An electrode structure, a battery cell and a battery

Abstract

This utility model relates to the technical field of batteries, and discloses an electrode structure, a battery cell, and a battery. The electrode structure includes an electrode sheet and a tab. The tab has multiple recesses on its side facing the electrode sheet, and each recess is filled with a first adhesive resistant to electrolyte corrosion. The first adhesive bonds the electrode sheet and the tab. The side of the tab with the multiple recesses is hot-pressed together with the electrode sheet. The recesses increase the composite area of ​​the tab and the electrode sheet, thus improving the strength of the tab and electrode sheet after hot pressing. The recesses are pre-filled with the first adhesive resistant to electrolyte corrosion before hot pressing, further enhancing the strength of the tab and electrode sheet after hot pressing. Compared with traditional laser welding or ultrasonic welding, the hot pressing bonding method of this solution results in a smaller thickness after the tab and electrode sheet are connected, leading to a smaller thickness after the battery cell is wound, which helps increase the energy density of the battery cell.

Description

Technical Field

[0001] This utility model relates to the technical field of batteries, and in particular to an electrode structure, a battery cell, and a battery. Background Technology

[0002] With the explosive growth of consumer products and technological innovation, people's demand for longer battery life and higher energy density is increasing. However, due to limitations in current materials and manufacturing processes, improving battery energy density is becoming increasingly difficult. A battery cell consists of a cell body and an aluminum-plastic film. The cell body is mostly a wound structure composed of positive electrode plates, separators, and negative electrode plates stacked and wound together. The cell body also includes positive and negative tabs. The positive tabs are welded to the positive electrode plates to form the positive electrode structure, and the negative tabs are welded to the negative electrode plates to form the negative electrode structure. The aluminum-plastic film is used to seal the cell body through heat pressing, with only the positive and negative tabs leading outwards. This prevents internal electrolyte leakage and also prevents external substances from entering the cell. When the positive and negative tabs are connected, the cell can supply power to external devices or charge its internal components. More specifically, the welding of electrodes and tabs currently mostly uses laser welding or ultrasonic welding. Both of these welding methods result in a large height after the electrodes and tabs are welded together. When the electrodes are wound, this leads to a large electrode thickness, which in turn results in a need to improve the energy density of the battery cell. Secondly, both of these welding methods produce large burrs on the surface of the tabs. When the aluminum-plastic film is wrapped around the battery cell body, the burrs on the surface of the tabs can easily pierce the aluminum-plastic film, which can easily cause leakage and short circuits. Therefore, the existing technology needs to be improved. Utility Model Content

[0003] This utility model provides an electrode structure, a battery cell, and a battery, mainly solving the technical problems of large weld thickness and easy puncture of the soft-pack outer shell after the current electrode and tab are laser welded or ultrasonically welded.

[0004] To achieve the above objectives, this utility model provides the following technical solution: An electrode structure includes an electrode and a tab. The tab has multiple recesses on the side facing the electrode. Each of the multiple recesses contains a first adhesive that is resistant to electrolyte corrosion. The first adhesive bonds the electrode and the tab respectively. The side of the tab with the multiple recesses is hot-pressed and bonded to the electrode.

[0005] In one of the technical solutions, a ring of second adhesive resistant to electrolyte corrosion is provided on the outer edge of the side of the tab facing the electrode sheet, and the second adhesive bondes the electrode sheet and the tab respectively.

[0006] In one of the technical solutions, the center distance between any two adjacent pits is 0.2mm-0.5mm.

[0007] In one of the technical solutions, the depth of the pit is 3um-6um.

[0008] In one of the technical solutions, the side of the tab facing away from the electrode sheet is heated and pressed to form a protrusion protruding towards the electrode sheet in at least one of the recesses.

[0009] In one of the technical solutions, the shape of the pit is circular, square, triangular, hexagonal, or rhomboid.

[0010] In one of the technical solutions, the electrode includes a current collector and an active material layer coated on at least one side of the current collector, and the side of the electrode tab with a plurality of the pits is hot-pressed and bonded to the current collector.

[0011] In one technical solution, the current collector is made of aluminum, and the thickness of the current collector is 8µm-12µm; or, The current collector is made of copper and has a thickness of 6µm-10µm.

[0012] In one of the technical solutions, an electrode groove is provided on the outer edge of the active material layer, and the electrode is hot-pressed and composited with the current collector in the electrode groove. The area of ​​the current collector opposite to the electrode groove is covered with the active material layer.

[0013] This application also provides a battery cell, including a positive electrode structure, a separator, and a negative electrode structure, wherein at least one of the positive electrode structure and the negative electrode structure is the electrode structure described above.

[0014] This application also provides a battery, including the cell described above.

[0015] In one of the technical solutions, the battery includes a pouch casing, the battery cell is disposed inside the pouch casing, and the outer end of the positive tab in the positive electrode structure and the outer end of the negative tab in the negative electrode structure both extend outside the pouch casing.

[0016] Compared with the prior art, the electrode structure provided by this utility model has at least the following beneficial effects: This solution involves pre-drilling holes (i.e., creating multiple pits) on the surface of the tab, and designing the side of the tab with the pits to be hot-pressed and bonded together with the electrode sheet. On the one hand, the pits increase the bonding area between the tab and the electrode sheet, thereby improving the strength of the tab and electrode sheet after hot pressing. On the other hand, the pits can be pre-filled with a first adhesive resistant to electrolyte corrosion before hot pressing, which further improves the strength of the tab and electrode sheet after hot pressing. Using this solution, the strength of the tab and electrode sheet after hot pressing is high. Moreover, compared with traditional laser welding or ultrasonic welding, the thickness of the tab and electrode sheet after connection is smaller, resulting in a smaller thickness after the battery cell is wound, which helps to increase the energy density of the battery cell. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of the tabs and electrode sheets before hot pressing, as provided in the embodiments of this application. Figure 2 A plan view of the tab provided in an embodiment of this application; Figure 3 This application provides a schematic diagram of the structure of a battery cell.

[0019] Figure label: 1. Electrode; 11. Current collector; 12. Active material layer; 13. Tab groove; 2. Tab; 21. Pits; 3. Soft outer shell. Detailed Implementation

[0020] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0021] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0022] It should be understood that the terms "upper", "lower", "top", "bottom", "inner", "outer", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and are not intended to 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 application.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0024] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments.

[0025] Please refer to the following: Figure 1 and Figure 2This utility model provides an electrode structure, which includes an electrode 1 and a tab 2. The electrode 1 can be understood as including a current collector 11 and an active material layer 12 coated on the current collector 11. The current collector 11 is usually made of aluminum foil or copper foil. When the current collector 11 is aluminum foil, the thickness of the current collector 11 is usually 8um-12um; when the current collector 11 is copper foil, the thickness of the current collector 11 is usually 6um-10um. The active material layer 12 can be coated on one side of the current collector 11 or on both sides of the current collector 11. When the active material layer 12 is a positive electrode slurry, the electrode 1 is understood as a positive electrode; when the active material layer 12 is a negative electrode slurry, the electrode 1 is understood as a negative electrode. The tab 2 has multiple recesses 21 on the side facing the electrode 1. Each recess 21 is filled with a first adhesive that is resistant to electrolyte corrosion. The first adhesive bonds the electrode 1 and the tab 2. Specifically, some or all of the recesses 21 may be filled with the first adhesive. The side of the tab 2 with the multiple recesses 21 is hot-pressed together with the current collector 11 on the electrode 1. In fact, a tab groove 13 is formed on the outer edge of the active material layer 12. The tab 2 is hot-pressed together with the current collector 11 in this tab groove 13. The tab groove 13 can be formed by intermittently coating the active material layer 12 (i.e., using two coating dies with different widths of the active material layer 12, and forming the tab groove 13 by changing the width of the active material layer 12 at a specified position) or by laser cleaning the active material layer 12 (i.e., removing a portion of the active material layer 12 to form the tab groove 13). In addition, the area of ​​the current collector 11 opposite to the tab groove 13 is usually covered with an active material layer 12. In other words, the electrode 1 with tab groove 13 is mostly coated with an active material layer 12 on both sides of the current collector 11 to improve the energy density of the battery.

[0026] The following details the hot-pressing process of tab 2 and electrode 1: First, the area on electrode 1 to be hot-pressed with the tab is cleaned. Multiple cleanings (3-5 times) are performed at low power to thin the surface until the current collector 11 is visible (i.e., the active material layer 12 in the designated area is removed to avoid affecting the subsequent hot-pressing bonding effect with the tab 2). Then, the side of the tab 2 with multiple pits 21 faces the current collector 11. Next, the tab 2 and the current collector 11 are hot-pressed together. When the current collector 11 is aluminum foil, the hot-pressing parameters are: pressure 2-5 MPa, temperature 180-220℃, and hot-pressing time 2-5 seconds. When the current collector 11 is copper foil, the hot-pressing parameters are: pressure 5-10 MPa, temperature 250-320℃, and hot-pressing time 4-8 seconds.

[0027] Specifically, this solution involves pre-drilling holes (i.e., setting multiple pits 21) on the surface of the tab 2, and designing the side of the tab 2 with the pits 21 to be hot-pressed and bonded together with the electrode 1. On the one hand, setting the pits 21 helps to increase the bonding area between the tab 2 and the electrode 1, thereby improving the firmness of the tab 2 and the electrode 1 after hot pressing. On the other hand, the pits 21 can also be pre-filled with a first adhesive resistant to electrolyte corrosion before hot pressing welding, which further helps to improve the firmness of the tab 2 and the electrode 1 after hot pressing. Using this solution, the firmness of the tab 2 and the electrode 1 after hot pressing is high. Moreover, compared with the traditional laser welding or ultrasonic welding method, the thickness of the tab 2 and the electrode 1 after being connected is smaller, which makes the thickness of the battery cell after winding smaller, thereby helping to increase the energy density of the battery cell.

[0028] In a preferred embodiment, after the tab 2 and the electrode 1 are hot-pressed together, a second adhesive is applied to the outer edge of the side of the tab 2 facing the electrode 1. This second adhesive bonds the electrode 1 and the tab 2 together, further enhancing the bond strength after hot pressing. The second adhesive also exhibits resistance to electrolyte corrosion, preventing the electrolyte from corroding the adhesive and causing bonding failure. Both the first and second adhesives can be systems where polyisobutylene rubber is cross-linked with epoxidized polyisobutylene and amino-terminated liquid nitrile rubber, respectively. This type of adhesive exhibits high adhesion and resistance to electrolyte corrosion.

[0029] Please see Figure 2 In this embodiment, the distance D between two adjacent recesses 21 on the tab 2 is 0.2mm-0.5mm, and the depth h is 3-6µm. The shape of the recesses 21 can be circular, square, triangular, hexagonal, or rhomboid, etc. If the distance D between two adjacent recesses 21 is too small, the conductive area between the tab 2 and the electrode 1 after hot pressing will be small; if the distance D between two adjacent recesses 21 is too large, the amount of first adhesive to be accommodated will be insufficient, resulting in insufficient bonding strength between the tab 2 and the electrode 1. In addition, by setting multiple recesses 21, even though the surface of the tab 2 is uneven when it is received, after the tab 2 and the electrode 1 are hot pressed, the protrusions on the surface of the tab 2 will be formed in at least one recess 21, protruding towards the electrode 1. This helps to reduce the thickness of the tab 2 after it is welded to the electrode 1, and when the protrusion contacts the electrode 1, it also helps to increase the conductive area between the electrode 1 and the tab 2, thereby enhancing the conductivity between the electrode 1 and the tab 2.

[0030] This embodiment also provides a battery cell, which includes a positive electrode structure, a separator, and a negative electrode structure. In fact, the positive electrode structure, the separator, and the negative electrode structure are stacked and wound in sequence to form a wound battery cell. At least one of the positive electrode structure and the negative electrode structure adopts the above-mentioned electrode structure. Preferably, both the positive electrode structure and the negative electrode structure adopt the above-mentioned electrode structure. That is, both the positive electrode structure and the negative electrode structure adopt the hot-pressing composite method to realize the connection between the electrode and the tab. Therefore, the thickness of the battery cell after winding in this solution is small, thus having the advantage of high energy density.

[0031] Please see Figure 3 This embodiment also provides a battery, which includes a pouch casing 3 and the aforementioned battery cell. The battery cell is disposed inside the pouch casing 3, and the external terminals of the positive tab in the positive electrode structure and the external terminals of the negative tab in the negative electrode structure both extend outside the pouch casing 3. The pouch casing is typically made of aluminum-plastic film. When the positive and negative tabs are connected, the battery discharges to the outside or is charged by an external power source. Because this embodiment uses the aforementioned battery cell, it also has the advantage of high energy density.

[0032] The above are merely preferred embodiments of the present utility model, and only specifically describe the technical principles of the present utility model. These descriptions are only for explaining the principles of the present utility model and should not be construed as limiting the scope of protection of the present utility model in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model, as well as other specific embodiments of the present utility model that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of the present utility model.

Claims

1. An electrode structure, characterized in that, The device includes an electrode sheet and an electrode tab. The side of the electrode tab facing the electrode sheet has multiple recesses. Each of the multiple recesses contains a first adhesive that is resistant to electrolyte corrosion. The first adhesive bondes the electrode sheet and the electrode tab to each other. The side of the electrode tab with the multiple recesses is hot-pressed and bonded together with the electrode sheet.

2. The electrode structure as described in claim 1, characterized in that, A second adhesive ring resistant to electrolyte corrosion is provided at the outer edge of the side of the tab facing the electrode sheet, and the second adhesive bondes the electrode sheet and the tab respectively.

3. The electrode structure as described in claim 1, characterized in that, The center distance between any two adjacent pits is 0.2mm-0.5mm.

4. The electrode structure as described in claim 1, characterized in that, The depth of the pit is 3um-6um.

5. The electrode structure as described in claim 1, characterized in that, After being heated and pressed, the side of the tab facing away from the electrode sheet forms a protrusion protruding towards the electrode sheet in at least one of the recesses.

6. The electrode structure as described in claim 1, characterized in that, The shape of the pit can be circular, square, triangular, hexagonal, or rhomboid.

7. The electrode structure as described in claim 1, characterized in that, The electrode includes a current collector and an active material layer coated on at least one side of the current collector, and the side of the electrode tab with a plurality of the pits is hot-pressed together with the current collector.

8. The electrode structure as described in claim 7, characterized in that, The current collector is made of aluminum, and its thickness is 8µm-12µm; or, The current collector is made of copper and has a thickness of 6µm-10µm.

9. The electrode structure as described in claim 7, characterized in that, The outer edge of the electrode sheet is provided with an electrode tab groove, and the electrode tab is hot-pressed and combined with the current collector in the electrode tab groove; The region of the current collector opposite to the tab groove is covered with the active material layer.

10. A battery cell, characterized in that, It includes a positive electrode structure, a separator, and a negative electrode structure, wherein at least one of the positive electrode structure and the negative electrode structure is the electrode structure according to any one of claims 1 to 9.

11. A battery, characterized in that, Including the battery cell as described in claim 10.

12. The battery as claimed in claim 11, characterized in that, The battery includes a pouch casing, and the battery cells are disposed inside the pouch casing. The outer ends of the positive tabs in the positive electrode structure and the outer ends of the negative tabs in the negative electrode structure both extend outside the pouch casing.

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