Cylindrical power battery

Abstract

The utility model discloses a cylindrical power battery which comprises a shell, a positive plate arranged in the shell and a cover body used for sealing the shell, the positive plate is wound to form a cylinder, the positive plate comprises a positive current collector, and the positive current collector is arranged in the shell. The positive electrode current collector is provided with a positive electrode coating area coated with a positive electrode active material and a blank current collecting area which is positioned at one end of the positive electrode current collector and is not coated with the positive electrode active material, and the blank current collecting area is provided with a folding part formed by upwards folding the free end part of the blank current collecting area; the end part of the folding part exceeds the upper edge of the positive electrode coating area and forms a winding welding part protruding out of the middle part of the positive electrode coating area, and the winding welding part is connected with the cover body in a welding manner. According to the utility model, the blank collector region with a certain length is reserved at the head part of the positive plate, the blank collector region is turned upwards and protrudes out of the upper edge of the positive coating region to form the winding welding part, and the winding welding part can be directly welded with the cover plate, so that the welding is convenient.

Description

Technical Field

[0001] The utility model relates to the field of batteries, in particular to a cylindrical power battery. Background Art

[0002] The number, thickness and position of the power battery tabs on the pole piece are related to the internal resistance of the battery cell, and are also related to the heating of the battery. The welding of the tabs is accompanied by the generation of contact impedance, electronic impedance and polarization impedance.

[0003] At present, the positive electrode of lithium-ion batteries generally adopts a single-pole ear structure welded at about 1 / 5 to 1 / 2 of the electrode. As charging and discharging proceed, the active material continues to expand and contract, and the ear will be subjected to great stress in the middle of the bare battery cell. This not only has the risk of cutting the foil, but is also not the best design for internal resistance and heat generation.

[0004] The bipolar lug structure used in the positive electrode of cylindrical lithium-ion batteries requires that the two lugs be located on the same side of the bare cell to ensure that the two lugs are welded together on the cover. In the case of different lengths of the pole pieces, the positions of the two lugs in the bare cell need to be calculated differently. Not only that, the cutting and winding machine must have high precision to ensure that the bipolar lugs of each cell can be located on the same side. This has certain requirements for design and equipment, and is difficult to achieve universalization. Summary of the invention

[0005] The utility model aims to provide a cylindrical power battery to solve the problem of inconvenience in welding the positive electrode ear and the cover plate of the existing power battery.

[0006] In order to achieve the above-mentioned purpose, the utility model provides a cylindrical power battery, comprising a shell, a positive electrode sheet arranged in the shell and a cover body for closing the shell, the positive electrode sheet is wound to form a cylinder, the positive electrode sheet comprises a positive current collector, the positive current collector is provided with a positive electrode coating area coated with a positive electrode active material and a blank current collecting area located at one end of the positive current collector and not coated with a positive electrode active material, the blank current collecting area is provided with a folded portion formed by folding the free end of the blank current collecting area upward, the end of the folded portion exceeds the upper edge of the positive electrode coating area and forms a winding welding portion protruding from the middle of the positive electrode coating area, and the winding welding portion is welded to the cover body.

[0007] Preferably, the blank current collecting area is located at the head of the positive electrode sheet, the lower part of the folded portion is triangular and the upper part of the folded portion is rectangular, and one side edge of the folded portion facing the positive electrode coating area is aligned with one side edge of the positive electrode coating area facing the folded portion.

[0008] Preferably, the height of the folded portion protruding from the upper edge of the positive electrode coating area is greater than or equal to 14 mm and less than or equal to 15 mm.

[0009] Preferably, at least two positive electrode ear connection areas are also provided on the positive electrode sheet, the positive electrode ear connection areas are not coated with the positive electrode active material, the positive electrode coating area is provided with at least two sub-coating areas corresponding to at least two of the positive electrode ear connection areas, the sub-coating areas are arranged at intervals from the positive electrode ear areas, each of the positive electrode ear connection areas is connected to a positive electrode ear protruding upward from the positive electrode ear connection area, and the positive electrode ears are all welded to the winding welding portion.

[0010] Preferably, the positive electrode tab has a first end connected to the positive electrode tab connection region and a second end opposite to the first end, and the second end extends toward the winding welding portion and is welded to the winding welding portion.

[0011] Preferably, there are four positive electrode tab connection areas, and the four positive electrode tab connection areas are evenly distributed on the positive electrode sheet.

[0012] Preferably, the cylindrical power battery further includes a negative electrode sheet and a separator, and the negative electrode sheet, the separator and the positive electrode sheet are wound to form a cylindrical bare battery cell.

[0013] Compared with the prior art, the utility model reserves a blank current collecting area of ​​a certain length at the head of the positive electrode sheet, and folds the blank current collecting area upward and protrudes the upper edge of the positive electrode coating area to form a winding welding part, which can be directly welded to the cover plate, with simple process and convenient welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a structural diagram of a positive electrode sheet according to an embodiment of the present utility model. At this time, the positive electrode sheet is not wound and the blank current collecting area is not folded.

[0015] Figure 2 This is a structural diagram of a positive electrode sheet according to an embodiment of the present invention. At this time, the positive electrode sheet is not wound and the blank current collecting area is folded.

[0016] Figure 3 This is a structural diagram of a bare battery cell according to an embodiment of the present invention.

[0017] Figure 4 This is a structural diagram of a positive electrode sheet in another embodiment of the present invention. At this time, the positive electrode sheet is not wound and the blank current collecting area is not folded.

[0018] Figure 5 This is a structural diagram of a positive electrode sheet in another embodiment of the present invention. At this time, the positive electrode sheet is not wound and the blank current collecting area is folded.

[0019] Figure 6 This is a structural diagram of a bare battery cell in another embodiment of the present invention. At this time, the positive electrode ear is not welded to the winding welding portion.

[0020] Figure 7 It is a schematic structural diagram of a positive electrode ear and a winding welding portion after welding in another embodiment of the utility model. DETAILED DESCRIPTION

[0021] In order to explain the technical content, structural features and effects achieved by the present invention in detail, the following is a detailed description in conjunction with the implementation modes and the accompanying drawings.

[0022] like Figures 1 to 7 As shown, an embodiment of the utility model provides a cylindrical power battery, including a shell, a positive electrode sheet 10 arranged in the shell and a cover body for sealing the shell, the positive electrode sheet 10 is wound to form a cylinder, the positive electrode sheet 10 includes a positive electrode collector 1, the positive electrode collector 1 is provided with a positive electrode coating area 11 coated with a positive electrode active material and a blank current collecting area 12 located at one end of the positive electrode collector 1 and not coated with a positive electrode active material, the blank current collecting area 12 is provided with a folding portion 13 formed by folding the free end of the blank current collecting area 12 upward, the end of the folding portion 13 exceeds the upper edge of the positive electrode coating area 11 and forms a winding welding portion 14 protruding from the middle of the positive electrode coating area 11, and the winding welding portion 14 is welded to the cover body. Specifically, the cylindrical power battery further includes a negative electrode sheet 3 and a separator. The negative electrode sheet 3, the separator and the positive electrode sheet 10 are stacked and wound to form a cylindrical bare cell 100. The outermost layer of the bare cell 100 is the negative electrode sheet 3. The foil material of the positive electrode current collector 1 is aluminum. Figure 1 As shown, when the blank current collecting area 12 is not folded, the length of the blank current collecting area 12 is greater than the width of the blank current collecting area 12. Figure 1 The dotted line in the figure is folded so that the upper end of the folded portion 13 exceeds the upper edge of the positive electrode coating area 11, and the negative electrode sheet 3, the isolation film and the positive electrode sheet 10 are wound from the head of the positive electrode sheet 10 where the blank current collecting area 12 is located to form a winding welding portion 14 protruding from the middle of the positive electrode coating area 11. The winding welding portion 14 is columnar and can be directly welded to the cover body using the side of the welding winding portion, which is convenient for welding. In addition, in this embodiment, the positive electrode sheet 10 is not additionally connected to the positive electrode ear 2, and is directly electrically connected to the cover body through the winding welding portion 14, thereby reducing the welding internal resistance between the positive electrode ear 2 and the positive current collector 1 and the corresponding polarization internal resistance. In addition, the positive electrode ear 2 is not additionally provided, which also avoids the risk of the positive electrode ear 2 cutting the positive current collector 1, and the cylindrical power battery has better safety.

[0023] In the embodiment of the utility model, the blank current collecting area 12 is located at the head of the positive electrode sheet 10, the lower part of the folded portion 13 is triangular and the upper part of the folded portion 13 is rectangular, and the side edge of the folded portion 13 facing the positive electrode coating area 11 is aligned with the side edge of the positive electrode coating area 11 facing the folded portion 13. Specifically, Figure 2 As shown, the triangular lower portion is the first portion 131, and the rectangular upper portion is the second portion 132. The side edge of the folding portion 13 facing the positive electrode coating area 11 is aligned with the side edge of the positive electrode coating area 11 facing the folding portion 13, so that the utilization rate of the positive electrode current collector 1 is maximized. Of course, in some other embodiments of the utility model, other upward folding forms can also be used, as long as the upper end of the folding portion 13 exceeds the upper edge of the positive electrode coating area 11 and can be welded to the cover.

[0024] In the embodiment of the utility model, Figure 1 to Figure 2 As shown, the height a of the folding portion 13 protruding from the upper edge of the positive electrode coating area 11 is greater than or equal to 14 mm and less than or equal to 15 mm. Specifically, the length L of the blank current collecting area 12 can be greater than or equal to 72 mm and less than or equal to 73 mm, and the width W of the blank current collecting area 12 can be greater than or equal to 57.5 mm and less than or equal to 59 mm, and the height a of the protruding first portion 131 is greater than or equal to 14 mm and less than or equal to 15 mm.

[0025] In the embodiment of the utility model, a blank current collecting area 12 of a certain length is reserved at the head of the positive electrode sheet 10, and the blank current collecting area 12 is folded upward and protrudes from the upper edge of the positive electrode coating area 11 to form a winding welding portion 14. The winding welding portion 14 can be directly welded to the cover plate, with a simple process and convenient welding, thereby reducing the welding internal resistance between the positive electrode ear 2 and the positive electrode collector 1 and the corresponding polarization internal resistance, and the design is very ingenious.

[0026] In some other specific embodiments of the present invention, for example Figures 4 to 7As shown, at least two positive electrode ear connection areas 15 are also provided on the positive electrode sheet 10, and the positive electrode ear connection areas 15 are not coated with positive electrode active materials. The positive electrode coating area 11 is provided with at least two sub-coating areas 111 corresponding to the at least two positive electrode ear connection areas 15, and the sub-coating areas 111 are arranged at intervals from the positive electrode ear connection areas 15. Each positive electrode ear connection area 15 is connected to a positive electrode ear 2 protruding upward from the positive electrode ear connection area 15, and the positive electrode ears 2 are all welded to the winding welding portion 14. Specifically, the positive electrode ear 2 has a first end connected to the positive electrode ear connection area 15 and a second end opposite to the first end, and the second end extends toward the winding welding portion 14 and is welded to the winding welding portion 14. There are four positive electrode ear connection areas 15, and the four positive electrode ear connection areas 15 are evenly distributed on the positive electrode sheet 10. Since the positive electrode ear 2 is welded to the winding welding portion 14 instead of the cover body, the position of the positive electrode ear 2 on the bare battery cell 100 does not need to be precisely calculated, and the cutting and winding machine does not need to be very precise, which reduces the requirements for design and equipment, and has very high versatility. Therefore, in this embodiment, a blank current collecting area 12 of a certain length is reserved at the head of the positive electrode sheet 10, and the blank current collecting area 12 is folded upward and protrudes from the upper edge of the positive electrode coating area 11 to form a winding welding portion 14. The winding welding portion 14 can be directly welded to the cover plate, which is convenient to weld and has a simple process.

[0027] The above disclosure is only a preferred example of the present invention, and certainly cannot be used to limit the scope of rights of the present invention. Therefore, equivalent changes made according to the scope of the patent application of the present invention still fall within the scope covered by the present invention.

Claims

1. A cylindrical power battery, characterized in that: It comprises a shell, a positive electrode sheet arranged in the shell and a cover body for sealing the shell, the positive electrode sheet is wound to form a cylinder, the positive electrode sheet comprises a positive current collector, the positive current collector is provided with a positive electrode coating area coated with a positive electrode active material and a blank current collecting area located at one end of the positive current collector and not coated with a positive electrode active material, the blank current collecting area is provided with a folded portion formed by folding the free end of the blank current collecting area upward, the end of the folded portion exceeds the upper edge of the positive electrode coating area and forms a winding welding portion protruding from the middle of the positive electrode coating area, and the winding welding portion is welded to the cover body.

2. The cylindrical power battery according to claim 1, characterized in that: The blank current collecting area is located at the head of the positive electrode sheet, the lower part of the folded portion is triangular and the upper part of the folded portion is rectangular, and one side edge of the folded portion facing the positive electrode coating area is aligned with one side edge of the positive electrode coating area facing the folded portion.

3. The cylindrical power battery according to claim 2, characterized in that: The height of the folded portion protruding from the upper edge of the positive electrode coating area is greater than or equal to 14 mm and less than or equal to 15 mm.

4. The cylindrical power battery according to claim 1, characterized in that: At least two positive electrode ear connection areas are also arranged on the positive electrode sheet, and the positive electrode active material is not coated on the positive electrode ear connection areas. The positive electrode coating area is provided with at least two sub-coating areas corresponding to at least two of the positive electrode ear connection areas, and the sub-coating areas are arranged at intervals from the positive electrode ear connection areas. Each of the positive electrode ear connection areas is connected to a positive electrode ear that protrudes upward from the positive electrode ear connection area, and the positive electrode ears are all welded to the winding welding portion.

5. The cylindrical power battery according to claim 4, characterized in that: The positive electrode tab has a first end connected to the positive electrode tab connection region and a second end opposite to the first end, wherein the second end extends toward the winding welding portion and is welded to the winding welding portion.

6. The cylindrical power battery according to claim 4, characterized in that: There are four positive electrode tab connection areas, and the four positive electrode tab connection areas are evenly distributed on the positive electrode sheet.

7. The cylindrical power battery according to claim 4, characterized in that: The cylindrical power battery further includes a negative electrode sheet and a separator. The negative electrode sheet, the separator and the positive electrode sheet are wound to form a cylindrical bare battery cell.

Images