Battery pole piece and preparation method thereof

Abstract

The invention belongs to the technical field of batteries, and particularly relates to a battery pole piece and a preparation method thereof.The battery pole piece comprises a pole piece body, the pole piece body comprises a current collector and an active material layer, the current collector comprises a main body part and an expansion part, and the active material layer is arranged on at least one side of the main body part in the thickness direction; the main body part is provided with an expansion part, the expansion part protrudes out of the main body part in the width direction of the current collector, the tab comprises an external connection part and a welding part which are connected, the welding part is arranged on the expansion part, and the width of the welding part in the length direction of the current collector is different from the width of the external connection part in the length direction of the current collector. According to the battery pole piece, the active material layer on the pole piece body does not need to be cleaned while the welding strength between the tab and the expansion part is ensured, so that the loss of the active material layer is avoided, and the energy density of the battery pole piece is improved.

Description

Technical Field

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

[0002] As the performance requirements for lithium-ion batteries become increasingly higher, battery electrodes with high energy density, fast charging and discharging, and low impedance are the biggest and most urgent demands in the current market.

[0003] An existing battery electrode comprises a electrode body and a pole ear. Both sides of the electrode body in the thickness direction are coated with active material layers. An empty foil area is provided on one edge in the length direction of the current collector. The empty foil area is formed by washing away a part of the active material layer on the electrode body. One end of the pole ear in the length direction is welded to the empty foil area, and the other end of the pole ear in the length direction exceeds the edge of the electrode body for electrical connection with electrical equipment.

[0004] However, in order to ensure the connection strength between the pole lug and the pole body, the existing battery pole piece occupies a larger area on the pole body of the empty foil area, resulting in a lower energy density of the battery pole piece. Summary of the invention

[0005] The technical problem to be solved by the present invention is: in view of the problem that the empty foil area of ​​the existing battery pole piece occupies a large area on the pole piece body, resulting in a low energy density of the battery pole piece, a battery pole piece and a preparation method thereof are provided. In order to solve the above technical problems, on the one hand, an embodiment of the present invention provides a battery pole piece, comprising: the pole piece body comprises a current collector and an active material layer, the current collector comprises a main body portion and an extension portion, at least one side of the main body portion in a thickness direction is provided with the active material layer, the extension portion protrudes from the main body portion in a width direction of the current collector, the pole tab comprises an external connection portion and a welding portion connected to each other, and the welding portion is arranged on the extension portion; A width of the welding portion in the length direction of the current collector is different from a width of the external connection portion in the length direction of the current collector.

[0006] Optionally, the tab meets the following conditions: 2mm≤e<f≤50mm; Wherein, f is the width of the welding portion in the length direction of the current collector, and e is the width of the external connection portion in the length direction of the current collector.

[0007] Optionally, the width of the welding portion in the width direction of the current collector is g, 2mm≤g≤30mm.

[0008] Optionally, a protective layer is further included, wherein the protective layer includes a first covering portion and a second covering portion that are connected, the first covering portion covering the joint portion between the extension portion and the main portion, the second covering portion covering the area exposed outside the pole ear on one side in the thickness direction of the extension portion, and the side of the pole ear facing away from the extension portion.

[0009] Optionally, the length of the first covering portion covering the main body along the width direction of the current collector is c, f>c≥g, 0 <c≤50mm。

[0010] Optionally, a side of the extension portion facing away from the pole ear is coated with another protective layer; Optionally, the protective layer is insulating tape.

[0011] Optionally, the tab further includes an adhesive layer, and the adhesive layer is disposed on the external connection portion.

[0012] According to the battery pole piece of the embodiment of the present invention, compared with the prior art, the expansion portion protrudes from the main body of the current collector, and the welding portion of the pole ear is connected to the expansion portion. While ensuring the welding area and welding strength between the pole ear and the expansion portion, there is no need to clean the active material on the pole piece body, thereby avoiding the loss of active material and improving the energy density of the battery pole piece.

[0013] On the other hand, an embodiment of the present invention provides a method for preparing the above-mentioned battery electrode sheet, comprising: The active material is coated on the foil to form an active material layer, and an empty foil area is reserved on the foil to obtain a pole piece assembly including a plurality of battery pole pieces: Die-cutting the empty foil area along the extension direction of the empty foil area to cut the electrode assembly into a plurality of strips, each strip having an empty foil edge formed by a portion of the empty foil area on one side in the width direction; The empty foil edge is a strip edge; the empty foil edge is die-cut along the length direction of the strip, and a part of the empty foil edge is retained as an expansion portion; Weld the tabs to the expansion part; The protective layer is coated on the pole piece body and the pole ear.

[0014] Optionally, the protective layer is coated on the pole piece body and the pole lug, comprising: A first covering portion of the protective layer covers the connecting portion between the main body portion and the extension portion, and a second covering portion covers the area of ​​the extension portion on one side in the thickness direction that is exposed outside the tab, and the side of the tab that is away from the extension portion; Another protective layer is coated on a side of the extension portion away from the tab.

[0015] According to the battery pole piece preparation method of the embodiment of the present invention, the pole ear is welded to the extension portion provided on the protruding main body, which can ensure the welding area and welding strength between the pole ear and the extension portion, and at the same time, does not need to clean the active material on the pole piece body, thereby avoiding the loss of active material and improving the energy density of the battery pole piece. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of a method for preparing a battery pole piece provided in one embodiment of the present invention after coating a foil; Figure 2 A schematic diagram of the method for preparing a battery electrode sheet according to an embodiment of the present invention after the empty foil area is cut; Figure 3 A schematic diagram of a battery electrode sheet preparation method according to an embodiment of the present invention after die-cutting the electrode strip; Figure 4 A schematic diagram of a coating protective layer of a method for preparing a battery pole piece according to an embodiment of the present invention (a schematic diagram of the structure of a battery pole piece according to an embodiment of the present invention); Figure 5 for Figure 4 Schematic diagram of the structure of the middle tab; Figure 6 for Figure 4 Schematic diagram of the structure of the intermediate fluid collector.

[0017] The figure numbers in the specification are as follows: 1. Pole piece body; 10. Current collector; 11. Main body; 12. Active material layer; 13. Extension part; 2. Pole ear; 21. External connection part; 22. Welding part; 23. Adhesive layer; 3. Protective layer; 31. First covering part; 32. Second covering part; 4. Pole piece assembly; 5. Cutting line; 6. Empty foil area; 7. Strip. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] like Figures 4 to 6As shown, an embodiment of the present invention provides a battery pole piece, including a pole piece body 1 and a pole tab 2, the pole piece body 1 includes a current collector 10 and an active material layer 12, the current collector 10 includes a main body 11 and an expansion portion 13, the active material layer 12 is provided on at least one side of the main body 11 in the thickness direction, the expansion portion 13 protrudes from the main body 11 in the width direction of the current collector 10, and the pole tab 2 includes a connected external portion 21 and a welding portion 22, and the welding portion 22 is arranged on the expansion portion 13.

[0020] The width of the welding portion 22 in the length direction of the current collector 10 is different from the width of the external connection portion 21 in the length direction of the current collector 10 .

[0021] Specifically, the expansion portion 13 protrudes from Figure 6 The main body 11 of the current collector 10 shown in the figure and the welding portion 22 of the pole tab 2 are connected to the expansion portion 13. While ensuring the welding area and welding strength between the pole tab 2 and the expansion portion 13, there is no need to clean the active materials on the pole piece body 1, thereby avoiding the loss of active materials and improving the energy density of the battery pole piece.

[0022] In one embodiment, the tab 2 satisfies the following conditions: 2mm≤e<f≤50mm; Wherein, f is the width of the welding portion 22 in the length direction of the current collector 10 , and e is the width of the external connection portion 21 in the length direction of the current collector 10 .

[0023] The width of the welding portion 22 in the width direction of the current collector 10 is g, and 2 mm ≤ g ≤ 30 mm.

[0024] Specifically, Figure 5 As shown, along the length direction of the current collector 10, the width of the welding portion 22 of the pole lug 2 is f, and the width of the external connection portion 21 is e, f>e, the external connection portion 21 is vertically connected to the welding portion 22, so that the pole lug 2 is in a "T" shape, and the width of the welding portion 22 is greater than the width of the external connection portion 21, which can not only reserve the external connection portion 21 for connecting the pole lug 2 with the electrical equipment, but also increase the area of ​​the welding portion 22, thereby increasing the welding area between the welding portion 22 and the expansion portion 13, and further improving the welding strength between the pole lug 2 and the pole piece body 1.

[0025] In one embodiment, it further includes a protective layer 3. One protective layer 3 includes a connected first covering portion 31 and a second covering portion 32. The first covering portion 31 covers the joint portion between the extending portion 13 and the main body portion 11. The second covering portion 32 covers the area exposed outside the tab 2 on one side in the thickness direction of the extending portion 13, and the side of the tab 2 facing away from the extending portion 13.

[0026] Another protective layer 3 is coated on the side of the extending portion 13 facing away from the tab 2, and the protective layer 3 is insulating adhesive paper.

[0027] Specifically, the protective layer 3 is transparent insulating adhesive paper. First, the first covering portion 31 of the insulating adhesive paper is covered and bonded to the joint portion between the main body portion 11 and the extending portion 13. The second covering portion 32 is covered and bonded to the welding portion 22 of the extending portion 13 and the tab 2, and the edge of the insulating adhesive paper covers the edge of the extending portion 13. Then, pressure is applied to the insulating adhesive through a pressing device. After that, insulating adhesive paper is also bonded to the side of the electrode tab body 1 facing away from the tab 2, and the insulating adhesive papers on both sides of the thickness of the electrode tab body 1 are bonded together, so as to wrap the extending portion 13 and the welding portion 22 of the tab 2 to form good protection, and avoid the burrs on the edge of the extending portion 13 piercing the diaphragm of the battery during battery manufacturing. Selecting insulating adhesive paper as the protective layer 3 is convenient for connection.

[0028] In one embodiment, the length of the main body portion 11 covered by the first covering portion 31 along the width direction of the current collector 10 is c, f > c ≥ g, 0 < c ≤ 50 mm. Specifically, along the width direction of the current collector 10, the length of the main body portion 11 covered by the first covering portion 31 is c, and f > c ≥ g, which can make the insulating adhesive paper cover the area of the active material layer 12 as little as possible and ensure good protection effect.

[0029] In one embodiment, the tab 2 further includes an adhesive layer 23, and the adhesive layer 23 is arranged on the external connection portion 21. Specifically, the adhesive layer 23 is connecting glue, and the connecting glue is pasted on the external connection portion 21 of the tab 2 for bonding the air bag of the battery, reducing the gap between the tab 2 and the battery air bag, and improving the connection strength between the tab 2 and the battery air bag.

[0030] Compared with the prior art, for the battery electrode tab according to the embodiment of the present invention, the extending portion 13 protrudes from the main body portion 11 of the current collector 10, and the welding portion 22 of the tab 2 is connected to the extending portion 13. While ensuring the welding area between the tab 2 and the extending portion 13 and the welding strength between the tab 2 and the extending portion 13, it is not necessary to perform a cleaning operation on the active material on the electrode tab body 1, avoiding the loss of the active material and improving the energy density of the battery electrode tab.

[0031] On the other hand, such as Figures 1 to 4 As shown, an embodiment of the present invention provides a method for preparing the above-mentioned battery electrode sheet, comprising: S1. Coating the active material on the foil to form an active material layer 12, and reserving an empty foil area 6 on the foil to obtain a pole piece assembly 4 including a plurality of battery pole pieces: S2, die-cutting the empty foil area 6 along the extension direction of the empty foil area 6, cutting the electrode assembly 4 into a plurality of strips 7, each strip 7 having an empty foil edge formed by part of the empty foil area 6 on one side in the width direction; S3, the empty foil edge is a strip edge; the empty foil edge is die-cut along the length direction of the strip 7, and a part of the empty foil edge is retained as the expansion portion 13; S4, welding the tab 2 to the expansion portion 13; S5, covering the protective layer 3 on the pole piece body 1 and the pole lug 2.

[0032] Specifically, in S1, the foil has a length direction and a width direction, and the active material is first coated on one side of the foil in the thickness direction along the length direction of the foil by a coating device, and a space is reserved such as Figure 1 The empty foil area 6 shown will form an active material layer 12 after the active material is solidified. Then, the other side of the foil in the thickness direction is facing the coating equipment to coat the active material on the other side of the foil. Similarly, the empty foil area 6 is reserved to form an active material layer 12 after the active material is solidified. The empty foil areas 6 on both sides of the foil in the thickness direction are facing each other.

[0033] In S2, along the extension direction of the empty foil area 6, that is, along Figure 1 The cutting line 5 shown in the figure cuts the empty foil area 6 on the pole piece assembly 4 to form Figure 2 The strip 7 shown has a hollow foil edge to be die-cut on its width edge.

[0034] In S3, the edge of the empty foil is a strip edge, along the length direction of the strip 7, Figure 2 The edges of the hollow foil edges of the strip 7 shown are die-cut to form Figure 3 The pole piece body 1 shown has an extension portion 13 and a main portion 11 , and the extension portion 13 protrudes from the main portion 11 of the pole piece body 1 along the width direction of the pole piece body 1 .

[0035] In S4, Figure 4 As shown, the welding portion 22 of the pole tab 2 is welded to the expanded portion 13 .

[0036] In S5, Figure 4 As shown, the protective layer 3 is coated on the pole piece body 1 and the pole ear 2.

[0037] The electrode tab 2 is welded to the extension portion 13 provided on the protruding main body portion 11. This ensures the welding area and welding strength between the electrode tab 2 and the extension portion 13, while eliminating the need to clean the active material layer 12 on the electrode body 1, thereby avoiding the loss of the active material layer 12 and improving the energy density of the battery electrode.

[0038] In one embodiment, during die-cutting, the empty foil edge reserved on the sheet strip 7 is die-cut by a laser die-cutting device.

[0039] Specifically, the strip 7 is installed at a position directly opposite to the laser emitted by the laser die-cutting device, so that the emitted laser can irradiate the strip 7 vertically. The power of the laser die-cutting device is first adjusted to between 110W and 200W, and then the laser die-cutting device is turned on, so that the laser emitted by the laser die-cutting device irradiates the strip 7. The laser irradiates the strip 7 and penetrates the strip 7, thereby forming the following Figure 3 The pole piece body 1 shown has an expansion portion 13 and a main body portion 11. Laser die-cutting is relatively fast, which is beneficial to improving die-cutting efficiency.

[0040] In one embodiment, the step of welding the tab 2 to the expansion portion 13 includes: Of the welding portion 22 and the external connection portion 21 of the electrode tab 2 , the welding portion 22 with a larger width is welded to the expansion portion 13 .

[0041] Specifically, the width of the welding portion 22 of the pole tab 2 is greater than the width of the external connection portion 21, and the external connection portion 21 is arranged vertically with the welding portion 22. During welding, the strip 7 is installed at a position directly opposite to the laser emitted by the laser welding equipment, so that the emitted laser can be irradiated vertically on the welding portion 22. The laser welding equipment is turned on so that the laser emitted by the laser welding equipment is irradiated on the welding portion 22, and the position of the welding portion 22 irradiated by the laser is melted on the expansion portion 13, thereby being welded with the expansion portion 13. The larger width of the welding portion 22 can increase the welding area between the pole tab 2 and the pole piece body 1, and improve the welding strength between the pole tab 2 and the pole piece body 1.

[0042] In one embodiment, the protective layer 3 is coated on the pole piece body 1 and the pole ear 2, including: Covering the first covering portion 31 of the protective layer 3 on the connecting portion between the main body portion 11 and the expansion portion 13; The second covering portion 32 of the protective layer 3 covers the area exposed outside the tab 2 on one side of the extension portion 13 in the thickness direction, and the side of the tab 2 facing away from the extension portion 13; Another protective layer 3 is coated on a side of the extended portion 13 away from the electrode tab 2 .

[0043] Specifically, the protective layer 3 includes a first covering portion 31 and a second covering portion 32 that are connected. When covering the protective layer 3, the first covering portion 31 is first covered on the expansion portion 13 and the main body portion 11, and then the second covering portion 32 is covered on the expansion portion 13 and the welding portion 22 of the tab 2 welded on the expansion portion 13, and the edge of the second covering portion 32 covers the edge of the expansion portion 13, thereby protecting the edge of the welding portion 22 to prevent burrs on the die-cut edge from piercing the battery diaphragm.

[0044] The protective layer 3 is a transparent insulating tape, such as Figure 4 As shown, the first covering portion 31 is first covered and bonded to the joint of the main body 11 and the expansion portion 13, and the second covering portion 32 is covered and bonded to the portion of the expansion portion 13 exposed to the pole ear 2 and the side of the pole ear 2 facing away from the expansion portion 13, and the edge of the insulating tape is covered on the edge of the expansion portion 13, and then the insulating tape is pressed by a pressing device, and the insulating tape is selected as the protective layer 3 to facilitate connection. After the insulating tape is adhered to the expansion portion 13 and the side of the pole ear 2 facing away from the expansion portion 13, the insulating tape is also adhered to the side of the pole piece body 1 facing away from the pole ear 2 through a pressing device. The insulating adhesives on both sides of the pole piece body 1 in the thickness direction are bonded together, thereby covering the expansion portion 13 and the welding portion 22 of the pole ear 2 to provide better protection.

[0045] According to the battery pole piece preparation method of the embodiment of the present invention, the pole ear 2 is welded to the extension portion 13 provided on the protruding main body 11. While ensuring the welding area and welding strength between the pole ear 2 and the extension portion 13, there is no need to clean the active material on the pole piece body 1, thereby avoiding the loss of active material and improving the energy density of the battery pole piece.

[0046] In other embodiments, the tab 2 is welded to the expansion portion 13 by ultrasonic welding equipment.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A battery pole piece, characterized in that: The invention comprises a pole piece body (1) and a pole lug (2), wherein the pole piece body (1) comprises a current collector (10) and an active material layer (12), the current collector (10) comprises a main body (11) and an extension part (13), the active material layer (12) is provided on at least one side of the main body (11) in a thickness direction, the extension part (13) protrudes from the main body (11) in a width direction of the current collector (10), and the pole lug (2) comprises an external connection part (21) and a welding part (22) connected to each other, and the welding part (22) is provided on the extension part (13); The width of the welding portion (22) in the length direction of the current collector (10) is different from the width of the external connection portion (21) in the length direction of the current collector (10).

2. The battery electrode according to claim 1, characterized in that: The tab (2) satisfies the following conditions: 2mm≤e<f≤50mm; Wherein, f is the width of the welding portion (22) in the length direction of the current collector (10), and e is the width of the external connection portion (21) in the length direction of the current collector (10).

3. The battery pole piece according to claim 2, characterized in that: The width of the welding portion (22) in the width direction of the current collector (10) is g, 2 mm ≤ g ≤ 30 mm.

4. The battery pole piece according to claim 3, characterized in that: The protective layer (3) further comprises a first covering portion (31) and a second covering portion (32) connected to each other, wherein the first covering portion (31) covers a portion where the extension portion (13) and the main body portion (11) meet, and the second covering portion (32) covers an area on one side of the extension portion (13) in the thickness direction that is exposed outside the pole lug (2), and a side of the pole lug (2) that is away from the extension portion (13).

5. The battery pole piece according to claim 4, characterized in that: The length of the first covering portion (31) covering the main portion (11) along the width direction of the current collector (10) is c, f>c≥g, 0 <c≤50mm。 6. The battery pole piece according to claim 4, characterized in that: A side of the expansion portion (13) facing away from the pole lug (2) is covered with another protective layer (3).

7. The battery pole piece according to claim 4, characterized in that: The protective layer (3) is insulating adhesive tape.

8. The battery pole piece according to claim 4, characterized in that: The electrode tab (2) further comprises an adhesive layer (23), wherein the adhesive layer (23) is arranged on the external connection portion (21).

9. A method for preparing the battery pole piece according to any one of claims 1 to 8, characterized in that: include: The active material is coated on the foil to form an active material layer (12), and a blank foil area (6) is reserved on the foil to obtain an electrode assembly (4) including a plurality of battery electrodes: Die-cutting the hollow foil area (6) along the extension direction of the hollow foil area (6) to cut the pole piece assembly (4) into a plurality of strips (7), each strip (7) having a hollow foil edge formed by part of the hollow foil area (6) on one side in the width direction; The hollow foil edge is a strip edge; the hollow foil edge is die-cut along the length direction of the strip (7), and a portion of the hollow foil edge is retained as an expansion portion (13); Welding the tab (2) to the expansion portion (13); The protective layer (3) is coated on the pole piece body (1) and the pole ear (2).

10. The method for preparing a battery pole piece according to claim 9, characterized in that: The protective layer (3) is coated on the pole piece body (1) and the pole ear (2), comprising: A first covering portion (31) of the protective layer (3) covers the junction between the main body portion (11) and the extension portion (13), and a second covering portion (32) covers an area on one side of the extension portion (13) in the thickness direction that is exposed outside the tab (2), and a side of the tab (2) that is away from the extension portion (13); Another protective layer (3) is coated on a side of the expansion portion (13) facing away from the pole lug (2).

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