Battery pole piece and preparation method thereof

Abstract

The present invention discloses a battery pole piece and a preparation method thereof, the battery pole piece comprises a tab and at least one current collector assembly, the current collector assembly comprises a current collector and a foil, the current collector comprises a polymer layer, a first metal layer arranged on one side of the polymer layer and a second metal layer arranged on the other side of the polymer layer, the foil comprises a folding part and a single piece part, and the single piece part is arranged between the folding part and the single piece part. The folding part is provided with a first inner wall and a second inner wall corresponding to the first inner wall, the first inner wall is fixedly connected with the first metal layer, the second inner wall is fixedly connected with the second metal layer, one end of the single sheet part is connected with the folding part, and the other end of the single sheet part is connected with the tab. Compared with traditional welding of the double-layer foil and the tab, the total thickness of a one-time welding material when the tab is welded on the current collector is reduced, the current collector can be matched with equipment and a process of an existing conventional current collector, the transformation cost of a mass production line body is saved, and the yield of the tab welded by the foil is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery preparation, and in particular to a battery pole piece and a preparation method thereof. Background Art

[0002] Lithium-ion battery is a secondary battery that mainly relies on the movement of lithium ions between the positive electrode and the negative electrode to work. During the charge and discharge process, lithium ions are embedded and de-embedded between the two electrodes: when charging, lithium ions are de-embedded from the positive electrode, embedded in the negative electrode through the electrolyte, and the negative electrode is in a lithium-rich state; the opposite is true during discharge. The current collector is an indispensable component of lithium-ion batteries. Its main function is to carry the active substances of the battery and collect the current generated by the active substances of the battery to form a larger current for external output. The composite current collector is a three-layer structure with a polymer layer in the middle layer and a metal layer on the top and bottom. However, there are some problems in the use of this current collector: the polymer layer in the middle of the current collector is completely insulated and non-conductive, and cannot be used normally, so it is necessary to weld conductors to the tabs on both sides to achieve the conduction of the electronic path.

[0003] The preparation process in the existing scheme is: use welding equipment (welding methods include but are not limited to laser welding, ultrasonic welding, and resistance welding) to weld a layer of pure metal foil on both sides of the composite current collector, and then weld multiple layers of pure metal foil to the metal pole ear to achieve conduction of all composite current collector circuits. As a result, the number of foil layers required to be welded to the pole ear is twice that of ordinary current collector cells. Therefore, the pole ear welding process of the composite current collector has high requirements on the existing welding equipment, and the process parameters and equipment need to be adjusted. It cannot match the existing mass production process. During welding, multi-layer foil delamination and the top / bottom foil welding fracture and damage are likely to occur. Summary of the invention

[0004] In order to solve the technical problem in the prior art that the number of foil layers required for welding to the pole tab is twice that of an ordinary current collector battery cell, the present invention proposes a battery pole sheet and a preparation method thereof, which reduces the total thickness of the one-time welding material when the current collector is welded to the pole tab, saves the cost of modifying the mass production line, and improves the yield rate of foil welding to the pole tab.

[0005] The technical solution adopted by the present invention is as follows: a battery electrode, comprising a pole ear and at least one current collecting assembly, the current collecting assembly comprising a current collector and a foil, the current collector comprising a polymer layer, a first metal layer arranged on one side of the polymer layer, and a second metal layer arranged on the other side of the polymer layer, the foil comprising a folded portion and a single-piece portion, the folded portion having a first inner wall and a second inner wall arranged corresponding to the first inner wall, the first inner wall is fixedly connected to the first metal layer, the second inner wall is fixedly connected to the second metal layer, one end of the single-piece portion is connected to the folded portion, and the other end of the single-piece portion is connected to the pole ear.

[0006] Optionally, the folding portion includes a first folding layer and a second folding layer, one end of the first folding layer is connected to the single-piece portion, the side wall of the first folding layer is connected to the second folding layer at an angle to form a first groove, the side of the first folding layer facing the second folding layer is fixedly connected to the first metal layer, and the side of the second folding layer facing the first folding layer is fixedly connected to the second metal layer.

[0007] Optionally, the folding portion includes a first overlapping layer, a second overlapping layer and a third overlapping layer, one end of the third overlapping layer is connected to the single-piece portion, the other end of the third overlapping layer is connected to the second overlapping layer at an angle, the second overlapping layer is connected to the first overlapping layer at an angle to form a second groove, the bottom of the second groove abuts against the end of the current collector, the side of the first overlapping layer facing the second overlapping layer is fixedly connected to the first metal layer, and the side of the second overlapping layer facing the first overlapping layer is fixedly connected to the second metal layer.

[0008] Optionally, the length of the first overlapping layer is greater than the length of the second overlapping layer.

[0009] Optionally, the length of the single-piece portion ranges from 3 to 10 mm.

[0010] Optionally, the foil has a thickness of 2-20 μm.

[0011] Optionally, the current collector is a positive electrode current collector, the foil is made of aluminum metal, and the electrode tab is made of aluminum metal.

[0012] Optionally, the current collector is a negative electrode current collector, the foil is made of copper metal, and the electrode tab is made of copper metal.

[0013] The present invention also discloses a method for preparing the battery electrode sheet mentioned above, comprising the following steps: cutting the foil into an L shape, bending the second folded layer so that the second folded layer is arranged corresponding to the first folded layer to form a first groove, placing the current collector in the first groove, and welding the first folded layer and the first metal layer together, welding the second folded layer and the second metal layer together, and welding the single piece part and the electrode ear together.

[0014] The present invention discloses another method for preparing the battery pole piece mentioned above, comprising the following steps: cutting a foil into straight strips, folding the foil according to a Z-shaped folding method so that a first overlapping layer and a second overlapping layer form a second groove, placing a current collector in the second groove, and making the end of the current collector abut against the bottom of the second groove, and then welding the first overlapping layer and the first metal layer together, welding the second overlapping layer and the second metal layer together, and welding the single-piece part and the pole ear together.

[0015] The beneficial effects of the present invention are as follows: (1) the first metal layer and the second metal layer are both connected to the folded portion, the folded portion and the single-piece portion are integrally formed, and the single-piece portion and the tab are welded together, that is, a current collector assembly only requires a single-layer foil to be welded to the tab, which reduces the total thickness of the one-time welding material when the current collector is welded to the tab compared to the traditional double-layer foil to the tab welding, and can match the existing conventional current collector equipment and process, saving the transformation cost of the mass production line, and improving the yield rate of foil welding to the tab;

[0016] (2) The first groove is connected to the two ends corresponding to the current collector, and one side wall is open, which is convenient for placing the current collector and simple to operate;

[0017] (3) The bottom of the second groove refers to the side of the second groove corresponding to the current collector. The current collector abuts against the bottom of the second groove, which limits the current collector. The staff can fold according to the required welding length of the first metal layer and the first overlapping layer, and the second metal layer and the second overlapping layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the structure of the battery pole piece proposed by the present invention;

[0019] Figure 2 A schematic diagram of the connection between the foil and the current collector proposed in the present invention;

[0020] Figure 3 A schematic diagram of the folded portion of a battery electrode sheet according to Embodiment 1 of the present invention;

[0021] Figure 4 A schematic diagram of a foil of a battery electrode proposed in Example 1 of the present invention;

[0022] Figure 5 A schematic diagram of a folded portion of a battery electrode sheet according to Embodiment 2 of the present invention;

[0023] Figure 6 This is a schematic diagram of the foil of the battery electrode proposed in Example 2 of the present invention.

[0024] The marks in the drawings are: 1. pole ear; 2. current collector; 21. polymer layer; 22. first metal layer; 23. second metal layer; 3. foil; 31. folded portion; 311. first folded layer; 312. second folded layer; 313. first groove; 314. first overlapping layer; 315. second overlapping layer; 316. third overlapping layer; 317. second groove; 32. single-piece portion. DETAILED DESCRIPTION

[0025] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0026] In the description of the embodiments of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the embodiments of the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0027] like Figures 1 to 3 As shown, a battery pole piece, characterized in that it includes a pole ear 1 and at least one current collecting assembly, the current collecting assembly includes a current collector 2 and a foil 3, the current collector 2 includes a polymer layer 21, a first metal layer 22 arranged on one side of the polymer layer 21, and a second metal layer 23 arranged on the other side of the polymer layer 21, the foil 3 includes a folding portion 31 and a single-piece portion 32, the folding portion 31 has a first inner wall and a second inner wall arranged corresponding to the first inner wall, the first inner wall is fixedly connected to the first metal layer 22, the second inner wall is fixedly connected to the second metal layer 23, one end of the single-piece portion 32 is connected to the folding portion 31, and the other end of the single-piece portion 32 is connected to the pole ear 1. The first metal layer 22 and the second metal layer 23 are both connected to the folding portion 31, and the folding portion 31 and the single-piece portion 32 are integrally formed, and the single-piece portion 32 is welded to the pole lug 1, that is, a current collecting assembly only requires a single-layer foil 3 to be welded to the pole lug 1. Compared with the traditional double-layer foil 3 to the pole lug 1 welding, the total thickness of the one-time welding material when the current collector 2 is welded to the pole lug 1 is reduced, which can match the equipment and process of the existing conventional current collector 2, save the modification cost of the mass production line, and improve the yield of the foil 3 welding to the pole lug 1.

[0028] The length of the single piece 32 is in the range of 3 to 10 mm. The length of the single piece 32 is at least 3 mm, in order to reserve a sufficiently long foil 3 and improve the convenience of multi-layer welding. When the length of the single piece 32 is greater than 10 mm, the material cost will increase. The length of the single piece 32 can be 3 mm, 5 mm, 8 mm, or 10 mm.

[0029] The thickness of the foil is 2-20 μm. If the foil is too thin, the foil is easily damaged during welding; if the foil is too thick, welding is difficult and the material cost will increase. The foil thickness can be 2 μm, 5 μm, 10 μm, 15 μm, or 20 μm.

[0030] The current collector 2 is a positive electrode current collector 2, the foil 3 is made of aluminum metal, and the tab 1 is made of aluminum metal. The current collector 2 is a negative electrode current collector 2, the foil 3 is made of copper metal, and the tab 1 is made of copper metal.

[0031] Example 1

[0032] The folding portion 31 includes a first folding layer 311 and a second folding layer 312, one end of the first folding layer 311 is connected to the single-piece portion 32, the side wall of the first folding layer 311 is connected to the second folding layer 312 at an angle to form a first groove 313, the side of the first folding layer 311 facing the second folding layer 312 is fixedly connected to the first metal layer 22, and the side of the second folding layer 312 facing the first folding layer 311 is fixedly connected to the second metal layer 23. The first groove 313 is a V-shaped groove or a U-shaped groove.

[0033] The method for preparing the battery pole piece in the preparation embodiment 1 includes the following steps: cutting the foil 3 into an L shape, bending the second folded layer 312 so that the second folded layer 312 is arranged corresponding to the first folded layer 311 to form a first groove 313, placing the current collector 2 in the first groove 313, and welding the first folded layer 311 and the first metal layer 22 together, welding the second folded layer 312 and the second metal layer 23 together, and welding the single piece 32 and the pole ear 1 together. The first groove 313 is connected at both ends corresponding to the current collector 2, and one side wall is open, which is convenient for placing the current collector 2, and the operation is simple.

[0034] Example 2

[0035] The folding portion 31 includes a first overlapping layer 314, a second overlapping layer 315 and a third overlapping layer 316. One end of the third overlapping layer 316 is connected to the single-piece portion 32, and the other end of the third overlapping layer 316 is connected to the second overlapping layer 315 at an angle. The second overlapping layer 315 is connected to the first overlapping layer 314 at an angle to form a second groove 317. The bottom of the second groove 317 abuts against the end of the current collector 2. The first overlapping layer 314 is fixedly connected to the first metal layer 22 on one side facing the second overlapping layer 315, and the second overlapping layer 315 is fixedly connected to the second metal layer 23 on one side facing the first overlapping layer 314. The second groove 317 is a V-shaped groove or a U-shaped groove. The angle between the third overlapping layer 316 and the second overlapping layer 315 can be 0. The length of the first overlapping layer 314 is greater than the length of the second overlapping layer 315. The length of the first overlapping layer 314 is longer, which increases the welding area between the first overlapping layer 314 and the first metal layer 22 and increases the stability of the welding.

[0036] The method for preparing the battery pole piece in the preparation embodiment 2 includes the following steps: cutting the foil 3 into a straight strip, folding the foil 3 according to the Z-shaped folding method, so that the first overlapping layer 314 and the second overlapping layer 315 form a second groove 317, placing the current collector 2 in the second groove 317, and making the end of the current collector 2 abut against the bottom of the second groove 317, and then welding the first overlapping layer 314 and the first metal layer 22 together, welding the second overlapping layer 315 and the second metal layer 23 together, and welding the single piece 32 and the pole ear 1 together. The bottom of the second groove 317 refers to the side of the second groove 317 corresponding to the current collector 2, and the current collector 2 abuts against the bottom of the second groove 317, which plays a limiting role on the current collector 2. The staff can fold according to the length required for welding the first metal layer 22 and the first overlapping layer 314, and the second metal layer 23 and the second overlapping layer 315.

[0037] It is understandable that the specific embodiments described above are only used to explain the relevant inventions, rather than to limit the inventions. It should also be noted that, for ease of description, only the parts related to the invention are shown in the drawings. Multiple technical solutions in the same embodiment, as well as multiple technical solutions in different embodiments, can be arranged and combined to form new technical solutions without contradictions or conflicts. All equivalent structural transformations made using the contents of the specification and drawings of the present invention, directly or indirectly used in other related technical fields, are similarly included in the protection scope of the present invention.

Claims

1. A battery pole piece, characterized in that: The present invention comprises a pole lug (1) and at least one current collecting assembly, wherein the current collecting assembly comprises a current collector (2) and a foil (3), wherein the current collector (2) comprises a polymer layer (21), a first metal layer (22) arranged on one side of the polymer layer (21), and a second metal layer (23) arranged on the other side of the polymer layer (21), wherein the foil (3) comprises a folded portion (31) and a single-piece portion (32), wherein the folded portion (31) comprises a first inner wall and a second inner wall arranged corresponding to the first inner wall, wherein the first inner wall is fixedly connected to the first metal layer (22), and the second inner wall is fixedly connected to the second metal layer (23), wherein one end of the single-piece portion (32) is connected to the folded portion (31), and the other end of the single-piece portion (32) is connected to the pole lug (1).

2. The battery electrode according to claim 1, characterized in that: The folding portion (31) comprises a first folding layer (311) and a second folding layer (312); one end of the first folding layer (311) is connected to the single-piece portion (32); a side wall of the first folding layer (311) is connected to the second folding layer (312) at an angle to form a first groove (313); a side of the first folding layer (311) facing the second folding layer (312) is fixedly connected to the first metal layer (22); and a side of the second folding layer (312) facing the first folding layer (311) is fixedly connected to the second metal layer (23).

3. The battery pole piece according to claim 1, characterized in that: The folded portion (31) comprises a first overlapping layer (314), a second overlapping layer (315) and a third overlapping layer (316); one end of the third overlapping layer (316) is connected to the single-piece portion (32); the other end of the third overlapping layer (316) is connected to the second overlapping layer (315) at an angle; the second overlapping layer (315) is connected to the first overlapping layer (314) at an angle to form a second groove (317); the bottom of the second groove (317) abuts against the end of the current collector (2); the first overlapping layer (314) is fixedly connected to the first metal layer (22) on one side facing the second overlapping layer (315); and the second overlapping layer (315) is fixedly connected to the second metal layer (23) on one side facing the first overlapping layer (314).

4. The battery pole piece according to claim 3, characterized in that: The length of the first overlapping layer (314) is greater than the length of the second overlapping layer (315).

5. The battery pole piece according to claim 1, characterized in that: The length of the single-piece portion (32) ranges from 3 to 10 mm.

6. The battery pole piece according to claim 1, characterized in that: The thickness of the foil (3) is 2-20 μm.

7. The battery pole piece according to claim 1, characterized in that: The current collector (2) is a positive electrode current collector (2), the foil (3) is made of aluminum metal, and the pole ear (1) is made of aluminum metal.

8. The battery pole piece according to claim 1, characterized in that: The current collector (2) is a negative electrode current collector (2), the foil (3) is made of copper metal, and the pole ear (1) is made of copper metal.

9. A method for preparing the battery electrode according to claim 2, characterized in that: The method comprises the following steps: cutting a foil (3) into an L shape, bending the second folded layer (312) so that the second folded layer (312) and the first folded layer (311) are arranged correspondingly to form a first groove (313), placing a current collector (2) in the first groove (313), welding the first folded layer (311) and the first metal layer (22) together, welding the second folded layer (312) and the second metal layer (23) together, and welding the single piece (32) and the pole ear (1) together.

10. A method for preparing the battery electrode according to claim 3, characterized in that: The method comprises the following steps: cutting a foil (3) into a straight strip, folding the foil (3) according to a Z-shaped folding method so that a first overlapping layer (314) and a second overlapping layer (315) form a second groove (317), placing a current collector (2) into the second groove (317), and making the end of the current collector (2) abut against the bottom of the second groove (317), and then welding the first overlapping layer (314) and the first metal layer (22) together, welding the second overlapping layer (315) and the second metal layer (23) together, and welding the single-piece portion (32) and the pole ear (1) together.

Images