Pole piece and battery cell

Abstract

The utility model relates to a battery technology field discloses a kind of pole piece and electric core, battery pole piece includes foil material, foil material includes main part and the pole lug part of the main part one side being set, two surfaces of main part are equipped with coating, along the length direction of foil material, foil material sequentially includes head section, middle section and tail section;Pole lug part is away from the side of foil material main body in wave shape, and the wave height and wavelength of wave shape of head section, middle section and tail section are all different.The utility model is by the side of pole lug part being set into wave shape away from main part, and the wave height and wavelength of wave shape of head section, middle section and tail section are all different, so that the pole lug bending degree of different area is different, so the ductility and support force of pole lug can be improved, the contact area of pole lug and rubbing flat head is increased, so as to avoid the phenomenon that pole lug cracks, inserts upside down caused by local stress concentration in rubbing process, reduce the risk of puncturing diaphragm, improve the safety and assembly efficiency of battery.

Description

Technical Field

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

[0002] Before welding current collectors, the empty foil areas at the edges of the all-tab cylindrical cells need to be shaped and flattened to ensure welding quality when welding to the current collectors. However, during the winding process, the foil at both ends of the cell is often uneven, leading to cracking or inversion at the base of the tabs during the flattening process. This poses a risk of puncturing the diaphragm and causing a short circuit, affecting the efficiency of the assembly process and the quality of the cell. Utility Model Content

[0003] To solve the above-mentioned technical problems, this utility model provides an electrode sheet and a battery cell, which improves the ductility and support of the electrode tab, increases the contact area between the electrode tab and the flattened head, avoids electrode tab cracking and inversion caused by local stress concentration, reduces the risk of puncturing the diaphragm, and improves safety and assembly efficiency.

[0004] The technical solution adopted by this utility model to solve its technical problem is:

[0005] A battery electrode includes a foil, the foil including a main body and an electrode tab disposed on one side of the main body, both surfaces of the main body are coated, and along the length direction of the foil, the foil sequentially includes a head section, a middle section and a tail section;

[0006] The side of the electrode ear that is away from the main body is wavy, and the wave height and wavelength of the wavy shape are different for the head section, the middle section and the tail section.

[0007] Preferably, the tab portion includes a rolling zone and a connecting zone, the connecting zone connecting the rolling zone and the main body portion, and the wave-shaped part is provided in the rolling zone.

[0008] Preferably, the heights of the roller pressing zones corresponding to the head section, the middle section, and the tail section are H1, H2, and H3, respectively, and the following condition is met: 0mm < H1 < H2 < H3 < 3mm.

[0009] Preferably, the thicknesses of the rolling zones corresponding to the head section, the middle section, and the tail section are T1, T2, and T3, respectively, where T3 = T1 + T2, and the values ​​of T1, T2, and T3 are all in the range of 5 to 20 μm.

[0010] Preferably, the widths of the connecting areas corresponding to the head segment, the middle segment, and the tail segment are W1, W2, and W3, respectively, and the following condition is met: 2mm < W3 < W2 < W1 < 7mm.

[0011] Preferably, in the wave-shaped wave of the head segment, the tangent line passing through its adjacent trough is the first tangent line, and the angle between the first tangent line and the vertical line is θ1; in the wave-shaped wave of the middle segment, the tangent line passing through its adjacent trough is the second tangent line, and the angle between the second tangent line and the vertical line is θ2; in the wave-shaped wave of the tail segment, the tangent line passing through its adjacent trough is the third tangent line, and the angle between the third tangent line and the vertical line is θ3, then the following conditions are met: 0° < θ1 < θ2 < θ3 < 90°.

[0012] Preferably, the lengths of the head segment, the middle segment, and the tail segment are L1, L2, and L3, respectively, with L1, L2, and L3 increasing sequentially, and satisfying Ln = L1 + 0.2(n-1), and the value of Ln ranges from 0.5 to 1.5m.

[0013] Preferably, the coating material is a positive electrode active material used to form a positive electrode sheet;

[0014] Alternatively, the coating material may be a negative electrode active material used to form a negative electrode sheet.

[0015] A battery cell includes a positive electrode, a negative electrode, and a separator, wherein the separator is disposed between the positive electrode and the negative electrode.

[0016] Both the positive electrode and the negative electrode are the electrodes described above.

[0017] Preferably, the battery cell body includes a positive electrode and a negative electrode disposed at both ends of the battery cell body, wherein the positive electrode is obtained by flattening the electrode portion of the positive electrode sheet, and the negative electrode is obtained by flattening the electrode portion of the negative electrode sheet.

[0018] The thickness of the positive electrode tab is B1 and the thickness of the negative electrode tab is B2, and the following relationship is satisfied: 1.5mm > B1 > B2 > 0.2mm.

[0019] The beneficial effects of this utility model are as follows:

[0020] By making the side of the tab away from the main body wavy, and with different wave heights and wavelengths in the head, middle and tail sections, the degree of tab bending varies in different areas. This improves the ductility and support of the tab, increases the contact area between the tab and the flattening head, and avoids the phenomenon of tab cracking and inversion caused by local stress concentration during the flattening process. It also reduces the risk of puncturing the separator and improves the safety and assembly efficiency of the battery. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the electrode structure of this utility model.

[0022] Figure 2 This is a schematic diagram of the battery cell structure of this utility model.

[0023] Wherein: 1-foil, 11-main body, 12-tab, 121-rolling area, 122-connection area, 13-head section, 14-middle section, 15-tail section, 2-first tangent, 3-second tangent, 4-third tangent; 10-cell body, 20-positive tab, 30-negative tab, 100-cell. Detailed Implementation

[0024] 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.

[0025] The specific embodiments of this utility model will be described in further 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 its scope.

[0026] like Figure 1-2 As shown, a preferred embodiment of the present invention provides a battery cell 100, comprising a positive electrode, a negative electrode, and a separator, wherein the separator is disposed between the positive electrode and the negative electrode. The positive and negative electrode have the same structure, differing only in the active material they are coated with; for ease of description, they are hereinafter referred to as electrode sheets. Each electrode sheet includes a foil 1, which comprises a main body 11 and a tab 12 (i.e., the full tab of the battery cell) disposed on one side of the main body 11. Both surfaces of the main body 11 are coated. When the coating material is a positive active material, a positive electrode sheet is formed; when the coating material is a negative active material, a negative electrode sheet is formed.

[0027] Along the length of the foil 1, the foil 1 includes a head section 13, a middle section 14 and a tail section 15 in sequence. The side of the tab 12 away from the main body 11 is wavy, and the wave height and wavelength of the wavy shape of the head section 13, the middle section 14 and the tail section 15 are different.

[0028] Based on the above-mentioned technical features, the battery cell 100 has a wave-shaped tab portion 12 on the side away from the main body portion 11. The wave height and wavelength of the head section 13, middle section 14 and tail section 15 are different, so that the degree of bending of the tab in different areas is different. This can improve the extensibility and support of the tab, increase the contact area between the tab and the flattening head, thereby avoiding the phenomenon of tab cracking and inverted insertion caused by local stress concentration during the flattening process, reducing the risk of puncturing the separator, and improving the safety and assembly efficiency of the battery.

[0029] In this embodiment, the tab portion 12 includes a rolling area 121 and a connecting area 122. The connecting area 122 connects the rolling area 121 and the main body portion 11, and the wavy shape is provided in the rolling area 121. After die-cutting, the foil 1 needs to be rolled in the rolling area 121 to remove burrs from the surface of the tab and avoid short circuits caused by puncturing the diaphragm. To avoid pressing on the material area during the rolling process and affecting the adhesion between the material area and the diaphragm, the connecting area 122 is provided to ensure the quality of the tab. During the rolling process, three different diameter rollers are set for the head section 13, the middle section 14, and the tail section 15, with diameters of G1, G2, and G3 respectively, where G1 < G2 < G3 and G3 = 2G2 + G1. The diameters of the three rollers are all in the range of 5 to 25 mm, such as 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, 23 mm, and 24 mm.

[0030] After rolling, the thicknesses of the rolling zones 121 corresponding to the head section 13, the middle section 14, and the tail section 15 are different, which can reduce the rolling resistance. Specifically, if the thicknesses of the rolling zones 121 corresponding to the head section 13, the middle section 14, and the tail section 15 are T1, T2, and T3, respectively, then they satisfy T3 = T1 + T2, and the values ​​of T1, T2, and T3 are all in the range of 5 to 20 μm, such as 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, etc.

[0031] In this embodiment, the heights of the rolling zones 121 corresponding to the head section 13, the middle section 14, and the tail section 15 are H1, H2, and H3, respectively, and they satisfy the following relationship: 0mm < H1 < H2 < H3 < 3mm, such as 1mm, 1.5mm, 2mm, 2.5mm, etc. Correspondingly, the widths of the connecting zones 122 corresponding to the head section 13, the middle section 14, and the tail section 15 are also different. If the widths of the connecting zones 122 corresponding to the head section 13, the middle section 14, and the tail section 15 are W1, W2, and W3, respectively, they satisfy the following relationship: 2mm < W3 < W2 < W1 < 7mm, such as 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, etc.

[0032] In this embodiment, in the wavy wave of the head segment 13, the tangent line passing through its adjacent trough is the first tangent line 2, and the angle between the first tangent line 2 and the numerical line is θ1; in the wavy wave of the middle segment 14, the tangent line passing through its adjacent trough is the second tangent line 3, and the angle between the second tangent line 3 and the vertical line is θ2; in the wavy wave of the tail segment 15, the tangent line passing through its adjacent trough is the third tangent line 4, and the angle between the third tangent line 4 and the vertical line is θ3. Therefore, the following conditions are met: 0° < θ1 < θ2 < θ3 < 90°, such as 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, etc. The different degrees of bending of the tabs in different regions help reduce stress concentration during the flattening process, prevent tab breakage, folding, and inversion, and reduce the risk of puncturing the diaphragm.

[0033] In this embodiment, the lengths of the head segment 13, the middle segment 14, and the tail segment 15 are L1, L2, and L3, respectively. The sizes of L1, L2, and L3 increase sequentially and satisfy Ln = L1 + 0.2(n-1). The value of Ln ranges from 0.5 to 1.5m, such as 0.6m, 0.7m, 0.8m, 0.9m, 1m, 1.1m, 1.2m, 1.3m, 1.4m, etc., and n is 1 to 3.

[0034] The positive electrode, negative electrode, and separator are wound together to form the main body 10 of the battery cell. The tab 12 of the positive electrode is flattened to obtain a positive tab 20, and the tab 12 of the negative electrode is flattened to obtain a negative tab 30. The positive tab 20 and the negative tab 30 are located at opposite ends of the main body 10 of the battery cell. The thickness of the positive tab 20 is B1, and the thickness of the negative tab 30 is B2, satisfying the following relationship: 1.5mm > B1 > B2 > 0.2mm, such as 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.2mm, 1.4mm, etc.

[0035] In summary, this application has the following beneficial effects:

[0036] By designing the edge of the electrode tab with a wavy structure, the extensibility and support of the electrode tab can be enhanced, making it less prone to breakage or inversion during kneading, thus improving safety;

[0037] The wavy edge of the electrode tab can increase the contact area between the electrode tab and the flattened head, reducing stress concentration;

[0038] During the rolling process, the tabs can eliminate surface burrs and avoid short circuits caused by puncturing the diaphragm.

[0039] 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 main body and an electrode tab disposed on one side of the main body. Both surfaces of the main body are coated. Along the length of the foil, the foil sequentially includes a head section, a middle section, and a tail section. The side of the electrode ear that is away from the main body is wavy, and the wave height and wavelength of the wavy shape are different for the head section, the middle section and the tail section.

2. The electrode sheet as described in claim 1, characterized in that: The tab portion includes a rolling zone and a connecting zone, the connecting zone connecting the rolling zone and the main body portion, and the wave-shaped part is provided in the rolling zone.

3. The electrode sheet as described in claim 2, characterized in that: The heights of the roller pressing zones corresponding to the head section, the middle section, and the tail section are H1, H2, and H3, respectively, and they satisfy the following condition: 0mm < H1 < H2 < H3 < 3mm.

4. The electrode sheet as described in claim 2, characterized in that: The thicknesses of the rolling zones corresponding to the head section, the middle section, and the tail section are T1, T2, and T3, respectively, where T3 = T1 + T2, and the values ​​of T1, T2, and T3 are all in the range of 5~20μm.

5. The electrode sheet as described in claim 2, characterized in that: The widths of the connecting areas corresponding to the head section, the middle section, and the tail section are W1, W2, and W3, respectively, and they satisfy the following condition: 2mm < W3 < W2 < W1 < 7mm.

6. The electrode sheet according to any one of claims 1-5, characterized in that: In the wave-shaped wave of the beginning segment, the tangent line passing through its adjacent trough is the first tangent line, and the angle between the first tangent line and the vertical line is θ1; in the wave-shaped wave of the middle segment, the tangent line passing through its adjacent trough is the second tangent line, and the angle between the second tangent line and the vertical line is θ2; in the wave-shaped wave of the end segment, the tangent line passing through its adjacent trough is the third tangent line, and the angle between the third tangent line and the vertical line is θ3. Then, the following conditions are met: 0° < θ1 < θ2 < θ3 < 90°.

7. The electrode sheet according to any one of claims 1-5, characterized in that: The lengths of the head segment, the middle segment, and the tail segment are L1, L2, and L3, respectively. The sizes of L1, L2, and L3 increase sequentially and satisfy Ln = L1 + 0.2(n-1), and the value of Ln ranges from 0.5 to 1.5m.

8. The electrode sheet according to any one of claims 1-5, 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.

9. A battery cell, characterized in that: It includes a positive electrode, a negative electrode, and a separator, wherein the separator is disposed between the positive electrode and the negative electrode; Both the positive electrode and the negative electrode are the electrodes described in claim 8.

10. The battery cell as described in claim 9, characterized in that: The battery cell includes a main body and positive and negative tabs disposed at both ends of the main body. The positive tab is obtained by flattening the tab portion of the positive electrode sheet, and the negative tab is obtained by flattening the tab portion of the negative electrode sheet. The thickness of the positive electrode tab is B1 and the thickness of the negative electrode tab is B2, and the following relationship is satisfied: 1.5mm > B1 > B2 > 0.2mm.

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