plates 11 to insulate and isolate adjacent positive electrode plates 11 and negative electrode plates 11, ensuring the normal function of the electrode assembly 1. The fixing members 12 are disposed on the sides of the multiple electrode plates 11 to bind the multiple electrode plates 11 and multiple insulating members together, forming a whole. Exemplarily, the fixing member 12 can be a strap, and the multiple electrode plates 11 and insulating members are bound together by the strap. The fixing element 12 can also be multiple adhesive tapes, which are applied at intervals along the edges of multiple electrode sheets 11 and insulating elements. Each adhesive tape presses against the sides of the multiple electrode sheets 11 and insulating elements, and the two ends of the adhesive tape are attached to the surface of the stacked electrode sheets 11 or insulating elements, so that the multiple layers of electrode sheets 11 and insulating elements can be fixed by the adhesive tape. Compared with binding tape, the adhesive tape covers a smaller area of ​​the electrode sheets 11 or insulating elements, which is beneficial to improving the heat dissipation of the electrode assembly 1.

[0038] It should be noted that both the positive electrode 11 and the negative electrode 11 belong to the electrode 11 category and have the same structure. They are distinguished only because of the different polarities of the current conducted by the electrode 11. In the subsequent description of the structure of the electrode 11, the positive electrode 11 and the negative electrode 11 will no longer be distinguished.

[0039] In some embodiments, see Figure 4 The electrode 11 includes a body 111 and a tab 112. The body 111 has a length direction X and a width direction Y. The tab 112 is connected to one side of the body 111 in the width direction Y. The body 111 and the tab 112 are integrally formed. The actual forming process involves die-cutting the electrode 11 and coating it with an active material, so that the un-die-cut parts of the electrode 11 are coated with the active material, while the die-cut parts are not coated with the active material, thus distinguishing the body 111 and the tab 112.

[0040] The tab 112 includes a first connecting portion 113 and a second connecting portion 114. Along the width direction Y, the two sides of the first connecting portion 113 are connected to the body 111 and the second connecting portion 114 respectively. The first connecting portion 113 and the second connecting portion 114 are integrally formed; exemplarily, both the first connecting portion 113 and the second connecting portion 114 are formed during the die-cutting process of the electrode sheet 11. Along the direction from the body 111 to the second connecting portion 114, the width of the first connecting portion 113 gradually decreases in the length direction X, allowing ions to be more evenly dispersed on the surface of the tab 112, avoiding ion aggregation and congestion in local areas, thereby reducing transmission resistance and helping to reduce the battery's internal resistance. In addition, the tab 112 structure with the width of the first connecting portion 113 gradually decreasing in the length direction X along the direction from the body 111 to the second connecting portion 114 has a smaller collision area than a traditional rectangular tab 112, which can reduce the risk of the tab 112 folding or cracking to a certain extent. In addition, by dividing the tab 112 into two parts, namely the first connecting part 113 and the second connecting part 114, the first connecting part 113 is connected to the body 111, and the second connecting part 114 is connected to the side of the first connecting part 113 away from the body 111, so that the second connecting part 114 can act as a connecting piece in a conventional battery, so that the tab 112 can be connected to the cover plate 2 without a connecting piece, thereby improving the utilization rate of the internal space of the battery and allowing a larger electrode assembly 1 to be installed in the internal space of the battery.

[0041] In some embodiments, the maximum length of the second connecting portion 114 in the length direction X is not greater than the minimum length of the first connecting portion 113 in the length direction X. For example, if the minimum width of the first connecting portion 113 in the length direction X is 5 mm, then the maximum length of the second connecting portion 114 in the length direction X can be set to 4 mm or 5 mm. Since the maximum length of the second connecting portion 114 in the length direction X is not greater than the minimum length of the first connecting portion 113 in the length direction X, during battery charging and discharging, when ions are conducted from the body 111 through the tab 112, ions can be guided to flow more smoothly from the wider first connecting portion 113 to the relatively narrower second connecting portion 114. This avoids ion aggregation and congestion that may occur due to an excessively large second connecting portion 114, allowing ions to be distributed more evenly on the tab 112, thereby optimizing the electric field distribution. In addition, from a mechanical structural perspective, the maximum length of the second connecting portion 114 in the length direction X is not greater than the minimum length of the first connecting portion 113 in the length direction X. This allows the stress on the tab 112 to be more rationally distributed between the first connecting portion 113 and the second connecting portion 114 when subjected to external forces. Compared to a case where the second connecting portion 114 is too large, a smaller second connecting portion 114 can reduce local stress concentration caused by external forces, thus reducing the risk of breakage or damage to the tab 112.

[0042] Furthermore, the first connecting portion 113 is trapezoidal in shape, and the second connecting portion 114 is rectangular, with the second connecting portion 114 connected to the short side of the first connecting portion 113. The trapezoidal first connecting portion 113 effectively guides ions to diffuse from the body 111 to the tab 112. Its gradually decreasing width allows ions to gradually converge during transmission without causing congestion, optimizing the ion transmission path. The rectangular second connecting portion 114 provides a relatively stable transition area for ions, further ensuring that ions can smoothly enter the external circuit and maintain the battery's stable performance. When the tab 112 is subjected to external force, the trapezoidal portion can effectively disperse stress, transmitting and dispersing the external force along the hypotenuse, reducing stress concentration points. The rectangular second connecting portion 114 provides a stable support structure for the tab 112, enhancing the overall deformation resistance of the tab 112.

[0043] In some embodiments, the first connecting portion 113 includes a first side 1131 and a second side 1132 disposed opposite to each other along the length direction X. The angle between the first side 1131 and the body 111 is a first angle α1, the opening of the first angle α1 faces the second side 1132, and the angle between the second side 1132 and the body 111 is a second angle α2, the opening of the second angle α2 faces the first side 1131. The angles of the first angle α1 and the second angle α2 are both in the range of 30° to 60°. Exemplarily, in actual production, the first angle α1 and the second angle α2 can both be set to 45° according to specific battery performance requirements and material characteristics. During processing, the cutting or stamping path and depth are strictly controlled to ensure the shape accuracy of the first connecting portion 113, so that its width gradually decreases along the length direction X from the electrode body 111 toward the second connecting portion 114. When the included angle is within the range of 30° to 60°, ions diffuse from the electrode body 111 to the tab 112 with more reasonable guidance. Compared to vertical or excessively small angle connections, an included angle within the range of 30° to 60° allows ions to be distributed more evenly on the surface of the tab 112, reducing ion aggregation and congestion, thereby reducing the battery's internal resistance and improving the battery's charging and discharging efficiency and power performance. From a mechanical point of view, a suitable included angle allows the first connection part 113 to better disperse stress when subjected to external forces. When the tab 112 is subjected to impact or compression, the stress will be dispersed along the inclined direction, rather than concentrated near the connection point. This effectively reduces the risk of breakage or damage to the tab 112 due to stress concentration, improving the mechanical stability and reliability of the tab 112.

[0044] Furthermore, the angles of the first included angle α1 and the second included angle α2 are equal, so that the first connecting portion 113 is an isosceles trapezoid. The isosceles trapezoidal shape of the first connecting portion 113 ensures that when ions are transported from the body 111 to the tab 112, the electric field force distribution on the ions is more uniform and symmetrical because the included angles between the two sides and the body 111 are equal. This helps guide ions to diffuse more evenly on the surface of the tab 112, avoiding the problems of local ion aggregation or poor transport that may be caused by shape asymmetry. This effectively reduces the battery's internal resistance and improves the battery's charge / discharge efficiency and overall performance. Electrochemical simulation analysis shows that, under the same charge / discharge conditions, the battery with the isosceles trapezoidal tab 112 has a more uniform ion concentration distribution, and the battery's polarization phenomenon is significantly improved. From a mechanical perspective, the symmetry of the isosceles trapezoid allows the stress on the tab 112 to be more evenly distributed throughout the first connecting portion 113 when subjected to external forces. Compared to non-isosceles trapezoidal designs, isosceles trapezoidal tabs 112 are better able to resist deformation and damage when subjected to external impacts, compression, and other stresses. In addition, due to the clear geometric symmetry of the isosceles trapezoid, it is easier to achieve standardization and precise control of the first connecting part 113 during mold manufacturing and stamping processes.

[0045] For example, the angles of the first included angle α1 and the second included angle α2 are both 30°.

[0046] In some embodiments, see Figure 5 The first side 1131 and the second connecting portion 114 are connected along one side in the length direction X to form a first rounded corner α3. A special rounded corner processing technique is used at the connection point of the first connecting portion 113 and the second connecting portion 114. CNC machining equipment or a dedicated mold can be used for rounded corner processing. When processing the connection of the first side 1131 and the second connecting portion 114 along one side in the length direction X to form the first rounded corner α3, a suitable rounded corner radius is set according to the size and material properties of the tab 112, for example, 0.5 mm. The first rounded corner α3 can effectively prevent stress concentration at the connection point of the tab 112. During the production, transportation, and use of the battery, the tab 112 may be subjected to various external forces, such as vibration and impact. Without a rounded corner design, the right-angle connection point is prone to becoming a stress concentration point, causing the tab 112 to break or be damaged at this location. The setting of the first rounded corner α3 also makes the ion path smoother during the process of ions being transported from the electrode body 111 through the tab 112 to the external circuit. Compared to right-angle connections, rounded corners reduce the obstruction of ion transport, allowing ions to move more smoothly in the tabs 112, which helps improve the charging and discharging efficiency of the battery, reduce the internal resistance of the battery, and improve the overall performance of the battery.

[0047] In some embodiments, the second side 1132 and the second connecting portion 114 are connected on the other side in the length direction X to form a second rounded corner α4. Similarly, the second rounded corner α4 can effectively avoid stress concentration at the connection point of the tab 112, and can also make the path of ions smoother during the process of ions being transported from the body 111 of the electrode 11 through the tab 112 to the external circuit.

[0048] In some embodiments, the first side 1131 and the second connecting portion 114 are connected on one side in the length direction X to form a first rounded corner α3, and the second side 1132 and the second connecting portion 114 are connected on the other side in the length direction X to form a second rounded corner α4. Furthermore, the arc of the first rounded corner α3 and the arc of the second rounded corner α4 are equal, making the distribution of external force on the tab 112 more uniform, dispersing stress over a larger area, thereby improving the mechanical strength and reliability of the tab 112 and extending the battery's lifespan.

[0049] In some embodiments, the length of the third side connecting the body 111 and the tab 112 in the length direction X is a, the length of the long side connecting the tab 112 and the body 111 in the length direction X is d, the shortest distance from the first side 1131 of the first connecting part 113 to the body 111 on one side in the length direction X is c, and the shortest distance from the second side 1132 of the first connecting part 113 to the body 111 on one side in the length direction X is b.

[0050] The dimensional relationship between the main body 111 and the first connecting part 113 is as follows:

[0051] b / a = 0.618;

[0052] 0.09≤c / a≤0.1;

[0053] 0.36≤d / a≤0.42.

[0054] When b / a = 0.618, it approximates the golden ratio. At the connection between the tab 112 and the body 111, this facilitates a more ideal electric field distribution and ion diffusion path, reducing ion accumulation and congestion in this area, thereby lowering the battery's internal resistance and improving its charging and discharging efficiency and power performance. Based on the proportional relationships of 0.09 ≤ c / a ≤ 0.1 and 0.36 ≤ d / a ≤ 0.42, the position of the first connection part 113 can satisfy the golden ratio as much as possible while also reserving space for bending of the tab 112 of the adjacent electrode 11.

[0055] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An electrode sheet, characterized in that, include: The body has a length direction and a width direction; The tab is connected to one side of the main body; The electrode includes a first connecting portion and a second connecting portion. Along the width direction, the two sides of the first connecting portion are respectively connected to the body and the second connecting portion. Along the direction from the body toward the second connecting portion, the width of the first connecting portion gradually decreases in the length direction.

2. The electrode sheet as described in claim 1, characterized in that, The maximum length of the second connecting part in the length direction is not greater than the minimum length of the first connecting part in the length direction.

3. The electrode sheet as described in claim 2, characterized in that, The first connecting part is trapezoidal in shape, and the second connecting part is rectangular in shape. The second connecting part is connected to the short side of the first connecting part.

4. The electrode sheet as described in claim 1, characterized in that, The first connecting portion includes a first side and a second side disposed opposite to each other along the length direction. The angle between the first side and the body is a first angle, and the opening of the first angle faces the second side. The angle between the second side and the body is a second angle, and the opening of the second angle faces the first side. The angle range of both the first angle and the second angle is 30° to 60°.

5. The electrode sheet as described in claim 4, characterized in that, The angles of the first included angle and the second included angle are equal, so that the first connecting part is in the shape of an isosceles trapezoid.

6. The electrode sheet as described in claim 4, characterized in that, The first side and the second connecting part are connected on one side of the length direction to form a first rounded corner, and / or the second side and the second connecting part are connected on the other side of the length direction to form a second rounded corner.

7. The electrode sheet as described in claim 6, characterized in that, The radian of the first rounded corner is equal to the radian of the second rounded corner.

8. An electrode assembly, characterized in that, include: A plurality of electrode sheets as described in any one of claims 1 to 7, wherein the plurality of electrode sheets comprises a plurality of positive electrode sheets and a plurality of negative electrode sheets, and the plurality of positive electrode sheets and the plurality of negative electrode sheets are alternately stacked; Multiple insulating elements, each of which is disposed between an adjacent positive electrode and a negative electrode; Multiple fasteners are provided on the sides of the multiple electrodes to bind the multiple electrodes and the multiple insulating elements.

9. A battery, characterized in that, include: At least one electrode assembly as described in claim 8; A cover plate is disposed on the electrode assembly and connected to the second connection portion of the electrode tab.

10. The battery as claimed in claim 9, characterized in that, The battery includes an even number of electrode assemblies, and the tabs of the even number of electrode assemblies are all connected to the same cover plate.

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