A method and equipment for welding battery electrodes with composite current collectors

Abstract

This invention relates to the field of battery manufacturing technology, specifically to a method and equipment for welding battery electrodes using composite current collectors. The battery electrode welding method for composite current collectors provided by this invention employs a three-step welding process. First, a first welding head is used to weld and connect the metal layers of two composite current collectors in contact. Then, a laser is used to perform laser sintering on the weld mark. The laser beam can penetrate the weld mark and reach the polymer material layer in the middle of the composite current collector, thereby burning away the polymer material and achieving direct contact between the metal layers on both sides of the polymer material layer in a single-layer composite current collector. Finally, a second welding head is used for shaping, resulting in a better welding effect.

Description

Technical Field

[0001] This invention relates to the field of battery manufacturing technology, specifically to a battery electrode welding method and welding equipment using a composite current collector. Background Technology

[0002] Lithium-ion batteries possess advantages such as high energy density, long cycle life, and environmental friendliness, and have been increasingly widely used in consumer electronics, new energy vehicles, and energy storage. There is a negative correlation between the energy density and safety performance of lithium-ion batteries. Composite current collectors, which are polymer-supported metal-layer current collectors, can balance battery safety and energy density, and lithium-ion batteries using composite current collectors are gradually being adopted.

[0003] The middle layer of a composite current collector is a polymer material layer, while the front and back sides are metallic conductive layers. The polymer material can reduce the battery's mass, thereby increasing its energy density. However, the polymer layer cannot transport electrons, thus limiting the conductivity of the composite current collector. Based on this structural characteristic of composite current collectors, a structure of external tab-composite current collector-external tab is currently commonly used to connect the electron transport behavior on both sides of the composite current collector.

[0004] However, the composite current collector has a 3-6 μm thick polymer material layer in the middle, and the metal layer on both sides of the polymer material layer is about 1 μm thick. This polymer-supported metal layer has weaker mechanical strength than pure metal foil. When commonly welding the external tab-composite current collector-external tab, the overall weak mechanical strength of the composite current collector and the thin metal layers on both sides must be taken into account. In order to maintain the integrity of the external tab connection, the power of the external tab welding is generally relatively low. Therefore, the external tab-composite current collector-external tab welding structure and method maintain the structural and appearance integrity of the electrode, but the thin conductive metal layers on both sides are prone to poor soldering. Poor soldering increases the obstacle to electron transport and collection of the composite current collector, thereby increasing the internal resistance of the battery and reducing the battery power. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defect that the traditional welding method of composite current collectors in the prior art is prone to producing incomplete welds, thereby providing a battery electrode welding method of composite current collectors that can effectively guarantee the welding effect of composite current collectors.

[0006] To address the aforementioned technical problems, this invention provides a battery electrode welding method for composite current collectors, suitable for welding composite current collectors. The composite current collector includes a polymer material layer and metal layers disposed on both sides of the polymer material layer in the thickness direction, comprising:

[0007] S1: Place at least two composite current collector layers on the welding base;

[0008] S2: The first welding head welds at least two metal layers in contact with each other on the first working parameter.

[0009] S3: The polymer material layer of the composite current collector in the welding area is removed by the laser at a preset output power;

[0010] S4: The second welding head shapes the weld marks within the welding area under the second working parameters.

[0011] Optionally, the height ratio of the welding teeth of the first welding head and the second welding head is in the range of 2≤R / r≤3, where R is the height of the first welding tooth on the first welding head and r is the height of the second welding tooth on the second welding head.

[0012] Optionally, the height R of the first welding tooth is in the range of 35μm≤R≤80μm; the height r of the second welding tooth is in the range of 15μm≤r≤30μm.

[0013] Optionally, the first operating parameters include a first welding frequency f1 and a first welding power P1, wherein the value of the first welding frequency f1 is in the range of 15kHz≤f1≤30kHz, and the value of the first welding power P1 is in the range of 4kW≤P1≤7kW.

[0014] Optionally, the second operating parameters include a second welding frequency f2 and a second welding power P2, wherein the value range of the second welding frequency f2 is 40kHz≤f2≤50kHz, and the value range of the second welding power P2 is 1kW≤P2≤4kW.

[0015] Optionally, the preset output power P3 of the laser is in the range of 1mW≤P3≤600mW.

[0016] The battery electrode welding equipment for composite current collectors provided by the present invention applies the method described above. The battery electrode welding equipment for composite current collectors includes:

[0017] Welding base, suitable for placing composite current collectors;

[0018] The first welding head has a first welding tooth with a height of R formed on it;

[0019] Laser;

[0020] The second welding head has a second welding tooth with a height of r formed on it;

[0021] The welding areas of at least two layers of the composite current collector are welded sequentially via the first welding head, the laser, and the second welding head.

[0022] Optionally, the welding base is adapted to move along a preset direction, and drive the composite current collector placed thereon to move sequentially to positions corresponding to the first welding head, the laser, and the second welding head.

[0023] Optionally, the welding base is fixed, and the first welding head, the laser, and the second welding head are moved in sequence to positions corresponding to the welding area of ​​the composite current collector placed on the welding base.

[0024] Optionally, the polymer material layer in the welding area of ​​the composite current collector disappears after welding, allowing the first metal layer to directly contact the second metal layer.

[0025] The technical solution of this invention has the following advantages:

[0026] 1. The battery electrode welding method for composite current collectors provided by this invention adopts a three-step welding approach. First, a first welding head is used to weld and connect the metal layers of two composite current collectors in contact. Then, a laser is used to perform laser sintering on the weld mark. The laser beam can penetrate the weld mark and reach the polymer material layer in the middle of the composite current collector, thereby burning away the polymer material layer and achieving direct contact between the metal layers on both sides of the polymer material layer in the single-layer composite current collector. Finally, a second welding head is used for shaping, resulting in a better welding effect.

[0027] 2. The battery electrode welding method for composite current collectors provided by this invention employs a three-step welding process. First, a first welding head connects the front and back metal layers. Then, a laser ablates the polymer material at the weld mark. Finally, a second welding head array shapes and reinforces the weld mark, achieving direct contact between the front and back metal layers for electronic connection. This avoids the phenomenon of incomplete welds in composite current collector welding and improves the power performance of the composite current collector. By rationally utilizing the structural characteristics of the composite current collector, direct connection between the front and back surfaces is achieved. The absence of polymer material in the weld mark results in a stronger weld and lower welding resistance. Furthermore, the shaping with small welding teeth enhances the weld bonding force.

[0028] 3. The battery electrode welding method for composite current collectors provided by the present invention sets the height ratio of the welding teeth of the first welding head and the second welding head to be within the range of 2≤R / r≤3, thereby using the first welding head with large welding teeth to achieve rapid connection of the metal layers in contact between the two composite current collectors. Subsequently, the second welding head with small welding teeth is used for shaping and reinforcement to achieve precision welding, so that the tensile force of the final welding effect can be greater than 20N / m and the welding resistance value is close to the welding effect of pure metal foil.

[0029] 4. The battery electrode welding equipment for composite current collectors provided by the present invention combines a first welding head with a first welding tooth of height R, a laser, and a second welding head with a second welding tooth of height r. The first welding head is used to connect the front and back metal layers, and the laser is used to burn the polymer material at the weld mark. Finally, the array of second welding heads is used to shape and reinforce the weld mark, achieving direct contact between the front and back metal layers for electronic connection. This avoids the phenomenon of incomplete welding in composite current collector welding and improves the power performance of the composite current collector.

[0030] 5. The battery electrode welding equipment for composite current collectors provided by the present invention ensures that the polymer material layer of the composite current collector disappears only in the welding area after welding, while the intermediate polymer material layer is retained in the non-welding area of ​​the composite current collector. This ensures a stronger weld and lower welding resistance, while also preserving the melting mechanism of the composite current collector and improving battery safety performance. Attached Figure Description

[0031] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the welding of the composite current collector using the first welding head according to the present invention;

[0033] Figure 2 This is a cross-sectional schematic diagram of the two-layer composite current collector of the present invention in a stacked state;

[0034] Figure 3 This is a schematic diagram illustrating the sequential welding of the composite current collector using a first welding head, a laser, and a second welding head according to the present invention.

[0035] Figure 4 This is a schematic cross-sectional view of the two-layer composite current collector of the present invention after welding is completed;

[0036] Explanation of reference numerals in the attached figures:

[0037] 1-First welding head, 11-First welding tooth, 2-Welding base, 21-Welding base tooth, 3-Composite current collector, 31-First metal layer, 32-Polymer material layer, 33-Second metal layer, 4-Laser, 5-Second welding head, 51-Second welding tooth, 9-Welding area. Detailed Implementation

[0038] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and 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. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0040] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0041] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0042] Example 1

[0043] The battery electrode welding method for the composite current collector provided in this embodiment is suitable for welding composite current collectors. The composite current collector includes a polymer material layer and metal layers disposed on both sides of the polymer material layer in the thickness direction, including:

[0044] S1: Place at least two composite current collector layers on the welding base;

[0045] S2: The first welding head welds at least two metal layers in contact with each other on the first working parameter.

[0046] S3: The polymer material layer of the composite current collector in the welding area is removed by the laser at a preset output power;

[0047] S4: The second welding head shapes the weld marks within the welding area under the second working parameters.

[0048] Combination Figure 2 As shown, the composite current collector 3 includes a polymer material layer 32, and a first metal layer 31 and a second metal layer 33 located on the upper and lower sides of the polymer material layer 32 along the thickness direction, respectively; the two composite current collectors 3 are stacked and welded together in the welding area 9.

[0049] The battery electrode welding method for composite current collectors provided in this embodiment adopts a three-step welding approach. First, a first welding head is used to weld and connect the metal layers of the two composite current collectors in contact. Then, a laser is used to perform laser sintering on the weld mark. The laser beam can penetrate the weld mark and reach the polymer material layer in the middle of the composite current collector, thereby burning away the polymer material layer and achieving direct contact between the metal layers on both sides of the polymer material layer in the single-layer composite current collector. Finally, a second welding head is used for shaping, resulting in a better welding effect.

[0050] Optionally, in this embodiment, the height of the welding teeth of the first welding head is greater than the height of the welding teeth of the second welding head. That is, the large welding teeth are used for welding first, and then the small welding teeth are used for shaping and reinforcement to achieve precision welding.

[0051] Optionally, the first welding head uses low-frequency high-power welding, making the welding process gentler.

[0052] The battery electrode welding method for composite current collectors provided in this embodiment employs a three-step welding approach. First, a first welding head connects the front and back metal layers. Then, a laser ablates the polymer material at the weld mark. Finally, a second welding head array shapes and reinforces the weld mark, achieving direct contact between the front and back metal layers for electronic connection. This avoids the incomplete weld phenomenon common in composite current collector welding and improves the power performance of the composite current collector. By rationally utilizing the structural characteristics of the composite current collector, direct connection between the front and back surfaces is achieved. The absence of polymer material in the weld mark results in a stronger weld and lower welding resistance. Furthermore, the small welding teeth shape the weld, leading to better bonding and a superior welding effect.

[0053] Furthermore, the battery electrode welding method with composite current collector provided in this embodiment avoids the structural design of external tab-composite current collector-external tab. This eliminates the need for external tabs, resulting in lower battery assembly costs, higher assembly efficiency, and reduced material usage, which is beneficial for improving battery energy density. The battery is also lighter, allowing for more battery material to be coated along the electrode height, potentially increasing battery energy density by 8% to 10%.

[0054] Specifically, the height ratio of the welding teeth of the first welding head and the second welding head is in the range of 2≤R / r≤3, where R is the height of the first welding tooth on the first welding head and r is the height of the second welding tooth on the second welding head.

[0055] The battery electrode welding method for composite current collectors provided in this embodiment sets the height ratio of the welding teeth of the first welding head and the second welding head to be within the range of 2≤R / r≤3. This allows the first welding head with large welding teeth to achieve rapid connection of the metal layers in contact between the two composite current collectors. Subsequently, the second welding head with small welding teeth is used for shaping and reinforcement to achieve precision welding. This results in a final welding effect with a tensile strength greater than 20N / m and a welding resistance value close to that of pure metal foil.

[0056] Before welding with the second welding head having small welding teeth, a laser system is used to generate laser light that passes through the weld mark of the large welding teeth and burns the polymer material layer between the composite current collectors, thereby achieving impurity-free welding of the metal layers on both sides. This results in a stronger weld bond and lower weld resistance, which is beneficial to the performance of the battery power.

[0057] Specifically, the height R of the first welding tooth is in the range of 35μm≤R≤80μm; the height r of the second welding tooth is in the range of 15μm≤r≤30μm.

[0058] Optionally, the area of ​​the weld mark corresponding to the first weld tooth is 12mm*6mm, and the weld teeth are evenly distributed.

[0059] Specifically, the first working parameters include a first welding frequency f1 and a first welding power P1. The value range of the first welding frequency f1 is 15kHz≤f1≤30kHz, and the value range of the first welding power P1 is 4kW≤P1≤7kW.

[0060] The first welding head performs welding within the range of the first welding frequency f1, using low-frequency high-power welding, which makes the welding process gentler and facilitates the quick connection of the two composite current collector metal layers.

[0061] Specifically, the second working parameters include a second welding frequency f2 and a second welding power P2. The value range of the second welding frequency f2 is 40kHz≤f2≤50kHz, and the value range of the second welding power P2 is 1kW≤P2≤4kW.

[0062] The second welding head performs welding within the range of the second welding frequency f2, which can shape and modify the weld mark, thereby achieving precise contact between the front and back metal layers.

[0063] Specifically, the preset output power P3 of the laser has a range of 1mW ≤ P3 ≤ 600mW.

[0064] The laser performs laser sintering on the weldment. The laser beam can penetrate the weldment and reach the polymer material in the middle of the composite current collector. The temperature can vary between 150℃ and 300℃. Specifically, the power of the laser can be adjusted according to the tensile strength and resistance of the weldment to control the temperature of the weldment.

[0065] Example 2

[0066] Combination Figures 1-4 As shown, this embodiment provides a battery electrode welding device with a composite current collector, using the method described in Embodiment 1 above. The battery electrode welding device with the composite current collector includes:

[0067] Welding base 2 is suitable for placing composite current collector 3; welding base 2 is provided with welding base teeth 21;

[0068] The first welding head 1 has a first welding tooth 11 with a height of R formed on it;

[0069] Laser 4;

[0070] The second welding head 5 has a second welding tooth 51 with a height of r formed on it;

[0071] The welding areas 9 of at least two layers of the composite current collector 3 are welded sequentially via the first welding head 1, the laser 4, and the second welding head 5.

[0072] The battery electrode welding equipment for composite current collectors provided in this embodiment combines a first welding head 1 with a first welding tooth 11 of height R, a laser 4, and a second welding head 5 with a second welding tooth 51 of height r. The first welding head is used to connect the front and back metal layers, and the laser is used to burn the polymer material at the weld mark. Finally, the array of second welding heads is used to shape and reinforce the weld mark, achieving direct contact between the front and back metal layers for electronic connection. This avoids the phenomenon of incomplete welding in composite current collector welding and improves the power performance of the composite current collector.

[0073] Specifically, the welding base 2 is adapted to move along a preset direction, thereby causing the composite current collector 3 placed on it to move sequentially to positions corresponding to the first welding head 1, the laser 4, and the second welding head 5. (Combined) Figure 1 , Figure 3 As shown, the welding base 2 can move horizontally in the figure. The first welding head 1 can move vertically in the figure to move closer to or further away from the welding base 2.

[0074] Specifically, the welding base 2 is fixed, and the first welding head 1, the laser 4, and the second welding head 5 are moved in sequence to positions corresponding to the welding area 9 of the composite current collector 3 placed on the welding base 2.

[0075] Optionally, before welding, at least two layers of composite current collector are stacked on the welding base, with the component to be welded positioned between the welding head and the welding base. Since the composite current collector 3 in this embodiment needs to be processed sequentially by the first welding head 1, the laser 4, and the second welding head 5, in one optional implementation, the welding base 2 can be moved to move the composite current collector 3 placed on it sequentially to positions corresponding to the first welding head 1, the laser 4, and the second welding head 5. In another optional implementation, the welding base 2 is fixed, and the first welding head 1, the laser 4, and the second welding head 5 can be moved to positions corresponding to the welding base 2.

[0076] In this embodiment, the welding base 2 is preferably movable, thereby enabling the step-by-step welding of the first welding head 1, the laser 4, and the second welding head 5. The first welding head 1 has high welding power, the laser 4 can be used to remove the polymer material in the middle of the composite current collector, and the second welding head 5 plays a role in shaping and reinforcing.

[0077] Specifically, after welding, the polymer material layer 32 in the welding area 9 of the composite current collector 3 disappears, allowing the first metal layer 31 to come into direct contact with the second metal layer 33.

[0078] This embodiment makes reasonable use of the structural characteristics of the composite current collector, so that the polymer material layer 32 in the welding area 9 of the composite current collector 3 disappears after welding, and the first metal layer 31 and the second metal layer 33 of the composite current collector are in direct contact. There is no polymer material in the solder, the welding is more solid and the welding resistance is lower.

[0079] The battery electrode welding equipment for the composite current collector provided in this embodiment ensures that the polymer material layer 32 disappears only in the welding area 9 after welding, while the intermediate polymer material layer is retained in the non-welding area 9. This ensures a stronger weld and lower welding resistance, while also preserving the melting mechanism of the composite current collector and improving battery safety performance.

[0080] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for welding battery electrodes with a composite current collector, suitable for welding a composite current collector, wherein the composite current collector comprises a polymer material layer and metal layers disposed on both sides of the polymer material layer in the thickness direction, characterized in that, include: S1: Place at least two composite current collector layers on the welding base; S2: The first welding head welds at least two metal layers in contact with each other on the first working parameter. S3: The polymer material layer of the composite current collector in the welding area is removed by the laser at a preset output power; S4: The second welding head shapes the weld marks within the welding area under the second working parameters; The welding areas of at least two layers of the composite current collector are welded sequentially via the first welding head, the laser, and the second welding head; The first working parameters include a first welding frequency f1 and a first welding power P1. The value range of the first welding frequency f1 is 15kHz≤f1≤30kHz, and the value range of the first welding power P1 is 4kW≤P1≤7kW. The second working parameters include a second welding frequency f2 and a second welding power P2. The value range of the second welding frequency f2 is 40kHz≤f2≤50kHz, and the value range of the second welding power P2 is 1kW≤P2≤4kW. The preset output power P3 of the laser has a range of 1mW≤P3≤600mW.

2. The battery electrode welding method for composite current collectors according to claim 1, characterized in that, The height ratio of the welding teeth of the first welding head and the second welding head is in the range of 2≤R / r≤3, where R is the height of the first welding tooth on the first welding head and r is the height of the second welding tooth on the second welding head.

3. The battery electrode welding method for composite current collectors according to claim 2, characterized in that, The height R of the first welding tooth is in the range of 35µm≤R≤80µm; the height r of the second welding tooth is in the range of 15µm≤r≤30µm.

4. A battery electrode welding device with a composite current collector, characterized in that, The battery electrode welding equipment for the composite current collector, using the method described in any one of claims 1-3, comprises: Welding base (2), suitable for placing composite current collector (3); The first welding head (1) has a first welding tooth (11) with a height of R. Laser (4); The second welding head (5) has a second welding tooth (51) with a height of r. The welding areas (9) of at least two layers of the composite current collector (3) are welded sequentially via the first welding head (1), the laser (4), and the second welding head (5).

5. The battery electrode welding equipment with composite current collector according to claim 4, characterized in that, The welding base (2) is adapted to move along a preset direction and drive the composite current collector (3) placed on it to move sequentially to the positions corresponding to the first welding head (1), the laser (4), and the second welding head (5).

6. The battery electrode welding equipment with composite current collector according to claim 4, characterized in that, The welding base (2) is fixed, and the first welding head (1), the laser (4), and the second welding head (5) are moved in sequence to positions corresponding to the welding area (9) of the composite current collector (3) placed on the welding base (2).

7. The battery electrode welding equipment with composite current collector according to claim 4, characterized in that, After welding, the polymer material layer (32) in the welding area (9) of the composite current collector (3) disappears, allowing the first metal layer (31) to come into direct contact with the second metal layer (33).

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