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 of the inner layer is provided with a first compaction area and a second compaction area, and the compaction density of the first compaction area is larger than that of the second compaction area. The pole piece is manufactured by coating and rolling two or more layers, and in the inner rolling layer, the compaction density of the first compaction area is greater than that of the second compaction area, that is, the active substance in the second compaction area is relatively loose than the active substance in the first compaction area, so that more ion rapid channels can be formed in the second compaction area; therefore, the migration speed of ions in the inner-layer active material can be improved, and the charge-discharge performance of the battery is further 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] To meet battery life requirements, some existing high-capacity lithium batteries use a thicker active material layer on the electrode sheet by coating and rolling at least two layers of active material onto the current collector. This thickening of the active material layer increases the battery's capacity. As the active material layer on the electrode sheet thickens, the migration rate of lithium ions in the inner layer of active material near the current collector is affected, which in turn affects the battery's charge and discharge performance. 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 provides a pole piece that can increase the migration speed of ions in the inner layer active material and improve the charge and discharge performance of the battery.

[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 disposed 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 rolled layer of the inner layer is provided with a first compaction area and a second compaction area, and the compaction density of the first compaction area is greater than the compaction density of the second compaction area.

[0006] The pole piece according to the embodiment of the first aspect of the present invention has at least the following beneficial effects: the pole piece is made by double-layer or more coating roller pressing. Since the compaction density of the first compaction area in the inner rolling layer is greater than the compaction density of the second compaction area, that is, the active material in the second compaction area is relatively looser than the active material in the first compaction area, more ion fast channels can be formed in the second compaction area, thereby increasing the migration speed of ions in the inner layer active material, thereby improving the charge and discharge performance of the battery.

[0007] According to some embodiments of the present invention, the compaction density of the first compaction area is A, the compaction density of the second compaction area is B, and 1.001≤A / B≤4 is satisfied.

[0008] According to some embodiments of the present invention, in two adjacent rolled layers, a pressing groove is provided on the outer side surface of the rolled layer of the inner layer corresponding to the first compaction zone, and a protrusion is provided on the inner side of the rolled layer of the outer layer, and the protrusion is accommodated in the pressing groove.

[0009] According to some embodiments of the present invention, in two adjacent rolled layers, the thickness of the outer rolled layer is C, and the depth of the pressed groove on the inner rolled layer is D, satisfying C≥D.

[0010] According to some embodiments of the present invention, the press-in groove is a strip-shaped groove, and the width of the press-in groove is E, which satisfies 0.5 μm≤E≤300 μm.

[0011] According to some embodiments of the present invention, the press-in groove is a dot-shaped groove, and the area of the press-in groove is F, which satisfies 0.5mm2≤F≤25mm 2 .

[0012] According to some embodiments of the present invention, in two adjacent rolled layers, the rolled layer of the outer layer includes a main sheet portion and the raised portion, the compaction density of the raised portion of the rolled layer of the outer layer is the same as the compaction density of the first compaction zone of the rolled layer of the inner layer, and the main sheet portion of the rolled layer of the outer layer is the same as the compaction density of the second compaction zone of the rolled layer of the inner layer.

[0013] According to some embodiments of the present invention, in two adjacent rolled layers, the rolled layer of the inner layer is provided with at least two first compacting areas arranged at intervals, and the rolled layer of the inner layer is provided with at least two press-in grooves arranged at intervals, and the first compacting areas correspond one to one to the press-in grooves.

[0014] According to some embodiments of the present invention, the overall thickness of the pole piece is consistent along the length direction.

[0015] The battery according to the embodiment of the second aspect of the present invention adopts the above-mentioned pole piece.

[0016] The battery according to the embodiment of the second aspect of the present utility model has at least the following beneficial effects: due to the use of the above-mentioned electrode sheet, the charge and discharge performance of the battery can be improved.

[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 A schematic cross-sectional view of an exploded view of a pole piece according to an embodiment of the present invention;

[0021] Figure 3 Schematic diagram of the current collector and inner rolled layer in some embodiments of the present invention;

[0022] Figure 4 Schematic diagrams of current collectors and inner rolled layers in other embodiments of the present invention;

[0023] Figure 5 Schematic diagrams of current collectors and inner rolled layers of other embodiments of the present invention.

[0024] Reference numerals:

[0025] Current collector 100;

[0026] Active material layer 200 , rolled layer 210 , first compacted area 211 , second compacted area 212 , pressed groove 213 , raised portion 214 , main sheet portion 215 . DETAILED DESCRIPTION

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] To improve fast-charging capabilities, some existing batteries use laser processing to create grooves on the outer surface of the active material layer of the electrode. These grooves form fast ion pathways. However, laser processing is prone to generating dust, which easily remains on the surface of the electrode. This can lead to a risk of rapid self-discharge, which can affect normal battery operation.

[0032] Reference Figures 1 to 5 , 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 and comprises two stacked roll-pressed layers 210. Of the two adjacent roll-pressed layers 210, the inner roll-pressed layer 210 is provided with a first compaction region 211 and a second compaction region 212. The compaction density of the first compaction region 211 is greater than the compaction density of the second compaction region 212.

[0033] The pole piece is made by double-layer or more coating roller pressing. Since the compaction density of the first compaction area 211 in the inner rolling layer 210 is greater than the compaction density of the second compaction area 212, that is, the active material in the second compaction area 212 is relatively loose than the active material in the first compaction area 211, more ion fast channels can be formed in the second compaction area 212, thereby increasing the migration speed of ions in the inner layer active material, thereby improving the charge and discharge performance of the battery.

[0034] Specifically, in this embodiment, active material layers 200 are provided on both sides of the electrode, which improves the performance of the electrode. It is understandable that in other embodiments, the active material layer 200 can also be provided on one side of the electrode.

[0035] Specifically, the active material layer 200 in this embodiment includes two stacked rolled layers 210, which can meet conventional battery usage requirements and has a relatively simple production process. It is understood that in other embodiments, the active material layer 200 of the electrode sheet may also include three, four, or more stacked rolled layers 210. The number of rolled layers 210 can be specifically selected based on the actual needs of those skilled in the art.

[0036] Specifically, of two adjacent rolled layers 210 , the inner rolled layer 210 is the rolled layer 210 relatively close to the current collector 100 , and the outer rolled layer 210 is the rolled layer 210 relatively far from the current collector 100 .

[0037] In the embodiment, the compaction density of the first compaction area 211 is A, and the compaction density of the second compaction area 212 is B, satisfying 1.001≤A / B≤4. The above-described first compaction area 211 and second compaction area 212 ensure that the second compaction area 212 is relatively loose, thereby forming more ion fast channels. The density of the first compaction area 211 is not too dense to affect the ion migration speed, and the total amount of active material in the first compaction area 211 and the second compaction area 212 is kept at a high level, thereby enabling the manufactured battery to have a higher capacity.

[0038] Specifically, the ratio of the compaction density of the first compaction area 211 to the compaction density of the second compaction area 212, that is, the ratio A / B can be arbitrarily selected within the above range. For example, the ratio A / B is 1.5, 2, 2.5, 3, 3.5, etc. Those skilled in the art can make a reasonable selection based on the type of active substance in the rolled layer 210.

[0039] In the embodiment, in two adjacent rolled layers 210 , a pressing groove 213 is provided on the outer side surface of the inner rolled layer 210 corresponding to the first compaction zone 211 , and a protrusion 214 is provided on the inner side of the outer rolled layer 210 , and the protrusion 214 is accommodated in the pressing groove 213 . During the electrode production process, the active material is first coated on the surface of the current collector 100 and rolled for the first time to form an inner rolled layer 210. The roller of the first rolling is protruded with a pressing block with a shape corresponding to the pressing groove 213. When the roller presses the active material, the pressing groove 213 is formed by the pressing block on the roller, thereby directly forming the corresponding first compaction area 211, and the other positions of the roller directly form the second compaction area 212; then the outer side surface of the inner rolled layer 210 is completely coated with active material, and rolled for the second time to form the outer rolled layer 210. The outer rolled layer 210 automatically forms a protrusion 214 filling the pressing groove 213 during rolling.

[0040] It can be understood that, as the depth of the pressed groove 213 increases, the compaction density of the first compacted area 211 should also increase accordingly.

[0041] In the embodiment, of the two adjacent rolled layers 210, the thickness of the outer rolled layer 210 is C, and the depth of the indentation 213 on the inner rolled layer 210 is D, satisfying C≥D. The outer rolled layer 210 needs to completely fill the indentation 213 on the inner rolled layer 210 to facilitate the consistency of the final overall thickness of the electrode. When the thickness of the outer rolled layer 210 is consistent with the depth of the indentation 213 of the inner rolled layer 210, the outer rolled layer 210 is completely filled in the indentation 213; when the thickness of the outer rolled layer 210 is greater than the depth of the indentation 213 of the inner rolled layer 210, the outer rolled layer 210 completely covers the inner rolled layer 210.

[0042] In some embodiments, the press-in groove 213 is a strip-shaped groove, and the width of the press-in groove 213 is E, satisfying 0.5μm≤E≤300μm. If the width of the press-in groove 213 is less than 0.5μm, the production process is likely to be more difficult, and the width of the second compaction area 212 is too large. Since the compaction density of the second compaction area 212 is less than the compaction density of the first compaction area 211, the total amount of active material in the electrode is low, affecting the battery capacity. If the width of the press-in groove 213 is greater than 300μm, the width of the first compaction area 211 is likely to be too large, affecting the difficulty of ion migration. When the press-in groove 213 is in the shape of a strip groove, the width of the press-in groove 213 is between 0.5μm and 300μm, which can prevent the width of the first compaction area 211 from being too large to affect the difficulty of ion migration, and allow the width of the second compaction area 212 to be larger and have more ion fast channels, thereby accelerating the ion migration speed in the active material in the inner layer. Specifically, the width of the pressed groove 213 can also be selected as 0.5μm, 1μm, 10μm, 50μm, 100μm, 150μm, 200μm, 250μm or 300μm, etc., or other values within the above range, which can be reasonably selected according to actual needs during production.

[0043] Specifically, when the press-in groove 213 is a strip-shaped groove, the cross section of the press-in groove 213 may be rectangular, trapezoidal, semicircular, triangular, or other shapes.

[0044] It is understandable that when the press-in groove 213 is a strip groove, the press-in groove 213 can be extended along the width direction of the pole piece, or can be extended along the length direction of the pole piece, or can be inclined relative to the width direction of the pole piece.

[0045] In some embodiments, the press-in groove 213 is a dot-shaped groove, and the area of the press-in groove 213 is F, which satisfies 0.5 mm ≤ F ≤ 25 mm. 2 If the area of the press groove 213 is less than 0.5mm 2 , which makes the production process more difficult, and the area of the second compaction area 212 is too large. Since the compaction density of the second compaction area 212 is less than the compaction density of the first compaction area 211, the total amount of active material in the electrode is low, affecting the battery capacity. If the area of the press-in groove 213 is larger than 25mm 2 , it is easy to make the area of the first compaction zone 211 too large and affect the difficulty of ion migration. 2 Up to 25mm 2When the width of the first compression zone 211 is not too large to affect the difficulty of ion migration, and the width of the second compression zone 212 can be larger to have more ion fast channels, thereby making the ion migration speed in the active material in the inner layer faster. Specifically, the area of a single compression groove 213 can be selected to be 0.5mm 2 , 1mm 2 , 5mm 2 , 10mm 2 , 15mm 2 , 20mm 2 or 25mm 2 Or other values within the above range can be selected, which can be reasonably selected according to actual needs during production.

[0046] Specifically, when the press-in groove 213 is a dot-shaped groove, the press-in groove 213 may be a cylindrical hole groove or a polygonal cylindrical hole groove, or may be in other shapes.

[0047] In some embodiments, of two adjacent rolled layers 210, the outer rolled layer 210 includes a main sheet portion 215 and a raised portion 214. The raised portion 214 of the outer rolled layer 210 has the same compaction density as the first compaction region 211 of the inner rolled layer 210, and the main sheet portion 215 of the outer rolled layer 210 has the same compaction density as the second compaction region 212 of the inner rolled layer 210. This compaction density distribution of the outer rolled layer 210 allows the outer rolled layer 210 to form a plurality of ion fast channels, thereby increasing the ion migration rate of the active material layer 200 within the outer active material layer.

[0048] Specifically, in other embodiments, the compaction density of the outer rolled layer 210 may also be higher than the compaction density of the first compaction zone 211 of the inner rolled layer 210, or the compaction density of the outer rolled layer 210 may also be between the compaction density of the first compaction zone 211 and the compaction density of the second compaction zone 212 of the inner rolled layer 210, or the compaction density of the outer rolled layer 210 may also be lower than the compaction density of the second compaction zone 212 of the inner rolled layer 210, which is not limited here.

[0049] In the embodiment, of two adjacent rolled layers 210, the inner rolled layer 210 is provided with a plurality of spaced first compaction areas 211, and the inner rolled layer 210 is provided with a plurality of spaced indentation grooves 213, with the first compaction areas 211 corresponding one to the indentation grooves 213. The first compaction areas 211 and the corresponding indentation grooves 213 are spaced apart on the electrode sheet, so that the second compaction areas 212 are also relatively evenly distributed on the electrode sheet, thereby increasing the ion migration speed at various locations on the electrode sheet and improving the charge and discharge performance of the battery.

[0050] It is conceivable that the number of the first compression areas 211 can be set to two, three or more, and the number of the corresponding pressing grooves 213 can also be set to two, three or more.

[0051] Specifically, when the press-in groove 213 is a strip groove, the second compacting area 212 is between two adjacent press-in grooves 213. At this time, the second compacting area 212 can be one, two, three or more; when the press-in groove 213 is a strip groove and extends along the width direction of the pole piece, different press-in grooves 213 are arranged at intervals along the length direction of the pole piece, that is, the first compacting area 211 and the second compacting area 212 of the inner layer of the rolled layer 210 are alternately arranged along the length direction of the pole piece; when the press-in groove 213 is a strip groove and extends along the length direction of the pole piece, the second compacting area 212 is arranged alternately along the length direction of the pole piece; When the pressing grooves 213 extend in the direction of the pole piece, different pressing grooves 213 are arranged at intervals along the width direction of the pole piece, that is, the first pressing area 211 and the second pressing area 212 of the inner rolled layer 210 are arranged alternately along the width direction of the pole piece; when the pressing grooves 213 are strip grooves and are inclined relative to the width direction of the pole piece, different pressing grooves 213 can be arranged at intervals along the length or width direction of the pole piece, that is, the first pressing area 211 and the second pressing area 212 of the inner rolled layer 210 can be arranged alternately along the length or width direction of the pole piece.

[0052] Specifically, when the pressing grooves 213 are dot-shaped grooves, the pressing grooves 213 may be arranged in an array at intervals on the pole piece. In this case, the first compacting area 211 is an integral, mesh-like structure.

[0053] In the embodiment, the overall thickness of the electrode is consistent along the length direction, which makes it convenient to use the electrode to manufacture batteries, and the production process is relatively mature.

[0054] It is understandable that the active materials of different rolled layers 210 of the active material layer 200 may be made of the same material or different materials.

[0055] Specifically, the above structure can be applied to both positive and negative electrode sheets.

[0056] The utility model also includes a battery that uses the above-mentioned pole piece. Due to the use of the above-mentioned pole piece, the charging and discharging performance of the battery can be improved.

[0057] 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.

[0058] 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 inner rolled layer (210) of the two adjacent rolled layers (210) is provided with a first compaction area (211) and a second compaction area (212), wherein the compaction density of the first compaction area (211) is greater than the compaction density of the second compaction area (212).

2. The pole piece according to claim 1, characterized in that: The compaction density of the first compaction area (211) is A, and the compaction density of the second compaction area (212) is B, satisfying 1.001≤A / B≤4.

3. The pole piece according to claim 1, characterized in that: In two adjacent rolled layers (210), a pressing groove (213) is provided on the outer side surface of the inner rolled layer (210) at a position corresponding to the first compacting area (211), and a protrusion (214) is provided on the inner side of the outer rolled layer (210), and the protrusion (214) is accommodated in the pressing groove (213).

4. The pole piece according to claim 3, characterized in that: In two adjacent rolled layers (210), the thickness of the outer rolled layer (210) is C, and the depth of the pressed groove (213) on the inner rolled layer (210) is D, satisfying C≥D.

5. The pole piece according to claim 3, characterized in that: The press-in groove (213) is a strip-shaped groove, and the width of the press-in groove (213) is E, satisfying 0.5 μm≤E≤300 μm.

6. The pole piece according to claim 3, characterized in that: The press-in groove (213) is a dot-shaped groove, and the area of the press-in groove (213) is F, satisfying 0.5 mm2≤F≤25 mm 2 .

7. The pole piece according to claim 3, characterized in that: In two adjacent rolled layers (210), the rolled layer (210) of the outer layer includes a main sheet portion (215) and the raised portion (214), the compaction density of the raised portion (214) of the rolled layer (210) of the outer layer is the same as the compaction density of the first compaction area (211) of the rolled layer (210) of the inner layer, and the main sheet portion (215) of the rolled layer (210) of the outer layer is the same as the compaction density of the second compaction area (212) of the rolled layer (210) of the inner layer.

8. The pole piece according to claim 3, characterized in that: In two adjacent rolled layers (210), the inner rolled layer (210) is provided with at least two first compacting areas (211) arranged at intervals, and the inner rolled layer (210) is provided with at least two press-in grooves (213) arranged at intervals, and the first compacting areas (211) correspond to the press-in grooves (213) one by one.

9. The pole piece according to claim 3, characterized in that: The overall thickness of the pole piece is consistent along the length direction.

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

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