Coating transfer diaphragm, coating roller and battery

Abstract

The invention relates to the technical field of batteries, in particular to a coating transfer diaphragm, a coating roller and a battery, the coating transfer diaphragm comprises a transfer coating and a base film, and the surface of the base film is coated with the transfer coating. The transfer coating comprises a uniform thickness part and a thickening part, the coating thickness of the thickening part is larger than that of the uniform thickness part, the uniform thickness part and the thickening part are continuously arranged in the first direction, and the thickening part is arranged on one side, in the first direction, of the uniform thickness part. And when the transfer coating is transferred to the surface of the pole piece, the thickening part corresponds to the thinning area, close to the tab, of the pole piece. According to the coating transfer diaphragm, the coating roller and the battery provided by the invention, the transfer coating can be effectively transferred on the surface of the pole piece. The 100% transfer rate of the coating on the surface of the pole piece is achieved, and weak areas without coating protection are thoroughly eliminated. The short-circuit probability of the battery cell is obviously reduced, and the safety performance of the battery is greatly improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a coating transfer separator, a coating roller, and a battery. Background Technology

[0002] With the rapid development of the new energy industry, lithium-ion batteries are widely used in electric vehicles, energy storage devices, and other fields due to their advantages such as high energy density and long cycle life. However, their safety performance has always been a core focus of the industry. Under battery charge-discharge cycles or extreme operating conditions, high-temperature environments can easily cause the internal separator of the battery to shrink. If the positive and negative electrodes lose effective isolation, it can easily lead to a short circuit in the cell, or even induce serious safety accidents such as thermal runaway.

[0003] To address this issue, a coating transfer separator is disclosed in the prior art (see Chinese Patent Document CN119009357A). This separator transfers a coating onto the surface of a base film via a hot-pressing process. Since the heat resistance of the positive electrode is significantly better than that of the separator, even if the separator shrinks at high temperatures, the coating on the surface of the positive electrode can still maintain its insulating effect on the positive and negative electrodes, thereby reducing the risk of short circuits in the battery cell to some extent.

[0004] However, in the current manufacturing process of positive electrode sheets, an extrusion coating process is typically used to adapt to the installation and current conduction requirements of the tabs. This inevitably results in a thinned area (i.e., the thickness of the positive electrode sheet in this area is less than that in other areas) near the tabs. When using a traditional uniform-thickness coated separator for hot-press transfer, because the overall thickness of the transferred coating is uniform, the coating at the position corresponding to the thinned area of ​​the positive electrode sheet cannot fully fill the thickness difference of the thinned area during hot-pressing, and therefore cannot be effectively transferred to the surface of the thinned area. This defect directly affects the coating transfer rate on the surface of the positive electrode sheet, making the thinned area of ​​the positive electrode sheet a weak area "without coating protection"—at high temperatures, due to the lack of coating isolation, the positive and negative electrodes can easily come into direct contact, and the risk of short circuit in the cell remains unresolved, seriously restricting further improvement in battery safety performance. Summary of the Invention

[0005] The purpose of this application is to provide a coating transfer separator, a coating roller, and a battery, so as to solve to a certain extent the technical problem in the prior art that, due to the uniform overall thickness of the transfer coating, the coating at the position corresponding to the thinned area of ​​the positive electrode sheet cannot fully fill the thickness difference of the thinned area during the hot pressing process, and thus cannot be effectively transferred to the surface of the thinned area.

[0006] According to a first aspect of this application, a coating transfer diaphragm is provided, comprising a transfer coating and a base film, wherein the transfer coating is coated on the surface of the base film; The transfer coating includes a uniform thickness portion and a thickened portion, the coating thickness of the thickened portion is greater than the coating thickness of the uniform thickness portion, the uniform thickness portion and the thickened portion are continuously disposed along a first direction, and the thickened portion is disposed on one side of the uniform thickness portion in the first direction; When the transfer coating is transferred to the electrode surface, the thickened portion is positioned corresponding to the thinned area of ​​the electrode near the tab.

[0007] Preferably, along the first direction, the thickened portion is divided into multiple gradient regions; In the direction of the thickened portion from one end near the uniform thickness portion to the other end in the first direction, the coating thickness of the plurality of gradient regions increases sequentially.

[0008] Preferably, in the direction of the thickened portion from one end near the uniformly thickened portion to the other end in the first direction, the size of the plurality of gradient regions gradually increases in the first direction.

[0009] Preferably, the number of gradient regions is four. In the first direction, the four gradient regions are defined sequentially as a first gradient region, a second gradient region, a third gradient region, and a fourth gradient region, wherein the first gradient region is connected to the uniform thickness portion. The coating thickness H1 in the first gradient region is 0.1 μm to 0.3 μm; The coating thickness H2 in the second gradient region is 0.3 μm to 0.6 μm; The coating thickness H3 in the third gradient region is 0.6 μm to 1.0 μm; The coating thickness H4 in the fourth gradient region is 1.0 μm to 1.4 μm.

[0010] Preferably, the number of gradient regions is four. In the first direction, the four gradient regions are defined sequentially as a first gradient region, a second gradient region, a third gradient region, and a fourth gradient region, wherein the first gradient region is connected to the uniform thickness portion. The size L1 of the first gradient region in the first direction is 1.0 mm to 2.5 mm; The second gradient region has a size L2 of 2.0 mm to 5 mm in the first direction; The dimension L3 of the third gradient region in the first direction is 3.0 mm to 7.5 mm; The fourth gradient region has a size L4 of 4.0 mm to 10.0 mm in the first direction.

[0011] Preferably, when the coating transfer membrane is transferred to the electrode surface, the adhesion force between the transfer coating and the electrode is 8 N / m to 15 N / m.

[0012] Preferably, the thickness of the base film is 5.0 μm to 20.0 μm; The thickness of the transfer coating is 1.0 μm to 6.0 μm; The coating thickness of the uniform thickness portion is 1.0 μm to 5.0 μm.

[0013] According to a second aspect of this application, a coating roller is provided for coating the coating transfer diaphragm described in any of the above technical solutions, and thus has all the beneficial technical effects of the coating transfer diaphragm, which will not be repeated here.

[0014] Specifically, the coating roller includes a roller body, the roller body includes a uniform diameter portion and a reduced diameter portion, the uniform diameter portion extends along the first direction, and the reduced diameter portion is fixedly disposed at both ends of the uniform diameter portion in the first direction; In the first direction of the reduced diameter portion, the diameter of the reduced diameter portion gradually decreases from one end near the uniform diameter portion to the other end.

[0015] Preferably, the roller body further includes a connecting shaft and a positioning part. The roller body is provided with connecting shafts at both ends in the first direction. The connecting shafts are coaxially arranged with the roller body. The positioning part is fixedly arranged at the end of the connecting shaft away from the roller body, and the outer diameter of the positioning part is larger than the outer diameter of the connecting shaft.

[0016] According to a third aspect of this application, a battery is provided, comprising the coating transfer separator described in any of the above technical solutions, and thus possesses all the beneficial technical effects of the coating transfer separator, which will not be repeated here.

[0017] Compared with the prior art, the beneficial effects of this application are as follows: The coating transfer separator provided in this application has a uniform thickness portion and a thickened portion continuously arranged along a first direction, such that the coating thickness of the thickened portion is greater than that of the uniform thickness portion. When the transfer coating is transferred to the electrode surface, the thickened portion corresponds to the thinned area (401) near the electrode tab. The thickness design of the thickened portion precisely compensates for the thickness difference in the thinned area. During hot pressing, the thickened portion, with its greater thickness, can fully fill the thickness gap between the thinned area and other areas of the electrode. Simultaneously, combined with the uniform thickness portion's conventional coverage of the non-thinned areas of the electrode, the transfer coating can be effectively transferred to both the thinned and non-thinned areas of the electrode surface. Furthermore, the continuous arrangement of the uniform thickness portion and the thickened portion along the first direction avoids gaps between sections, further ensuring the integrity of the coating transfer. Ultimately, a 100% coating transfer rate is achieved on the electrode surface, completely eliminating weak areas with "no coating protection." This significantly reduces the probability of cell short circuits and greatly improves battery safety performance.

[0018] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of the coating transfer diaphragm provided in the embodiments of this application; Figure 2 This is a schematic diagram of the structure of the coating roller provided in the embodiments of this application; Figure 3 This is a schematic diagram of the structure of the coating transfer diaphragm assembly formed by coating roller coating according to an embodiment of this application; Figure 4 This is a schematic diagram of the structure of the electrode provided in an embodiment of this application.

[0021] Figure label: 1-Base film; 2-Transfer coating; 21-Thickness uniform section; 22-Thickening section; 221-First gradient region; 222-Second gradient region; 223-Third gradient region; 224-Fourth gradient region; 31-Roller body; 311-Diameter uniform section; 312-Diameter reduction section; 32-Connecting shaft; 33-Positioning section; 4-Electrode sheet; 40-Sheet body; 41-Electrode tab; 401-Thinning region; F1-First direction. Detailed Implementation

[0022] The technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this application, but not all embodiments.

[0023] The components of the embodiments of this application described and shown in the accompanying drawings can be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of this application provided in the drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application.

[0024] Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0027] The following reference Figures 1 to 4 This application describes a coating transfer diaphragm, coating roller, and battery according to some embodiments thereof.

[0028] See Figures 1 to 4 As shown, an embodiment of the first aspect of this application provides a coating transfer diaphragm, which includes a transfer coating 2 and a base film 1. The transfer coating 2 is coated on the surface of the base film 1. The transfer coating 2 includes a uniform thickness portion 21 and a thickened portion 22. The coating thickness of the thickened portion 22 is greater than the coating thickness of the uniform thickness portion 21. The uniform thickness portion 21 and the thickened portion 22 are continuously disposed along a first direction F1, and the thickened portion 22 is disposed on one side of the uniform thickness portion 21 in the first direction F1. When the transfer coating 2 is transferred to the surface of an electrode 4 (e.g., a positive electrode), the thickened portion 22 is disposed corresponding to the thinned region 401 of the electrode 4 near the tab 41.

[0029] According to the coating transfer diaphragm provided by the above-mentioned technical features, the uniform thickness portion 21 and the thickening portion 22 are continuously arranged along the first direction F1, so that the coating thickness of the thickening portion 22 is greater than that of the uniform thickness portion 21. When the transfer coating 2 is transferred to the surface of the electrode 4, the thickening portion 22 is correspondingly arranged with the thinned area 401 of the electrode 4 near the tab 41. The thickness design of the thickening portion 22 precisely compensates for the thickness difference of the thinned area. During hot pressing, the thickening portion 22, with its greater thickness, can fully fill the thickness gap between the thinned area 401 of the electrode 4 and other areas. At the same time, combined with the regular coverage of the non-thinned area of ​​the electrode 4 by the uniform thickness portion 21, the transfer coating 2 can be effectively transferred on the surface of the electrode 4 (including both the thinned and non-thinned areas). In addition, the uniform thickness portion 21 and the thickening portion 22 are continuously arranged along the first direction F1, avoiding gaps between the partitions, further ensuring the integrity of the coating transfer, and finally achieving a 100% coating transfer rate on the surface of the electrode 4, completely eliminating the weak areas of "uncoated protection". It significantly reduces the probability of cell short circuits and greatly improves battery safety performance.

[0030] like Figure 4 As shown in the figure, the structure of the above-mentioned electrode 4 is illustrated. The electrode 4 may include a sheet body 40 and an electrode tab 41. The electrode tab 41 is disposed at one end of the sheet body 40 in the first direction F1, and the above-mentioned thinning area 401 is located at the end of the sheet body 40 near the electrode tab 41.

[0031] Preferably, such as Figure 1 and Figure 3 As shown, along the first direction F1, the thickened portion 22 can be divided into multiple gradient regions. In the direction from one end of the thickened portion 22 near the uniform thickness portion 21 to the other end in the first direction F1, the coating thickness of the multiple gradient regions increases sequentially. In this way, on the one hand, stress concentration points caused by abrupt changes in thickness are eliminated, and the coating in each gradient region is subjected to more uniform stress during hot pressing, which can effectively avoid cracking and peeling problems. On the other hand, the gradual thickening of multiple gradient regions can adapt to the "micro-gradient thickness difference" that may exist in the thinning area of ​​the electrode 4 (some thinning areas of the electrode 4 are not absolutely steep thickness abrupt changes, and there may be a small transition section), ensuring that the coating in the transition area can also accurately adhere to the surface of the electrode 4, further improving the integrity of coating transfer and laying a solid foundation for achieving a 100% transfer rate.

[0032] like Figure 1 As shown in the figure, an example of four gradient regions is presented. For ease of description, the four gradient regions are defined sequentially along the first direction F1 as the first gradient region 221, the second gradient region 222, the third gradient region 223, and the fourth gradient region 224. The first gradient region 221 is connected to the uniform thickness portion 21.

[0033] Preferably, such as Figure 1As shown, the coating thickness H1 of the first gradient region 221 can be 0.1μm~0.3μm.

[0034] Preferably, such as Figure 1 As shown, the coating thickness H2 of the second gradient region 222 can be 0.3μm~0.6μm.

[0035] Preferably, such as Figure 1 As shown, the coating thickness H3 of the third gradient region 223 can be 0.6μm~1.0μm.

[0036] Preferably, such as Figure 1 As shown, the coating thickness H4 of the fourth gradient region 224 can be 1.0μm~1.4μm.

[0037] It should be noted that the coating thickness H1 of the first gradient region 221, the coating thickness H2 of the second gradient region 222, the coating thickness H3 of the third gradient region 223, and the coating thickness H4 of the fourth gradient region 224 are the coating thicknesses of the portions of the corresponding gradient regions that are more than the uniform thickness portion 21 in the thickness direction. The coating thickness here can be understood as the average thickness within the corresponding gradient region.

[0038] like Figure 1 and Figure 3 As shown in the figure, an example is illustrated where the side of the gradient region away from the base film 1 is a slope (that is, within the same gradient region, the thickness of the gradient region gradually increases in the direction from one end near the uniform thickness portion 21 to the other end in the first direction F1). However, this is not the only limitation. As long as the average thickness of each gradient region shows an increasing trend in the direction from one end near the uniform thickness portion 21 to the other end in the first direction F1, the side of the gradient region away from the base film 1 can also be a plane (i.e., parallel to the upper surface of the base film 1), a curved surface, a wavy surface, a bent surface, or other irregular surface.

[0039] Preferably, such as Figure 1 As shown, in the direction of the thickened portion 22 from one end near the uniformly thickened portion 21 to the other end in the first direction F1, the size of multiple gradient regions gradually increases in the first direction F1. In this way, the coating material distribution in each region of the thickened portion 22 is optimized, ensuring that the coating fully covers the thinned area while avoiding waste of coating material. At the same time, it enhances the stability of the overall structure of the thickened portion 22, reduces the problem of uneven transfer caused by excessively thick or thin local coatings during hot pressing, and further improves the stability of battery safety performance.

[0040] Correspondingly, such as Figure 1 As shown, the size L1 of the first gradient region 221 in the first direction F1 can be 1.0mm to 2.5mm.

[0041] Correspondingly, such as Figure 1 As shown, the size L2 of the second gradient region 222 in the first direction F1 can be 2.0mm~5mm.

[0042] Correspondingly, such as Figure 1 As shown, the size L3 of the third gradient region 223 in the first direction F1 can be 3.0mm~7.5mm.

[0043] Correspondingly, such as Figure 1 As shown, the size L4 of the fourth gradient region 224 in the first direction F1 can be 4.0mm ~ 10.0mm.

[0044] In this embodiment, preferably, when the coating transfer membrane is transferred to the surface of the electrode 4, the adhesion force between the transferred coating 2 and the electrode 4 can be 8 N / m to 15 N / m. If the adhesion force is insufficient (e.g., <8 N / m), during battery cycling, the expansion and contraction of the electrode 4, vibration and impact, etc., will cause the coating to separate from the electrode 4. The detached coating not only loses its insulating function but may also become internal impurities, causing micro-short circuits. If the adhesion force is too strong (e.g., >15 N / m), the coating may become too hard, affecting the flexibility of the electrode 4, and even causing the coating to crack when the electrode 4 is bent. Controlling the adhesion force between the transferred coating 2 and the electrode 4 within the range of 8 N / m to 15 N / m ensures a stable bond between the transferred coating 2 and the surface of the electrode 4, preventing the coating from detaching from the surface of the electrode 4 under conditions such as charge-discharge cycles, vibration, or impact. This maintains the long-term insulating effect of the coating on the positive and negative electrodes, further extending the safe service life of the battery and improving its reliability.

[0045] Specifically, the bonding force between the uniform thickness portion 21 and the electrode 4 can be 8 N / m to 15 N / m. The bonding force between the thickened portion 22 and the electrode 4 can also be 8 N / m to 15 N / m.

[0046] Preferably, such as Figure 1 As shown, the thickness of base film 1 (i.e. Figure 1 The T1 value shown can be 5.0μm to 20.0μm. To ensure the mechanical strength of the separator, if the base film 1 is too thin (e.g., <5.0μm), the mechanical strength of the separator will be insufficient and it will be easily damaged during battery assembly. If the base film 1 is too thick (e.g., >20.0μm), it will not only increase the material cost but also increase the difficulty of demolding.

[0047] Preferably, the thickness of the transfer coating 2 can be 1.0 μm to 6.0 μm. If the transfer coating 2 is too thin (e.g., <1.0 μm), it cannot effectively isolate the positive and negative electrodes; if it is too thick (e.g., >6.0 μm), it will further increase the internal resistance.

[0048] Among them, the coating thickness of the uniform thickness portion 21 (i.e. Figure 1The T2 value shown can be 1.0μm to 5.0μm. If the uniform thickness 21 is too thin (e.g., <1.0μm), it cannot cover the non-thinned area; if it is too thick (e.g., >5.0μm), it will waste material and affect performance.

[0049] Optionally, the coating transfer diaphragm can be formed by brush coating the base film 1 onto the surface of the base film using a coating roller.

[0050] See Figure 2 The second aspect of this application also provides a coating roller for coating the coating transfer diaphragm described in any of the above embodiments, and thus has all the beneficial technical effects of the coating transfer diaphragm, which will not be repeated here.

[0051] Specifically, such as Figure 2 As shown, the coating roller includes a roller body 31, which includes a uniform diameter portion 311 and a reduced diameter portion 312. The uniform diameter portion 311 extends along a first direction F1, and the reduced diameter portion 312 is fixedly disposed at both ends of the uniform diameter portion 311 in the first direction F1. In the first direction F1, the diameter of the reduced diameter portion 312 gradually decreases from one end near the uniform diameter portion 311 to the other end. Thus, through the structural design of the uniform diameter portion 311 and the reduced diameter portion 312, the uniform thickness portion 21 and the thickened portion 22 (including the gradient region) can be coated in one step without the need for subsequent secondary processing, simplifying the production process, improving production efficiency, and ensuring the accuracy of the coating thickness, thereby guaranteeing the consistency of the diaphragm product quality.

[0052] like Figure 3 As shown in the figure, a schematic diagram of the coating transfer diaphragm assembly formed by the coating roller is presented. Two coating transfer diaphragms are obtained by cutting the coating transfer diaphragm assembly along the center line (i.e., the dotted line shown in the figure). In other words, two coating transfer diaphragms can be obtained simultaneously by performing one coating operation using the coating roller, which effectively improves the coating efficiency.

[0053] like Figure 3 As shown in the figure, an example of the outer wall of the aforementioned tapered portion 312 having a conical surface is shown. However, it is not limited to this. As long as the average thickness of the aforementioned multiple gradient regions of the tapered portion 312 can be gradually reduced, the shape of the outer wall of the aforementioned tapered portion 312 can be adaptively adjusted according to the surface structure of the side of the gradient region away from the base film 1.

[0054] Preferably, such as Figure 3As shown, the coating roller may further include a connecting shaft 32 and a positioning part 33. Connecting shafts 32 are respectively provided at both ends of the roller body 31 in the first direction F1. The connecting shafts 32 are coaxially arranged with the roller body 31. The positioning part 33 is fixedly disposed at the end of the connecting shaft 32 away from the roller body 31, and the outer diameter of the positioning part 33 is larger than the outer diameter of the connecting shaft 32. Thus, on the one hand, the connecting shaft 32 is used to cooperate with the bearings of the equipment to achieve rotational support for the roller body; on the other hand, the positioning part 33, through its design of having an outer diameter larger than the connecting shaft 32, can be locked in the positioning groove of the equipment, limiting the axial displacement of the roller body. This structure ensures that the coating roller is stable and does not wobble when rotating at high speed, and that the gap between the roller body and the substrate remains precise throughout the coating process, thereby ensuring the uniformity and accuracy of the coating thickness and reducing the scrap rate.

[0055] According to a third aspect of this application, a battery is provided, comprising the coating transfer separator described in any of the above technical solutions, and thus possesses all the beneficial technical effects of the coating transfer separator, which will not be repeated here.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A coating transfer diaphragm, characterized in that, It includes a transfer coating and a base film, wherein the transfer coating is applied to the surface of the base film; The transfer coating includes a uniform thickness portion and a thickened portion, the coating thickness of the thickened portion is greater than the coating thickness of the uniform thickness portion, the uniform thickness portion and the thickened portion are continuously disposed along a first direction, and the thickened portion is disposed on one side of the uniform thickness portion in the first direction; When the transfer coating is transferred to the electrode surface, the thickened portion is provided corresponding to the thinned area of ​​the electrode near the tab; Along the first direction, the thickened portion is divided into multiple gradient regions; In the direction of the thickened portion from one end near the uniform thickness portion to the other end in the first direction, the coating thickness of the plurality of gradient regions increases sequentially, and the size of the plurality of gradient regions gradually increases in the first direction; The number of gradient regions is four. In the first direction, the four gradient regions are defined as the first gradient region, the second gradient region, the third gradient region and the fourth gradient region, wherein the first gradient region is connected to the uniform thickness portion. The coating thickness H1 in the first gradient region is 0.1 μm to 0.3 μm; The coating thickness H2 in the second gradient region is 0.3 μm to 0.6 μm; The coating thickness H3 in the third gradient region is 0.6 μm to 1.0 μm; The coating thickness H4 in the fourth gradient region is 1.0 μm to 1.4 μm; The size L1 of the first gradient region in the first direction is 1.0 mm to 2.5 mm; The second gradient region has a size L2 of 2.0 mm to 5 mm in the first direction; The dimension L3 of the third gradient region in the first direction is 3.0 mm to 7.5 mm; The fourth gradient region has a size L4 of 4.0 mm to 10.0 mm in the first direction.

2. The coating transfer diaphragm according to claim 1, characterized in that, When the coating transfer membrane is transferred to the electrode surface, the adhesion between the transferred coating and the electrode is 8 N / m to 15 N / m.

3. The coating transfer diaphragm according to any one of claims 1 to 2, characterized in that, The thickness of the base film is 5.0 μm to 20.0 μm; The thickness of the transfer coating is 1.0 μm to 6.0 μm; The coating thickness of the uniform thickness portion is 1.0 μm to 5.0 μm.

4. A coating roller, characterized in that, For coating the coating transfer diaphragm according to any one of claims 1 to 3; The coating roller includes a roller body, which includes a uniform diameter portion and a reduced diameter portion. The uniform diameter portion extends along the first direction, and the reduced diameter portion is fixedly disposed at both ends of the uniform diameter portion in the first direction. In the first direction of the reduced diameter portion, the diameter of the reduced diameter portion gradually decreases from one end near the uniform diameter portion to the other end.

5. The coating roller according to claim 4, characterized in that, It also includes a connecting shaft and a positioning part. The roller body is provided with connecting shafts at both ends in the first direction. The connecting shafts are coaxially arranged with the roller body. The positioning part is fixedly arranged at the end of the connecting shaft away from the roller body, and the outer diameter of the positioning part is larger than the outer diameter of the connecting shaft.

6. A battery, characterized in that, It includes the electrode sheet and the coating transfer diaphragm according to any one of claims 1 to 3.

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