Cathode plate, battery cell and battery

Abstract

The utility model discloses a cathode piece, a battery cell and a battery. The cathode piece comprises a foil piece body, and two sides of the foil piece body in the width direction are respectively a first side edge and a second side edge; the thinning groove is formed in the foil body and is arranged between the first side edge and the second side edge; a cutting groove is formed between the first end, in the length direction, of the thinning groove and the first side edge, a material reserving area is formed between the second end, in the length direction, of the thinning groove and the second side edge, and the width of the material reserving area is larger than that of the cutting groove. According to the cathode sheet provided by the utility model, the cutting groove is arranged between the thinning groove and the first side edge of the foil sheet body, so that the distance is formed between the first end of the thinning groove and the first side edge; even if the equipment cannot accurately slit along the slitting tangent line due to the fluctuation of the position of the laser milling groove or the fluctuation of the equipment during superposition slitting, the condition that part of the thinned grooves are slit to another cathode plate is avoided, and the defective rate of the cathode plate is further reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a cathode sheet, a battery core and a battery. Background Art

[0002] In order to reduce the overall thickness and improve the energy density of the battery, the current wound battery generally has a thinning groove on the cathode sheet for the tab to be embedded. Striping refers to cutting a strip foil along the strip tangent to separate multiple cathode sheets, and the cathode sheet is usually laser milled with the thinning groove before stripping; due to the fluctuation of the laser milling position and the fluctuation of the equipment during striping, the equipment may not be able to accurately cut along the strip tangent, and part of the thinning groove may be cut into another cathode sheet, which may cause the other cathode sheet to leak at the tail edge, resulting in an increase in the defective rate of the cathode sheet. Utility Model Content

[0003] The utility model aims to solve at least one of the technical problems existing in the prior art. To this end, the utility model provides a cathode sheet that can solve the problem that the thinning groove cannot be accurately cut to the edge, thereby reducing the defective rate of the cathode sheet.

[0004] The utility model also provides a battery core having the cathode sheet.

[0005] The cathode sheet according to the first embodiment of the utility model comprises:

[0006] A foil body, wherein two sides of the foil body in a width direction are respectively a first side edge and a second side edge;

[0007] A thinning groove is arranged in the foil body and between the first side and the second side; a cutting groove is provided between the first end of the thinning groove in the length direction and the first side, and a material retention area is provided between the second end of the thinning groove in the length direction and the second side, and the width of the material retention area is greater than the width of the cutting groove.

[0008] The cathode sheet according to the embodiment of the utility model has at least the following beneficial effects:

[0009] By arranging a cutting groove between the thinning groove and the first side edge of the foil body, a spacing is formed between the first end of the thinning groove and the first side edge. Therefore, during striping, even if the fluctuation of the laser milling groove position or the fluctuation of the equipment during superimposed striping causes the equipment to be unable to accurately cut along the stripping line, part of the thinning groove will not be cut to another cathode sheet, thereby reducing the defective rate of the cathode sheet.

[0010] According to some embodiments of the present invention, the maximum width of the cutting groove is 0.2 mm to 2 mm.

[0011] According to some embodiments of the present invention, a slot adhesive tape is pasted on the foil body, the slot adhesive tape covers the thinning slot, and one side of the slot adhesive tape is aligned with the first side edge.

[0012] According to some embodiments of the present invention, the width of the slot adhesive tape is greater than the width of the thinning slot.

[0013] According to some embodiments of the present invention, the difference between the width of the slot adhesive tape and the width of the thinning slot is 4 mm to 6 mm.

[0014] According to some embodiments of the present invention, the slot adhesive tape is provided with an avoidance area corresponding to the cutting slot.

[0015] According to some embodiments of the present invention, along the width direction of the cutting groove, the lengths of the cutting grooves at various positions are the same; the length of the cutting grooves is smaller than the width of the slot adhesive tape and larger than the width of the thinning grooves.

[0016] According to some embodiments of the present invention, the lengths of the cutting grooves at various positions along the width direction of the foil body are different; the maximum length of the cutting grooves is smaller than the width of the slot adhesive tape, and the minimum length of the cutting grooves is greater than the width of the thinning grooves.

[0017] The battery cell according to the second embodiment of the utility model comprises: an anode sheet, a separator and the above-mentioned cathode sheet, wherein the separator is arranged between the anode sheet and the cathode sheet.

[0018] The battery cell according to the embodiment of the utility model comprises the cathode sheet mentioned above, and thus has at least all the beneficial effects of the cathode sheet, which will not be described in detail here.

[0019] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention is further described below with reference to the accompanying drawings and embodiments, wherein:

[0021] Figure 1 This is a schematic structural diagram of a cathode sheet and a stripped foil sheet according to an embodiment of the utility model;

[0022] Figure 2 It is a structural schematic diagram of the cutting groove of the cathode sheet of the first aspect of an embodiment of the utility model;

[0023] Figure 3 It is a structural schematic diagram of the cutting groove of the cathode sheet of the second aspect of an embodiment of the utility model;

[0024] Figure 4 This is a schematic structural diagram of the cutting groove of the cathode sheet of the third aspect of an embodiment of the utility model.

[0025] Figure Number:

[0026] Slit foil 100;

[0027] The foil body 200 , the first side edge 210 , the second side edge 220 , the thinning groove 230 , the cutting groove 240 , and the groove adhesive tape 250 . DETAILED DESCRIPTION

[0028] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0029] In the description of the present invention, it should be understood that the descriptions involving orientation, such as the orientation or positional relationship indicated as up, down, etc., are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0030] In the description of the present utility model, "a plurality" means more than two. If there is a description of "first" or "second", it is only for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0031] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0032] When the cathode sheet is slit, the fluctuation of the position of the laser milling groove and / or the fluctuation of the equipment during slitting may cause the equipment to be unable to accurately cut along the slitting line, which may cause a part of the thinning groove 230 to be cut into another cathode sheet, thereby causing the other cathode sheet to leak at the tail edge, resulting in an increase in the defective rate of the cathode sheet; in order to solve the above technical problems, this embodiment proposes a cathode sheet that can avoid the situation where a part of the thinning groove 230 is cut into another cathode sheet, thereby reducing the defective rate of the cathode sheet. The following is combined with the attached Figures 1 to 4 The cathode sheet of this embodiment is explained in detail.

[0033] Embodiment 1

[0034] Reference Figure 1 , Figure 2 As shown, the cathode sheet of an embodiment of the utility model is usually cut into a plurality of cathode sheets by cutting a strip foil 100 along a strip cutting line, and each cathode sheet is provided with a thinning groove 230, and the shape of the thinning groove 230 corresponds to the shape of the electrode ear. A cutting groove 240 is provided between the first end of the thinning groove 230 in the length direction and the first side 210, and a material reserve area is provided between the second end of the thinning groove 230 in the length direction and the second side 220, and the width of the material reserve area is greater than the width of the cutting groove 240. For details, refer to Figures 2 to 4 As shown, the length direction of the thinning groove 230 is also the width direction of the cathode sheet; the cutting groove 240 passes through the cathode sheet, but the cutting groove 240 is processed after the stripped foil 100 is cut into multiple cathode sheets, that is, the cutting groove 240 is processed separately for the cathode sheet, rather than directly processing the stripped foil 100; cutting the cutting groove 240 separately for the cathode sheet can effectively improve the cutting accuracy and convenience.

[0035] Further, in the embodiments of the present invention, referring to Figure 1 As shown, the thinning groove 230 is rectangular before stripping, and has a first short side and a second short side that are relatively set; on the current stripped foil 100, the first short side of the thinning groove 230 of each cathode sheet coincides with the stripping tangent line, so if the stripping equipment cannot completely stripe the stripped foil 100 along the stripping tangent line, the thinning groove 230 may be cut off; and in the cathode sheet in this embodiment, there is a certain distance between the first short side of the thinning groove 230 and the stripping tangent line, so even if the stripping equipment cannot completely stripe the stripped foil 100 along the stripping tangent line, the thinning groove 230 will not be cut off, thereby reducing the defective rate of the cathode sheet.

[0036] It should be understood that although the cathode sheet has a first short side after stripping, the first short side is located within the cutting groove 240 , that is, after the cutting groove 240 is processed on the cathode sheet, the first short side of the thinning groove 230 will no longer exist.

[0037] Reference Figure 1 As shown, the distance between the two slit lines of the slit foil 100 is the width of the cathode sheet. For ease of understanding, in this embodiment, the two opposite sides in the width direction of the cathode sheet are positioned as the first side edge 210 and the second side edge 220. Figure 1 It can be seen that the distance between the second short side and the second side 220 is significantly greater than the distance between the first short side and the first side 210 . This design is because the thinning groove 230 needs to be aligned with the position of the anode tab.

[0038] It should be understood that in order to reduce the overall thickness of the battery cell and increase the energy density of the battery cell, a wound battery generally has a thinning groove 230 on both the anode and cathode sheets. The thinning groove 230 of the anode sheet is used for embedding the tabs of the cathode sheet, and the thinning groove 230 of the cathode sheet is used for embedding the tabs of the anode sheet. However, since the processing procedures of the anode sheet and the cathode sheet are slightly different, the anode sheet is generally laser milled after stripping, and the cathode sheet is generally laser milled before stripping. Therefore, the thinning groove 230 of the anode sheet will not be affected by the stripping equipment, while the thinning groove 230 of the cathode sheet may be cut into two parts by the stripping equipment.

[0039] In an embodiment of the present utility model, the width of the cutting groove 240 is 0.2 mm to 2 mm. Specifically, the width of the cutting groove 240 refers to the width in the width direction of the cathode sheet. If the width of the cutting groove 240 is too large, it means that there is a wide distance between the first end of the thinning groove 230 and the first side 210 in the length direction, and the cutting groove 240 will also cut off a larger area of ​​the cathode sheet, which may affect the capacity of the battery; in addition, if the maximum width of the cutting groove 240 is too large, it may also cause the problem that the cutting groove 240 cannot be processed in place at one time when processing the cutting groove 240, thereby reducing the processing efficiency and increasing the processing cost; if the maximum width of the cutting groove 240 is too small, there may be problems with the processing accuracy, which will also lead to an increase in the processing cost of the cutting groove 240.

[0040] In the embodiment of the utility model, the foil body 200 is pasted with a slot adhesive tape 250, the slot adhesive tape 250 covers the thinning groove 230, and one side of the slot adhesive tape 250 is aligned with the first side 210. Specifically, the slot adhesive tape 250 can completely cover the thinning groove 230, and the width of the slot adhesive tape 250 is greater than the width of the thinning groove 230, and the length of the slot adhesive tape 250 is also greater than the length of the thinning groove 230. The purpose of pasting the slot adhesive tape 250 is to prevent the tab of the anode sheet from contacting the cathode sheet.

[0041] In the embodiment of the utility model, the slot adhesive tape 250 is provided with an avoidance area corresponding to the cutting groove 240. Specifically, the slot adhesive tape 250 is pasted on the cathode sheet after the slit foil 100 is slit, and the avoidance area is also processed by the equipment for processing the cutting groove 240. Such operation can facilitate the alignment of one side of the slot adhesive tape 250 with the first side edge 210 of the cathode sheet. At the same time, the slot adhesive tape 250 is pasted first and then the cutting groove 240 is processed, which can ensure that the size of the avoidance area is consistent with that of the cutting groove 240, and the step of re-cutting the slot adhesive tape 240 is eliminated, which reduces the processing cost and ensures that the slot adhesive tape 250 will not be uncut; in the peripheral area of ​​the cutting groove 240, the slot adhesive tape 250 can also be completely attached to the cathode sheet.

[0042] It should be understood that after the cutting groove 240 is processed on the cathode sheet, it is necessary to check the cutting position of the cutting groove 240 and the cutting position of the slot adhesive tape 250 to avoid the burrs at the cutting position being too large to pierce the diaphragm subsequently covered on the cathode sheet; if the burrs at the cutting position of the cutting groove 240 and the cutting position of the slot adhesive tape 250 are too large, the burrs need to be processed to eliminate or reduce the burrs.

[0043] In the embodiment of the present invention, the difference between the width of the slot adhesive tape 250 and the width of the thinning slot 230 is 4 mm to 6 mm. Figures 1 to 4 As shown, the width of the skived groove 230 refers to the distance between the two long sides of the skived groove 230 along the length direction of the cathode sheet, and the width of the slot adhesive tape 250 also refers to the distance between the two long sides of the slot adhesive tape 250 along the length direction of the cathode sheet. For ease of understanding, in this embodiment, the two long sides of the skived groove 230 are defined as the first long side and the second long side, and the two long sides of the slot adhesive tape 250 are defined as the third long side and the fourth long side. The third long side is located on the same side as the first long side, and the fourth long side is located on the same side as the second long side. There is a first spacing between the first long side and the third long side, and there is a second spacing between the second long side and the fourth long side. The first spacing and the second spacing are substantially the same, both of which are 2 mm to 3 mm.

[0044] It is conceivable that the first spacing and the second spacing may be slightly different due to the error in pasting the slot tape 250 or the error in the size of the slot tape 250 itself, but it does not affect the function of the slot tape 250. If the first spacing and the second spacing are set too large, it will affect the capacity of the battery; since the slot tape 250 needs to fit in the thinning groove 230, if the first spacing and the second spacing are set too small, it may easily cause the edge of the slot tape 250 to separate from the cathode sheet, which may cause the anode sheet's tab to contact the cathode sheet; therefore, setting the first spacing and the second spacing to 2mm to 3mm is a more reasonable range.

[0045] In the embodiment of the present invention, along the width direction of the cutting groove 240, the length of each position of the cutting groove 240 is the same; the length of the cutting groove 240 is less than the width of the slot adhesive tape 250 and greater than the width of the thinning groove 230. Figure 2As shown, the cutting groove 240 is rectangular, and the length of the cutting groove 240 is smaller than the width of the slot tape 250 in order to prevent cutting to the area not covered by the slot tape 250, resulting in loss of battery capacity; the length of the cutting groove 240 is greater than the width of the thinning groove 230 because before processing the cutting groove 240, there is a gap between the first short side of the thinning groove 230 and the first side 210, and the thickness of the gap is greater than the thickness at the thinning groove 230. Therefore, if the length of the cutting groove 240 is smaller than the width of the thinning groove 230, there will still be some protrusions between the first end of the thinning groove 230 in the length direction and the first side 210, which will cause the anode plate's ear to be unable to be completely placed in the thinning groove 230, resulting in uneven overall thickness of the battery, affecting the flatness and energy density of the battery.

[0046] In the embodiment of the present invention, the lengths of the cutting grooves 240 at different positions in the width direction of the foil body 200 are different; the maximum length of the cutting grooves 240 is less than the width of the slot adhesive tape 250, and the minimum length of the cutting grooves 240 is greater than the width of the thinning grooves 230. Specifically, Figure 2 In the embodiment shown, the cutting groove 240 is trapezoidal. Figure 3 The cutting groove 240 shown is fan-shaped, that is, as long as the length and width of the cutting groove 240 meet the above conditions, there is no specific limitation on the shape of the cutting groove 240, and a suitable shape can be determined according to actual conditions or personal preferences. However, in this embodiment, it is preferred to set the cutting groove 240 to be fan-shaped, because the fan-shaped shape has only one side after cutting and has no corners, so it is easy to clean the burrs at the cut.

[0047] The battery cell of the second embodiment of the utility model comprises: an anode sheet, a separator and the above-mentioned cathode sheet, wherein the separator is arranged between the anode sheet and the cathode sheet. Specifically, for a wound battery, the anode sheet, the separator and the cathode sheet are stacked and then wound to form a battery cell. Since the battery cell includes the above-mentioned cathode sheet, it has at least all the beneficial effects of the cathode sheet, which will not be described in detail here.

[0048] The battery of the third embodiment of the utility model includes the above-mentioned battery cell, and also includes a shell, an electrolyte and other structures. The battery cell is placed in the shell, and then the electrolyte is poured into the shell and the shell is sealed, and the positive electrode and the negative electrode are led out of the shell to form a complete battery. The battery in this embodiment mainly refers to a lithium battery. Since the battery includes the above-mentioned battery cell, it has at least all the beneficial effects of the battery cell, which will not be repeated here.

[0049] In order to verify the beneficial effects of the battery using the cathode sheet of this embodiment, the following experiments were designed for verification:

[0050] Three groups of batteries were designed for comparison. Example group 1 is a conventional non-air-avoiding group, that is, the cathode sheet of example group 1 is not provided with thinning groove 230 and cutting groove 240; example group 2 is a conventional air-avoiding group, that is, the cathode sheet of example group 2 is provided with thinning groove 230, but the first end of the thinning groove 230 in the length direction is aligned with the strip tangent line; example group 3 is an air-avoiding improved group, that is, the cathode sheet of example group 3 is provided with both thinning groove 230 and cutting groove 240.

[0051] As shown in the table below, the three groups of batteries all have the same capacity, and each group has five batteries. At the same time, the cathode surfaces of the three groups of batteries have the same density.

[0052]

[0053] It can be seen from the above table:

[0054] In terms of battery capacity, the capacities of the three groups of batteries in sample group 1, sample group 2, and sample group 3 are basically the same;

[0055] In terms of battery thickness, Example Group 2 and Example Group 3 are about 20μm thinner than Example Group 1. At the same time, the battery thickness of Example Group 2 fluctuates due to fluctuations in the striping equipment. The overall thickness of Example Group 3 is more than 20μm thinner, and the overall thickness is relatively uniform.

[0056] In terms of battery energy density, the energy density of Example Group 3 is the highest and also the most uniform.

[0057] From the above comparison, it can be seen that the cathode sheet provided with both the thinning groove 230 and the cutting groove 240 and the battery including the above cathode sheet have the most stable battery thickness and energy density, which also proves that the cathode sheet provided with the thinning groove 230 and the cutting groove 240 has a lower defective rate.

[0058] In order to further verify the influence of the cutting groove 240 in the cathode sheet of this embodiment on the battery, this embodiment also designs the following experiments for verification:

[0059] Three groups of cathode sheets were designed for comparison. All three groups of cathode sheets were provided with thinning grooves 230 and slot adhesive tapes 250. The width of the thinning grooves 230 of the three groups was 18 mm, and the width of the slot adhesive tapes 250 was 23 mm. The width of the cutting groove 240 of Example Group 1 is between 18 mm and 20 mm, that is, the length of the cutting groove 240 of Example Group 1 meets the requirement of being less than the width of the slot adhesive tape 250 and greater than the width of the thinning groove 230; the minimum width of the cutting position of Example Group 2 is 25 mm, that is, the length of the cutting groove 240 of Example Group 2 does not meet the requirement of being less than the width of the slot adhesive tape 250; the maximum width of the cutting position of Example Group 3 is 16 mm, that is, the length of the cutting groove 240 of Example Group 3 does not meet the requirement of being greater than the width of the thinning groove 230. The measurement results are shown in the figure below:

[0060]

[0061] It can be seen from the above table:

[0062] In terms of battery capacity, the capacity of Example Group 1 and Example Group 3 are close and relatively uniform, while in Example Group 2, due to the over-cutting of the cutting groove 240, the cutting groove 240 partially cuts to the cathode sheet position not covered by the slot adhesive tape 250, resulting in the loss of battery capacity of the cathode sheet, so the battery capacity of Example Group 2 is relatively low;

[0063] In terms of battery thickness, the battery thicknesses of Example Group 1 and Example Group 3 are similar and relatively uniform. However, in Example Group 3, the cutting length of the cutting groove 240 is too small, resulting in that a portion of the area between the first end of the thinning groove 230 in the length direction and the first side 210 of the foil body 200 is not completely cut off, so that the thickness of the anode tab at some positions overlaps with the thickness of the cathode sheet, which leads to the uneven thickness of Example Group 3.

[0064] In terms of battery energy density, Example Group 1 has the highest energy density, while Example Group 2 and Example Group 3 have energy densities slightly lower than that of Example Group 1.

[0065] Based on the above conclusions, it can be seen that when the length of the cutting groove 240 of the cathode sheet is within the range of the width of the slot tape 250 and the width of the thinning groove 230, the battery using this cathode sheet can obtain a more uniform thickness and energy density without affecting the battery capacity, and can also obtain a higher energy density.

[0066] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0067] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A cathode sheet, characterized in that: include: A foil body, wherein two sides of the foil body in a width direction are respectively a first side edge and a second side edge; a thinning groove, disposed on the foil body and between the first side and the second side; A cutting groove is provided between the first end of the thinning groove in the length direction and the first side edge, and a material reserve area is provided between the second end of the thinning groove in the length direction and the second side edge, wherein the width of the material reserve area is greater than the width of the cutting groove.

2. The cathode sheet according to claim 1, characterized in that: The width of the cutting groove is 0.2 mm to 2 mm.

3. The cathode sheet according to claim 1, characterized in that: The shape of the cutting groove can be selected from any one of a rectangle, a trapezoid and a sector.

4. The cathode sheet according to claim 1, characterized in that: The foil body is pasted with slot adhesive tape, the slot adhesive tape covers the thinning slot, and one side of the slot adhesive tape is aligned with the first side edge.

5. The cathode sheet according to claim 4, characterized in that: The width of the slot adhesive tape is greater than the width of the thinning groove.

6. The cathode sheet according to claim 5, characterized in that: The difference between the width of the slot adhesive tape and the width of the thinning slot is 4 mm to 6 mm.

7. The cathode sheet according to claim 4, characterized in that: The slot adhesive tape is provided with an avoidance area corresponding to the cutting slot.

8. The cathode sheet according to claim 4, characterized in that: Along the width direction of the cutting groove, the lengths of the cutting grooves at various positions are the same; the length of the cutting grooves is smaller than the width of the slot adhesive tape and larger than the width of the thinning grooves.

9. The cathode sheet according to claim 4, characterized in that: Along the width direction of the foil body, the lengths of the cutting grooves at various positions are different; the maximum length of the cutting grooves is smaller than the width of the slot adhesive tape, and the minimum length of the cutting grooves is larger than the width of the thinning grooves.

10. A battery cell, characterized in that: The invention comprises an anode sheet, a separator and a cathode sheet as claimed in any one of claims 1 to 8, wherein the separator is arranged between the anode sheet and the cathode sheet.

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