Pole piece and battery

Abstract

The utility model discloses a pole piece and a battery. The pole piece comprises a current collector and an active material layer, the active material layer is arranged on at least one side of the current collector, the active material layer comprises at least two overlapped rolling layers, in every two adjacent rolling layers, the rolling layer on the outer layer is provided with a first compaction area and a second compaction area, and the compaction density of the second compaction area is smaller than that of the first compaction area. When two or more layers of coated and rolled pole pieces are manufactured, the outer rolling layer is provided with the first compaction area and the second compaction area, and the compaction density of the second compaction area is smaller than that of the first compaction area, so that active substances in the second compaction area are relatively loose; and a more efficient ion transmission channel is formed in the second compaction area of the outer rolling layer, so that the ion transmission efficiency and the charge-discharge capacity of the battery are improved, and the capacity of the battery is favorably improved.

Description

Technical Field

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

[0002] As demand for lithium-ion battery capacity increases, the current mainstream solution is to thicken the active material layer of the electrode. Electrodes typically consist of a current collector and active material layers positioned on either side of the current collector. Conventional methods thicken the active material layer by applying two or more layers and rolling them together. However, as the active material layer thickens, the inner layer near the current collector becomes less likely to come into contact with the electrolyte, impacting lithium-ion transmission efficiency and the battery's charge and discharge capabilities, thus hindering capacity increases. Utility Model Content

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a pole piece that can improve the ion transmission efficiency and the charge and discharge capacity of the battery, thereby facilitating the improvement of the battery capacity.

[0004] The utility model also provides a battery having the above-mentioned electrode piece.

[0005] According to an embodiment of the first aspect of the present invention, a pole piece includes a current collector and an active material layer. The active material layer is provided on at least one side of the current collector, and the active material layer includes at least two stacked rolled layers. Of two adjacent rolled layers, the outer rolled layer has a first compacted region and a second compacted region, and the compaction density of the second compacted region is less than the compaction density of the first compacted region.

[0006] The pole piece according to the embodiment of the first aspect of the present invention has at least the following beneficial effects: when making two or more layers of coated roller-pressed pole pieces, since the outer rolled layer has a first compaction area and a second compaction area, and the compaction density of the second compaction area is less than the compaction density of the first compaction area, the active material in the second compaction area is relatively loose, and a more efficient ion transmission channel is formed in the second compaction area of the outer rolled layer, thereby improving the ion transmission efficiency and the battery's charge and discharge capabilities, which is beneficial to the improvement of battery capacity.

[0007] According to some embodiments of the present invention, in two adjacent rolled layers, a groove is provided on the outer side surface of the inner rolled layer corresponding to the second compaction zone, and a convex end is provided on the inner side of the second compaction zone of the outer rolled layer, and the convex end is embedded in the groove.

[0008] According to some embodiments of the present invention, the depth of the groove is A, the thickness of the rolled layer where the groove is located is B, and 1 / 3B≤A≤1 / 2B is satisfied.

[0009] According to some embodiments of the present invention, the cross section of the groove is conical, semicircular, rectangular or trapezoidal.

[0010] According to some embodiments of the present invention, at least two grooves are arranged at intervals on the outer side surface of the inner rolled layer, and at least two second compaction areas are arranged at intervals on the outer rolled layer, and the grooves are arranged in one-to-one correspondence with the second compaction areas.

[0011] According to some embodiments of the present invention, the groove is a strip-shaped groove, a dotted-line groove, or a dot-shaped groove.

[0012] According to some embodiments of the present invention, in two adjacent rolled layers, the compaction density of the second compaction zone of the outer rolled layer is smaller than the compaction density of the inner rolled layer.

[0013] According to some embodiments of the present invention, all the rolled layers are made of the same material.

[0014] According to some embodiments of the present invention, the active material layer includes two stacked rolled layers, the thickness of the active material layer is C, the thickness of the inner rolled layer is B, and 1 / 3C≤B≤3 / 4C is satisfied.

[0015] A battery according to an embodiment of the second aspect of the present invention includes the above-mentioned electrode piece.

[0016] The battery according to the embodiment of the second aspect of the present invention has at least the following beneficial effects: due to the use of the above-mentioned pole pieces, the ion migration efficiency between the pole pieces inside the battery is accelerated, the battery's charging and discharging capabilities are improved, and it is beneficial to increase the battery capacity.

[0017] Additional aspects and advantages of the present invention will be given in part in the following description and will become apparent from the following description or learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0019] Figure 1 A schematic cross-sectional view of a pole piece according to an embodiment of the present utility model;

[0020] Figure 2 This is an exploded schematic cross-sectional view of a pole piece according to an embodiment of the present invention;

[0021] Figure 3 Schematic diagram of grooves of different shapes according to an embodiment of the present invention.

[0022] Reference numerals:

[0023] Current collector 100;

[0024] Active material layer 200 , rolled layer 210 , first compacting area 211 , second compacting area 212 , groove 213 . DETAILED DESCRIPTION

[0025] The following describes embodiments of the present invention in detail. 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 intended only to explain the present invention and are not to be construed as limiting the present invention.

[0026] In the description of the present invention, it should be understood that descriptions involving orientation, such as the orientation or positional relationship indicated by up, down, etc., are based on the orientation or positional relationship shown in the accompanying 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.

[0027] In the description of this utility model, "a plurality" means more than two. The use of "first" or "second" is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features indicated, or implicitly indicating the order of the technical features indicated.

[0028] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting 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.

[0029] To improve the battery's charge and discharge capabilities, another existing method involves laser etching a portion of the active material layer 200 directly on the electrode surface to form grooves 213. Grooves 213 also create ion channels, improving ion transport efficiency and, in turn, the battery's charge and discharge capabilities. However, laser processing easily generates dust, which remains on the surface of the active material layer 200 and is difficult to remove, leading to abnormalities such as rapid self-discharge.

[0030] Reference Figures 1 to 3, is a pole piece of an embodiment of the present invention, comprising a current collector 100 and an active material layer 200. The active material layer 200 is disposed on both sides of the current collector 100. The active material layer 200 comprises two or more stacked roll-pressed layers 210. Of two adjacent roll-pressed layers 210, the outer roll-pressed layer 210 has a first compacted region 211 and a second compacted region 212. The compacted density of the second compacted region 212 is less than the compacted density of the first compacted region 211.

[0031] When making two or more layers of coated rolled electrodes, since the outer rolled layer 210 has a first compaction area 211 and a second compaction area 212, and the compaction density of the second compaction area 212 is less than the compaction density of the first compaction area 211, the active material in the second compaction area 212 is relatively loose, and a more efficient ion transmission channel is formed in the second compaction area 212 of the outer rolled layer 210, thereby improving the ion transmission efficiency and the battery's charge and discharge capabilities, which is beneficial to the improvement of battery capacity.

[0032] Specifically, active material layers 200 are provided on both sides of the current collector 100. It is conceivable that in other embodiments, the current collector 100 may also have an active material layer 200 provided on one side, and those skilled in the art may configure it specifically according to actual needs.

[0033] It should be understood that the thickness of the electrode of the present invention should be consistent at all locations to meet the requirements of normal electrode usage.

[0034] Specifically, among two adjacent rolled layers 210 , the one closer to the current collector 100 is defined as the inner rolled layer 210 , and the one farther from the current collector 100 is defined as the outer rolled layer 210 .

[0035] In the embodiment, in two adjacent rolled layers 210, a groove 213 is provided on the outer side surface of the inner rolled layer 210 at a position corresponding to the second compacting area 212, and a convex end is provided on the inner side of the second compacting area 212 of the outer rolled layer 210, and the convex end is embedded in the groove 213. During production, the inner rolled layer 210 is first coated and rolled on the current collector 100 to form the inner rolled layer, and then a portion of the active material is etched on the inner rolled layer 210 by laser to open the groove 213. Then, when the outer rolled layer 210 is coated and rolled, part of the active material is embedded in the groove 213. Since there is more space at the groove 213, the density of the outer rolled layer 210 at the position corresponding to the groove 213 is relatively low, naturally forming the second compacting area 212, and making the position of the second compacting area 212 correspond to the position of the groove 213, while the density in the area outside the groove 213 is relatively high, naturally forming the first compacting area 211. Therefore, grooves 213 are provided on the outer side of the inner rolled layer 210. This allows for the automatic formation of first and second compressed areas 211, 212, of varying densities on the outer rolled layer 210 during the roll-coating process of two or more active material layers 200. This eliminates the need for complex process control and facilitates a simplified production process. Furthermore, the outer rolled layer 210 covers the inner rolled layer 210, thus covering the dust generated by the laser on the surface of the inner rolled layer 210. This effectively eliminates the adverse effects of laser etching dust on battery self-discharge, thereby enhancing battery durability.

[0036] In the embodiment, the depth of the groove 213 is A, and the thickness of the rolled layer 210 where the groove 213 is located is B, satisfying 1 / 3B≤A≤1 / 2B. The above-mentioned depth of the groove 213 can make the density and thickness of the second compacted area 212 of the outer rolled layer 210 relatively appropriate, which is conducive to forming an efficient lithium ion channel and reduces defects such as the local thickness of the rolled layer 210 where the groove 213 is located being too small at the groove 213, which affects the strength of the electrode. It is understandable that the depth A of the groove 213 can be any value between 1 / 2B and 1 / 3B, and those skilled in the art can make specific configurations based on actual needs.

[0037] In the embodiment, the cross-section of the groove 213 is tapered, which is relatively convenient for laser etching and scribing, and helps to maintain a substantially consistent density of the active material within the second compacted area 212. It is conceivable that the cross-section of the groove 213 can also be other shapes, such as semicircular, rectangular, or trapezoidal, which can be selected according to actual production and processing requirements.

[0038] In the embodiment, two or more grooves 213 are provided at intervals on the outer side surface of the inner rolled layer 210, and two or more second compacting areas 212 are provided at intervals on the outer rolled layer 210, with the grooves 213 corresponding to the second compacting areas 212. Providing two or more grooves 213 means that the corresponding outer rolled layer 210 also has second compacting areas 212 corresponding to the number of grooves 213, thereby enabling the active material layer 200 to have more efficient lithium ion channels, further improving the charge and discharge capabilities of the battery, and further contributing to increasing the battery capacity.

[0039] Specifically, the different grooves 213 can be evenly arranged along the length of the electrode, so that the lithium ion channels of the active material layer 200 are relatively evenly dispersed, so that each part of the electrode has efficient lithium ion channels, facilitating the migration of lithium ions throughout the electrode. Alternatively, grooves 213 can be provided in some areas of the electrode and not provided in other areas, depending on certain needs. The number of grooves 213 can be two, three, or more, and those skilled in the art can configure them according to actual needs.

[0040] In the embodiment, the grooves 213 may be strip-shaped, dashed-line-shaped, or dot-shaped. Production personnel can select the type of grooves 213 based on actual needs. The aforementioned grooves 213 facilitate rolling the outer layer 210, forming the first and second compacted areas 211, 212 with different compaction densities during rolling. It is understood that the grooves 213 may also have other shapes, such as polygonal, arc-shaped, or irregularly shaped grooves, and are not limited to the aforementioned embodiments.

[0041] Specifically, when the groove 213 is a strip groove or a dotted line groove, the extension direction of the groove 213 can be set along the length direction of the pole piece. At this time, if there are two or more grooves 213, different grooves 213 can be arranged at intervals along the width direction of the pole piece; the extension direction of the groove 213 can also be inclined relative to the length direction of the pole piece. At this time, if there are two or more grooves 213, different grooves 213 can be arranged at intervals along the width direction of the pole piece, or can be arranged at intervals along the length direction of the pole piece; the extension direction of the groove 213 can also be set along the width direction of the pole piece. At this time, if there are two or more grooves 213, different grooves 213 can be arranged at intervals along the length direction of the pole piece; the arrangement of the grooves 213 is not limited here.

[0042] Optionally, when the active material layer 200 has three or more rolled layers 210, the shapes of the grooves 213 located on different rolled layers 210 can be different. For example, the grooves 213 on some rolled layers 210 can be strip grooves, and the grooves 213 on some rolled layers 210 can be dotted grooves or dot grooves, etc.; or the grooves 213 on the same rolled layer 210 can also be of different shapes, for example, the same rolled layer 210 has strip grooves, dotted grooves and dot grooves, etc.

[0043] In an embodiment, in two adjacent rolled layers 210, the compaction density of the second compaction area 212 of the outer rolled layer 210 is less than the compaction density of the inner rolled layer 210, so that the second compaction area 212 can be looser than other areas of the active material layer 200, thereby forming a more efficient lithium ion channel.

[0044] Specifically, the density of the inner rolled layer 210 is usually the same as or similar to the density of the first compacted area 211 of the outer rolled layer 210. Therefore, the density of the second compacted area 212 of the outer rolled layer 210 is less than the density of the first compacted area 211 and the density of the inner rolled layer 210.

[0045] In an embodiment, the material of all rolled layers 210 is the same. This facilitates the simplification of the processing flow and material preparation requirements of the active material layer 200, and the electrode production process is relatively simple and efficient. Specifically, if the active material materials of different rolled layers 210 are different, then it is necessary to perform coating and rolling of different layers on different coating and rolling equipment to complete the production of the electrode. When preparing the materials, it is necessary to prepare the active materials of different materials separately, and it is usually impossible to directly mix the coating and rolling equipment. When the active material materials of all rolled layers 210 are the same, it is only necessary to prepare and make one active material, which simplifies the production process of the active material layer 200.

[0046] Specifically, the material of the active material layer 200 can be graphite, lithium ion-containing material, sodium ion-containing material, etc., depending on the type of electrode. The above-mentioned electrode structure is suitable for the production of positive electrode sheets or negative electrode sheets.

[0047] It is understood that when the active material layer 200 has three or more rolled layers 210, the second compacted areas 212 on different rolled layers 210 may be aligned, and in this case, the second compacted areas 212 on different rolled layers 210 are connected to each other. It is understood that when the active material layer 200 has three or more rolled layers 210, the second compacted areas 212 on different rolled layers 210 may be staggered.

[0048] In an embodiment, the active material layer 200 includes two stacked rolled layers 210, the thickness of the active material layer 200 is C, and the thickness of the inner rolled layer 210 is B, which satisfies 1 / 3C≤B≤3 / 4C, meets the normal two-layer coating and rolling production process requirements, and the quality of the finished electrode is relatively good. Correspondingly, the thickness of the outer rolled layer 210 is between 1 / 4C and 2 / 3C. It is understandable that when the active material layer 200 includes two stacked rolled layers 210, the thickness of the inner rolled layer 210 can be any value within the above-mentioned value range, such as B=1 / 2C, etc., and those skilled in the art can make specific configurations according to actual needs.

[0049] Specifically, the thickness of each rolled layer 210 should be between 10 microns and 150 microns, for example, 20 microns, 30 microns, 40 microns, 50 microns, 60 microns, 70 microns, 80 microns, 90 microns, 100 microns, 110 microns, 120 microns, 130 microns or 140 microns, etc., and those skilled in the art can make specific configurations according to actual needs.

[0050] The utility model also discloses a battery using the above-mentioned pole piece. Due to the use of the above-mentioned pole piece, the ion migration efficiency between the pole pieces inside the battery is accelerated, the battery's charging and discharging capabilities are improved, and the battery capacity is increased.

[0051] After the electrode is produced, it can be cut into a specified shape as needed to make a stacked battery or a wound battery.

[0052] Throughout this specification, reference to terms such as "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 that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the illustrative use of the above terms does not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0053] Although the embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and purpose of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A pole piece, characterized in that: include: current collector(100); An active material layer (200) is provided on at least one side of the current collector (100), wherein the active material layer (200) comprises at least two stacked rolled layers (210), wherein the outer rolled layer (210) of the two adjacent rolled layers (210) has a first compaction area (211) and a second compaction area (212), and the compaction density of the second compaction area (212) is less than the compaction density of the first compaction area (211).

2. The pole piece according to claim 1, characterized in that: In the two adjacent rolled layers (210), a groove (213) is provided on the outer side surface of the inner rolled layer (210) at a position corresponding to the second compaction area (212), and a convex end is provided on the inner side of the second compaction area (212) of the outer rolled layer (210), and the convex end is embedded in the groove (213).

3. The pole piece according to claim 2, characterized in that: The depth of the groove (213) is A, and the thickness of the rolled layer (210) where the groove (213) is located is B, satisfying 1 / 3B≤A≤1 / 2B.

4. The pole piece according to claim 2, characterized in that: The cross section of the groove (213) is conical, semicircular, rectangular or trapezoidal.

5. The pole piece according to claim 2, characterized in that: The outer side surface of the inner layer's rolled layer (210) is provided with at least two of the grooves (213) at intervals, and the outer layer's rolled layer (210) is provided with at least two of the second compacting areas (212) at intervals, and the grooves (213) and the second compacting areas (212) are provided in a one-to-one correspondence.

6. The pole piece according to claim 2, characterized in that: The groove (213) is a strip-shaped groove, a dotted-line groove, or a dot-shaped groove.

7. The pole piece according to claim 1 or 2, characterized in that: In two adjacent rolled layers (210), the compaction density of the second compacted area (212) of the outer rolled layer (210) is smaller than the compaction density of the inner rolled layer (210).

8. The pole piece according to claim 1, characterized in that: All the rolled layers (210) are made of the same material.

9. The pole piece according to claim 8, characterized in that: The active material layer (200) comprises two stacked rolled layers (210), the thickness of the active material layer (200) is C, the thickness of the inner rolled layer (210) is B, and 1 / 3C≤B≤3 / 4C is satisfied.

10. A battery, characterized in that: A pole piece comprising any one of claims 1 to 9.

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