Composite current collector electrode and preparation method thereof

Abstract

The invention discloses a composite current collector electrode and a preparation method thereof. The composite current collector electrode comprises a composite current collector, the composite current collector comprises a coating area and an empty foil area, an active material layer is arranged in the coating area, a communicating hole is formed in the empty foil area, and the communicating hole penetrates through the composite current collector in the thickness direction of the composite current collector; the foil materials are located in the empty foil area, the number of the foil materials is at least two, the two foil materials are located on the A face and the B face of the composite current collector respectively, the two foil materials abut against the communicating hole, and the A face and the B face of the composite current collector can be conducted through the two foil materials. Through the arrangement of the communicating hole, the foil does not need to be folded manually, automatic operation can be achieved in the whole process, electrodes can be automatically produced and manufactured on a large scale, and the electrode manufacturing efficiency is improved. And through the arrangement of the connecting holes, the foils positioned on the A surface and the B surface are directly welded together, so that the welding impedance is greatly reduced, and the electrode can well improve the impedance of the battery.

Description

A composite current collector electrode and its preparation method Technical Field

[0001] This invention relates to the field of lithium-ion battery manufacturing, specifically to a composite current collector electrode and its preparation method. Background Technology

[0002] Typically, composite current collector electrodes are mainly used in cylindrical or prismatic batteries. When winding the battery, a full tab method is used. The specific operation method is as follows: a certain width of empty foil is reserved on both sides of the composite current collector battery, and the electrode sheet is rolled to connect the A and B sides of the composite current collector; then the connected parts are fused together and the tabs are welded. This winding structure is only suitable for full tab product structures, and its application range is very limited. This process cannot be applied to gap coating structures, which greatly limits the promotion and application of composite foil materials in lithium-ion batteries.

[0003] Currently, in interstitial coated structures, the typical electrode fabrication process involves folding a foil in half, with the two ends of the folded foil positioned on sides A and B of the hollow foil region of the composite current collector, respectively. The foil and the composite current collector are then connected by welding, and finally, tabs are welded onto the foil to fabricate the electrode. In this method, folding the foil ensures conductivity between sides A and B. However, due to the foil's mere 6μm thickness, automated folding is currently impossible, requiring manual folding and hindering automated electrode fabrication. Summary of the Invention

[0004] To overcome the above-mentioned shortcomings, the present invention aims to provide a composite current collector electrode that uses an open-hole combined with welding method to conduct the A and B sides of the composite current collector, omitting the step of folding the foil material in the traditional method, and realizing the automated production of the electrode.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: a composite current collector electrode, comprising: a composite current collector, the composite current collector including a coated area and an empty foil area, an active material layer being disposed in the coated area, and a connecting hole being disposed in the empty foil area, the connecting hole penetrating the composite current collector along the thickness direction; and a foil material, the foil material being located in the empty foil area, at least two foil materials being disposed, the two foil materials being respectively located on surface A and surface B of the composite current collector, the two foil materials abutting at the connecting hole, and the two foil materials being able to conduct electricity between surface A and surface B of the composite current collector.

[0006] By incorporating connecting holes, the foil does not need to be folded. It only needs to be cut to the size corresponding to the empty foil area. The cut foil is then placed on sides A and B of the empty foil area before welding. No manual folding of the foil is required, allowing for fully automated operation and mass production of electrodes, thus improving manufacturing efficiency. Furthermore, the connecting holes allow the foil on sides A and B to be directly welded together, significantly reducing welding resistance and effectively improving battery impedance.

[0007] Furthermore, the two foils located on sides A and B of the composite current collector are connected by ultrasonic welding.

[0008] Ultrasonic welding is a welding technique that uses high-frequency vibration energy to induce plastic deformation and intermolecular diffusion in metal workpieces under pressure, thereby achieving a strong connection. In the battery electrode manufacturing process of this invention, ultrasonic welding is used to connect two foils on the A and B sides of a composite current collector, greatly reducing welding impedance and improving battery performance.

[0009] Furthermore, the coated area and the empty foil area are spaced apart along the length of the electrode.

[0010] Furthermore, the shape of the connecting hole is circular, elliptical, or square.

[0011] Furthermore, multiple connecting holes are provided, and the multiple connecting holes are arranged in a matrix in the empty foil area, with the distance L between two adjacent connecting holes being ≥10mm.

[0012] Furthermore, the density of the connecting holes is 1-5 per 50mm.

[0013] Furthermore, the electrode also includes a tab, which is connected to the foil. The direction of the tab is parallel to the width direction of the composite current collector. One end of the tab is fixedly connected to the foil by welding, and the other end protrudes out of the composite current collector.

[0014] Furthermore, a protective adhesive layer is provided on the tab, the protective adhesive layer being located outside the composite current collector and close to the composite current collector.

[0015] A process for fabricating a composite current collector electrode includes the following steps: S1, drilling holes in the empty foil area of ​​the composite current collector to form connecting holes; S2, cutting foil, the width of which is not greater than the width of the empty foil area of ​​the composite current collector; S3, placing the cut foil on side A and side B of the empty foil area of ​​the composite current collector, respectively, the foil covering the connecting holes; S4, welding the foil in the empty foil area of ​​the composite current collector using ultrasonic welding, so that the foil on side A and side B of the empty foil area of ​​the composite current collector is connected and conductive; S5, connecting tabs on the foil using a welding process, and applying a protective adhesive layer to the tabs.

[0016] Furthermore, in step S4, the welding time of the welding foil is 250~350ms, the pressure is 0.15Mpa~0.35Mpa, and the DC voltage is 120V.

[0017] Furthermore, in S5, the welding time for the welding tabs is 650~750ms, the pressure is 0.25Mpa~0.45Mpa, and the DC voltage is 120V. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 is a front view of a composite current collector according to an embodiment of the present invention; Figure 2 is a partial enlarged view of Figure 1; Figure 3 is a top view of a composite current collector according to an embodiment of the present invention; Figure 4 is a front view of a composite current collector after preparing a connecting hole according to an embodiment of the present invention; Figure 5 is a top view of a composite current collector after preparing a connecting hole according to an embodiment of the present invention; Figure 6 is a schematic diagram of setting foil in an empty foil area according to an embodiment of the present invention; Figure 7 is a schematic diagram of welding foil according to an embodiment of the present invention; Figure 8 is a front view of a composite current collector electrode according to an embodiment of the present invention; Figure 9 is a top view of a composite current collector electrode according to an embodiment of the present invention; Figure 10 is a line graph of the internal resistance of the battery prepared in Embodiment 1 of the present invention; Figure 11 is a line graph of the internal resistance of the battery prepared in Comparative Example 1 of the present invention.

[0021] In the diagram: 1. Composite current collector; 11. Insulating layer; 12. Metal layer; 13. Active material layer; 14. Coated area; 15. Empty foil area; 16. Side A; 17. Side B; 2. Connecting hole; 3. Foil material; 4. Tab; 5. Protective adhesive layer. Detailed Implementation

[0022] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0023] Referring to Figures 1-3, a composite current collector electrode in this embodiment includes a composite current collector 1. The composite current collector 1 includes an insulating layer 11 and metal layers 12 disposed on the upper and lower surfaces of the insulating layer 11. The insulating layer 11 is made of polymer materials such as PET, PP or PI, providing insulation support and mechanical strength. The metal layer 12 is responsible for current conduction. The metal layer 12 used as the negative electrode composite current collector is a copper layer, and the metal layer 12 used as the positive electrode composite current collector is an aluminum layer.

[0024] The electrode also includes a coated area 14 with active material and an uncoated foil area 15. The electrode has a length direction X and a width direction Y. The coated area 14 and the uncoated foil area 15 are spaced apart along the length direction X of the electrode. Active material is coated on the coated area 14 to form an active material layer 13. The uncoated foil area 15 is used for connection with the tab 4. This arrangement ensures effective coverage of the active material and reserves the necessary metal foil area for connection with the tab 4. The presence of the uncoated foil area 15 avoids damage to the active material layer 13 during tab 4 soldering, thus improving connection reliability.

[0025] Referring to Figures 4-7, in some embodiments, a connecting hole 2 is provided in the empty foil area 15, and the connecting hole 2 penetrates the composite current collector along the thickness direction. The electrode also includes patch foil 3, and two patch foils 3 are provided in the empty foil area 15. The two patch foils 3 are located on the A-side 16 and B-side 17 of the composite current collector 1, respectively. The two patch foils 3 located on the A-side 16 and B-side 17 of the composite current collector 1 are connected by ultrasonic welding, and the two patch foils 3 and the composite current collector 1 are welded into a whole, improving the welding strength between the foils 3 and the composite current collector. At the connecting hole 2, the two patch foils 3 located on the A-side 16 and B-side 17 are welded together, making the two patch foils 3 located on the A-side 16 and B-side 17 conductive. By providing the connecting hole 2 in the empty foil area 15, effective conductivity of the patch foils 3 on the A-side 16 and B-side 17 is achieved, thereby connecting the A-side and B-side of the composite current collector. In this invention, the A-side and B-side of the composite current collector refer to the two sides of the composite current collector in the thickness direction.

[0026] In existing technologies, foil 3 is typically folded in half, with the two ends of the folded foil 3 located on side A 16 and side B 17 of the composite current collector, respectively. The foil 3 and the composite current collector are then connected by welding. Folding foil 3 ensures conductivity between sides A 16 and B 17. However, because foil 3 is only 6 μm thick, automated folding is currently impossible, requiring manual folding, which prevents automated production of the electrode.

[0027] In the technical solution of this invention, by setting the connecting hole 2, the foil 3 does not need to be folded. It only needs to be cut to a size corresponding to the empty foil area 15. The cut foil 3 is then placed on the A side 16 and B side 17 of the empty foil area 15 and welded. There is no need for manual folding of the foil 3, and the entire process can be automated, enabling mass automated production of electrodes and improving the efficiency of electrode manufacturing. Furthermore, by setting the connecting hole, the foils located on the A side and B side are directly welded together, which greatly reduces the welding resistance, and the electrode can effectively improve the battery impedance.

[0028] In some embodiments, the connecting hole 2 is circular, elliptical, or square. Different shapes of connecting holes 2 are adapted to different process requirements. Circular connecting holes 2 are simple to process, while square connecting holes 2 are easy to position. The distance L between two adjacent connecting holes 2 is ≥10mm. A spacing of L≥10mm ensures the structural integrity of the composite current collector. The hole distribution density varies depending on the length of the battery, with a density of 1-5 holes / 50mm. A density of 1-5 holes / 50mm ensures sufficient conductivity while avoiding excessive weakening of mechanical strength. Preferably, it is 2 holes / 50mm.

[0029] Referring to Figures 8-9, in some embodiments, the electrode further includes a tab 4, which is connected to the foil 3 located in the empty foil area 15 by welding. The tab 4 is arranged parallel to the width direction of the composite current collector. One end of the tab 4 is fixedly connected to the foil 3 by welding, while the other end protrudes from the outside of the composite current collector 1 for connection to an external circuit.

[0030] In some embodiments, a protective adhesive layer 5 is provided on the tab 4. The protective adhesive layer 5 protrudes from the outside of the composite current collector 1 and is disposed close to the composite current collector 1. The protective adhesive layer 5 prevents the tab 4 from being mechanically damaged or chemically corroded during battery manufacturing and use. The protective adhesive layer 5 is disposed close to the composite current collector 1 to ensure the cleanliness and stability of the welding area. Furthermore, the external protective adhesive layer 5 can act as a buffer to reduce the impact of external stress on the connection point of the tab 4.

[0031] In the composite current collector 1 battery technology, the tab 4 is a key component connecting to the external circuit, and its reliability directly affects the battery's performance and safety. The protective adhesive layer 5 reflects the precision of the composite current collector 1 technology in its detailed design, and this structural optimization improves the overall manufacturing yield and long-term stability of the battery.

[0032] The fabrication process of the electrode of the composite current collector 1 includes the following steps: S1, drilling holes in the empty foil area 15 of the composite current collector 1 to form connecting holes 2; S2, cutting foil 3, the width of foil 3 not exceeding the width of the empty foil area 15 of the composite current collector 1; S3, placing the cut foil 3 on the A side 16 and B side 17 of the empty foil area 15 of the composite current collector 1, respectively, the foil 3 covering the connecting holes 2; S4, welding the foil 3 in the empty foil area 15 of the composite current collector 1 by ultrasonic welding, so that the electrode located in the composite current collector... 1. Connect the foil 3 on side A 16 and side B 17 of the empty foil area 15 to conduct electricity. The welding time of the foil 3 is 250~350ms, the pressure is 0.15Mpa~0.35Mpa, and the DC voltage is 120V. S5. Connect the electrode tab 4 on the foil 3 by welding process. The welding time of the electrode tab 4 is 650~750ms, the pressure is 0.25Mpa~0.45Mpa, and the DC voltage is 120V. S6. Apply the protective adhesive layer 5 to the electrode tab 4, and cut the electrode according to the process length. The electrode manufacturing is completed.

[0033] Example 1 involves preparing a composite current collector electrode using the following steps: S1. Referring to Figures 4-5, holes are drilled in the empty foil area of ​​the composite current collector to form connecting holes. The connecting holes are elliptical in shape, and there are three connecting holes arranged sequentially along the width of the composite current collector, with a distance of 20 mm between adjacent connecting holes; S2. The foil is cut, with a width smaller than the width of the empty foil area of ​​the composite current collector; S3. Referring to Figure 6, the cut foil is placed on sides A and B of the empty foil area of ​​the composite current collector, respectively, covering the connecting holes; S4. Referring to Figure 7, the electrode is ultrasonically welded... The foil in the empty foil area of ​​the composite current collector is welded to connect the foil on side A and side B of the empty foil area of ​​the composite current collector. The welding time of the foil is 300ms ± 50ms, the pressure is 0.25Mpa ± 0.1Mpa, and the DC voltage is 120V; S5. Referring to Figure 8, the electrode tabs are connected to the foil by welding. The welding time of the electrode tabs is 700ms ± 50ms, the pressure is 0.35Mpa ± 0.1Mpa, and the DC voltage is 120V; S6. Referring to Figure 9, a protective adhesive layer is applied to the electrode tabs, and the electrodes are cut according to the process length. The electrode fabrication is completed.

[0034] Comparative Example 1: A composite current collector electrode was prepared using conventional steps: S1. Cut the foil, ensuring the foil width is less than the width of the empty foil area of ​​the composite current collector; S2. Manually fold the foil so that both ends are located on side A and side B of the empty foil area of ​​the composite current collector, respectively; S4. Weld the foil in the empty foil area of ​​the composite current collector using ultrasonic welding, connecting the foil on side A and side B of the empty foil area and the composite current collector into a single unit. The welding time for the foil was 300ms ± 50ms, the pressure was 0.25MPa ± 0.1MPa, and the DC voltage was 120V; S5. Connect the electrode tabs to the foil using a welding process. The welding time for the electrode tabs was 700ms ± 50ms, the pressure was 0.35MPa ± 0.1MPa, and the DC voltage was 120V; S6. Apply a protective adhesive layer to the electrode tabs and cut the electrode to the required length. The electrode fabrication is now complete.

[0035] In the experimental examples, 103450-1800mAh batteries were fabricated using the electrodes prepared in Example 1 and Comparative Example 1, respectively, and the internal resistance of the 103450-1800mAh batteries was tested. To improve the accuracy of the test, the electrode fabrication and 103450-1800mAh battery fabrication were repeated 28 times in Example 1 and Comparative Example 1, respectively, and the internal resistance of the fabricated 103450-1800mAh batteries was tested. The test results are shown in Figure 1 and Figure 2.

[0036] As can be seen from Figures 10 and 11, the internal resistance of the battery prepared by conventional process is 60~90mΩ, while the internal resistance of the battery cell prepared by the process of the present invention is 45~55mΩ. According to the test data, the battery prepared by the electrode of the present invention has lower impedance and smaller impedance fluctuation. The electrode prepared by the present invention can effectively improve the battery impedance.

[0037] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A composite current collector electrode, characterized in that, include: A composite current collector (1) includes a coating area (14) and an empty foil area (15). An active material layer (13) is provided in the coating area (14), and a connecting hole (2) is provided in the empty foil area (15). The connecting hole (2) penetrates the composite current collector (1) along the thickness direction of the composite current collector (1). A foil (3) is located in the empty foil area (15). At least two foils are provided. The two foils (3) are located on the A side (16) and B side (17) of the composite current collector (1), respectively. The two foils (3) abut against each other at the connecting hole (2). The two foils (3) can conduct the A side (16) and B side (17) of the composite current collector (1).

2. The composite current collector electrode according to claim 1, characterized in that, The two foils (3) located on the A side (16) and B side (17) of the composite current collector (1) are connected by ultrasonic welding.

3. The composite current collector electrode according to claim 1, characterized in that, The coated area (14) and the empty foil area (15) are spaced apart along the length of the electrode.

4. The composite current collector electrode according to claim 1, characterized in that, The shape of the connecting hole (2) is circular, elliptical or square.

5. The composite current collector electrode according to claim 1, characterized in that, Multiple connecting holes (2) are provided, and the multiple connecting holes (2) are arranged in a matrix in the empty foil area (15), with the distance L between two adjacent connecting holes (2) being ≥10mm.

6. The composite current collector electrode according to claim 1, characterized in that, The density of the connecting holes (2) is 1-5 per 50 mm.

7. The composite current collector electrode according to claim 1, characterized in that, The electrode also includes a tab (4), which is connected to the foil (3). The direction of the tab (4) is parallel to the width direction of the composite current collector (1). One end of the tab (4) is fixedly connected to the foil (3) by welding, and the other end protrudes outside the composite current collector (1).

8. The composite current collector electrode according to claim 7, characterized in that, A protective adhesive layer (5) is provided on the tab (4). The protective adhesive layer (5) is located outside the composite current collector (1) and is disposed close to the composite current collector (1).

9. The fabrication process of the composite current collector electrode according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Drill holes in the empty foil area (15) of the composite current collector (1) to form a connecting hole (2); S2. Cut foil (3), the width of foil (3) is not greater than the width of the empty foil area (15) of the composite current collector (1); S3. Place the cut foil (3) on the A side (16) and B side (17) of the empty foil area (15) of the composite current collector respectively, the foil (3) can cover the connecting hole (2); S4. Weld the foil (3) of the empty foil area (15) of the composite current collector (1) by ultrasonic welding, so that the foil (3) located on the A side (16) and B side (17) of the empty foil area (15) of the composite current collector (1) is connected and conductive to the A side (16) and B side (17); S5. Connect the tab (4) on the foil (3) by welding process, and attach a protective adhesive layer (5) on the tab (4).

10. The fabrication process of the composite current collector electrode according to claim 9, characterized in that, In step S4, the welding time of the welding foil (3) is 250~350ms, the pressure is 0.15Mpa~0.35Mpa, and the DC voltage is 120V; in step S5, the welding time of the welding tab (4) is 650~750ms, the pressure is 0.25Mpa~0.45Mpa, and the DC voltage is 120V.

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