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 and a tab, the pole piece body comprises a current collector and an active material layer, the current collector comprises a main body part and a welding part, and the active material layer is arranged on at least one side of the main body part in the thickness direction; the welding part comprises a main welding area and an expansion area which are connected with each other, the main welding area is arranged at the edge of the main body part, and the main body part and the main welding area are combined to form a square foil area; the expansion area protrudes out of the square foil area in the width direction of the pole piece body, the tabs are arranged on the welding parts, one part of a welding area between the tabs and the welding parts is located between the tabs and the main welding area, and the other part of the welding area is located between the tabs and the expansion area. While the welding strength of the tabs and the pole piece body is ensured, the cleaning area of the active material layer on the pole piece body is reduced, and the energy density of the battery pole piece can be 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 an active material layer. An edge of one side of the electrode body in the length direction is provided with a hollow foil area. One end of the pole ear in the length direction is welded to the hollow foil area, and the other end of the pole ear in the length direction is exposed from the electrode body for electrical connection with an electrical device.

[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: to provide a battery pole piece and a preparation method thereof in view of the problem that the energy density of existing battery pole pieces is low.

[0006] In order to solve the above technical problems, on the one hand, an embodiment of the present invention provides a battery pole piece, including a pole piece body and a pole ear; The pole piece body comprises a current collector and an active material layer; The current collector comprises a main body and a welding part, and the active material layer is provided on at least one side of the main body in a thickness direction; The welding portion includes a main welding area and an expansion area connected to each other; The main welding area is arranged at the edge of the main body, and the main body and the main welding area are combined to form a square foil area; The expansion area protrudes from the square foil area in the width direction of the pole piece body, and the pole ear is arranged on the welding portion; A portion of the welding area between the pole lug and the welding portion is located between the pole lug and the main welding area, and the remaining portion is located between the pole lug and the expansion area.

[0007] Optionally, the width of the expansion area in the length direction of the pole piece body is consistent with the width of the main welding area in the length direction of the pole piece body.

[0008] Optionally, the width of the main welding area in the length direction of the pole piece body is 1 mm to 10 mm; The width of the expansion area in the length direction of the pole piece body is b, 1mm≤b≤10mm.

[0009] Optionally, the distance between the side of the expansion area away from the square foil area and the long side of the square foil area is d, the width of the main welding area along the width direction of the pole piece body is c, and 1mm≤d≤c≤100mm.

[0010] Optionally, the distance between the side edge of the pole ear and the corresponding side edge of the welding portion along the length direction of the pole piece body is f, 0<f<20mm.

[0011] Optionally, the pole lug comprises a connected welding area and an external connection area, the welding area is connected to the welding portion, the external connection area protrudes from the expansion area in the width direction of the pole piece body, and an adhesive layer is provided on the external connection area.

[0012] Optionally, a protective layer is further included, wherein the protective layer covers an area on one side of the welding portion exposed outside the pole ear, and a side of the pole ear facing away from the welding portion.

[0013] Optionally, the other side of the welding portion is covered with another protective layer.

[0014] Optionally, the protective layer is insulating tape.

[0015] According to the battery pole piece of the embodiment of the present invention, compared with the prior art, the expansion area protrudes from the main body of the current collector, and together with the main welding area on the main body constitutes a welding portion for welding the pole tab. While being able to ensure the welding area between the pole tab and the pole piece body, thereby ensuring the welding strength between the pole tab and the pole piece body, it also reduces the cleaned area or uncoated area of ​​the active material layer on the foil area in the direction of the pole piece body, thereby being able to improve the energy density of the battery pole piece.

[0016] On the other hand, an embodiment of the present invention provides a method for preparing the above-mentioned battery pole piece, wherein an active material is coated on a 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 sheet strip, and a part of the empty foil edge is retained as the expansion area, and the active material layer at the portion of the sheet strip that is connected to the expansion area is cleaned, and the portion of the foil exposed by cleaning the part of the active material layer forms the main welding area; or, the empty foil edge is a T-shaped edge, and the empty foil edge is die-cut along the length direction of the sheet strip, and a part of the empty foil edge is retained as the expansion area and the main welding area; The tabs are welded to the welding portions.

[0017] According to the method for preparing a battery pole piece in an embodiment of the present invention, the cleaning area of ​​the active material layer on the pole piece body is reduced, which can improve the energy density of the battery pole piece. In addition, the setting of the expansion area can also ensure the welding area between the pole ear and the pole piece body, thereby ensuring the welding strength between the pole ear and the pole piece body. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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 provided in one 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 method for preparing a battery electrode sheet according to an embodiment of the present invention for cleaning an electrode sheet body to form a main welding area; Figure 5 A schematic diagram of the insulating adhesive paper coated on the battery electrode sheet preparation method provided by one embodiment of the present invention; Figure 6 A schematic diagram of the structure of a battery electrode provided by an embodiment of the present invention; Figure 7 for Figure 6 Schematic diagram of the structure of the intermediate fluid collector.

[0019] The figure numbers in the specification are as follows: 1. Pole body; 10. Current collector; 11. Main body; 12. Active material layer; 13. Welding part; 131. Main welding area; 132. Expansion area; 2. Pole ear; 21. Welding area; 22. External connection area; 23. Adhesive layer; 3. Protective layer; 31. Insulating tape; 4. Empty foil area; 41. Empty foil edge; 5. Cutting line; 6. Strip; 7. Pole assembly. DETAILED DESCRIPTION

[0020] 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.

[0021] like Figure 6 and Figure 7 As shown, an embodiment of the present invention provides a battery pole piece, including a pole piece body 1 and a pole lug 2, the pole piece body 1 including a current collector 10 and an active material layer 12, the current collector 10 including a main body 11 and a welding part 13, the active material layer 12 is provided on at least one side of the main body 11 in the thickness direction, the welding part 13 includes a main welding area 131 and an expansion area 132 connected to each other, the main welding area 131 is arranged at the edge of the main body 11, the main body 11 and the main welding area 131 are combined to form a square foil area, the expansion area 132 protrudes from the square foil area in the width direction of the pole piece body 1, the pole lug 2 is arranged on the welding part 13, and a part of the welding area between the pole lug 2 and the welding part 13 is located between the pole lug 2 and the main welding area 131, and the rest is located between the pole lug 2 and the expansion area 132.

[0022] Specifically, in Figure 7 The active material layer 12 is coated on both sides of the current collector 10 in the thickness direction, the main welding area 131 and the main body 11 form a square foil area, the expansion area 132 protrudes from the main body 11 of the current collector 10, and together with the main welding area 131 on the main body 11, constitutes a welding part 13 for welding the pole tab 2. A part of the welding area between the pole tab 2 and the welding part 13 is located between the pole tab 2 and the main welding area 131, and the rest is located between the pole tab 2 and the expansion area 132. While ensuring the welding area between the pole tab 2 and the pole piece body 1, thereby ensuring the welding strength between the pole tab 2 and the pole piece body 1, the cleaning area of ​​the active material layer 12 on the current collector 10 is also reduced, which can improve the energy density of the battery pole piece.

[0023] In one embodiment, the width of the expansion area 132 in the length direction of the pole piece body 1 is consistent with the width of the main welding area 131 in the length direction of the pole piece body 1. The width of the expansion area 132 is consistent with the width of the main welding area 131 in the length direction of the pole piece body, the structure is neat, and it is easy to design. It can reduce the scope of the main welding area 131 as much as possible, and further improve the energy density of the battery pole piece. If the width of the expansion area 132 is smaller than the main welding area 131, it will cause the loss of active materials on the pole piece body 1. If the width of the expansion area 132 is greater than the width of the main welding area 131, it will cause the width of the pole ear 2 to increase, resulting in an increase in production costs.

[0024] In one embodiment, the width of the main welding area 131 in the length direction of the pole piece body 1 is 1 mm to 10 mm, the distance between the side of the expansion area 132 away from the square foil area and the long side of the square foil area is d, and the width of the main welding area 131 along the width direction of the pole piece body 1 is c, 1mm≤d≤c≤100mm.

[0025] Specifically, the width of the expansion area 132 is b, 1mm≤b≤10mm, the distance between the side of the expansion area 132 away from the main body 11 and the long side of the main body 11 is d, the width of the main welding area 131 is c, and the distance between the side of the expansion area 132 away from the main body 11 and the long side of the main body 11 is smaller than the width of the main welding area 131, that is, 1mm≤d≤c≤100mm.

[0026] In one embodiment, the distance between the side of the pole ear 2 and the corresponding side of the welding portion 13 along the length direction of the pole piece body 1 is f, 0<f<20mm. In the length direction of the pole piece body 1, the distance between the edge of the pole ear 2 and the edge of the main welding area 131 is f, 0<f<20mm, and the pole ear 2 is arranged in the middle of the main welding area 131 for easy installation.

[0027] In one embodiment, the pole ear 2 includes a connected welding area 21 and an external connection area 22, the welding area 21 is connected to the welding portion 13, the external connection area 22 protrudes from the expansion area 132 in the width direction of the pole piece body 1, and a bonding layer 23 is provided on the external connection area 22.

[0028] Specifically, the pole lug 2 includes a connected welding area 21 and an external connection area 22, the welding area 21 is welded on the welding portion 13, the external connection area 22 of the pole lug 2 protrudes the expansion area 132 in the length direction of the pole piece body 1, and is used to connect with the electrical equipment, and the external connection area 22 is provided with an adhesive layer 23 near the welding area 21, and the adhesive layer 23 is specifically a connecting glue, which is used to bond with the outer skin of the pole core, thereby reducing the gap between the pole lug 2 and the outer skin, and improving the connection strength between the pole lug 2 and the outer skin. The preset adhesive layer 23 is convenient for subsequent operations of the battery.

[0029] In one embodiment, a protective layer 3 is further included, wherein the protective layer 3 covers an area on one side of the welding portion 13 exposed outside the pole tab 2 and a side of the pole tab 2 facing away from the welding portion 13 .

[0030] The welding part 13 and the part where the pole tab 2 is welded to the welding part 13 are covered with a protective layer 3, and the protective layer 3 is a transparent insulating adhesive tape 31. The insulating adhesive tape 31 is selected as the protective layer 3 for easy connection.

[0031] In one embodiment, the other side of the welding portion 13 is covered with another protective layer 3, and the side of the welding portion 13 facing away from the pole lug 2 is also bonded with insulating tape 31. The insulating adhesives on both sides of the thickness direction of the pole piece body 1 are bonded together, thereby covering the welding portion 13 and the welding area 21 of the pole lug 2.

[0032] According to the battery electrode of the embodiment of the present invention, compared with the prior art, the expansion area 132 protrudes from the main body 11 of the electrode body 1, and together with the main welding area 131 on the main body 11, constitutes a welding portion 13 for welding the pole tab 2. While being able to ensure the welding area between the pole tab 2 and the pole piece body 1, thereby ensuring the welding strength between the pole tab 2 and the pole piece body 1, it also reduces the cleaning area of ​​the active material layer 12 on the pole piece body 1, and can improve the energy density of the battery electrode.

[0033] In addition, if Figures 1 to 5 As shown, an embodiment of the present invention further 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 4 on the foil to obtain a pole piece assembly 7 including a plurality of battery pole pieces: S2, die-cutting the empty foil area 4 along the extension direction of the empty foil area 4, cutting the electrode assembly 7 into a plurality of strips 6, each strip 6 having an empty foil edge 41 formed by part of the empty foil area 4 on one side in the width direction; S3, the empty foil edge 41 is a strip edge; the empty foil edge 41 is die-cut along the length direction of the sheet strip 6, and a part of the empty foil edge 41 is reserved as the expansion area 132, and the active material layer 12 on the sheet strip 6 that is connected to the expansion area 132 is cleaned, and the part of the active material layer 12 that is exposed after cleaning forms the main welding area 131; S4, welding the electrode tab 2 to the welding portion 13.

[0034] 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 As shown in the empty foil area 4, after the active material is solidified, an active material layer 12 is formed on the side surface of the foil. Then, the other side of the foil in the thickness direction is facing the coating device to coat the active material on the other side of the foil in the thickness direction. Similarly, the empty foil area 4 is reserved. After the active material is solidified, an active material layer 12 is formed on the other side surface of the foil.

[0035] In S2, the empty foil area 4 is die-cut along the extension direction of the empty foil area 4, that is, along the length direction of the foil material, that is, along the Figure 1The slitting line 5 shown cuts the empty foil area 4 on the foil material to form Figure 2 The strip 6 shown has a hollow foil edge 41 formed by part of the hollow foil area 4 on its edge in the width direction.

[0036] In this embodiment, in S3, the empty foil edge 41 is a strip edge. Figure 2 The hollow foil edge 41 shown in the figure is die-cut, and a portion of the hollow foil edge 41 is retained at the edge in the width direction of the sheet strip 6 to form a hollow foil edge 41 at the edge of the edge strip. Figure 3 The expansion area 132 protrudes from the long side edge of the strip 6 along the width direction of the strip 6. Specifically, the strip 66 is first installed at a position directly opposite to the laser emitted by the laser die-cutting device, so that the emitted laser can be vertically irradiated on the strip 6, and 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 6, and the laser irradiates on the strip 6 and penetrates the strip 6, thereby forming Figure 3 The strip 6 with the expansion area 132 shown can be laser die-cut relatively quickly, which is beneficial to improving the die-cutting efficiency.

[0037] After die cutting, Figure 4 As shown, the active material layer 12 on the strip 6 that is connected to the expansion area 132 is cleaned to form a main welding area 131. The main welding area 131 is connected to the expansion area 132 to form a welding portion 13. Specifically, the strip 6 is installed at a position directly opposite to the laser emitted by the laser cleaning device, so that the emitted laser can be vertically irradiated on the pole body 1, and then the laser cleaning device is turned on to irradiate the laser emitted by the laser cleaning device on the strip 6. The laser irradiation on the strip 6 causes the active material layer 12 to heat up, thereby separating from the strip 6, so as to form a strip 6 as shown in FIG. Figure 6 The main welding area 131 shown, the main welding area 131 and the expansion area 132 form the welding part 13. Laser cleaning is relatively rapid, which is conducive to improving cleaning efficiency.

[0038] In S4, Figure 5 As shown, the pole tab 22 is welded to the welding portion 13 , so that one end of the pole tab 2 protrudes out of the expansion area 132 along the width direction of the pole piece body 1 .

[0039] The cleaning area of ​​the active material layer 1212 on the pole piece body 11 is reduced, which can improve the energy density of the battery pole piece. In addition, the setting of the expansion area 132132 can also ensure the welding area between the pole ear 22 and the pole piece body 11, thereby ensuring the welding strength between the pole ear 22 and the pole piece body 11.

[0040] In one embodiment, after welding the tab 2 to the welding portion 13, the method further includes: The protective layer 3 is coated on the welding portion 13 and the portion where the electrode tab 2 is welded to the welding portion 13 .

[0041] In one embodiment, the protective layer 3 is coated on the welding portion 13, and the portion where the tab 2 is welded to the welding portion 13 includes: One side of the welding portion 13 is coated with the protective layer 3 , and the protective layer 3 covers the area of ​​the welding portion 13 exposed outside the electrode tab 2 and the side of the electrode tab 2 facing away from the welding portion 13 .

[0042] Specifically, the protective layer 3 includes a first covering portion and a second covering portion. The first covering portion is firstly applied to cover the area exposed outside the pole lug 2 on one side of the welding portion 13 and the side of the pole lug 2 facing away from the welding portion 13, and the second covering portion is applied to cover the edge of the expansion area 132. Then, the first covering portion is crimped onto the welding portion 13 and the pole lug 2 by a pressing device, so that the second covering portion covers the edge of the expansion area 132.

[0043] In one embodiment, the other side of the welding portion 13 is covered with the protective layer 3 , and the protective layer 3 is an insulating tape 31 .

[0044] Specifically, the other side of the welding portion 13 is also covered with a protective layer 33, and the protective layer 33 is a transparent insulating adhesive tape 31, such as Figure 5 As shown, the insulating tape 31 is first covered and bonded to the welding portion 13 and the side of the pole ear 2 facing away from the welding portion 13, and then pressure is applied to the insulating tape 31 by a pressing device, so that the insulating tape 31 on both sides exposed at the edges of the welding portion 13 are bonded together, so that the insulating tape 31 on both sides wraps the welding portion 13, and the insulating tape 31 is selected as the protective layer 3 to facilitate connection.

[0045] In other embodiments, in S3, the empty foil edge 41 is a T-shaped edge, and the empty foil edge 41 is die-cut along the length direction of the strip 6, and a portion of the empty foil edge 41 is retained as the expansion area 132 and the main welding area 131, and there is no need to clean the active material layer 12 on the strip 6.

[0046] 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: It comprises a pole piece body (1) and a pole ear (2); The pole piece body (1) comprises a current collector (10) and an active material layer (12); The current collector (10) comprises a main body portion (11) and a welding portion (13), and the active material layer (12) is provided on at least one side of the main body portion (11) in a thickness direction; The welding portion (13) comprises a main welding area (131) and an expansion area (132) which are connected to each other; The main welding area (131) is arranged at the edge of the main body (11), and the main body (11) and the main welding area (131) are combined to form a square foil area; The expansion area (132) protrudes from the square foil area in the width direction of the pole piece body (1), and the pole ear (2) is arranged on the welding portion (13); A portion of the welding area between the pole lug (2) and the welding portion (13) is located between the pole lug (2) and the main welding area (131), and the remaining portion is located between the pole lug (2) and the expansion area (132).

2. The battery electrode according to claim 1, characterized in that: The width of the expansion area (132) in the length direction of the pole piece body (1) is consistent with the width of the main welding area (131) in the length direction of the pole piece body (1).

3. The battery pole piece according to claim 1, characterized in that: The width of the main welding area (131) in the length direction of the pole piece body (1) is 1 mm to 10 mm; The width of the expansion area (132) in the length direction of the pole piece body (1) is b, 1mm≤b≤10mm.

4. The battery pole piece according to any one of claims 1 to 3, characterized in that: The distance between the side of the expansion area (132) away from the square foil area and the long side of the square foil area is d, the width of the main welding area (131) along the width direction of the pole piece body (1) is c, and 1mm≤d≤c≤100mm.

5. The battery pole piece according to claim 4, characterized in that: The distance between the side edge of the pole ear (2) and the corresponding side edge of the welding portion (13) along the length direction of the pole piece body (1) is f, 0<f<20mm.

6. The battery pole piece according to claim 1, characterized in that: The pole lug (2) comprises a connected welding area (21) and an external connection area (22), the welding area (21) being connected to the welding portion (13), the external connection area (22) protruding from the expansion area (132) in the width direction of the pole piece body (1), and an adhesive layer (23) being provided on the external connection area (22).

7. The battery pole piece of the battery pole piece according to claim 6, characterized in that: It also comprises a protective layer (3), wherein the protective layer (3) covers an area on one side of the welding portion (13) exposed outside the pole lug (2), and a side of the pole lug (2) facing away from the welding portion (13).

8. The battery pole piece of the battery pole piece according to claim 7, characterized in that: The other side of the welding portion (13) is covered with another protective layer (3).

9. The battery pole piece of the battery pole piece according to claim 8, characterized in that: The protective layer (3) is insulating adhesive tape (31).

10. A method for preparing the battery pole piece according to any one of claims 1 to 9, characterized in that: include: The active material is coated on the foil to form an active material layer (12), and a blank foil area (4) is reserved on the foil to obtain an electrode assembly (7) including a plurality of battery electrodes: Die-cutting the hollow foil area (4) along the extension direction of the hollow foil area (4) to cut the pole piece assembly (7) into a plurality of strips (6), each strip (6) having a hollow foil edge (41) formed by part of the hollow foil area (4) on one side in the width direction; The empty foil edge (41) is a strip edge; the empty foil edge (41) is die-cut along the length direction of the sheet strip (6), a portion of the empty foil edge (41) is retained as the expansion area (132), the active material layer (12) at the portion of the sheet strip (6) in contact with the expansion area (132) is cleaned, and the portion of the foil exposed by cleaning the active material layer (12) forms the main welding area (131); or, the empty foil edge (41) is a T-shaped edge, the empty foil edge (41) is die-cut along the length direction of the sheet strip (6), and a portion of the empty foil edge (41) is retained as the expansion area (132) and the main welding area (131); The electrode tab (2) is welded to the welding portion (13).

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