Winding type battery cell and battery

Abstract

The utility model relates to the technical field of lithium ion batteries, and discloses a winding type battery cell and a battery, the winding type battery cell comprises a positive plate, a negative plate and a diaphragm; the positive plate comprises a long-strip-shaped positive current collector, and the positive current collector is provided with a first blank area and a positive material coating area; the negative plate comprises a long-strip-shaped negative current collector, the negative current collector is provided with a fourth blank space area and a negative material coating area, and an inner negative lug is welded on the fourth blank space area; one end, close to the inner negative tab, of the diaphragm is folded towards the direction far away from the positive plate and wraps the end part of the blank space IV, an angle is formed between the blank space I and the inner negative tab, and the positive plate, the diaphragm and the negative plate are overlapped and wound; and the condition that the negative plate is cut by the positive plate is effectively avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium - ion batteries, and particularly relates to a wound battery cell and a battery. Background Art

[0002] Lithium - ion batteries have the advantages of large voltage, large specific energy, long cycle life, good safety performance, etc., and are widely used in electronic devices such as mobile phones and laptop computers. In the prior art, the battery cells of lithium - ion batteries are mainly wound type. The positive electrode sheet and the negative electrode sheet obtained through processes such as slurry mixing, coating, rolling, slitting, and baking are separated by a separator and co - wound to obtain a battery cell. During the charging process of a lithium - ion battery, the positive electrode sheet may cut the negative electrode sheet at the inlet of the winding, resulting in poor cycle performance of the battery and even causing serious consequences such as short - circuit between the positive and negative electrodes. Summary of the Utility Model

[0003] The purpose of the utility model is to overcome the problem that the positive electrode sheet cuts the negative electrode sheet at the inlet of the winding during the charging of a lithium - ion battery in the prior art, and provide a wound battery cell and a battery. By the structure of the wound battery cell, a separator and an inner negative electrode tab are used to block between the end of the first blank area and the fourth blank area to avoid the positive electrode sheet from cutting the negative electrode sheet.

[0004] To achieve the above purpose, on the one hand, the utility model provides a wound battery cell, including:

[0005] A positive electrode sheet, the positive electrode sheet includes a strip - shaped positive electrode current collector, the positive electrode current collector is provided with a first blank area and a positive electrode material coating area, the positive electrode material coating area is used for coating positive electrode active substances, the first blank area is connected to the positive electrode material coating area and is arranged at the inlet of the positive electrode current collector;

[0006] A negative electrode sheet, the negative electrode sheet includes a strip - shaped negative electrode current collector, the negative electrode current collector is provided with a fourth blank area and a negative electrode material coating area, the negative electrode material coating area is used for coating negative electrode active substances, the fourth blank area is connected to the negative electrode material coating area and is arranged at the inlet of the negative electrode current collector, and an inner negative electrode tab is welded on the fourth blank area; and

[0007] A separator, the separator is arranged between the positive electrode sheet and the negative electrode sheet;

[0008] Wherein, one end of the first blank area far from the positive electrode material coating area is opposite to the inner negative electrode tab, and the positive electrode sheet, the separator and the negative electrode sheet are laminated and wound.

[0009] Preferably, one end of the separator close to the inner negative electrode tab is folded towards the direction away from the positive electrode sheet and wraps the end of the fourth blank area.

[0010] Preferably, one end of the positive current collector away from the first blank area has a third blank area, the positive electrode material coating area is arranged in two sections, and the two sections of the positive electrode material coating areas are arranged at intervals and a second blank area is formed between the two ends of the positive electrode material coating areas for welding the positive electrode tab.

[0011] Preferably, the length of the positive electrode sheet is 970 mm, the lengths of the first blank area and the third blank area are 10 - 12 mm respectively, and the length of the second blank area is 7 - 9 mm.

[0012] Preferably, the thickness of the positive current collector is 13 μm, and the thickness of the positive active material arranged on the positive current collector is 120 - 200 μm.

[0013] Preferably, one end of the negative current collector away from the fourth blank area is provided with a fifth blank area, and an external negative electrode tab is welded on the fifth blank area.

[0014] Preferably, the length of the negative electrode sheet is 1050 mm, and the lengths of the fourth blank area and the fifth blank area are 19 - 21 mm respectively.

[0015] Preferably, the thickness of the negative current collector is 8 μm, and the thickness of the negative active material arranged on the negative current collector is 120 - 200 μm.

[0016] Preferably, one end of the third blank area away from the positive electrode material coating area is provided with a first thinning area;

[0017] One end of the fifth blank area away from the negative electrode material coating area is provided with a second thinning area.

[0018] In a second aspect of the present invention, a battery is provided. The battery includes the above-mentioned wound core, the wound core is arranged inside a battery steel shell, and an electrolyte is provided inside the battery steel shell to fully soak the wound core.

[0019] Through the above technical solution, at the place where the electrode sheet enters the roll, one end of the first blank area away from the positive electrode material coating area is opposite to the inner negative electrode tab, so that the separator and the inner negative electrode tab are blocked between the end of the first blank area and the fourth blank area. At the same time, the first blank area and the fourth blank area give a buffer space for the expansion of the electrode sheet, effectively avoiding the situation that the positive electrode sheet cuts the negative electrode sheet. Description of the Drawings

[0020] Figure 1 is a front view of the positive electrode sheet, separator and negative electrode sheet of a wound core provided by the present invention;

[0021] Figure 2 is a top view of a wound core provided by the present invention after being unfolded.

[0022] Description of Reference Numerals

[0023] 1. Positive electrode sheet; 11. Positive electrode material coating area; 12. Blank area 1; 13. Blank area 2; 14. Positive electrode ear; 15. Blank area 3; 2. Negative electrode ear; 21. Negative electrode material coating area; 22. Blank area 4; 23. Inner negative electrode ear; 24. Outer negative electrode ear; 25. Blank area 5; 3. Diaphragm. DETAILED DESCRIPTION

[0024] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0025] As mentioned above, the utility model provides a wound battery cell on one hand, through the structure of the wound battery cell, the separator and the inner negative electrode ear are blocked between the end of the blank area 1 and the blank area 4 to prevent the positive electrode sheet from cutting the negative electrode sheet.

[0026] like Figure 1 , 2 As shown, the wound battery cell includes a positive electrode sheet 1, a negative electrode sheet 2 and a separator 3. The positive electrode sheet 1 includes a long strip of positive electrode current collector, the positive electrode current collector is provided with a blank area 12 and a positive electrode material coating area 11, the positive electrode material coating area 11 is used to coat the positive electrode active material, the blank area 12 is connected to the positive electrode material coating area 11 and is arranged at the winding position of the positive electrode current collector; the negative electrode sheet 2 includes a long strip of negative electrode current collector, the negative electrode current collector is provided with a blank area 22 and a negative electrode material coating area 21, the negative electrode The material coating area 21 is used to coat the negative electrode active material, the blank four areas 22 are connected to the negative electrode material coating area 21 and are arranged at the roll-in position of the negative electrode current collector, and the inner negative electrode ear 23 is welded on the blank four areas 22; the separator 3 is arranged between the positive electrode sheet 1 and the negative electrode sheet 2; the end of the blank one area 12 away from the positive electrode material coating area 11 is opposite to the inner negative electrode ear 23, the positive electrode sheet 1, the separator 3 and the negative electrode sheet 2 are arranged according to Figure 2 The structure shown is folded and wound counterclockwise.

[0027] Those skilled in the art commonly use aluminum foil as the positive current collector material of the battery cell and copper foil as the negative current collector material of the battery cell. Since the hardness of aluminum is higher than that of copper, it is often found that the positive electrode sheet 1 cuts the negative electrode sheet 2 during charging. To solve this problem, in the present utility model, at the winding-in position of the electrode sheet, one end of the blank area 12 away from the positive electrode material coating area 11 faces the inner negative electrode tab 23, so that the separator 3 and the inner negative electrode tab 23 are arranged between the ends of the blank area 22 and the blank area 12, and no other substances are coated on the blank area 12 and the blank area 22, providing a buffer space for expansion and movement for the blank area 12, and effectively avoiding the situation that the positive electrode sheet 1 cuts the negative electrode sheet 2 during charging.

[0028] In this solution, one end of the blank area 12 away from the positive electrode material coating area 11 faces the inner negative electrode tab 23, and the relative angle is not limited. As long as one end of the blank area 12 away from the positive electrode material coating area 11 falls within the range where the inner negative electrode tab 23 is located.

[0029] Considering that the end of the blank area 22 is also relatively sharp, in the present utility model, one end of the separator 3 close to the inner negative electrode tab 23 folds towards the direction away from the positive electrode sheet 1 and wraps the end of the blank area 22, so that there are two layers of the separator 3 between the end of the blank area 22 and the positive electrode sheet 1, effectively protecting the positive electrode sheet 1 from being cut by the end of the blank area 22.

[0030] One end of the positive current collector away from the blank area 12 has a blank area 15, and the positive electrode material coating area 11 is arranged in two sections. The two sections of the positive electrode material coating area 11 are arranged at intervals and a blank area 13 is formed between the two ends of the positive electrode material coating area 11 for welding the positive electrode tab 14.

[0031] In an embodiment of the present utility model, the length of the positive electrode sheet 1 is 970 mm, and the lengths of the blank area 12 and the blank area 15 are both 11 mm. In order to provide enough welding space for the positive electrode tab 14 while improving the utilization rate of the positive current collector material, the length of the blank area 13 is 8 mm. Considering the product fluctuations caused by the production equipment, adaptively, the lengths of the blank area 12 and the blank area 15 can be respectively made to be 10 - 12 mm, and the length of the blank area 12 can be made to be 7 - 9 mm.

[0032] If the thickness of the positive current collector is too thick, the flexibility of the positive current collector will be too small, which is not conducive to winding. At the same time, in order to maintain a good adhesion between the positive active material and the positive current collector, thereby improving the energy density of the battery cell, further enhancing the cycle performance and charge-discharge rate of the battery, and improving the safety performance of the battery. Therefore, in the above embodiment, the thickness of the positive current collector is 13 μm, and the thickness of the positive active material provided on the positive current collector is 120 - 200 μm.

[0033] In order to prevent the separator 3 from coming into contact with the encapsulation layer and causing a short circuit during the process of assembling the battery cell into a battery, the length of the negative electrode sheet 2 is 1050 mm. A fifth blank area 25 is provided at one end of the negative current collector away from the fourth blank area 22. Considering that the negative electrode material coating area 21 in the outermost circle of the negative electrode sheet 2 should wrap the positive electrode material coating area 11, the lengths of both the fourth blank area 22 and the fifth blank area 25 are 20 mm. Considering the product fluctuations caused by the production equipment, the lengths of the fourth blank area 22 and the fifth blank area 25 can be made to be 19 - 21 mm respectively. An external negative electrode tab 24 is welded on the fifth blank area 25. Within this length range, there is sufficient engineering margin for welding the external negative electrode tab 24.

[0034] If the thickness of the positive current collector is too thin, the positive current collector will be difficult to resist the pressure generated during rolling and break. At the same time, in order to maintain a good adhesion between the negative active material and the negative current collector, thereby improving the energy density of the battery cell, further enhancing the cycle performance and charge-discharge rate of the battery. In the present utility model, the thickness of the negative current collector is 8 μm, and the thickness of the negative active material provided on the negative current collector is 120 - 200 μm.

[0035] In the present utility model, in order to make the outer circle of the wound battery cell transition smoothly and reduce the influence of the end of the third blank area 15 on the negative electrode sheet 2, a first thinning area is provided at one end of the third blank area 15 away from the positive electrode material coating area 11; a second thinning area is provided at one end of the fifth blank area 25 away from the negative electrode material coating area 21.

[0036] In the second aspect of the present utility model, a battery is provided. The battery includes the above-mentioned wound battery cell. The wound battery cell is disposed inside a battery steel case. An electrolyte is provided inside the battery steel case to fully infiltrate the wound battery cell. Through the application of this wound battery cell in the battery, at the winding-in area of the battery cell electrode sheet, one end of the first blank area away from the positive electrode material coating area is opposite to the internal negative electrode tab. The positive electrode sheet, the separator, and the negative electrode sheet are arranged in the order of Figure 2The structure shown is wound in a counterclockwise overlapping manner. The separator and the inner negative tab are blocked between the end of the positive electrode sheet and the negative electrode sheet, which can effectively prevent the positive electrode sheet from cutting the negative electrode sheet. The end of the separator wraps the end of the negative electrode sheet, which can effectively prevent the negative electrode sheet from cutting the positive electrode sheet, thereby improving the safety of the battery and extending the life of the battery.

[0037] It should be noted that the indication and the position of the structure in the present utility model are only for a specific posture. If the specific posture changes, the directional indication also changes accordingly. For example, if the positions, lengths of the positive electrode sheet and the negative electrode sheet, and the length of the blank area thereon are swapped, it still falls within the protection scope of the present application.

[0038] The preferred embodiments of the present utility model have been described in detail above with reference to the accompanying drawings. However, the present utility model is not limited thereto. Within the technical concept of the present utility model, various simple modifications can be made to the technical solutions of the present utility model. To avoid unnecessary repetition, the present utility model will not separately describe various possible combinations. But these simple modifications and combinations should also be regarded as the content disclosed by the present utility model and all fall within the protection scope of the present utility model.

Claims

1. A wound battery cell, characterized in that: include: A positive electrode sheet (1), the positive electrode sheet (1) comprising a long strip of positive electrode current collector, the positive electrode current collector being provided with a blank area (12) and a positive electrode material coating area (11), the positive electrode material coating area (11) being used for coating positive electrode active material, the blank area (12) being connected to the positive electrode material coating area (11) and being provided at the roll-in position of the positive electrode current collector; A negative electrode sheet (2), the negative electrode sheet (2) comprising a long strip of negative electrode current collector, the negative electrode current collector being provided with four blank areas (22) and a negative electrode material coating area (21), the negative electrode material coating area (21) being used to coat a negative electrode active material, the four blank areas (22) being connected to the negative electrode material coating area (21) and being provided at a roll-in position of the negative electrode current collector, the four blank areas (22) being provided with an inner negative electrode ear (23) welded thereto; and A diaphragm (3), the diaphragm (3) being arranged between the positive electrode sheet (1) and the negative electrode sheet (2); Wherein, one end of the blank area (12) away from the positive electrode material coating area (11) is opposite to the inner negative electrode ear (23), and the positive electrode sheet (1), the separator (3) and the negative electrode sheet (2) are stacked and wound.

2. The wound battery cell according to claim 1, characterized in that: One end of the separator (3) close to the inner negative electrode ear (23) is folded in a direction away from the positive electrode sheet (1) and wraps around the end of the four blank areas (22).

3. The wound battery cell according to claim 1, characterized in that: The positive electrode current collector has a third blank area (15) at one end away from the first blank area (12), and the positive electrode material coating area (11) is arranged in two sections, the two sections of the positive electrode material coating area (11) are arranged at intervals, and a second blank area (13) is formed between the positive electrode material coating areas (11) at both ends for welding the positive electrode ear (14).

4. The wound battery cell according to claim 3, characterized in that: The length of the positive electrode sheet (1) is 970 mm, the lengths of the blank area 1 (12) and the blank area 3 (15) are 10-12 mm respectively, and the length of the blank area 2 (13) is 7-9 mm.

5. The wound battery cell according to claim 4, characterized in that: The thickness of the positive electrode current collector is 13 μm, and the thickness of the positive electrode active material disposed on the positive electrode current collector is 120 to 200 μm.

6. The wound battery cell according to claim 5, characterized in that: A fifth blank area (25) is provided at one end of the negative electrode current collector away from the fourth blank area (22), and an external negative electrode ear (24) is welded to the fifth blank area (25).

7. The wound battery cell according to claim 6, characterized in that: The length of the negative electrode sheet (2) is 1050 mm, and the lengths of the fourth blank area (22) and the fifth blank area (25) are respectively 19 to 21 mm.

8. The wound battery cell according to claim 7, characterized in that: The thickness of the negative electrode current collector is 8 μm, and the thickness of the negative electrode active material disposed on the negative electrode current collector is 120 to 200 μm.

9. The wound battery cell according to claim 8, characterized in that: A first thinning area is provided at one end of the blank three-area (15) away from the positive electrode material coating area (11); A second thinning area is provided at one end of the blank fifth area (25) away from the negative electrode material coating area (21).

10. A battery, characterized in that: The battery comprises the wound battery cell according to any one of claims 1 to 9, wherein the wound battery cell is arranged inside a battery steel shell, and an electrolyte is provided inside the battery steel shell for fully soaking the wound battery cell.

Images