Pole piece and battery

Abstract

This utility model discloses an electrode and a battery. The electrode includes a substrate, a coating layer, and a tab. The substrate has a coating area and a welding area on one side of its surface. The coating area surrounds the outer periphery of the welding area. The coating layer covers the coating area and includes a positive electrode material or a negative electrode material. The tab includes a first part and a second part opposite to each other along a first direction. The end of the first part away from the second part is welded to the welding area. The projection of the first part along the thickness direction of the substrate is within the range of the surface. The second part is located on the outer side of the substrate along the first direction. Along the first direction, the welding area has a size L1, and the first part has a size L2, where 15% ≤ L1 / L2 ≤ 35%. This allows the coating layer to surround the welding area, and the connection edge length between the coating layer and the welding area is longer, which can effectively reduce the internal resistance between the coating layer and the first part, thereby reducing the current density near the connection between the tab and the substrate.

Description

Technical Field

[0001] This utility model relates to the field of energy storage battery technology, and in particular to an electrode and a battery. Background Technology

[0002] Energy storage batteries in related technologies typically include electrodes, specifically positive and negative electrodes. Each electrode typically comprises a substrate, a coating layer, and tabs. The coating layer is applied to the surface of the substrate, and the tabs are welded to the substrate to conduct electricity between the substrate and the battery terminals. The tabs are usually welded to the edge of the substrate, and to avoid direct contact between the tabs and the substrate, the coating layer and the welding points are spaced apart. In other words, the coating layer typically surrounds the welding points of the tabs and the substrate on three sides.

[0003] However, in related technologies, energy storage batteries suffer from the problem that excessive current density near the connection between the tab and the substrate leads to rapid consumption of electrolyte near the connection, causing lithium plating and consequently reducing the safe service life of the energy storage battery. Utility Model Content

[0004] One objective of this invention is to provide an electrode that can reduce the current density near the connection between the electrode tab and the substrate.

[0005] Another objective of this invention is to provide a battery that, by using the aforementioned electrode plates, can extend the battery's safe service life.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] Firstly, an electrode sheet is provided, comprising:

[0008] A substrate, wherein one side of the substrate has a coating area and a welding area, the coating area surrounding the outer periphery of the welding area;

[0009] A coating layer covering the coating area, the coating layer comprising a positive electrode material or a negative electrode material; and,

[0010] The electrode includes a first portion and a second portion opposite each other along a first direction. The end of the first portion away from the second portion is welded to the welding area. The projection of the first portion along the thickness direction of the substrate is located within the range of the setting surface. The second portion is located outside the substrate along the first direction. Along the first direction, the welding area has a size L1, and the first portion has a size L2, 15% ≤ L1 / L2 ≤ 35%.

[0011] Wherein, the first direction is perpendicular to the thickness direction of the substrate.

[0012] As a preferred technical solution for the electrode sheet, the welding area is located at the exact center of the surface along the first direction.

[0013] As a preferred technical solution for the electrode sheet, along the second direction, the first portion has a width W1, and the welding area has a size W2, 60% ≤ W1 / W2 ≤ 95%, wherein the second direction is perpendicular to the first direction and the thickness direction of the substrate.

[0014] As a preferred technical solution for the electrode sheet, the first part is rectangular, the welding area is rectangular, and the two opposite edges of the welding area are parallel to the first direction.

[0015] As a preferred embodiment of the electrode sheet, at least a portion of the surface of the electrode tab facing away from the substrate is provided with an insulating layer.

[0016] As a preferred technical solution for the electrode sheet, the insulating layer covers the surface of the first portion that is away from the substrate.

[0017] As a preferred technical solution for the electrode sheet, the second part, on the surface away from the substrate, has at least one end connected to the first part covered with the insulating layer.

[0018] As a preferred technical solution for the electrode sheet, the insulating layer is an insulating coating, and the insulating coating has a thickness d, where 0um < d ≤ 10um.

[0019] As a preferred technical solution for the electrode sheet, the second part is further provided with tab adhesive, which is located on the side of the insulating layer away from the welding area.

[0020] In a second aspect, a battery is provided, comprising a positive electrode and a negative electrode, wherein at least one of the positive electrode and the negative electrode is an electrode as described in the foregoing technical solutions.

[0021] The beneficial effects of this utility model are as follows:

[0022] By making the coating area surround the outer periphery of the welding area, the coating layer can be set around the welding area, making the connection edge length between the coating layer and the welding area longer. This can effectively reduce the internal resistance between the coating layer and the first part, thereby effectively reducing the current density of the current flowing between the coating layer and the first part through the welding area. In other words, it can effectively reduce the current density near the connection between the tab and the substrate.

[0023] Furthermore, in order to reduce the internal resistance at the welding position between the first part and the welding area, the ratio of the welding area size L1 to the first part size L2, L1 / L2, should be as large as possible. However, the larger L1 / L2 is, the larger the space occupied by the welding area along the first direction. In other words, the smaller the size of the coating area where the coating layer can be set along the first direction, the lower the energy density of the electrode. Based on this, this solution also makes L1 / L2 relatively large but not large by ensuring that the ratio of the welding area size L1 to the first part size L2, L1 / L2, satisfies: 15% ≤ L1 / L2 ≤ 35%, so that the internal resistance at the welding position between the first part and the welding area is small while the energy density of the electrode is large. Attached Figure Description

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0025] Figure 1 This is a schematic diagram of the structure of the electrode sheet (insulating layer omitted) described in the embodiment.

[0026] Figure 2 for Figure 1 Enlarged schematic diagram of point M in the middle.

[0027] Figure 3 This is a schematic diagram of the structure of the substrate described in the embodiment.

[0028] Figure 4 This is a cross-sectional view of the electrode sheet (with tabs omitted) described in the embodiment.

[0029] In the picture:

[0030] 1. Substrate; 10. Surface to be coated; 100. Coated area; 101. Welding area;

[0031] 2. Coating layer;

[0032] 3. Electrode; 31. Part 1; 32. Part 2; 33. Electrode adhesive;

[0033] 4. Insulation layer. Detailed Implementation

[0034] To make the technical problems solved by this utility model, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the embodiments of this utility model will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0035] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0036] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0037] like Figures 1 to 4 As shown, this utility model provides an electrode sheet, including a substrate 1, a coating layer 2, and an electrode tab 3. A surface 10 on one side of the substrate 1 has a coating area 100 and a welding area 101. The coating area 100 surrounds the outer periphery of the welding area 101. The coating layer 2 covers the coating area 100 and includes a positive electrode material or a negative electrode material. The electrode tab 3 includes a first portion 31 and a second portion 32 opposite each other along a first direction S1. The end of the first portion 31 away from the second portion 32 is welded to the welding area 101. The projection of the first portion 31 along the thickness direction of the substrate 1 lies within the area of ​​the surface 10. The second portion 32 is located on the outer side of the substrate 1 along the first direction S1. Along the first direction S1, the welding area 101 has a dimension L1, and the first portion 31 has a dimension L2, where 15% ≤ L1 / L2 ≤ 35%. The first direction S1 is perpendicular to the thickness direction of the substrate 1. Figure 2 and Figure 4 The boundary between the first part 31 and the second part 32 is shown by a dashed line. It is understood that the dashed line is only used to show the boundary between the first part 31 and the second part 32, and is not used to indicate that there is a specific shape or structure at that point.

[0038] By having the coating area 100 surround the outer periphery of the welding area 101, the coating layer 2 can be disposed around the welding area 101, making the connection edge length between the coating layer 2 and the welding area 101 longer. This can effectively reduce the internal resistance between the coating layer 2 and the first part 31, thereby effectively reducing the current density of the current flowing between the coating layer 2 and the first part 31 through the welding area 101. In other words, it can effectively reduce the current density near the connection between the tab 3 and the substrate 1.

[0039] Furthermore, in order to reduce the internal resistance at the welding position between the first part 31 and the welding area 101, the ratio L1 / L2 of the size L1 of the welding area 101 to the size L2 of the first part 31 should be as large as possible. However, the larger L1 / L2 is, the larger the space occupied by the welding area 101 along the first direction S1. In other words, the smaller the size of the coating area 100 where the coating layer 2 can be set along the first direction S1, the lower the energy density of the electrode. Based on this, this solution also makes the ratio L1 / L2 of the size L1 of the welding area 101 to the size L2 of the first part 31 satisfy: 15% ≤ L1 / L2 ≤ 35%, so that L1 / L2 is large but not large enough, so that the internal resistance at the welding position between the first part 31 and the welding area 101 is small while the energy density of the electrode is large.

[0040] Specifically, the ratio L1 / L2 of the size L1 of the welding area 101 to the size L2 of the first part 31 can be 15%, 17%, 20%, 22%, 25%, 27%, 30%, 32% or 35%, etc.

[0041] It is understandable that when the coating layer 2 includes a positive electrode material, the substrate 1 is also a positive electrode substrate and the tab 3 is a positive electrode tab; when the coating layer 2 includes a negative electrode material, the substrate 1 is also a negative electrode substrate and the tab 3 is a negative electrode tab.

[0042] Since the substrate 1 is usually a structure whose length is much greater than its width, and the width direction of the substrate 1 is usually parallel to the winding axis when the electrode is wound to obtain the core structure, it is preferable that the first direction S1 can be parallel to the width direction of the substrate 1 itself, which is beneficial to allow the tab 3 to extend from one side of the substrate 1 along the extension direction of the winding axis after the electrode is wound to obtain the core.

[0043] Optionally, along the first direction S1, the welding area 101 is located at the exact center of the surface 10, so that the coating layer 2 on both sides of the welding area 101 along the first direction S1 has an equal area, which can make the current flowing through the welding area 101 on both sides along the first direction S1 approximately equal, and thus make the current density near the connection between the tab 3 and the substrate 1 on both sides along the first direction S1 approximately equal, which can avoid the situation where the current density on one side of the connection between the tab 3 and the substrate 1 along the first direction S1 is larger.

[0044] Along the second direction S2, the first part 31 has a width W1, and the welding area 101 has a size W2. The larger the ratio W1 / W2 of the width W1 of the first part 31 to the size W2 of the welding area 101, the larger the size of the connection between the first part 31 and the welding area 101, and the smaller the internal resistance at the welding position of the first part 31 and the welding area 101. However, if the ratio W1 / W2 of the width W1 of the first part 31 to the size W2 of the welding area 101 is too large, it will cause the first part 31 to be prone to defects due to manufacturing errors of the first part 31 and coating layer 2 when welding the first part 31 to the welding area 101. The setting error and operation error cause interference between the first part 31 and the coating layer 2. Therefore, W1 / W2 should not be too large. Based on this, the ratio W1 / W2 of the width W1 of the first part 31 to the size W2 of the welding area 101 can optionally satisfy: 60% ≤ W1 / W2 ≤ 95%. For example, the ratio W1 / W2 of the width W1 of the first part 31 to the size W2 of the welding area 101 can be 60%, 65%, 70%, 75%, 80%, 85%, 90% or 95%, etc., wherein the second direction S2 is perpendicular to the first direction S1 and the thickness direction of the substrate 1.

[0045] Optionally, the first part 31 is rectangular, and the welding area 101 is also rectangular. The two opposite edges of the welding area 101 are parallel to the first direction S1, so that the shape of the welding area 101 is adapted to the shape of the first part 31 welded to one end of the welding area 101. That is, both the welding area 101 and the first part 31 welded to one end of the welding area 101 are rectangular, so that the area of ​​the part of the welding area 101 that cannot be welded to the first part 31 is relatively small, thereby making the internal resistance at the welding position of the first part 31 and the welding area 101 relatively small.

[0046] Optionally, at least a portion of the surface of the tab 3 facing away from the substrate 1 is provided with an insulating layer 4, thereby preventing the side of the tab 3 facing away from the substrate 1 from being electrically connected to other electrodes or conductive structures, so as to avoid short circuit problems.

[0047] Optionally, the insulating layer 4 covers the surface of the first portion 31 facing away from the substrate 1, thereby preventing the side of the first portion 31 facing away from the substrate 1 from being electrically connected to other electrodes or conductive structures.

[0048] Since the second part 32 connected to one end of the first part 31 may also come into contact with other electrodes or conductive structures, optionally, at least one end of the second part 32 connected to the first part 31 on the surface away from the substrate 1 is covered with an insulating layer 4, thereby preventing the side of the second part 32 connected to the first part 31 away from the substrate 1 from being electrically connected to other electrodes or conductive structures.

[0049] Optionally, the insulating layer 4 is an insulating coating. In other words, the insulating layer 4 is a structure formed by coating an insulating coating onto the surface of the tab 3 and curing it. The insulating coating may include, but is not limited to, insulating coatings containing ceramic particles, acrylic insulating varnish, nitrocellulose lacquer, etc. Since the insulating coating is coated onto the surface of the tab 3, the thickness of the insulating layer 4 can be relatively thin, which is beneficial to reduce the installation space occupied by the insulating layer 4 and improve the energy density of the electrode.

[0050] It is understandable that, especially when the insulating coating is applied to the surface of the tab 3 by spraying, the thickness of the insulating coating can be approximately close to 0 μm. Based on this, preferably, the thickness d of the insulating coating can satisfy: 0 μm < d ≤ 10 μm. For example, the thickness d of the insulating coating can be 0.01 μm, 0.05 μm, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.7 μm, 1 μm, 2 μm, 3 μm, 5 μm, 7 μm or 10 μm, etc.

[0051] In other embodiments, the insulating layer 4 may also be insulating tape, which is applied to the surface of the tab 3 by means of adhesive.

[0052] Optionally, the second part 32 is also provided with tab adhesive 33. Tab adhesive 33 is located on the side of the insulating layer 4 away from the welding area 101. On the one hand, since tab adhesive 33 has good insulation properties, it can insulate the part of tab 3 with tab adhesive 33 from other external structures. On the other hand, it can also bond tab adhesive 33 to the external encapsulation film during battery encapsulation, so as to seal the tab 3 with the external encapsulation film and prevent electrolyte leakage.

[0053] Preferably, the tab adhesive 33 is connected to the insulating layer 4, so that the insulating layer 4 and the tab adhesive 33 work together to further reduce the possibility of electrical conduction between the tab 3 and other external structures.

[0054] This utility model also provides a battery, including a positive electrode and a negative electrode, wherein at least one of the positive electrode and the negative electrode is an electrode as described in the aforementioned technical solution, that is, the positive electrode is an electrode as described in the aforementioned technical solution, in which case the coating layer 2 of the positive electrode includes a positive electrode material and the substrate 1 is also a positive electrode substrate; or the negative electrode is an electrode as described in the aforementioned technical solution, in which case the coating layer 2 of the negative electrode includes a negative electrode material and the substrate 1 is also a negative electrode substrate; or, both the positive electrode and the negative electrode are electrodes as described in the aforementioned technical solution, in which case the coating layer 2 of the positive electrode includes a positive electrode material and the substrate 1 is also a positive electrode substrate, and the coating layer 2 of the negative electrode includes a negative electrode material and the substrate 1 is also a negative electrode substrate.

[0055] By using an electrode with a low current density near the connection between the tab 3 and the substrate 1, the electrolyte consumption rate near the connection between the tab 3 and the substrate 1 can be reduced, thus mitigating the problem of lithium desorption and extending the safe service life of the battery.

[0056] In the description herein, it should be understood that the terms "upper," "lower," "left," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings, and are used only for ease of description and simplification of operation. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first" and "second" are merely used for distinction in description and have no special meaning.

[0057] In the description of this specification, references to terms such as "an embodiment," "example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0058] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0059] The technical principles of this utility model have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of this utility model and should not be construed as limiting the scope of protection of this utility model in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of this utility model without any inventive effort, and these embodiments will all fall within the scope of protection of this utility model.

Claims

1. An electrode sheet, characterized in that, include: The substrate (1) has a surface (10) on one side having a coating area (100) and a welding area (101), the coating area (100) surrounding the outer periphery of the welding area (101); A coating layer (2) covering the coating area (100), the coating layer (2) comprising a positive electrode material or a negative electrode material; and, A tab (3) is provided, comprising a first portion (31) and a second portion (32) opposite each other along a first direction. The first portion (31) is welded to the welding area (101) at one end away from the second portion (32). The projection of the first portion (31) along the thickness direction of the substrate (1) is located within the range of the setting surface (10). The second portion (32) is located on the outer side of the substrate (1) along the first direction. Along the first direction, the welding area (101) has a size L1, and the first portion (31) has a size L2, 15% ≤ L1 / L2 ≤ 35%. Wherein, the first direction is perpendicular to the thickness direction of the substrate (1).

2. The electrode sheet according to claim 1, characterized in that, Along the first direction, the welding area (101) is located at the exact center of the setting surface (10).

3. The electrode sheet according to claim 1, characterized in that, Along the second direction, the first portion (31) has a width W1, and the welding area (101) has a size W2, 60% ≤ W1 / W2 ≤ 95%, wherein the second direction is perpendicular to the first direction and the thickness direction of the substrate (1).

4. The electrode sheet according to any one of claims 1-3, characterized in that, The first part (31) is rectangular, the welding area (101) is rectangular, and the two opposite edges of the welding area (101) are parallel to the first direction.

5. The electrode sheet according to any one of claims 1-3, characterized in that, The tab (3) has an insulating layer (4) on at least a portion of its surface facing away from the substrate (1).

6. The electrode sheet according to claim 5, characterized in that, The insulating layer (4) covers the surface of the first portion (31) facing away from the substrate (1).

7. The electrode sheet according to claim 6, characterized in that, The second part (32) has an insulating layer (4) covering at least one end connected to the first part (31) on the surface opposite to the substrate (1).

8. The electrode sheet according to claim 5, characterized in that, The insulating layer (4) is an insulating coating with a thickness d, where 0um < d ≤ 10um.

9. The electrode sheet according to claim 5, characterized in that, The second part (32) is also provided with tab adhesive (33), which is located on the side of the insulating layer (4) away from the welding area (101).

10. A battery, characterized in that, It includes a positive electrode and a negative electrode, wherein at least one of the positive electrode and the negative electrode is an electrode as described in any one of claims 1-9.

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