Pole piece, battery cell and battery

Abstract

The utility model discloses a pole piece, a battery cell and a battery. The pole piece comprises a current collector, an active material layer and an insulating coating. Wherein the current collector has a set length direction and a set width direction; the active material layer is coated on the current collector; the current collector is coated with the insulating coating, the insulating coating is located on at least one side of the active material layer in the width direction of the current collector, and the hardness of the insulating coating is larger than that of the active material layer. In the width direction of the current collector, the insulating coating is located on at least one side of the active material layer, the hardness of the insulating coating is larger than that of the active material layer, and part of pressure can be offset when the insulating coating is subjected to the acting force of a compression roller, so that the overpressure condition of the edge of the pole piece is improved, the fluctuation degree of wavy wrinkles is reduced, and the occurrence possibility is reduced; the flatness of the pole piece is improved, the possibility of lithium precipitation when the pole piece is applied to a battery cell is reduced, and the service life of the battery cell is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium ion batteries, in particular to a pole piece, a battery core and a battery. Background Art

[0002] During the manufacturing process of the electrode, a rolling step is required after the active material coating is completed to compact the active material to a preset compaction density. However, due to the large force applied to the pressing roller, the two axial ends of the pressing roller will deform, causing the edge of the electrode along the width direction to be subjected to greater pressure than the middle area, resulting in overpressure at the edge of the electrode. Wave-like wrinkles will appear on the edge of the electrode, the flatness of the electrode is poor and this affects the deintercalation of lithium ions, resulting in a high risk of lithium plating when the electrode is used in a battery cell. 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 pole piece, which can reduce the possibility of lithium deposition at the edge of the pole piece and increase the service life.

[0004] The utility model also provides a battery core having the pole piece.

[0005] The utility model also provides a battery having the battery core.

[0006] The pole piece according to the first embodiment of the utility model comprises:

[0007] A current collector having a set length direction and a set width direction;

[0008] An active material layer, coated on the current collector;

[0009] An insulating coating is coated on the current collector. Along the width direction of the current collector, the insulating coating is located on at least one side of the active material layer. The hardness of the insulating coating is greater than that of the active material layer.

[0010] The pole piece according to the embodiment of the utility model has at least the following beneficial effects: along the width direction of the current collector, the insulating coating is located on at least one side of the active material layer, and the hardness of the insulating coating is greater than the hardness of the active material layer. When subjected to the force of the pressure roller, it can offset part of the pressure, thereby improving the overpressure situation at the edge of the pole piece on the side where the insulating coating is located, thereby reducing the degree of fluctuation of the wavy wrinkles and reducing the possibility of their occurrence, improving the flatness of the pole piece, reducing the possibility of lithium deposition when the pole piece is used in the battery cell, and improving the service life of the battery cell.

[0011] According to some embodiments of the present invention, the insulating coating has a Mohs hardness of 6.5 to 9.

[0012] According to some embodiments of the present invention, the current collector also has a set thickness direction. Along the thickness direction of the current collector, the thickness of the active material layer is D1, the thickness of the insulating coating is D2, and the thickness D1 of the active material layer and the thickness D2 of the insulating coating satisfy: 0.4D1≤D2≤0.8D1.

[0013] According to some embodiments of the present invention, the thickness D1 of the active material layer and the thickness D2 of the insulating coating layer satisfy the following relationship: 0.5D1≤D2≤0.7D1.

[0014] According to some embodiments of the present invention, the thickness D1 of the active material layer is 60 μm to 100 μm; or the thickness of the insulating coating is 30 μm to 70 μm.

[0015] According to some embodiments of the present invention, along the width direction of the current collector, the size of the insulating coating is 1 mm to 6 mm.

[0016] According to some embodiments of the present invention, along the width direction of the current collector, the insulating coating is located on both sides of the active material layer.

[0017] According to some embodiments of the utility model, it also includes a plurality of pole ears, the current collector includes a coating area and a plurality of empty foil areas, the empty foil area is located on one side of the current collector along the width direction, and the plurality of empty foil areas are spaced apart along the length direction of the current collector, the active material layer and the insulating coating are both coated on the coating area, and each of the pole ears corresponds to each of the empty foil areas one by one and is connected to the empty foil areas.

[0018] According to the second aspect embodiment of the utility model, the battery cell includes a positive electrode sheet, a negative electrode sheet and a separator, at least one of the positive electrode sheet and the negative electrode sheet is the electrode sheet provided by the first aspect embodiment above, the separator is arranged between the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet, the negative electrode sheet and the separator are wound to form the battery cell.

[0019] The battery cell according to the embodiment of the utility model has at least the following beneficial effects: the battery cell has at least all the advantages of the pole piece because it includes the pole piece provided by the embodiment of the first aspect mentioned above, and when the flatness of the pole piece is better and the possibility of lithium plating is reduced, the safety performance and service life of the battery cell are also correspondingly improved.

[0020] A battery according to an embodiment of the third aspect of the utility model includes the battery cell provided by the embodiment of the second aspect.

[0021] The battery according to the embodiment of the utility model has at least the following beneficial effects: since the battery includes the battery cell provided by the embodiment of the second aspect above, the battery has at least all the advantages of the battery cell.

[0022] 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

[0023] The present invention is further described below with reference to the accompanying drawings and embodiments, wherein:

[0024] Figure 1 It is a schematic diagram of a pole piece of an embodiment of the utility model;

[0025] Figure 2 It is a cross-sectional view of a pole piece of an embodiment of the utility model;

[0026] Figure 3 A schematic diagram of another pole piece of an embodiment of the utility model;

[0027] Reference numerals:

[0028] The current collector 100 , the coating area 110 , the empty foil area 120 , the active material layer 200 , the insulating coating 300 , and the tab 400 . DETAILED DESCRIPTION

[0029] 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.

[0030] In the description of the present invention, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply 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.

[0031] In the description of the present utility model, "several" means more than one, "many" means more than two, "greater than", "less than", "exceed" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used to distinguish the technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0032] 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.

[0033] In the description of the utility model, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" 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 representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0034] Reference Figure 1 and Figure 2 The first embodiment of the utility model provides a pole piece, including a current collector 100, an active material layer 200 and an insulating coating 300. The current collector 100 has a set length direction and a width direction; the active material layer 200 is coated on the current collector 100; the insulating coating 300 is coated on the current collector 100, and along the width direction of the current collector 100, the insulating coating 300 is located on at least one side of the active material layer 200, that is, along the width direction of the current collector 100, the insulating coating 300 is closer to the edge of the corresponding side of the current collector 100 than the active material layer 200, and the hardness of the insulating coating 300 is greater than the hardness of the active material layer 200.

[0035] Along the width direction of the current collector 100, the insulating coating 300 is located on at least one side of the active material layer 200, and the hardness of the insulating coating 300 is greater than that of the active material layer 200. When subjected to the force of the pressure roller, it can offset part of the pressure, thereby improving the overpressure at the edge of the electrode, thereby reducing the degree of fluctuation of the wavy wrinkles and reducing the possibility of their occurrence, improving the flatness of the electrode, reducing the possibility of lithium deposition when the electrode is used in a battery cell, and improving the service life of the battery cell.

[0036] When the electrode sheet is rolled, for example, the designed compaction density of the active material layer 200 is 1.65 g / cm 3 When the insulating coating 300 is not provided, the compaction density of the active material layer 200 along the width direction of the edge of the electrode sheet after rolling will reach 1.75 g / cm 3 , and there are significant wrinkles, which affects the flatness of the pole piece, and the possibility of lithium deposition when the pole piece is used in the battery cell increases accordingly. After the insulating coating 300 is set on the edge of the pole piece in the width direction, the compaction density of the insulating coating 300 on the edge of the pole piece after rolling is 1.68g / cm 3The edge of the pole piece along the width direction is smooth, and the wrinkles are significantly reduced. Compared with the pole piece without the insulating coating 300, the overvoltage can be significantly improved, and the risk of lithium plating when the pole piece is used in the battery cell can be reduced.

[0037] It should be noted that the electrode of the present application can be a positive electrode or a negative electrode. When the electrode is a positive electrode, the current collector 100 is generally made of aluminum foil, which has a low strength. Therefore, when the edge of the electrode is subjected to excessive pressure, it is more likely to produce wavy fluctuations, and the height of the fluctuations is also large. Coating an insulating coating 300 with a certain hardness at the edge of the electrode in the width direction can better solve the above problem. When the electrode is a negative electrode, coating an insulating coating 300 with a certain hardness at the edge of the electrode in the width direction can also improve the problem of wavy fluctuations at the edge of the electrode.

[0038] In some embodiments, the Mohs hardness of the insulating coating 300 is 6.5 to 9, and the hardness of the active material layer 200 is 1 to 2. The hardness of the insulating coating 300 and the active material layer 200 are measured by an existing hardness measuring instrument after rolling. The insulating coating 300 can be selected as a ceramic coating, and the ceramic coating includes ceramic particles and a binder. The mass ratio of the ceramic particles to the binder is 0.6 to 0.8: 0.2 to 0.4, and the ceramic particles are bonded and bonded to the surface of the current collector 100 by the binder. The ceramic particles can be selected as alumina, and the binder can be selected as polyvinylidene fluoride. The hardness of the insulating coating 300 is mainly related to the mass percentage of the ceramic particles in the insulating coating 300. The higher the mass percentage of the ceramic particles, the higher the hardness of the insulating coating 300. Therefore, the hardness of the insulating coating 300 can be adjusted by adjusting the mass percentage of the ceramic particles so that the hardness of the insulating coating 300 is within the above range.

[0039] Reference Figure 2 In some embodiments, the current collector 100 also has a set thickness direction. Along the thickness direction of the current collector 100, the thickness of the active material layer 200 is D1, and the thickness of the insulating coating 300 is D2. The thickness D1 of the active material layer 200 and the thickness D2 of the insulating coating 300 satisfy: 0.4D1≤D2≤0.8D1. Among them, D2 can be selected as 0.4D1, 0.5D1, 0.6D1, 0.7D1, 0.8D1 or any other value from 0.4D1 to 0.8D1. It should be noted that the above thickness ratios are all measured after the pole piece is rolled.

[0040] Since the compression rates of the insulating coating 300 and the active material layer 200 are different, the thickness of the insulating coating 300 needs to be smaller than that of the active material layer 200. Under the premise that the hardness of the insulating coating 300 is greater than that of the active material layer 200, if D2>0.8D1 or even D2>D1, when the insulating material layer is pressed by the pressure roller, the insulating material layer may be subjected to greater force, which may cause the particles in the insulating material layer to be embedded in the current collector 100, resulting in a decrease in the strength of the corresponding position of the current collector 100, which is prone to breakage when subjected to force. If D2 is less than 0.4D1, the insulating coating 300 will less likely offset the pressure of the pressure roller, resulting in wavy undulations on the edge of the pole piece along the width direction, and the purpose of coating the insulating coating 300 will not be achieved.

[0041] Reference Figure 2 , further, the thickness D1 of the active material layer 200 and the thickness D2 of the insulating coating 300 satisfy: 0.5D1≤D2≤0.7D1. Specifically, the thickness D1 of the active material layer 200 is 60μm to 100μm; or, the thickness D2 of the insulating coating 300 is 30μm to 70μm. The thickness D1 of the active material layer 200 can be selected as 60μm, 70μm, 80μm, 90μm, 100μm or any other value from 60μm to 100μm. The thickness D2 of the insulating coating 300 can be selected as 30μm, 40μm, 50μm, 60μm, 70μm or any other value from 30μm to 70μm. When selecting the values ​​of the insulating coating 300 and the active material layer 200, 0.4D1≤D2≤0.8D1 must be satisfied.

[0042] In some embodiments, along the width direction of the current collector 100, the size of the insulating coating 300 is 1mm to 6mm. The size of the insulating coating 300 along the width direction of the current collector 100 can be selected as 1mm, 2mm, 3mm, 4mm, 5mm, 6mm or any other value between 1mm and 6mm. The insulating coating 300 needs a certain width to disperse the pressure when subjected to the pressure of the roller, to avoid excessive force in the local area and unable to absorb the pressure, and to reduce the wrinkles at the edge of the pole piece. If the size of the insulating coating 300 along the width direction of the current collector 100 is too large, for example, greater than 6mm, although it can play a good protective role for the current collector 100, it will cause the size of the active material layer 200 in the width direction of the current collector 100 to be reduced, resulting in a more obvious decrease in the energy density of the pole piece when it is applied to the battery cell. Therefore, the size of the insulating coating 300 along the width direction of the current collector 100 is controlled within the above range, which can reduce the possibility of overpressure in the active material layer 200 of the pole piece and wrinkles at the edge, while not causing a significant impact on the energy density of the pole piece when it is applied to the battery cell.

[0043] Reference Figure 1In some embodiments, along the width direction of the current collector 100, the insulating coating 300 is located on both sides of the active material layer 200, and along the width direction of the current collector 100, the insulating coating 300 is symmetrically coated on both sides of the active material layer 200. The sizes of the insulating coatings 300 on both sides along the thickness direction of the current collector 100 can be the same or different. When coating the current collector 100, the coating of the active material layer 200 and the insulating coating 300 can be carried out simultaneously, which reduces the coating steps and improves the manufacturing efficiency of the electrode.

[0044] Reference Figure 3 In some embodiments, the pole piece further includes a plurality of pole ears 400, the current collector 100 includes a coating area 110 and a plurality of empty foil areas 120, the empty foil area 120 is located on one side of the current collector 100 along the width direction, and the plurality of empty foil areas 120 are arranged at intervals along the length direction of the current collector 100, the active material layer 200 and the insulating coating 300 are both coated on the coating area 110, and each pole ear 400 corresponds to each empty foil area 120 and is connected to the empty foil area 120. The pole piece can be a multi-pole ear pole piece, and by connecting the pole ears 400 to the plurality of empty foil areas 120, multiple locations in the length direction of the current collector 100 can be charged simultaneously during the charging process, so as to achieve the effect of fast charging. It should be noted that along the width direction of the current collector 100, the insulating coating 300 on the side where the empty foil area 120 is located is coated at intervals, and the empty foil area 120 is defined between them, while on the other side of the width direction of the current collector 100, the insulating coating 300 is coated continuously.

[0045] The second aspect of the utility model provides a battery cell (not shown in the figure), including a positive electrode sheet, a negative electrode sheet and a separator, at least one of the positive electrode sheet and the negative electrode sheet is the electrode sheet provided in the first aspect embodiment above, the separator is arranged between the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet, the negative electrode sheet and the separator are wound to form a battery cell. The battery cell in this embodiment is a wound structure battery cell. Since the battery cell includes the electrode sheet provided in the first aspect embodiment above, it has at least all the advantages of the electrode sheet. When the flatness of the electrode sheet is good and the possibility of lithium deposition is reduced, the safety performance and service life of the battery cell are also improved accordingly. Among them, the positive electrode sheet and the negative electrode sheet can also be the electrode sheets provided in the first aspect embodiment above, and when one of the positive electrode sheet or the negative electrode sheet is a multi-pole ear electrode sheet, the other is also a multi-pole ear electrode sheet.

[0046] The third aspect of the present invention provides a battery (not shown in the figure), including the battery cell provided by the second aspect. Since the battery includes the battery cell provided by the second aspect, it has at least all the advantages of the battery cell, which will not be described in detail here.

[0047] The embodiments of the utility model are described in detail above in conjunction with the accompanying drawings, but the utility model is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the utility model. In addition, the embodiments of the utility model and the features in the embodiments can be combined with each other without conflict.

Claims

1. A pole piece, characterized in that: include: A current collector having a set length direction and a set width direction; An active material layer, coated on the current collector; An insulating coating is coated on the current collector. Along the width direction of the current collector, the insulating coating is located on at least one side of the active material layer. The hardness of the insulating coating is greater than that of the active material layer.

2. The pole piece according to claim 1, characterized in that: The insulating coating has a Mohs hardness of 6.5 to 9.

3. The pole piece according to claim 1, characterized in that: The current collector also has a set thickness direction. Along the thickness direction of the current collector, the thickness of the active material layer is D1, the thickness of the insulating coating is D2, and the thickness D1 of the active material layer and the thickness D2 of the insulating coating satisfy: 0.4D1≤D2≤0.8D1.

4. The pole piece according to claim 3, characterized in that: The thickness D1 of the active material layer and the thickness D2 of the insulating coating layer satisfy the following relationship: 0.5D1≤D2≤0.7D1.

5. The pole piece according to claim 2, characterized in that: The thickness D1 of the active material layer is 60 μm to 100 μm; or the thickness of the insulating coating layer is 30 μm to 70 μm.

6. The pole piece according to claim 1, characterized in that: Along the width direction of the current collector, the size of the insulating coating layer is 1 mm to 6 mm.

7. The pole piece according to any one of claims 1 to 5, characterized in that: Along the width direction of the current collector, the insulating coating is located on both sides of the active material layer.

8. The pole piece according to any one of claims 1 to 6, characterized in that: It also includes a plurality of pole ears, the current collector includes a coating area and a plurality of empty foil areas, the empty foil area is located on one side of the current collector along the width direction, and the plurality of empty foil areas are arranged at intervals along the length direction of the current collector, the active material layer and the insulating coating are both coated on the coating area, and each of the pole ears corresponds to each of the empty foil areas one by one and is connected to the empty foil areas.

9. A battery cell, characterized in that: It includes a positive electrode sheet, a negative electrode sheet and a separator, at least one of the positive electrode sheet and the negative electrode sheet is the electrode sheet according to any one of claims 1 to 8, the separator is arranged between the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet, the negative electrode sheet and the separator are wound to form the battery cell.

10. A battery, characterized in that: Comprising the battery cell as claimed in claim 9.

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