Pole piece, battery cell and battery

Abstract

The utility model relates to battery technology field discloses a kind of pole piece, battery cell and battery, the battery pole piece includes foil, the foil includes foil main body and multiple pole lug being arranged in the foil main body one side, both surfaces of the foil main body are equipped with coating;The pole lug is trapezoidal, including oppositely arranged upper base and lower base, the length of the upper base is greater than the length of the lower base, the lower base connects the foil main body, along the length direction of the foil main body, between two adjacent the pole lug, and interval increases gradually, the length of the upper base also increases gradually.The utility model not only reduces welding interface contact resistance, improves the charging efficiency of battery, also avoids the root crack of pole lug, to avoid short-circuit risk.In addition, improve the injection effect and improve the injection efficiency, reduce injection time.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to an electrode, a battery cell, and a battery. Background Technology

[0002] Currently, the tabs of large cylindrical batteries are usually arranged in a continuous ring or dense arrangement. These two tab structures have the following defects in the subsequent flattening process of the battery cell:

[0003] 1. Insufficient welding current: The continuous stacking of tabs results in a higher flattening area after the cell is flattened. That is, when welding with the current collector, the length in the direction of the welding interface extending outward is longer, which leads to high contact resistance and affects the battery charging and discharging efficiency.

[0004] 2. Limited electrolyte penetration: The dense area of ​​the tabs hinders electrolyte flow, prolonging the injection time;

[0005] 3. Poor mechanical stability: After being flattened, the base of the electrode is prone to cracks due to stress concentration, which may lead to short circuit risk. Utility Model Content

[0006] To solve the above-mentioned technical problems, this utility model provides an electrode sheet, a battery cell, and a battery, which reduces the height of the flattened area of ​​the battery cell, thereby reducing the contact resistance at the welding interface, improving the charging efficiency of the battery, reducing the electrolyte injection time, and avoiding cracks at the root of the electrode tabs, thus avoiding the risk of short circuits.

[0007] The technical solution adopted by this utility model to solve its technical problem is:

[0008] A battery electrode includes a foil, the foil comprising a foil body and a plurality of tabs disposed on one side of the foil body, and both surfaces of the foil body are provided with a coating.

[0009] The tab is trapezoidal, including an upper base and a lower base arranged opposite to each other. The length of the upper base is greater than the length of the lower base. The lower base is connected to the foil body. Along the length direction of the foil body, two adjacent tabs are spaced apart, and the spacing increases sequentially. The length of the upper base also increases sequentially.

[0010] Preferably, the tab is an isosceles trapezoid, the length of the upper base is L1, the length of the lower base is L2, the value of L1 is in the range of 12 to 1000 mm, and the value of L2 is in the range of 10 to 500 mm.

[0011] Preferably, the angle between the leg of the isosceles trapezoid and the lower base is α, and the value of α ranges from 30° to 88°.

[0012] Preferably, the coating material is a positive electrode active material used to form a positive electrode sheet;

[0013] Alternatively, the coating material may be a negative electrode active material used to form a negative electrode sheet.

[0014] A battery cell is formed by winding a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode.

[0015] Both the positive electrode and the negative electrode are the electrodes described above.

[0016] Preferably, it includes a battery cell body and flattening areas disposed at both ends of the battery cell body, wherein the foil body is wound to form the battery cell body, and the tabs are flattened to form the flattening areas.

[0017] Preferably, the tabs include a positive tab connected to the positive electrode plate and a negative tab connected to the negative electrode plate. The positive tab is disposed at one end of the main body of the battery cell and is formed into a positive flattened area by kneading. The negative tab is disposed at the other end of the main body of the battery cell and is formed into a negative flattened area by kneading.

[0018] Preferably, the middle portion has injection holes extending to both ends thereto, and the battery cell body includes a plurality of winding coil layers arranged sequentially from the center of the injection holes toward the radial direction of the battery cell body, each of the tabs forming a tab coil layer, and at least one winding coil layer is spaced apart between two adjacent tab coil layers.

[0019] Preferably, there is a gap between the lower bottom edge and the diaphragm, and the height of the gap is 0.2 to 0.5 mm.

[0020] A battery comprising the aforementioned battery cell.

[0021] The beneficial effects of this utility model are as follows:

[0022] By spacing adjacent tabs along the length of the foil body with the spacing increasing sequentially and the length of the top bottom edge also increasing sequentially, the bottom edge of each tab is formed into a circle when the foil is wound. This means that after the foil is wound into a cell, there will inevitably be a winding layer of the cell between adjacent tabs. This reduces the continuous stacking of tabs during the flattening process, lowers the height of the cell flattening zone, reduces the contact resistance at the welding interface, improves the charging efficiency of the battery, and avoids cracks at the root of the tabs, thus avoiding the risk of short circuit.

[0023] In addition, the flattening zone reduces the height and improves the electrolyte injection effect. Furthermore, the tabs are set in a trapezoidal shape, and the shorter bottom edge of the trapezoid connects to the foil body. This ensures that there is a gap between the tabs on the side of the flattening zone closest to the cell body and the end of the cell body, which facilitates electrolyte flow, improves injection efficiency, and reduces injection time. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the battery cell structure of this utility model.

[0025] Figure 2 This is a cross-sectional view of the battery cell of this utility model.

[0026] Figure 3 This is a schematic diagram of the electrode structure of this utility model.

[0027] Figure 4 This is a schematic diagram of the electrode tab of this utility model.

[0028] Wherein: 1-foil material, 11-foil material body, 12-electrode tab, 121-upper bottom edge, 122-lower bottom edge;

[0029] 10-Positive electrode sheet, 20-Negative electrode sheet, 30-Separator, 40-Battery cell, 401-Battery cell body, 402-Positive flattening area, 403-Negative flattening area, 404-Injection hole, 405-Wound coil layer, 406-Taper coil layer. Detailed Implementation

[0030] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0031] The specific embodiments of this utility model will be further described in detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this utility model, but are not intended to limit the scope of this utility model.

[0032] like Figure 1-3 As shown, a preferred embodiment of the present invention provides a battery cell 40, which is formed by winding a positive electrode 10, a negative electrode 20, and a separator 30 disposed between the positive electrode 10 and the negative electrode 20. The positive electrode 10 and the negative electrode 20 have the same structure, except that the active material coated on them is different. For ease of description, they are both referred to as electrodes below. Each electrode includes a foil 1, which includes a foil body 11 and a plurality of tabs 12 disposed on one side of the foil body 11. Both surfaces of the foil body 11 are coated. When the material of the coating is a positive electrode active material, a positive electrode 10 is formed; when the material of the coating is a negative electrode active material, a negative electrode 20 is formed.

[0033] like Figure 4 As shown, the tab 12 is trapezoidal, including an upper base 121 and a lower base 122 arranged opposite to each other. The length of the upper base 121 is greater than the length of the lower base 122. The lower base 122 is connected to the foil body 11. Along the length direction of the foil body 11, two adjacent tabs 12 are spaced apart, and the spacing increases sequentially. Along the length direction of the foil body 11, the length of the upper base 121 also increases sequentially, so that when the foil 1 is wound, the upper base 121 of each tab 12 forms a circle.

[0034] like Figure 1-2 As shown, specifically, the battery cell 40 includes a battery cell body 401 and flattened areas disposed at both ends of the battery cell body 401. The battery cell body 401 is formed by winding the foil body 11 of the positive electrode 10 and the negative electrode 20, and the separator 30. The tabs 12 are flattened to form the flattened areas. After manufacturing, the battery cell 40 has injection holes 404 extending to both ends in the middle. The diameter of the injection holes is approximately 0.5 mm, used for injection. The battery cell body 401 is formed by winding, thereby creating a plurality of winding layers 405 arranged sequentially from the center of the injection holes outward along the radial direction of the battery cell body 401. That is, each winding layer 405 is formed by winding the positive electrode 10, the negative electrode 20, and the separator 30. Each of the tabs 12 forms a tab coil layer 406, and at least one winding coil layer 405 is spaced apart between two adjacent tab coil layers 406.

[0035] In specific configuration, the spacing between two adjacent tabs 12 and the length of the upper bottom edge 121 of each tab 12 must be determined based on the number of winding layers 405 between adjacent tab layers 406, so that the upper bottom edge 121 of each tab 12 forms a complete circle. The specific length can be determined by calculating the radius of the winding layers based on the specific spacing. The circumference of each circle is the spacing distance of that circle or the length of the upper bottom edge 121. When there are multiple winding layers 405, the spacing between two tabs 12 can be determined by adding the lengths of the multiple winding layers 405.

[0036] In addition, during actual manufacturing, the distance between two adjacent tabs 12 can be determined by setting a correction parameter k, where k ranges from 1 to 5 mm. The calculated value plus the correction parameter is the final value. Generally, the length calculated based on the circumference is the theoretical length, and there may be a slight deviation. This can be finally determined by the correction parameter, and in mass production, once finalized, it can remain unchanged.

[0037] like Figure 4As shown, however, in specific settings, its length is not entirely unlimited. Preferably, the tab 12 is an isosceles trapezoid, the length of the upper base 121 is L1, and the length of the lower base 122 is L2. The value of L1 ranges from 12 to 1000 mm, such as 20 mm, 50 mm, 100 mm, 120 mm, 150 mm, 200 mm, 220 mm, 250 mm, 300 mm, 320 mm, 350 mm, 400 mm, 420 mm, 450 mm, 500 mm, 520 mm, 550 mm, 600 mm, 620 mm, 650 mm, 700 mm, 720 mm, 750 mm, 800 mm, 820 mm, 850 mm, 900 mm, 920 mm, 950 mm, 980 mm, etc., or the intermediate value or intermediate range between any two of the above values. The value of L2 ranges from 10 to 500 mm, such as 20 mm, 50 mm, 100 mm, 120 mm, 150 mm, 200 mm, 220 mm, 250 mm, 300 mm, 320 mm, 350 mm, 400 mm, 420 mm, 450 mm, 480 mm, etc., or any intermediate value or range between any two of the above values. That is, although the size of each electrode tab is different, all electrode tabs must be set within this range.

[0038] Meanwhile, the angle between the leg of the isosceles trapezoid and the lower base 122 is α, and the value of α ranges from 30° to 88°, such as 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, etc., or any intermediate value or range between any two of the above values. When the value of the included angle α is within this range, the density of the head of the kneaded layer can be ensured. The values ​​of the upper base 121, the lower base 122, and the included angle of the trapezoid affect each other, so the above value range must be satisfied simultaneously when setting them.

[0039] In specific configurations, the winding layers 405 spaced apart between two adjacent tab coil layers 406 can be configured in two ways: one is that the same number of winding layers 405 are provided between two adjacent tab coil layers 406; the other is that different numbers of winding layers 405 are provided between two adjacent tab coil layers 406. Two specific embodiments are described below:

[0040] Example 1: Same interval

[0041] 1. Electrode arrangement: A winding layer 405 is provided between the two electrode ring layers 406;

[0042] 2. Trapezoid parameters: upper base 121 length 1.0mm, lower base 122 length 3.0mm, included angle 45°;

[0043] 3. Kneading process: Pressure 1.0MPa, temperature 100℃, PTFE lubricating coating sprayed on the mold surface;

[0044] 4. Effect Verification:

[0045] The height of the flattened zone was reduced to 3.5mm, and the welding contact resistance was 3.8mΩ;

[0046] The injection time was shortened to 42 minutes, and no puncture was observed during the short-circuit test.

[0047] Example 2: Dynamically spaced tabs

[0048] 1. Tab arrangement: The number of intervals is dynamically adjusted according to the battery capacity (1-3 intervals are variable);

[0049] 2. Inverted trapezoid optimization:

[0050] Top area (near the diaphragm): angle 60°, top bottom edge 121, length 4.0mm;

[0051] Central area: included angle 30°, bottom edge length 2.0mm;

[0052] 3. Application scenarios: Suitable for high energy density batteries (such as the 4695 model), with an energy density increase of 5%.

[0053] Correspondingly, the tab 12 includes a positive tab connected to the positive electrode 10 and a negative tab connected to the negative electrode 20. The positive tab is disposed at one end of the cell body 401 and is formed into a positive flattened area 402 by flattening. The negative tab is disposed at the other end of the cell body 401 and is formed into a negative flattened area 403 by flattening.

[0054] Based on the above-mentioned technical features, the battery cell 40 has adjacent tabs 12 spaced apart along the length of the foil body 11, with the spacing increasing sequentially, and the length of the upper bottom edge 121 also increasing sequentially. This ensures that when the foil 1 is wound, the bottom edge of each tab 12 is formed into a circle. That is, after being wound into the battery cell 40, there must be a winding layer 405 of the battery cell 40 between adjacent tabs 12. This reduces the continuous stacking of tabs 12 during the flattening process, lowers the height of the flattening area of ​​the battery cell, not only reduces the contact resistance of the welding interface and increases the overcurrent capacity by 20%-30%, improving the charging efficiency of the battery, but also avoids root cracks of the tabs 12, thereby avoiding the risk of short circuit.

[0055] In addition, the flattening zone reduces the height and improves the electrolyte injection effect. Furthermore, the tab 12 is set as a trapezoid, and the shorter lower bottom edge 122 of the trapezoid is connected to the foil body 11. This ensures that there is a gap between the tab 12 on the side of the flattening zone closest to the cell body 401 and the end of the cell body 401, which facilitates electrolyte flow, improves the electrolyte injection efficiency (by 25% to 33%), and reduces the electrolyte injection time.

[0056] In this embodiment, there is a gap between the lower bottom edge 122 and the diaphragm 30, and the height of the gap is 0.2 to 0.5 mm, such as 0.21 mm, 0.22 mm, 0.25 mm, 0.27 mm, 0.29 mm, 0.3 mm, 0.31 mm, 0.32 mm, 0.35 mm, 0.37 mm, 0.39 mm, 0.4 mm, 0.41 mm, 0.42 mm, 0.45 mm, 0.47 mm, 0.49 mm, etc. The setting of this gap can form an electrolyte channel, thereby improving the electrolyte injection efficiency.

[0057] The cell leveling parameters in this embodiment are: leveling pressure: 0.8-1.2MPa (10%-20% lower than traditional process), leveling temperature: 80-120℃, which can avoid root cracks of the tab 12, and the surface roughness of the end face of the leveled area away from the cell body 401 after leveling is ≤Ra0.8μm.

[0058] To solve the above-mentioned technical problems, this application also provides a battery, including a casing, the aforementioned battery cell 40, and a cap. The casing is made of stainless steel, preferably nickel-plated stainless steel, and has an opening. The battery cell 40 is disposed inside the casing through the opening. The positive electrode flattening area 402 is connected to a positive electrode current collector, and the negative electrode flattening area 403 is connected to a negative electrode current collector, and the negative electrode current collector is connected to the bottom wall of the casing. The cap is connected to the casing to cover the opening, and the positive electrode current collector is connected to the cap.

[0059] The battery described in this application can reduce the height of the flattened area of ​​the cell, thereby reducing the contact resistance at the welding interface, improving the charging efficiency of the battery, and reducing the electrolyte injection time. At the same time, it can also prevent cracks at the root of the tabs, thus avoiding the risk of short circuits.

[0060] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present utility model, and these improvements and substitutions should also be considered within the protection scope of the present utility model.

Claims

1. An electrode sheet, characterized in that: The foil includes a foil body and a plurality of tabs disposed on one side of the foil body, wherein both surfaces of the foil body are coated. The tab is trapezoidal, including an upper base and a lower base arranged opposite to each other. The length of the upper base is greater than the length of the lower base. The lower base is connected to the foil body. Along the length direction of the foil body, two adjacent tabs are spaced apart, and the spacing increases sequentially. The length of the upper base also increases sequentially.

2. The electrode sheet as described in claim 1, characterized in that: The electrode tab is an isosceles trapezoid with the length of the upper base being L1 and the length of the lower base being L2. The value of L1 ranges from 12 to 1000 mm, and the value of L2 ranges from 10 to 500 mm.

3. The electrode sheet as described in claim 2, characterized in that: The angle between the leg and the lower base of the isosceles trapezoid is α, and the value of α ranges from 30° to 88°.

4. The electrode sheet as described in claim 1, characterized in that: The coating material is a positive electrode active material, used to form a positive electrode sheet; Alternatively, the coating material may be a negative electrode active material used to form a negative electrode sheet.

5. A battery cell, characterized in that: It is formed by winding a positive electrode, a negative electrode, and a diaphragm disposed between the positive electrode and the negative electrode; Both the positive electrode and the negative electrode are the electrodes described in claim 4.

6. The battery cell as described in claim 5, characterized in that: It includes a battery cell body and flattening areas disposed at both ends of the battery cell body, wherein the foil body is wound to form the battery cell body, and the tabs are flattened to form the flattening areas.

7. The battery cell as described in claim 6, characterized in that: The electrode tabs include a positive electrode tab connected to the positive electrode plate and a negative electrode tab connected to the negative electrode plate. The positive electrode tab is disposed at one end of the main body of the battery cell and is formed into a positive electrode flattening area by kneading. The negative electrode tab is disposed at the other end of the main body of the battery cell and is formed into a negative electrode flattening area by kneading.

8. The battery cell as described in claim 6, characterized in that: The middle part has liquid injection holes extending to both ends thereon. The battery cell body includes a plurality of winding coil layers arranged sequentially from the center of the liquid injection holes toward the radial direction of the battery cell body. Each of the tabs forms a tab coil layer, and at least one winding coil layer is spaced apart between two adjacent tab coil layers.

9. The battery cell as described in claim 5, characterized in that: There is a gap between the bottom edge and the diaphragm, and the height of the gap is 0.2~0.5mm.

10. A battery, characterized in that, Includes the battery cell as described in any one of claims 5-9.

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