Electrode sheet assembly and battery

Abstract

Disclosed in the present application is an electrode sheet assembly, comprising a cathode sheet, an anode sheet and a protective sheet, wherein the anode sheet is arranged opposite the cathode sheet; the direction of length of the anode sheet is the same as the direction of length of the cathode sheet; the width of the anode sheet is not smaller than the width of the cathode sheet; the anode sheet is provided with a rectangular empty foil area, and a first long edge of the empty foil area located on the anode sheet coincides with a long edge of the anode sheet, and / or the cathode sheet is provided with a rectangular empty foil area, and a first long edge of the empty foil area located on the cathode sheet coincides with a long edge of the cathode sheet; the protective sheet is located between the cathode sheet and the anode sheet and is opposite the empty foil area; the protective sheet is rectangular; a first long edge of the protective sheet coincides with the long edge of the cathode sheet; and two wide edges of the protective sheet and a second long edge of the protective sheet are all located outside of the projection of the empty foil area on the cathode sheet. When the electrode sheet assembly is applied to a battery, the energy density of the battery can be improved. Further disclosed in the present application is a battery using the electrode sheet assembly.

Description

Pole piece assembly and battery Technical Field

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

[0002] During the battery production process, the tabs need to be connected to the electrode sheets. Taking the connection of the tabs to the anode sheet as an example, a rectangular hollow foil area is processed on the anode sheet through laser cleaning or other methods. One of the wide sides of the hollow foil area coincides with the long side of the anode sheet. Subsequently, a portion of the straight tab is welded to the hollow foil area. A rectangular protective sheet is placed in the area opposite the hollow foil area on the cathode sheet. The size of the protective sheet is larger than the projection of the hollow foil area on the cathode sheet, and one of the wide sides of the protective sheet coincides with the long side of the cathode sheet. The remaining edges of the protective sheet extend beyond the scope of the hollow foil area. However, after the protective sheet is placed on the cathode sheet, the cathode active material layer in the area covered by the protective sheet cannot function. The above-mentioned arrangement of the hollow foil area and the protective sheet significantly affects the energy density of the battery.

[0003] Summary of the Invention

[0004] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a pole piece assembly that can reduce the area of ​​the cathode piece covered by the protective sheet, thereby improving the energy density of the battery.

[0005] The present application also proposes a battery having the above-mentioned pole piece assembly.

[0006] According to the first embodiment of the present application, the electrode assembly includes a cathode sheet, an anode sheet, and a protective sheet. The anode sheet is arranged opposite to the cathode sheet, the length direction of the anode sheet is the same as the length direction of the cathode sheet, and the width of the anode sheet is not less than the width of the cathode sheet; the anode sheet is provided with a rectangular empty foil area, the first long side of the empty foil area located on the anode sheet coincides with the long side of the anode sheet, and / or the cathode sheet is provided with a rectangular empty foil area, the first long side of the empty foil area located on the cathode sheet coincides with the long side of the cathode sheet; the protective sheet is located between the cathode sheet and the anode sheet and opposite to the empty foil area, the protective sheet is rectangular, the first long side of the protective sheet coincides with the long side of the cathode sheet, and both wide sides of the protective sheet and the second long side of the protective sheet are located outside the projection of the empty foil area on the cathode sheet.

[0007] According to the electrode assembly of the embodiment of the first aspect of the present application, there are at least the following beneficial effects: the first long side of the empty foil area is overlapped with the long side of the anode sheet or the cathode sheet, the first long side of the protective sheet is overlapped with the long side of the cathode sheet, and the two wide sides and the second long side of the protective sheet are both located outside the projection range of the empty foil area. Compared with the existing method, the part where the long side of the protective sheet overlaps with the long side of the cathode sheet is changed from one of the wide sides of the protective sheet to the first long side, which can reduce the area of ​​the cathode active material layer of the cathode sheet covered by the protective sheet, so that the cathode sheet has more cathode active material layers that can function. When the above-mentioned electrode assembly is applied to a battery, the energy density of the battery can be improved.

[0008] According to some embodiments of the present application, the distances between the two wide sides of the protection sheet and the second long side of the protection sheet and the projection of the empty foil area on the cathode sheet are the same.

[0009] According to some embodiments of the present application, the protective sheet is connected to the cathode sheet.

[0010] According to some embodiments of the present application, the width of the anode sheet is greater than the width of the cathode sheet.

[0011] According to some embodiments of the present application, a tab is further included, wherein the tab is provided with a rectangular horizontal bar portion, the horizontal bar portion is connected to the empty foil area, and the length direction of the horizontal bar portion is the same as the length direction of the empty foil area.

[0012] According to some embodiments of the present application, the length of the empty foil area is greater than the length of the horizontal strip portion, and the width of the empty foil area is greater than the width of the horizontal strip portion.

[0013] According to some embodiments of the present application, the tab is provided with a rectangular vertical bar portion, the length direction of the vertical bar portion is the same as the width direction of the horizontal bar portion, and one end of the vertical bar portion is connected to the horizontal bar portion.

[0014] According to some embodiments of the present application, the vertical strip portion is provided with tab glue, and the tab glue is located outside the empty foil area.

[0015] According to some embodiments of the present application, the cathode sheet is provided with the empty foil area, and the cathode sheet is provided with a cathode active material layer in the area outside the empty foil area; the anode sheet is provided with the empty foil area, and the anode sheet is provided with an anode active material layer in the area outside the empty foil area.

[0016] According to some embodiments of the present application, the width dimension of the empty foil area is A, and the length dimension of the empty foil area is B, satisfying: 1.1A≤B≤5.5A.

[0017] According to some embodiments of the present application, the thickness of the vertical bar portion is E, and the thickness of the horizontal bar portion is F, satisfying: 0.4E≤F≤E.

[0018] According to some embodiments of the present application, the tab is further provided with a protrusion, the protrusion and the vertical bar portion are placed on opposite sides of the horizontal bar portion, one end of the protrusion is connected to the horizontal bar portion, and the distance between the other end of the protrusion and the horizontal bar portion is G, satisfying G≤4mm.

[0019] The battery according to the embodiment of the second aspect of the present application includes the above-mentioned pole piece assembly.

[0020] The battery according to the embodiment of the second aspect of the present application has at least the following beneficial effects: due to the use of the above-mentioned pole piece assembly, the cathode piece has more cathode active material layers that can function, thereby improving the energy density of the battery.

[0021] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0023] FIG1 is a schematic diagram of a pole piece assembly in the prior art when an empty foil area is provided on the anode piece;

[0024] FIG2 is a schematic diagram of a pole piece assembly according to an embodiment of the present application when a hollow foil area is provided on the anode piece;

[0025] FIG3 is a schematic diagram of a prior art electrode assembly in which an empty foil area is provided on the cathode plate;

[0026] FIG4 is a schematic diagram of a pole piece assembly according to an embodiment of the present application when a hollow foil area is provided on the cathode piece;

[0027] FIG5 is a schematic diagram of a first embodiment of a pole ear of a pole piece assembly according to an embodiment of the present application;

[0028] FIG6 is a schematic diagram of a second embodiment of a pole ear of a pole piece assembly according to an embodiment of the present application;

[0029] FIG7 is a schematic diagram of a third embodiment of a pole ear of a pole piece assembly according to an embodiment of the present application;

[0030] FIG8 is a schematic diagram of a pole piece assembly according to an embodiment of the present application in which the pole tab has a protruding portion.

[0031] Reference numerals:

[0032] cathode sheet 100;

[0033] Anode sheet 200;

[0034] Empty foil area 300;

[0035] Protective sheet 400;

[0036] Tab 500, horizontal bar portion 510, vertical bar portion 520, protruding portion 530;

[0037] Tab glue 600. DETAILED DESCRIPTION

[0038] The following describes in detail embodiments of the present application. 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 application and are not to be construed as limiting the present application.

[0039] In the description of this application, 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 this application 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 this application.

[0040] In the description of this application, "a plurality" refers to 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.

[0041] In the description of this application, 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 this application based on the specific content of the technical solution.

[0042] Improving the energy density of lithium batteries has always been a key area of ​​research. Adjusting the material system often results in performance changes or even deterioration. However, improving energy density through structural adjustments to the battery structure, while preserving the chemical system, is less likely to cause performance changes or deterioration.

[0043] During the battery production process, the tab 500 needs to be connected to the electrode sheet. Taking the connection of the tab 500 to the anode sheet 200 as an example, a rectangular hollow foil area 300 is processed on the anode sheet 200 through laser cleaning or other methods. One of the wide sides of the hollow foil area 300 coincides with the long side of the anode sheet 200. Subsequently, a portion of the straight tab 500 is welded to the hollow foil area 300. A rectangular protective sheet 400 is placed on the cathode sheet 100 in the area opposite the hollow foil area 300. The protective sheet 400 is larger than the projection of the hollow foil area 300 on the cathode sheet 100, and one of the wide sides of the protective sheet 400 coincides with the long side of the cathode sheet 100. The remaining edges of the protective sheet 400 extend beyond the scope of the hollow foil area 300. However, after the protective sheet 400 is placed on the cathode sheet 100, the cathode active material layer in the area covered by the protective sheet 400 cannot function. The above arrangement of the hollow foil area 300 and the protective sheet 400 significantly affects the energy density of the battery.

[0044] 1 to 7 , a pole piece assembly according to an embodiment of the present application is shown, including a cathode piece 100 , an anode piece 200 and a protective piece 400 . The anode sheet 200 is arranged opposite to the cathode sheet 100, the length direction of the anode sheet 200 is the same as the length direction of the cathode sheet 100, and the width of the anode sheet 200 is not less than the width of the cathode sheet 100; the anode sheet 200 is provided with a rectangular empty foil area 300, and the first long side of the empty foil area 300 located in the anode sheet 200 coincides with the long side of the anode sheet 200, or the cathode sheet 100 is provided with a rectangular empty foil area 300, and the first long side of the empty foil area 300 located in the cathode sheet 100 coincides with the long side of the cathode sheet 100; the protective sheet 400 is located between the cathode sheet 100 and the anode sheet 200 and opposite to the empty foil area 300, the protective sheet 400 is rectangular, the first long side of the protective sheet 400 coincides with the long side of the cathode sheet 100, and the two wide sides of the protective sheet 400 and the second long side of the protective sheet 400 are all located outside the projection of the empty foil area 300 on the cathode sheet 100.

[0045] The first long side of the empty foil area 300 is overlapped with the long side of the anode sheet 200 or the cathode sheet 100, and the first long side of the protective sheet 400 is overlapped with the long side of the cathode sheet 100. The two wide sides and the second long side of the protective sheet 400 are both located outside the projection range of the empty foil area 300. Compared with the existing method, the part where the protective sheet 400 overlaps with the long side of the cathode sheet 100 is changed from one of the wide sides of the protective sheet 400 to the first long side, which can reduce the area of ​​the cathode active material layer of the cathode sheet 100 covered by the protective sheet 400, so that the cathode sheet 100 has more functional cathode active material layer. When the above-mentioned electrode assembly is used in a battery, the energy density of the battery can be improved.

[0046] Specifically, both the cathode sheet 100 and the anode sheet 200 may be provided with the above-mentioned empty foil area 300 to further improve the energy density of the battery when the above-mentioned electrode assembly is used in the battery.

[0047] Specifically, the empty foil area 300 is positioned near the long side of the cathode sheet 100 or the anode sheet 200. The first long side of the empty foil area 300 is closer to the long side of the cathode sheet 100 or the anode sheet 200 than the second long side. The first long side and the second long side of the empty foil area 300 are the same length. Specifically, the first long side of the protective sheet 400 is closer to the projection of the empty foil area 300 than the second long side of the protective sheet 400. The first long side and the second long side of the protective sheet 400 are the same length. The projection of the protective sheet 400 on the cathode sheet 100 does not extend beyond the cathode sheet 100.

[0048] In an embodiment, the two wide sides of the protective sheet 400 and the second long side of the protective sheet 400 are at the same distance from the projection of the empty foil area 300 on the cathode sheet 100. In order to completely block the influence of the empty foil area 300 on the adjacent cathode sheet 100 or the anode sheet 200, the protective sheet 400 is usually made to extend beyond a certain range of the empty foil area 300. With the above structure, the protective sheet 400 can be calculated and processed according to the size of the empty foil area 300, which is relatively convenient to process, has a good protection effect on the empty foil area 300, and improves safety performance. The first long side of the protective sheet 400 coincides with the long side of the cathode sheet 100 and the long side of the projection of the empty foil area 300 on the cathode sheet 100, and the second long side is located outside the projection range of the empty foil area 300.

[0049] In the embodiment, the protective sheet 400 is connected to the cathode sheet 100, which facilitates processing and saves material for the protective sheet 400. It is conceivable that in some cases, the protective sheet 400 can also be connected to the anode sheet 200, and can cover the cathode sheet 100.

[0050] Specifically, the protective sheet 400 is an insulating adhesive tape, which is attached to and covers the cathode sheet 100. It is conceivable that the protective sheet 400 can also be other insulating sheets, which are connected to and cover the cathode sheet 100 by gluing or other methods.

[0051] When the cathode sheet 100 is covered by the protective sheet 400 , the cathode active material layer in the covered area cannot function, thereby affecting the battery energy density.

[0052] In an embodiment, the width of the anode sheet 200 is greater than the width of the cathode sheet 100 , thereby improving safety. It is conceivable that the width of the anode sheet 200 can also be the same as the width of the cathode sheet 100 .

[0053] In an embodiment, a tab 500 is further included, and the tab 500 is provided with a rectangular horizontal bar portion 510, which is connected to the empty foil area 300, and the length direction of the horizontal bar portion 510 is the same as the length direction of the empty foil area 300. Compared with the previous tab 500, the horizontal bar portion 510 is provided so that the tab 500 can maintain the same contact area as before to connect with the empty foil area 300, and the connection strength is the same. Specifically, the tab 500 is welded to the empty foil area 300 by welding. The previous tab 500 is in the shape of a straight bar, and a part of it is welded to the empty foil area 300. After the horizontal bar portion 510 is provided, since the empty foil areas 300 of the two are the same size, the corresponding tab 500 should also be provided with a horizontal bar portion 510 to adapt to the shape of the empty foil area 300 to maintain the connection strength between the two.

[0054] In the embodiment, the length of the empty foil area 300 is greater than the length of the horizontal strip portion 510, and the width of the empty foil area 300 is greater than the width of the horizontal strip portion 510. The size of the horizontal strip portion 510 is smaller than the size of the empty foil area 300, so that the horizontal strip portion 510 of the tab 500 can be completely attached to the empty foil area 300.

[0055] In an embodiment, the tab 500 is provided with a rectangular vertical bar portion 520 , the length direction of the vertical bar portion 520 is the same as the width direction of the horizontal bar portion 510 , one end of the vertical bar portion 520 is connected to the horizontal bar portion 510 , and the vertical bar portion 520 is provided to facilitate the output of current through the vertical bar portion 520 of the tab 500 .

[0056] In the embodiment, the vertical strip portion 520 is provided with a tab glue 600, and the tab glue 600 is located outside the empty foil area 300. The provision of the tab glue 600 can reduce the risk of leakage of the soft-pack battery during use.

[0057] In an embodiment, the cathode sheet 100 is provided with an empty foil area 300, and the cathode sheet 100 is provided with a cathode active material layer in an area outside the empty foil area 300; the anode sheet 200 is provided with an empty foil area 300, and the anode sheet 200 is provided with an anode active material layer in an area outside the empty foil area 300. The above-mentioned cathode sheet 100 and anode sheet 200 are both provided with an empty foil area 300, which further improves the energy density of the battery when the above-mentioned electrode assembly is used in a battery. Specifically, the empty foil area 300 on the cathode sheet 100 can be formed by removing the cathode active material layer on the cathode sheet 100 through laser cleaning, or it can be directly formed during the process of coating the cathode active material layer on the cathode current collector. Similarly, the empty foil area 300 on the anode sheet 200 can be formed by removing the anode active material layer on the anode sheet 200 through laser cleaning, or it can be directly formed during the process of coating the anode active material layer on the anode current collector.

[0058] The following example illustrates how the above method reduces the impact on energy density. While maintaining the existing welding strength and current capacity, the size of the empty foil area 300 remains the same. The rectangular empty foil area 300 has a width dimension A and a length dimension B, with B>A. One edge of the protective sheet 400 overlaps with the edge of the cathode sheet 100, and the remaining edge of the protective sheet 400 extends beyond the empty foil area 300 by a dimension C. When the width of the anode sheet 200 is not less than the width of the cathode sheet 100, the long side of the anode sheet 200 extends beyond the long side of the cathode sheet 100 by a dimension D.

[0059] Regarding the case where the empty foil area 300 is provided on the anode sheet 200:

[0060] In the prior art, one wide side of the hollow foil area 300 coincides with the long side of the anode sheet 200. At this time, the hollow foil area 300 has a projection on the cathode sheet 100. Therefore, the area of ​​the protective sheet 400 connected to the cathode sheet 100 opposite to the hollow foil area 300 is: S1 = (B-D+C)*(A+2C).

[0061] After the improvement, one long side of the empty foil area 300 coincides with the long side of the anode sheet 200. At this time, the empty foil area 300 has a projection on the cathode sheet 100. Therefore, the area of ​​the protective sheet 400 connected to the cathode sheet 100 opposite to the empty foil area 300 is: S2 = (B + 2C) * (A-D + C).

[0062] S1-S2=(B-D+C)*(A+2C)-(B+2C)*(A-D+C)=(BA)*(C+D), since B>A, BA>0; since C+D must be>0, S1-S2>0, that is, S1>S2. Therefore, after the implementation of this technical solution, the area of ​​the cathode sheet 100 blocked by the protective sheet 400 can be reduced, and the influence of the protective sheet 400 on the energy density of the electrode assembly can be reduced, that is, the energy density of the electrode assembly and the battery can be improved.

[0063] For the case where the empty foil area 300 is provided on the cathode sheet 100:

[0064] In the prior art, one wide side of the hollow foil area 300 coincides with the long side of the cathode sheet 100. At this time, the projection of the hollow foil area 300 on the cathode sheet 100 is the hollow foil area 300 itself. Therefore, the area of ​​the protective sheet 400 connected to the cathode sheet 100 opposite to the hollow foil area 300 is: S3 = (B + C) * (A + 2C).

[0065] After the improvement, one long side of the empty foil area 300 coincides with the long side of the cathode sheet 100. At this time, the empty foil area 300 is projected on the cathode sheet 100 as the empty foil area 300 itself. Therefore, the area of ​​the protective sheet 400 connected to the cathode sheet 100 opposite to the empty foil area 300 is: S4 = (B + 2C) * (A + C).

[0066] S3-S4=(B+C)*(A+2C)-(B+2C)*(A+C)=(BA)*C. Since B>A, BA>0.

[0067] Since C must be greater than 0, S3-S4>0, that is, S3>S4, the implementation of this technical solution can reduce the area of ​​the cathode sheet 100 blocked by the protective sheet 400, reduce the impact of the protective sheet 400 on the energy density of the electrode assembly, and thus improve the energy density of the electrode assembly and the battery.

[0068] In the embodiment, the width dimension of the empty foil area 300 is A, and the length dimension of the empty foil area 300 is B, satisfying the following: 1.1A≤B≤5.5A. When the above-mentioned empty foil area 300 is disposed on the cathode sheet 100 or the anode sheet 200, it is within the above-mentioned size range, which effectively improves the battery energy density. It is understood that the length dimension B of the empty foil area 300 can be, for example, 2A, 3A, 4A, or 5A, or other values ​​within the range. Those skilled in the art can configure the empty foil area 300 according to actual needs.

[0069] In the embodiment, the thickness of the vertical strip 520 is E, and the thickness of the horizontal strip 510 is F, satisfying the following relationship: 0.4E≤F≤E. Since the horizontal strip 510 is stacked and connected to the empty foil area 300 of the electrode, when the thickness of the horizontal strip 510 is relatively small, the problem of excessive thickness after the horizontal strip 510 and the electrode are stacked can be avoided, thereby reducing the thickness occupation of the electrode assembly and the battery, which is beneficial to improving the energy density of the electrode assembly and the battery; while the vertical strip 520 maintains a relatively thick size, so that the vertical strip 520 can maintain sufficient current flow capacity.

[0070] 8 , in some embodiments, the tab 500 is further provided with a protrusion 530. The protrusion 530 and the vertical bar portion 520 are respectively placed on opposite sides of the horizontal bar portion 510. One end of the protrusion 530 is connected to the horizontal bar portion 510, and the distance between the other end of the protrusion 530 and the horizontal bar portion 510 is G, satisfying G≤4mm. Due to the existence of tolerances in the production process, the tab 500 will have the above-mentioned protrusion 530. If the protruding dimension G of the protrusion 530 is too large, it will occupy too much space in the empty foil area 300. Therefore, in actual use, it is necessary to limit the protruding dimension G of the protrusion 530 to 4mm, which can make the use effect of the tab 500 better. It is understandable that the distance G between the other end of the protrusion 530 and the horizontal bar portion 510 can be, for example, 1mm, 2mm or 3mm, or other values ​​within the range. Those skilled in the art can make specific configurations according to actual needs. It should be understood that, during the production process of the tab 500 , the protrusion 530 may not exist, and in this case G=0 mm.

[0071] Specifically, the edge of the tab 500 may be a right angle or a rounded angle, preferably a rounded angle.

[0072] Furthermore, the layout of the vertical strips 520 and the horizontal strips 510 allows the tabs 500 to be T-shaped or L-shaped, or any other arrangement, to facilitate current flow. Preferably, the tabs 500 are T-shaped for better current flow.

[0073] This technical solution rotates and reverses the empty foil area 300 relative to the conventional solution, thereby maintaining the welding strength and current capacity of the existing tab 500, while improving the energy density of the pole piece assembly and the battery and leaving the electrochemical performance of the battery unaffected.

[0074] The present application also discloses a battery using the above-mentioned pole piece assembly. Due to the use of the above-mentioned pole piece assembly, the cathode sheet 100 has more cathode active material layers that can function, thereby improving the energy density of the battery.

[0075] 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 the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the illustrative expressions 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 suitable manner in any one or more embodiments or examples.

[0076] Although the embodiments of the present application 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 intent of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A pole piece assembly, comprising: A cathode sheet (100); an anode sheet (200) arranged opposite to the cathode sheet (100), the length direction of the anode sheet (200) being the same as the length direction of the cathode sheet (100), and the width of the anode sheet (200) being not less than the width of the cathode sheet (100); The anode sheet (200) is provided with a rectangular empty foil area (300), and the first long side of the empty foil area (300) located in the anode sheet (200) coincides with the long side of the anode sheet (200), and / or the cathode sheet (100) is provided with a rectangular empty foil area (300), and the first long side of the empty foil area (300) located in the cathode sheet (100) coincides with the long side of the cathode sheet (100); A protective sheet (400) is located between the cathode sheet (100) and the anode sheet (200) and opposite to the empty foil area (300); the protective sheet (400) is rectangular; a first long side of the protective sheet (400) coincides with a long side of the cathode sheet (100); two wide sides of the protective sheet (400) and a second long side of the protective sheet (400) are both located outside a projection of the empty foil area (300) on the cathode sheet (100).

2. The pole piece assembly according to claim 1, wherein: The distances between the two wide sides of the protection sheet (400) and the second long side of the protection sheet (400) and the projection of the empty foil area (300) on the cathode sheet (100) are the same.

3. The pole piece assembly according to claim 1, wherein: The protection sheet (400) is connected to the cathode sheet (100).

4. The pole piece assembly according to claim 1, wherein: The width of the anode sheet (200) is greater than the width of the cathode sheet (100).

5. The pole piece assembly according to claim 1 further comprises a pole ear (500), wherein the pole ear (500) is provided with a rectangular horizontal strip portion (510), wherein the horizontal strip portion (510) is connected to the empty foil area (300), and the length direction of the horizontal strip portion (510) is the same as the length direction of the empty foil area (300).

6. The pole piece assembly according to claim 5, wherein: The length of the empty foil area (300) is greater than the length of the transverse strip portion (510), and the width of the empty foil area (300) is greater than the width of the transverse strip portion (510).

7. The pole piece assembly according to claim 5, wherein: The pole lug (500) is provided with a rectangular vertical bar portion (520), the length direction of the vertical bar portion (520) is the same as the width direction of the horizontal bar portion (510), and one end of the vertical bar portion (520) is connected to the horizontal bar portion (510).

8. The pole piece assembly according to claim 7, wherein: The vertical strip portion (520) is provided with a tab glue (600), and the tab glue (600) is located outside the empty foil area (300).

9. The pole piece assembly according to claim 1, wherein: The cathode sheet (100) is provided with the empty foil area (300), and the cathode sheet (100) is provided with a cathode active material layer in an area outside the empty foil area (300); the anode sheet (200) is provided with the empty foil area (300), and the anode sheet (200) is provided with an anode active material layer in an area outside the empty foil area (300).

10. The pole piece assembly according to claim 1, wherein: The width dimension of the empty foil area (300) is A, and the length dimension of the empty foil area (300) is B, satisfying: 1.1A≤B≤5.5A.

11. The pole piece assembly according to claim 7, wherein: The thickness of the vertical stripe portion (520) is E, and the thickness of the horizontal stripe portion (510) is F, satisfying: 0.4E≤F≤E.

12. The pole piece assembly according to claim 7, wherein: The pole ear (500) is also provided with a protruding portion (530), and the protruding portion (530) and the vertical bar portion (520) are respectively arranged on opposite sides of the horizontal bar portion (510), one end of the protruding portion (530) is connected to the horizontal bar portion (510), and the distance between the other end of the protruding portion (530) and the horizontal bar portion (510) is G, satisfying G≤4mm.

13. A battery comprising the pole piece assembly according to any one of claims 1 to 12.

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