Battery pole piece and method of manufacturing the same

Abstract

The application discloses a battery pole piece and a preparation method thereof. The battery pole piece comprises a tab and at least one current collecting assembly. The current collecting 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. The folding part has a first inner wall and a second inner wall arranged correspondingly to the first inner wall. The first inner wall is fixedly connected with the first metal layer, and the second inner wall is fixedly connected with the second metal layer. One end of the single-piece part is connected with the folding part, and the other end of the single-piece part is connected with the tab. Compared with the conventional welding of the double-layer foil and the tab, the total thickness of the one-time welding material when the current collector is welded with the tab is reduced, the existing conventional current collector equipment and process can be matched, the transformation cost of the mass production line body is saved, and the yield of the foil welded with the tab is improved.

Description

TECHNICAL FIELD

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

[0002] Lithium ion battery is a kind of secondary battery, which mainly relies on lithium ion moving between positive and negative electrodes to work. In the process of charging and discharging, lithium ions are embedded and de-embedded between two electrodes: when charging, lithium ions are de-embedded from the positive electrode, embedded into the negative electrode through the electrolyte, and the negative electrode is in a lithium-rich state; when discharging, it is the opposite. The current collector is an indispensable component in the lithium ion battery, and its main function is to carry the battery active material and collect the current generated by the battery active material to form a larger current for external output. The composite current collector is a three-layer structure, with a polymer layer in the middle and a metal layer on each side. However, there are some problems in the use of this current collector: the polymer layer in the middle of the current collector is completely insulating and non-conductive, which cannot be used normally, so it is necessary to weld conductors to the tabs on both sides to realize the conduction of the electronic path.

[0003] The preparation process in the prior art is to use welding equipment (welding methods include but are not limited to laser welding, ultrasonic welding, 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 tab to realize the conduction of all composite current collector circuits, resulting in the need to weld twice as many foil layers to the tab as ordinary current collector cells, so the tab welding process of the composite current collector requires high welding equipment, and the process parameters and equipment need to be adjusted, which cannot match the existing mass production process, and the top / bottom layer of foil is prone to delamination and welding fracture during welding. SUMMARY

[0004] In view of the technical problem in the prior art that the number of foil layers welded to the tab is twice that of ordinary current collector cells, the present application proposes a battery pole piece and a preparation method thereof, which reduces the total thickness of the welding material for welding the tab of the current collector at one time, saves the modification cost of the mass production line, and improves the yield of the foil tab welding.

[0005] The technical scheme adopted by the present application is as follows: a battery pole piece, comprising a tab 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 part and a single piece part, the folded part having a first inner wall and a second inner wall corresponding to the first inner wall, the first inner wall being fixedly connected with the first metal layer, the second inner wall being fixedly connected with the second metal layer, one end of the single piece part being connected with the folded part, and the other end of the single piece part being connected with the tab.

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

[0007] Optionally, the folding part comprises a first overlapping layer, a second overlapping layer and a third overlapping layer, one end of the third overlapping layer is connected with the single-piece part, the other end of the third overlapping layer is connected with the second overlapping layer at an angle, the second overlapping layer is connected with 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, one side of the first overlapping layer facing the second overlapping layer is fixedly connected with the first metal layer, and one side of the second overlapping layer facing the first overlapping layer is fixedly connected with 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 part ranges from 3 to 10 mm.

[0010] Optionally, the thickness of the foil ranges from 2 to 20 μm.

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

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

[0013] The application further discloses a preparation method of the battery tab, comprising the following steps: cutting the foil into an L shape, bending the second folding layer to correspondingly arrange the second folding layer and the first folding layer to form a first groove, placing the current collector into the first groove, and welding the first folding layer and the first metal layer together, welding the second folding layer and the second metal layer together, and welding the single-piece part and the tab together.

[0014] The application further discloses another preparation method of the battery tab, comprising the following steps: cutting the foil into a straight line, folding the foil according to a Z-shaped folding method to form a second groove by the first overlapping layer and the second overlapping layer, placing the current collector into the second groove and abutting the end of the current collector against the bottom of the second groove, 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 tab together.

[0015] The beneficial effects of the present application are: (1) the first metal layer and the second metal layer are both connected with the folding part, the folding part is integrally formed with the single piece part, the single piece part is welded together with the tab, that is, only a single layer of foil needs to be welded with the tab, compared with the traditional double layer of foil and the tab, the total thickness of the welding material is reduced when the current collector is welded with the tab, the existing conventional current collector equipment and process can be matched, the modification cost of the mass production line is saved, and the yield of the foil welded tab is improved;

[0016] (2) the first groove is through at both ends corresponding to the current collector, and the side wall is open, which facilitates the placement of the current collector and is simple to operate;

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

[0018] Fig. 1 The structure of the battery tab proposed in the present application is shown in the figure;

[0019] Fig. 2 The schematic diagram of the connection of the foil and the current collector proposed in the present application is shown in the figure;

[0020] Fig. 3 The schematic diagram of the folding part of the battery tab proposed in embodiment 1 of the present application is shown in the figure;

[0021] Fig. 4 The schematic diagram of the foil of the battery tab proposed in embodiment 1 of the present application is shown in the figure;

[0022] Fig. 5 The schematic diagram of the folding part of the battery tab proposed in embodiment 2 of the present application is shown in the figure;

[0023] Fig. 6 The schematic diagram of the foil of the battery tab proposed in embodiment 2 of the present application is shown in the figure.

[0024] The marks in each figure are: 1, tab; 2, current collector; 21, high molecular layer; 22, first metal layer; 23, second metal layer; 3, foil; 31, folding part; 311, first folding layer; 312, second folding layer; 313, first groove; 314, first overlapping layer; 315, second overlapping layer; 316, third overlapping layer; 317, second groove; 32, single piece part. DETAILED DESCRIPTION

[0025] The present application will be further described in detail below in combination with the 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" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and 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 devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the present application. In addition, the terms "first", "second", "third" are only for the purpose of description and cannot be understood as indicating or implying relative importance.

[0027] As shown in Figs. 1 to 3 A battery pole piece, characterized in that it comprises a tab 1 and at least one current collecting assembly, the current collecting assembly comprises a current collector 2 and a foil 3, 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, the foil 3 comprises a folding part 31 and a single piece part 32, the folding part 31 has 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 22, the second inner wall is fixedly connected with the second metal layer 23, one end of the single piece part 32 is connected with the folding part 31, and the other end of the single piece part 32 is connected with the tab 1. The first metal layer 22 and the second metal layer 23 are both connected with the folding part 31, the folding part 31 is integrally formed with the single piece part 32, and the single piece part 32 is welded with the tab 1, that is, only one layer of foil 3 needs to be welded with the tab 1, compared with the conventional double-layer foil 3 and the tab 1, the total thickness of the welding material is reduced when the current collector 2 is welded with the tab 1, the existing conventional current collector 2 equipment and process can be matched, the modification cost of the mass production line body is saved, and the yield of the foil 3 welded with the tab 1 is improved.

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

[0029] The thickness of the foil ranges from 2 to 20 microns. If the thickness of the foil is too small, the foil is easy to break during welding; if the thickness of the foil is too large, welding is difficult to perform and the material cost is increased. The thickness of the foil can be 2 microns, 5 microns, 10 microns, 15 microns or 20 microns.

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

[0031] Embodiment 1

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

[0033] The preparation method of the battery pole piece in Embodiment 1 comprises the following steps: cutting the foil 3 into an L shape, bending the second folding layer 312 to correspondingly arrange the second folding layer 312 with the first folding layer 311 to form the first groove 313, placing the current collector 2 into the first groove 313, and welding the first folding layer 311 and the first metal layer 22 together, welding the second folding layer 312 and the second metal layer 23 together, and welding the single piece part 32 and the pole lug 1 together. The two ends of the first groove 313 corresponding to the current collector 2 are through, and one side wall is open, which facilitates the placement of the current collector 2 and is simple to operate.

[0034] Embodiment 2

[0035] The folding part 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 with the single piece part 32, the other end of the third overlapping layer 316 is connected with the second overlapping layer 315 at an angle, the second overlapping layer 315 is connected with 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, one side of the first overlapping layer 314 facing the second overlapping layer 315 is fixedly connected with the first metal layer 22, and one side of the second overlapping layer 315 facing the first overlapping layer 314 is fixedly connected with the second metal layer 23. The second groove 317 is a V-shaped groove or a U-shaped groove. The included 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 of the first overlapping layer 314 and the first metal layer 22 and increases the stability of welding.

[0036] The preparation method of the battery pole piece in the preparation example 2 comprises the following steps: cutting the foil 3 into a straight line shape, folding the foil 3 according to a 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 into the second groove 317, and making the end of the current collector 2 abut against the bottom of the second groove 317, 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 part 32 and the tab 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, thereby limiting the current collector 2. The worker 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 can be understood that the specific embodiments described above are only used to explain the related application, and are not limited to the application. In addition, it should be noted that only the parts related to the application are shown in the drawings for convenience of description. The technical solutions in the same embodiment and the technical solutions in different embodiments can be arranged and combined to form new technical solutions without contradiction or conflict. Any equivalent structural transformation, direct or indirect application in other related technical fields, is also included in the protection scope of the application.

Claims

1. A battery electrode, characterized in that, The device includes a tab (1) and at least one current collector assembly. The current collector assembly includes a current collector (2) and a foil (3). The current collector (2) includes a polymer layer (21), a first metal layer (22) disposed on one side of the polymer layer (21), and a second metal layer (23) disposed on the other side of the polymer layer (21). The foil (3) includes a folded portion (31) and a single piece portion (32). The folded portion (31) has a first inner wall and a second inner wall disposed corresponding to the first inner wall. 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). 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 tab (1). The folded portion (31) includes a first folded layer (311) and a second folded layer (312). One end of the first folded layer (311) is connected to the single piece portion (32). The sidewall of the first folded layer (311) is connected to the second folded layer (312) at an angle to form a first groove (313). The side of the first folded layer (311) facing the second folded layer (312) is fixedly connected to the first metal layer (22). The side of the second folded layer (312) facing the first folded layer (311) is fixedly connected to the second metal layer (23). Alternatively, the folded 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 side of the first overlapping layer (314) facing the second overlapping layer (315) is fixedly connected to the first metal layer (22), and the side of the second overlapping layer (315) facing the first overlapping layer (314) is fixedly connected to the second metal layer (23). The foil (3) has a thickness of 2~20μm.

2. The battery electrode according to claim 1, characterized in that, The length of the first overlapping layer (314) is greater than the length of the second overlapping layer (315).

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

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

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

6. A method for preparing the battery electrode sheet according to claim 1, characterized in that, The process 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 aligned with the first folded layer (311) to form a first groove (313), placing the current collector (2) into the first groove (313), welding the first folded layer (311) to the first metal layer (22), welding the second folded layer (312) to the second metal layer (23), and welding the single piece (32) to the tab (1).

7. A method for preparing the battery electrode sheet according to claim 1, characterized in that, The process includes the following steps: cutting the foil (3) into straight strips, folding the foil (3) in a Z-shaped folding method to form a second groove (317) with the first overlapping layer (314) and the second overlapping layer (315), placing the 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), then welding the first overlapping layer (314) to the first metal layer (22), welding the second overlapping layer (315) to the second metal layer (23), and welding the single piece (32) to the tab (1).

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