Pole piece, battery device, coating die head and coating device

Abstract

The utility model relates to a pole piece, a battery device, a coating die head and a coating device, and the pole piece comprises a current collector which comprises a first area and a second area located on at least one side of the first area along the width direction; the active material layer is coated on the first region; and the protective layer is coated on the second region, the protective layer comprises a first part and a second part which are connected with each other, the first part is positioned between the active material layer and the second part along the width direction, and the thickness of the first part is greater than that of the second part along the thickness direction of the current collector. Through the cooperation of the first part and the second part, on the basis of improving and covering burrs, a larger space can be provided for the folded tab, namely, different requirements of different processes are considered, and the performance of the battery monomer is improved.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and particularly to an electrode sheet, a battery device, a coating die head, and a coating device. Background Art

[0002] During the production process of a battery electrode sheet, it is necessary to die-cut tabs on the electrode sheet. In order to improve the burr problem formed during the cutting process, a tab glue is usually coated at the die-cut position in the tab area to protect the electrode sheet. After die-cutting the tabs, processes such as folding the tabs are also required to assemble the electrode sheet to form a battery cell.

[0003] However, different processing procedures have different requirements for the thickness of the tab glue. At present, the setting of the tab glue cannot take into account the different requirements of different procedures, which limits the performance of the finally assembled battery cell. Summary of the Utility Model

[0004] Based on this, in view of the problem that the current setting of the tab glue cannot take into account the different requirements of different procedures, which limits the performance of the finally assembled battery cell, it is necessary to provide an electrode sheet, a battery device, a coating die head, and a coating device.

[0005] In a first aspect, the present application provides an electrode sheet, which includes a current collector, an active material layer, and a protective layer. The current collector includes a first region and a second region located on at least one side of the first region along the width direction of the current collector; the active material layer is coated on the first region; the protective layer is coated on the second region. The protective layer includes a first part and a second part connected to each other. The first part is located between the active material layer and the second part along the width direction. Along the thickness direction of the current collector, the thickness of the first part is greater than the thickness of the second part.

[0006] Through the cooperation of the first part and the second part, on the basis of improving and covering burrs, a larger space can be provided for folding the tabs, that is, taking into account the different requirements of different procedures and improving the performance of the battery cell.

[0007] In some embodiments, the protective layer further includes a thinning part. The thinning part is connected between the first part and the active material layer along the width direction, and in the thickness direction, the thickness of the thinning part is less than the thickness of the first part.

[0008] Based on this, a thinning part is provided between the first part and the active material layer, and the thickness of the thinning part is less than the thickness of the first part. In this way, when the thinning part is connected to the active material layer, the problem of virtual edges can be effectively improved.

[0009] In some embodiments, in the thickness direction, the thickness of the first part ranges from 15 μm to 40 μm. By setting the thickness of the first part within the above range, on the one hand, the probability of burr generation can be successfully reduced and the burrs can be covered. On the other hand, keeping the thickness of the first part within the above range, it will not change following the thickness change of the active material layer, and the effect of die-cutting the tab can be better adjusted.

[0010] In some embodiments, in the thickness direction, the thickness of the second part ranges from 5 μm to 15 μm. By setting the thickness of the second part within the above range, the burrs can also be covered, and the thickness of the second part can be unified, making the effect of die-cutting the tab more uniform. In addition, the second part can also provide more space for folding the tab.

[0011] In some embodiments, in the thickness direction, the thickness of the thinning part ranges from 5 μm to 15 μm. Thus, the thinning part can not only improve the problem of virtual edges between the active material layer and the protective layer, but also effectively improve the burr problem.

[0012] In some embodiments, in the width direction, the thinning part includes a connecting section and an embedding section. The embedding section is located between the current collector and the active material layer in the thickness direction, and the connecting section is connected between the embedding section and the first part in the width direction.

[0013] By setting the embedding section, there is a partial overlap between the thinning part and the active material layer. In this way, the probability of generating a gap between the active material layer and the protective layer to expose the current collector can be further reduced.

[0014] In some embodiments, in the width direction, the width range of the embedding section is 0.5 mm to 1 mm; and / or, in the width direction, the width range of the connecting section is 0.5 mm to 1 mm.

[0015] Among them, setting the width of the embedding section within the above range can make the active material layer and the protective layer better overlap and reduce the probability of generating a gap between them. Setting the width of the connecting section within the above range can better match the die-cutting range and make the root of the tab fall smoothly on the first part with a thicker thickness.

[0016] In some embodiments, in the width direction, the width range of the first part is 3 mm to 8 mm. Therefore, setting the width of the first part within the above range can better match the die-cutting area, make the root of the die-cut tab fall smoothly on the first part, effectively improve the burr problem, and cover the burrs.

[0017] In some embodiments, in the width direction, the width of the second portion ranges from 2 mm to 12 mm. Therefore, setting the width of the second portion to the above range can provide a larger space for the folded electrode ear while smoothly covering the burr.

[0018] In a second aspect, the present application further provides a battery device, including a box body and a battery cell disposed inside the box body, wherein the battery cell includes the above-mentioned pole piece.

[0019] On the third aspect, the present application also provides a coating die head for coating the above-mentioned electrode piece, the coating die head has a storage cavity inside, and the coating die head is provided with a first discharge port and a second discharge port which are respectively connected to the storage cavity, the first discharge port is used to coat the first part of the protective layer, and the second discharge port is used to coat the second part of the protective layer; wherein, along the transport direction of the electrode piece, the width of the first discharge port is greater than the width of the second discharge port.

[0020] Through the above structure, the coating die head can simultaneously coat the first part and the second part with different thicknesses, so that the electrode piece formed by coating can improve the burr problem while providing as much space as possible for the folded electrode ear.

[0021] In some embodiments, a thinning outlet connected to the first outlet is also provided on the coating die head, and the thinning outlet is located on the side of the first outlet away from the second outlet along the width direction of the electrode piece; wherein, along the transportation direction of the electrode piece, the width of the thinning outlet is smaller than the width of the first outlet.

[0022] In this way, by setting the thinning outlet and the first discharge port, the first part and the thinned part of the protective layer can be coated on the current collector respectively, and the thinned part is located between the first part and the active material layer, which can effectively improve the problem of virtual edges between the active material layer and the protective layer.

[0023] In some embodiments, the storage chamber includes a first sub-chamber and a second sub-chamber that are independent of each other, the first sub-chamber is connected to the first discharge port, and the second sub-chamber is connected to the second discharge port.

[0024] During the coating process, the first sub-cavity and the second sub-cavity can realize independent feeding of the first outlet and the second outlet respectively, and the feeding pressure and feeding speed can be adjusted more flexibly according to the different opening sizes of the first outlet and the second outlet, so that the first part and the second part can be coated more smoothly.

[0025] In some embodiments, along the transport direction of the electrode sheet, the depth range of the first sub-cavity is 0.3 mm to 0.8 mm; and / or, along the transport direction of the electrode sheet, the depth range of the second sub-cavity is 0.4 mm to 1 mm. Based on this, by setting the depths of the first sub-cavity and the second sub-cavity within the above ranges respectively, the pressure and speed during the coating process can be better controlled, and the coating of the first part and the second part can be made more stable.

[0026] In some embodiments, the coating die head includes an upper die head and a lower die head that jointly enclose a material storage cavity. The upper die head has a first upper lip and a second upper lip, and the lower die head has a first lower lip and a second lower lip. A first discharge port is formed by the interval between the first upper lip and the first lower lip, and a second discharge port is formed by the interval between the second upper lip and the second lower lip; wherein, along the thickness direction of the electrode sheet, the first upper lip is set to be retracted away from the electrode sheet relative to the first lower lip, and the second upper lip is set to be retracted away from the electrode sheet relative to the second lower lip.

[0027] Thus, by setting the lip offset amount between the first upper lip and the first lower lip, and setting the lip offset amount between the second upper lip and the second lower lip, the first discharge port and the second discharge port can be made to abut against the surface of the electrode sheet, so that the electrode sheet provides support for the slurry, and the slurry can be coated on the electrode sheet more stably, and the thickness of the formed protective layer is more uniform.

[0028] In some embodiments, the retraction range between the first upper lip and the first lower lip is 50 μm to 100 μm; and / or, the retraction range between the second upper lip and the second lower lip is 30 μm to 60 μm.

[0029] Therefore, by setting the retraction ranges between the first upper lip and the first lower lip and between the second upper lip and the second lower lip within the above ranges respectively, the thicknesses of the first part, the second part, and the thinning part on the electrode sheet are more uniform.

[0030] Fourthly, the present application also provides a coating device, including at least one first die head, and the first die head is the coating die head as above.

[0031] In some embodiments, the coating device includes a conveying roller and a first supporting roller that are used for conveying the electrode sheet and are arranged in sequence along the transport direction of the electrode sheet. Each first die head corresponds to a first supporting roller one by one, and they are respectively arranged on opposite sides of the electrode sheet along the thickness direction of the electrode sheet, and the first supporting roller is used to provide a pressing force against the electrode sheet for the corresponding first die head.

[0032] By setting the conveying roller and the first supporting roller, the smooth conveying of the electrode sheet can be realized. At the same time, the first supporting roller and the corresponding first die head cooperate to provide a more stable supporting force for the electrode sheet, make the coating process more stable, and make the thickness of the coated protective layer more uniform.

[0033] In some embodiments, the coating device further includes a second die head and a second support roller respectively disposed on opposite sides of the electrode sheet in the thickness direction. The second support roller is configured to provide a pressing force against the electrode sheet to the second die head. The second die head is configured to coat the active material layer, and the second die head is located on at least one side of all the first die heads along the transport direction of the electrode sheet.

[0034] With the above structure, it is possible to coat the active material layer on the electrode sheet, and utilize the second support roller to provide the supporting force during the coating process, making the thickness of the active material layer more uniform.

[0035] In some embodiments, the coating device further includes an oven, which is disposed downstream of the first die head and the second die head along the transport direction of the electrode sheet.

[0036] Thus, by providing the oven, the electrode sheet after coating the active material layer and the protective layer can be quickly dried.

[0037] In some embodiments, the coating device further includes a first control valve, a second control valve, a first pipeline, and a second pipeline. The first pipeline is communicated with the first discharge port, and the first control valve is disposed on the first pipeline and configured to control the on / off of the first pipeline; the second pipeline is communicated with the second discharge port, and the second control valve is disposed on the second pipeline and configured to control the on / off of the second pipeline.

[0038] By providing the first control valve and the second control valve, the discharging of the first discharge port and the second discharge port can be independently controlled. In this way, the first control valve and the second control valve can respectively control the pressure in the first pipeline and the second pipeline, realizing the pressure holding design in the first sub-chamber and the second sub-chamber, and reducing the probability of mutual interference between the first discharge port and the second discharge port.

[0039] For the above-mentioned electrode sheet, battery device, coating die head, and coating device, the active material layer is coated on the first region of the current collector and forms the main body portion of the electrode sheet in the first region, while the second region forms the electrode tab portion of the electrode sheet. The protective layer is coated on the second region, that is, on the electrode tab portion. The protective layer can improve the generation of burrs and cover the burrs when die-cutting the electrode tab. In addition, the protective layer is provided with a first portion and a second portion having different thicknesses, and the first portion with a larger thickness is closer to the active material layer, and the second portion with a smaller thickness is farther from the active material layer. In this way, when die-cutting the electrode tab, the root of the electrode tab falls on the first portion, and the first portion can better improve the burr problem. When folding the electrode tab, the second portion with a smaller thickness does not affect the space for folding the electrode tab. In this way, the different thicknesses of the protective layer can take into account both the die-cutting and folding of the electrode tab, improving the performance of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic plan view of an electrode sheet according to one or more embodiments.

[0041] Figure 2 Side view of a pole piece according to one or more embodiments.

[0042] Figure 3 Side view of a pole piece according to one or more embodiments.

[0043] Figure 4 Schematic three-dimensional structure diagram of a coating die according to one or more embodiments.

[0044] Figure 5 is Figure 4 Partial enlarged view of location A in

[0045] Figure 6 Exploded structure schematic diagram of a coating die according to one or more embodiments.

[0046] Figure 7 Schematic structure diagram of the upper die head of a coating die according to one or more embodiments.

[0047] Figure 8 Exploded structure schematic diagram of a coating die according to one or more embodiments.

[0048] Figure 9 Overall structure schematic diagram of a coating device according to one or more embodiments.

[0049] Figure 10 Partial structure schematic diagram of a coating device according to one or more embodiments.

[0050] Explanation of reference numerals: 100, coating device; 10, pole piece; 20, coating die; 30, first die head; 40, conveying roller; 50, first support roller; 60, second die head; 70, second support roller; 80, oven; 11, current collector; 12, active material layer; 13, protective layer; 21, storage cavity; 22, first discharge port; 23, second discharge port; 24, thinning outlet; 25, upper die head; 26, lower die head; 91, first control valve; 92, second control valve; 93, first pipeline; 94, second pipeline; 95, transfer tank; 111, first zone; 112, second zone; 131, first part; 132, second part; 133, thinning part; 134, connecting section; 135, embedding section; 211, first sub-cavity; 212, second sub-cavity; 251, first upper lip; 252, second upper lip; 261, first lower lip; 262, second lower lip; a, width direction; b, thickness direction; c, transportation direction. Detailed implementation manners

[0051] To make the above objects, features, and advantages of the present application more apparent and understandable, the following provides a detailed description of the specific embodiments of the present application with reference to the accompanying drawings. Many specific details are set forth in the following description to facilitate a thorough understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0052] In the description of the present application, it should be understood that if terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or positional relationship indicated by these terms is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present 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 thus should not be construed as a limitation to the present application.

[0053] In addition, if terms such as "first" and "second" appear, these terms are only for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0054] In the present application, unless otherwise clearly specified and limited, if terms such as "install", "connect", "join", "fix", etc. appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0055] In this application, unless otherwise clearly specified and defined, when a first feature is described as being "on" or "under" a second feature or the like, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or simply means that the first feature has a lower horizontal height than the second feature.

[0056] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or there may also be an intermediate element. If an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. If so, the terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used in this application are only for the purpose of illustration and do not represent the only implementation.

[0057] Currently, from the perspective of the development of the market situation, the application of power batteries is becoming more and more widespread. Power batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric transportation tools such as electric bicycles, electric motorcycles, electric vehicles and other fields. With the continuous expansion of the application fields of power batteries, the market demand is also continuously increasing.

[0058] A battery cell is the smallest unit that makes up a battery device, and the battery device may include one or more battery cells. In the structure of a battery cell, it usually includes a housing and an electrode assembly disposed inside the housing. The electrode assembly is the component in the battery cell where an electrochemical reaction actually occurs. The electrode assembly mainly includes a positive electrode plate, a negative electrode plate and a separator disposed between the positive electrode plate and the negative electrode plate. The positive electrode plate, the separator and the negative electrode plate are stacked or wound in sequence to form the electrode assembly.

[0059] Furthermore, the parts of the positive electrode plate and the negative electrode plate coated with the active material layer constitute the main body of the electrode assembly, while the parts of the positive electrode plate and the negative electrode plate not coated with the active material layer respectively constitute the positive electrode tab and the negative electrode tab, collectively referred to as the tab parts. Among them, the positive electrode tab and the negative electrode tab can be located at one end of the main body at the same time, or can be located at opposite ends of the main body respectively.

[0060] During the production process of the electrode plate, the electrode tab is usually formed by laser die-cutting, and during the die-cutting process, burrs are easily formed at the cutting position. When the positive electrode plate, the separator and the negative electrode plate are stacked, the burrs are easily puncture the separator or insert between the positive electrode plate and the negative electrode plate, resulting in problems such as short circuit.

[0061] Under such a premise, currently, a layer of tab glue is usually coated on the tab. The tab glue can reduce the probability of burr generation during the die-cutting process and can also cover the burrs.

[0062] After die-cutting the tabs, the positive electrode sheet, the separator, and the negative electrode sheet need to be stacked and wound in sequence to form an electrode assembly, and then the tabs are folded so that the tabs can be better connected to the connecting member and are electrically connected to the electrode terminals on the housing through the connecting member.

[0063] However, during the process of coating the tab glue currently, it is impossible to just cover the die-cut area with the tab glue. Usually, the width of the tab glue is relatively large. Although it can effectively improve the burr problem, during the process of folding the tabs, the tab glue will affect the space for folding the tabs, thereby affecting the connection stability between the tabs and the connecting member.

[0064] Based on the above considerations, in order to solve the problem that the current setting of the tab glue cannot take into account the different requirements of different processes, resulting in the performance of the finally assembled battery cell being limited, in one or more embodiments of the present application, a pole piece is provided. The active material layer is coated on the first area of the current collector, and the main body part of the pole piece is formed in the first area, while the second area is formed as the tab part of the pole piece. The protective layer is coated on the second area, that is, on the tab part. The protective layer can improve the generation of burrs and cover the burrs when die-cutting the tabs. In addition, the protective layer is set as a first part and a second part with different thicknesses, and the first part with a larger thickness is close to the active material layer, and the second part with a smaller thickness is far from the active material layer. In this way, when die-cutting the tabs, the root of the tab falls on the first part, and the first part can better improve the burr problem, while when folding the tabs, the second part will not affect the space for folding the tabs because of its smaller thickness. In this way, the different thicknesses of the protective layer can take into account both tab die-cutting and tab folding, improving the performance of the battery cell.

[0065] It should be noted that the battery device (Battery Apparatus) mentioned in the embodiments of the present application may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly (Battery Cell Assembly) may include a plurality of battery cells, and the plurality of battery cells are connected in series, parallel, or in a hybrid connection through a bus bar component.

[0066] In some embodiments, the battery cell assembly (Battery Cell Assembly) is usually formed by arranging a plurality of battery cells. As an example, the battery cell assembly can be a battery module (Battery Module), and the battery module is formed by arranging and fixing a plurality of battery cells to form an independent module. As an example, the battery module can be formed by bundling a plurality of battery cells with a cable tie.

[0067] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more battery cell assemblies accommodated in the housing.

[0068] As an example, the battery cell assembly may be a battery module, and the battery cell assembly may be accommodated in the housing by fixing the battery module in the housing.

[0069] As an example, the battery cell assembly may also be accommodated in the housing by directly fixing a plurality of battery cells to the housing.

[0070] Please refer to Figure 1 and Figure 2 As shown in, an embodiment of the present application provides a pole piece 10, which includes a current collector 11, an active material layer 12, and a protective layer 13. The current collector 11 includes a first region 111 and a second region 112 located on at least one side of the first region 111 along the width direction a of the current collector 11. The active material layer 12 is coated on the first region 111. The protective layer 13 is coated on the second region 112. The protective layer 13 includes a first part 131 and a second part 132 connected to each other. The first part 131 is located between the active material layer 12 and the second part 132 along the width direction a. Along the thickness direction b of the current collector 11, the thickness of the first part 131 is greater than the thickness of the second part 132.

[0071] It should be noted that the pole piece 10 may be a positive pole piece or a negative pole piece. The current collector 11 is usually a metal foil such as aluminum foil or copper foil. The current collector 11 can provide a support base for the active material layer 12 or other materials to form the pole piece 10.

[0072] The current collector 11 includes a first region 111 and a second region 112. The first region 111 is located at the middle position of the current collector 11. The second region 112 may be located on one side of the first region 111 along the width direction a, or may be located on both sides of the first region 111 along the width direction a. Among them, the active material layer 12 is coated on the first region 111. When the active material layer 12 is a positive active material, the pole piece 10 is a positive pole piece 10, and when the active material layer 12 is a negative active material, the pole piece 10 is a negative pole piece 10.

[0073] Further, since the active material layer 12 is coated on the first region 111, the first region 111 is formed as the main body part of the pole piece 10, and the second region 112 is formed as the pole ear part of the pole piece 10. Among them, the position of the second region 112 relative to the first region 111 can be adjusted according to the actual structure of the pole piece 10, which will not be elaborated here.

[0074] Specifically, the protective layer 13 can be an insulating glue. The insulating glue is coated on the second region 112. When die-cutting the tab, the insulating glue can reduce the probability of forming burrs and can cover the burrs.

[0075] In addition, the protective layer 13 includes a first part 131 and a second part 132. The first part 131 and the second part 132 are connected to each other, that is, the first part 131 and the second part 132 are continuous and there is no gap between them. The thickness of the first part 131 is greater than the thickness of the second part 132, and the first part 131 is connected between the active material layer 12 and the second part 132 along the width direction a.

[0076] When die-cutting the tab, the cut extends from the edge of the current collector 11 towards the middle along the width direction a. The tab root is the end point close to the middle position, and usually the probability of forming burrs at the tab root is greater and there are more burrs. Thus, making the tab root fall on the first part 131, the first part 131 can not only reduce the probability of generating burrs but also cover the burrs, thereby improving the burr problem.

[0077] Furthermore, the second part 132 can also cover the burrs to a certain extent. At the same time, the second part 132 is close to the edge of the current collector 11 and the thickness of the second part 132 is small. Therefore, the second part 132 is more conducive to the subsequent tab folding process and can provide a larger space for tab folding.

[0078] Based on this, through the cooperation of the first part 131 and the second part 132, on the basis of improving and covering burrs, a larger space can be provided for tab folding, that is, taking into account the different requirements of different processes and improving the performance of the battery cell.

[0079] In some embodiments, the protective layer 13 further includes a thinning part 133. The thinning part 133 is connected between the first part 131 and the active material layer 12 along the width direction a, and in the thickness direction b, the thickness of the thinning part 133 is less than the thickness of the first part 131.

[0080] It should be noted that when the protective layer 13 does not have the thinning part 133, the first part 131 is connected between the active material layer 12 and the second part 132, that is, the first part 131 and the active material layer 12 are continuous and there is no gap between them. When the protective layer 13 includes the thinning part 133, the thinning part 133 is connected between the first part 131 and the active material layer 12.

[0081] Specifically, during the coating process, no gap is allowed to appear between the active material layer 12 and the protective layer 13 to expose the bottom current collector 11. Therefore, the active material layer 12 and the protective layer 13 will fuse with each other, resulting in the problem of unclear boundaries, that is, virtual edges.

[0082] Based on this, a thinning portion 133 is provided between the first portion 131 and the active material layer 12, and the thickness of the thinning portion 133 is less than the thickness of the first portion 131. In this way, when the thinning portion 133 is connected to the active material layer 12, the problem of virtual edges can be effectively improved.

[0083] In some embodiments, the thickness range of the first portion 131 is 15 μm to 40 μm.

[0084] As a specific embodiment, the thickness of the first portion 131 can be but is not limited to being set to 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm.

[0085] It should be noted that for die-cutting tabs, the thickness of the protective layer 13 will affect the die-cutting result. That is to say, if the thickness of the protective layer 13 changes, in order to keep the die-cutting effect unchanged, the parameters during die-cutting need to be adjusted, such as the die-cutting pressure, etc.

[0086] However, for different electrode tabs 10, the required thicknesses of the active material layers 12 are not the same. Currently, the active material layer 12 and the protective layer 13 are usually coated using the same die head. In this way, the thickness of the protective layer 13 will change following the thickness of the active material layer 12, which is not conducive to maintaining the consistency of die-cutting.

[0087] Based on this, setting the thickness of the first portion 131 within the above range, on the one hand, can successfully reduce the probability of burr generation and cover the burrs. On the other hand, keeping the thickness of the first portion 131 within the above range will not change following the thickness of the active material layer 12, and can better adjust the effect when die-cutting tabs.

[0088] In some embodiments, in the thickness direction b, the thickness range of the second portion 132 is 5 μm to 15 μm.

[0089] As a specific embodiment, the thickness of the second portion 132 can be but is not limited to being set to 5 μm, 10 μm, 15 μm.

[0090] By setting the thickness of the second portion 132 within the above range, the burrs can also be covered, and the thickness of the second portion 132 is unified, making the effect of die-cutting tabs more uniform. In addition, the second portion 132 can also provide more space for folding tabs.

[0091] In some embodiments, in the thickness direction b, the thickness range of the thinning portion 133 is 5 μm to 15 μm.

[0092] As a specific embodiment, the thickness of the thinning portion 133 can be, but is not limited to, set to 5μm, 10μm, 15μm.

[0093] Thus, the thinning portion 133 can not only improve the problem of the virtual edge between the active material layer 12 and the protective layer 13, but also effectively improve the burr problem.

[0094] As Figure 3 shown, in some embodiments, in the width direction a, the thinning portion 133 includes a connecting section 134 and an embedding section 135. The embedding section 135 is located between the current collector 11 and the active material layer 12 along the thickness direction b, and the connecting section 134 is connected between the embedding section 135 and the first portion 131 along the width direction a.

[0095] Specifically, the thinning portion 133 includes a connecting section 134 and an embedding section 135 that are connected to each other. The connecting section 134 is connected between the first portion 131 and the embedding section 135. The embedding section 135 is located between the current collector 11 and the active material layer 12 along the thickness direction b, that is, the embedding section 135 is inserted between the current collector 11 and the active material layer 12.

[0096] By setting the embedding section 135, there is a partial overlap between the thinning portion 133 and the active material layer 12. In this way, the probability that a gap is generated between the active material layer 12 and the protective layer 13 to expose the current collector 11 can be further reduced.

[0097] In some embodiments, in the width direction a, the width range of the embedding section 135 is 0.5mm to 1mm. And / or, in the width direction a, the width range of the connecting section 134 is 0.5mm to 1mm.

[0098] Specifically, in the width direction a, the width range of the embedding section 135 is set to 0.5mm to 1mm, and the width direction a of the connecting section 134 is set to 0.5mm to 1mm.

[0099] As a specific embodiment, the width of the embedding section 135 can be, but is not limited to, set to 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, and the width of the connecting section 134 can be, but is not limited to, set to 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm.

[0100] Among them, setting the width of the embedding section 135 within the above range can make the active material layer 12 and the protective layer 13 overlap better and reduce the probability of generating a gap between the two. Setting the width of the connecting section 134 within the above range can better match the die-cutting range and make the ear root fall smoothly on the thicker first portion 131.

[0101] In some embodiments, in the width direction a, the width of the first part 131 ranges from 3 mm to 8 mm.

[0102] As a specific embodiment, the width of the first part 131 can be, but is not limited to, set to 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm.

[0103] The first part 131 is the part with the largest thickness in the protective layer 13, and its main function is to improve the burr problem and cover the burrs. Therefore, setting the width of the first part 131 within the above range can better match the die-cutting area, enable the die-cutting tab root to smoothly fall on the first part 131, effectively improve the burr problem, and cover the burrs.

[0104] In some embodiments, in the width direction a, the width of the second part 132 ranges from 2 mm to 12 mm.

[0105] As a specific embodiment, the width of the second part 132 can be, but is not limited to, set to 2 mm, 4 mm, 6 mm, 8 mm, 10 mm, 12 mm.

[0106] Specifically, on the one hand, the second part 132 can cover the burrs, and on the other hand, the width of the second part 132 affects the space for folding the tabs. Therefore, setting the width of the second part 132 within the above range can provide a larger space for folding the tabs on the basis of smoothly covering the burrs.

[0107] Based on the same concept as the above-mentioned pole piece 10, the present application also provides a battery device (not shown in the figure), including a box body and battery cells disposed inside the box body, and the battery cells include the pole piece 10 as described above.

[0108] Specifically, the battery cell usually includes a housing and an electrode assembly disposed inside the housing, and the electrode assembly includes a stacked positive electrode sheet 10, a separator, and a negative electrode sheet 10, wherein at least one of the positive electrode sheet 10 and the negative electrode sheet 10 is the pole piece 10 as described above.

[0109] Please refer to Figure 4 、 Figure 5 、 Figure 6 and Figure 7, based on the same concept as the above-mentioned electrode sheet 10, the present application also provides a coating die head 20 for coating the electrode sheet 10 as described above. The interior of the coating die head 20 has a material storage cavity 21, and the coating die head 20 is provided with a first discharge port 22 and a second discharge port 23 that are respectively communicated with the material storage cavity 21. The first discharge port 22 is used for coating the first part 131 of the protective layer 13, and the second discharge port 23 is used for coating the second part 132 of the protective layer 13. Among them, along the transportation direction c of the electrode sheet 10, the width D1 of the first discharge port 22 is greater than the width D2 of the second discharge port 23.

[0110] Specifically, the coating die head 20 refers to a structure for coating the protective layer 13 on the current collector 11. The interior of the coating die head 20 is provided with a material storage cavity 21, and a feed port communicated with the material storage cavity 21 is opened on the coating die head 20. The slurry can be filled into the material storage cavity 21 through the feed port.

[0111] Furthermore, the coating die head 20 is provided with a first discharge port 22 and a second discharge port 23. Both the first discharge port 22 and the second discharge port 23 are communicated with the material storage cavity 21, so that the slurry in the material storage cavity 21 can be extruded through the first discharge port 22 and the second discharge port 23 to achieve coating.

[0112] The transportation direction c of the electrode sheet 10 is the feeding direction of the electrode sheet 10, which is usually set as the length direction of the electrode sheet 10. That is to say, the transportation direction c of the electrode sheet 10 is perpendicular to the width direction a of the electrode sheet 10.

[0113] When the coating die head 20 coats the electrode sheet 10, the coating die head 20 is usually arranged directly above the current collector 11. Both the first discharge port 22 and the second discharge port 23 are arranged facing the surface of the current collector 11. The slurry is extruded from the first discharge port 22 and the second discharge port 23 and can be smoothly coated on the current collector 11.

[0114] Along the transportation direction c of the electrode sheet 10, the width of the first discharge port 22 is greater than the width of the second discharge port 23. Thus, the thickness of the slurry extruded from the first discharge port 22 is larger. When the slurry is coated on the current collector 11, the thickness of the part corresponding to the first discharge port 22 is greater than the part corresponding to the second discharge port 23.

[0115] Therefore, when the coating die head 20 performs coating, the part coated corresponding to the first discharge port 22 forms the first part 131 of the protective layer 13, and the part coated corresponding to the second discharge port 23 forms the second part 132 of the protective layer 13.

[0116] With the above structure, the coating die head 20 can simultaneously coat the first part 131 and the second part 132 with different thicknesses, so that the formed electrode sheet 10 can provide as much space as possible for folding the tab while improving the burr problem.

[0117] In some embodiments, a thinning outlet 24 communicating with the first discharge port 22 is further provided on the coating die head 20. The thinning outlet 24 is located on the side of the first discharge port 22 away from the second discharge port 23 along the width direction a of the electrode sheet 10. Wherein, along the transport direction c of the electrode sheet 10, the width D3 of the thinning outlet 24 is smaller than the width D1 of the first discharge port 22.

[0118] Specifically, the thinning outlet 24 communicates with the first discharge port 22, and the thinning outlet 24 is located on the side of the first discharge port 22 away from the second discharge port 23 along the width direction a of the electrode sheet 10. Wherein, the width of the thinning outlet 24 is smaller than the width of the first discharge port 22.

[0119] Thus, the first discharge port 22 and the thinning outlet 24 can simultaneously extrude the slurry, and the thickness of the slurry extruded from the thinning outlet 24 is smaller than the thickness of the slurry extruded from the first discharge port 22.

[0120] In this way, through the settings of the thinning outlet 24 and the first discharge port 22, the first part 131 and the thinning part 133 of the protective layer 13 can be respectively coated and formed on the current collector 11, and the thinning part 133 is located between the first part 131 and the active material layer 12, which can effectively improve the problem of virtual edges generated between the active material layer 12 and the protective layer 13.

[0121] In some embodiments, the storage cavity 21 includes independent first and second sub-cavities 211 and 212. The first sub-cavity 211 communicates with the first discharge port 22, and the second sub-cavity 212 communicates with the second discharge port 23.

[0122] Specifically, the storage cavity 21 is divided into independent first and second sub-cavities 211 and 212, and the first and second sub-cavities 211 and 212 can be fed through their respective feed ports. Wherein, the first sub-cavity 211 communicates with the first discharge port 22, and the second sub-cavity 212 communicates with the second discharge port 23.

[0123] During the coating process, the first and second sub-cavities 211 and 212 can respectively achieve independent feeding of the first and second discharge ports 22 and 23, and the feeding pressure and feeding speed can be adjusted more flexibly according to the different opening sizes of the first and second discharge ports 22 and 23, so that the first part 131 and the second part 132 can be coated more smoothly.

[0124] In some embodiments, along the transport direction c of the electrode tab 10, the depth range of the first sub-cavity 211 is 0.3 mm to 0.8 mm. And / or, along the transport direction c of the electrode tab 10, the depth range of the second sub-cavity 212 is 0.4 mm to 1 mm.

[0125] As a specific embodiment, the depth of the first sub-cavity 211 can be but is not limited to being set to 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm. The depth of the second sub-cavity 212 can be but is not limited to being set to 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm.

[0126] Specifically, along the transport direction c of the electrode tab 10, the depth range of the first sub-cavity 211 can be set to 0.3 mm to 0.8 mm, and the depth range of the second sub-cavity 212 can be set to 0.4 mm to 1 mm. The depths of the first sub-cavity 211 and the second sub-cavity 212 will affect the filling amount of the slurry in the first sub-cavity 211 and the second sub-cavity 212, and further affect the pressure and speed when extruding the slurry.

[0127] Based on this, setting the depths of the first sub-cavity 211 and the second sub-cavity 212 within the above ranges respectively can better control the pressure and speed during the coating process, making the coating of the first part 131 and the second part 132 more stable.

[0128] As Figure 8 shown, in some embodiments, the coating die head 20 includes an upper die head 25 and a lower die head 26 that jointly enclose to form a storage cavity 21. The upper die head 25 has a first upper lip 251 and a second upper lip 252, the lower die head 26 has a first lower lip 261 and a second lower lip 262. A first discharge port 22 is formed by the interval between the first upper lip 251 and the first lower lip 261, and a second discharge port 23 is formed by the interval between the second upper lip 252 and the second lower lip 262. Among them, along the thickness direction b of the electrode tab 10, the first upper lip 251 is set to be retracted inward relative to the first lower lip 261 in a direction away from the electrode tab 10, and the second upper lip 252 is set to be retracted inward relative to the second lower lip 262 in a direction away from the electrode tab 10.

[0129] Specifically, the coating die head 20 is usually assembled by the upper die head 25 and the lower die head 26. In addition, the coating die head 20 usually further includes a gasket, and the gasket is arranged between the upper die head 25 and the lower die head 26. A storage cavity 21 can be formed by grooving on the surface of the upper die head 25 facing the lower die head 26, or a storage cavity 21 can be formed by grooving on the surface of the lower die head 26 facing the upper die head 25. Of course, half-grooves can also be opened on both the upper die head 25 and the lower die head 26 at the same time, and the storage cavity 21 is formed by the mutual enclosure of the two half-grooves.

[0130] Further, the upper die head 25 has a first upper lip 251 and a second upper lip 252, and the lower die head 26 has a first lower lip 261 and a second lower lip 262. When the upper die head 25 and the lower die head 26 are assembled with each other to form the coating die head 20, the first upper lip 251 and the first lower lip 261 cooperate with each other, and a first discharge port 22 and a thinning outlet 24 are formed at an interval therebetween. The second upper lip 252 and the second lower lip 262 cooperate with each other, and a second discharge port 23 is formed at an interval therebetween.

[0131] Along the thickness direction b of the pole piece 10, the first upper lip 251 is retracted inward relative to the first lower lip 261 in a direction away from the pole piece 10, and the second upper lip 252 is retracted inward relative to the second lower lip 262 in a direction away from the pole piece 10. Thus, a certain amount of lip misalignment is formed between the first upper lip 251 and the first lower lip 261, and a certain amount of lip misalignment is formed between the second upper lip 252 and the second lower lip 262.

[0132] It should be noted that when the upper lip and the lower lip are flush, the lip opening located downstream along the transportation direction c of the pole piece 10 will affect the slurry coated on the current collector 11. That is, the upper lip or the lower lip may scrape off a part of the slurry coated on the current collector 11, affecting the thickness of the coated slurry.

[0133] Therefore, in order not to affect the thickness of the coated slurry, the current coating die head 20 usually needs to have a certain distance between the discharge port and the current collector 11. However, in this way, the supporting force of the pole piece 10 on the slurry during the coating process is insufficient, and the pole piece 10 will generate a certain amount of jitter during transportation, making the thickness of the coated slurry uneven.

[0134] Thus, by setting the lip misalignment amount between the first upper lip 251 and the first lower lip 261, and setting the lip misalignment amount between the second upper lip 252 and the second lower lip 262, the first discharge port 22 and the second discharge port 23 can abut against the surface of the pole piece 10, enabling the pole piece 10 to provide support for the slurry, so that the slurry can be more stably coated onto the pole piece 10, and the thickness of the formed protective layer 13 is more uniform.

[0135] In some embodiments, the retraction range between the first upper lip 251 and the first lower lip 261 is 50 μm to 100 μm. And / or, the retraction range between the second upper lip 252 and the second lower lip 262 is 30 μm to 60 μm.

[0136] Specifically, the retraction range between the first upper lip 251 and the first lower lip 261 can be set to 50 μm to 100 μm, and the retraction range between the second upper lip 252 and the second lower lip 262 can be set to 30 μm to 60 μm.

[0137] As a specific embodiment, the amount of retraction between the first upper lip 251 and the first lower lip 261 may but is not limited to being set to 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, and the amount of retraction between the second upper lip 252 and the second lower lip 262 may but is not limited to being set to 30 μm, 40 μm, 50 μm, 60 μm.

[0138] Furthermore, the retraction range between the first upper lip 251 and the first lower lip 261 and the retraction range between the second upper lip 252 and the second lower lip 262 will affect the specific thicknesses of the first portion 131, the second portion 132, and the thinning portion 133 formed by the slurry on the electrode sheet 10.

[0139] Therefore, setting the retraction ranges between the first upper lip 251 and the first lower lip 261 and between the second upper lip 252 and the second lower lip 262 within the above ranges respectively makes the thicknesses of the first portion 131, the second portion 132, and the thinning portion 133 on the electrode sheet 10 more uniform.

[0140] As Figure 9 and Figure 10 shown, based on the same concept as the coating die head 20 described above, the present application further provides a coating device 100, including at least one first die head 30, and the first die head 30 is the coating die head 20 as described above.

[0141] In some embodiments, the coating device 100 includes a conveying roller 40 and a first supporting roller 50 that are used to convey the electrode sheet 10 and are sequentially arranged along the conveying direction c of the electrode sheet 10. Each first die head 30 corresponds to the first supporting roller 50 one by one, and is respectively arranged on opposite sides of the electrode sheet 10 along the thickness direction b of the electrode sheet 10. The first supporting roller 50 is used to provide a pressing force against the corresponding first die head 30 to the electrode sheet 10.

[0142] Specifically, both the conveying roller 40 and the first supporting roller 50 are used to convey the electrode sheet 10, and the conveying roller 40 may include a plurality of them, which are sequentially arranged along the conveying direction c of the electrode sheet 10, so that the electrode sheet 10 is more stable during transportation.

[0143] The first die head 30 may be set to one, or may be set to two or more. The specific number of the first die heads 30 can be adjusted according to the position of the protective layer 13 that needs to be coated actually, and will not be elaborated here.

[0144] The first support roller 50 is arranged corresponding to the first die head 30 one by one, that is, each first support roller 50 and each first die head 30 form a group. The first support roller 50 and the first die head 30 in each group are respectively located on opposite sides of the pole piece 10 along the thickness direction b of the pole piece 10. In this way, the first support roller 50 supports the pole piece 10 along the thickness direction b of the pole piece 10, and then the corresponding first die head 30 abuts against the surface of the pole piece 10, so that the pole piece 10 can be better coated.

[0145] By arranging the conveying roller 40 and the first support roller 50, the smooth conveyance of the pole piece 10 can be realized. At the same time, the first support roller 50 cooperates with the corresponding first die head 30, which can provide a more stable supporting force for the pole piece 10, make the coating process more stable, and make the thickness of the coated protective layer 13 more uniform.

[0146] In some embodiments, the coating device 100 further includes a second die head 60 and a second support roller 70 which are respectively arranged on opposite sides of the pole piece 10 along the thickness direction b. The second support roller 70 is used to provide a contact force with the pole piece 10 to the second die head 60. The second die head 60 is used to coat the active material layer 12, and the second die head 60 is located on at least one side of all the first die heads 30 along the conveying direction c of the pole piece 10.

[0147] Specifically, the second die head 60 and the second support roller 70 are respectively arranged on opposite sides of the pole piece 10 along the thickness direction b of the pole piece 10. The pole piece 10 is wound around the second support roller 70, and the second die head 60 abuts against the surface of the pole piece 10, and the active material layer 12 is coated on the pole piece 10 through the second die head 60.

[0148] Furthermore, the second die head 60 can be arranged upstream of all the first die heads 30 along the conveying direction c of the pole piece 10, or can be arranged downstream of all the first die heads 30 along the conveying direction c of the pole piece 10. That is, the active material layer 12 can be formed by coating through the second die head 60 first, and then the protective layer 13 can be formed by coating through the first die head 30; or the protective layer 13 can be formed by coating through the first die head 30 first, and then the active material layer 12 can be formed by coating through the second die head 60.

[0149] Through the above structure, the active material layer 12 can be coated on the pole piece 10, and the supporting force during the coating process is provided by the second support roller 70, so that the thickness of the active material layer 12 is more uniform.

[0150] In some embodiments, the coating device 100 further includes an oven 80, and the oven 80 is arranged downstream of the first die head 30 and the second die head 60 along the conveying direction c of the pole piece 10.

[0151] After the electrode sheet 10 is coated with the active material layer 12 and the protective layer 13, the electrode sheet 10 enters the oven 80 along the transport direction c. In the oven 80, the coated active material layer 12 and the protective layer 13 on the electrode sheet 10 are dried. Thus, by providing the oven 80, the electrode sheet 10 after coating the active material layer 12 and the protective layer 13 can be quickly dried.

[0152] In some embodiments, the coating device 100 further includes a first control valve 91, a second control valve 92, a first pipeline 93, and a second pipeline 94. The first pipeline 93 is communicated with the first discharge port 22, and the first control valve 91 is disposed on the first pipeline 93 and is used to control the on / off of the first pipeline 93. The second pipeline 94 is communicated with the second discharge port 23, and the second control valve 92 is disposed on the second pipeline 94 and is used to control the on / off of the second pipeline 94.

[0153] Specifically, both the first control valve 91 and the second control valve 92 can be configured as screw pumps. Usually, the slurry is stored in the transfer tank 95. One end of the first pipeline 93 is communicated with the transfer tank 95, and the other end is communicated with the first discharge port 22. Among them, the first control valve 91 is disposed on the first pipeline 93. When the first control valve 91 is opened, the first pipeline 93 communicates the transfer tank 95 and the first discharge port 22, and the slurry in the transfer tank 95 can be conveyed to the first discharge port 22 and then extruded from the first discharge port 22 to complete the coating.

[0154] Furthermore, one end of the second pipeline 94 is also communicated with the transfer tank 95, and the other end is communicated with the second discharge port 23. Among them, the second control valve 92 is disposed on the second pipeline 94. When the second control valve 92 is opened, the second pipeline 94 communicates the transfer tank 95 and the second discharge port 23, and the slurry in the transfer tank 95 can be conveyed to the second discharge port 23 and then extruded from the second discharge port 23 to complete the coating.

[0155] By providing the first control valve 91 and the second control valve 92, the discharging of the first discharge port 22 and the second discharge port 23 can be independently controlled. In this way, the first control valve 91 and the second control valve 92 can respectively control the pressure in the first pipeline 93 and the second pipeline 94, realize the pressure build-up design in the first sub-chamber 211 and the second sub-chamber 212, and reduce the probability of mutual interference between the first discharge port 22 and the second discharge port 23.

[0156] According to one or more embodiments, when the present application is in use, first, the feeding pressures in the first pipeline 93 and the second pipeline 94 are adjusted, and the first pipeline 93 and the second pipeline 94 are cut off or communicated by the first control valve 91 and the second control valve 92.

[0157] Transfer the slurry from the intermediate tank 95 into the first sub-chamber 211 and the second sub-chamber 212, and then realize the slurry coating of the first part 131, the second part 132, and the thinning part 133 through the first discharge port 22, the second discharge port 23, and the thinning outlet 24 respectively. In this way, the first part 131, the second part 132, and the thinning part 133 with different thicknesses can be formed on the current collector 11.

[0158] Furthermore, the coating of the active material layer 12 on the current collector 11 can be realized through the second die head 60. After the coating is completed, the electrode sheet 10 is sent into the oven 80 for drying.

[0159] After drying, the electrode tab of the electrode sheet 10 can be die-cut. During the die-cutting process, the root of the electrode tab just falls on the first part 131. Since the thickness of the first part 131 is relatively large, it can effectively reduce the probability of burr generation and can well cover the burrs.

[0160] After the electrode tab die-cutting is completed, subsequent processes such as folding the electrode tab are still required. When folding the electrode tab, since the thickness of the second part 132 is relatively small, it can provide a larger space for folding the electrode tab, thereby improving the performance of the battery cell.

[0161] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0162] The above-described embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A pole piece, characterized in that, include: A current collector, comprising a first region and a second region located at at least one side of the first region along a width direction of the current collector; an active material layer, coated on the first region; and A protective layer is coated on the second area, the protective layer includes a first part and a second part connected to each other, the first part is located between the active material layer and the second part along the width direction, and the thickness of the first part is greater than the thickness of the second part along the thickness direction of the current collector.

2. The pole piece according to claim 1, characterized in that, The protective layer further includes a thinned portion connected between the first portion and the active material layer along the width direction, and a thickness of the thinned portion in the thickness direction is smaller than a thickness of the first portion.

3. The pole piece according to claim 2, characterized in that, In the thickness direction, the thickness of the first portion ranges from 15 μm to 40 μm.

4. The pole piece according to claim 2, wherein In the thickness direction, the thickness of the second portion ranges from 5 μm to 15 μm.

5. The pole piece according to claim 2, characterized in that, In the thickness direction, the thickness of the thinned portion ranges from 5 μm to 15 μm.

6. The pole piece according to any one of claims 2-5, characterized in that, In the width direction, the thinned portion includes a connecting segment and an embedding segment, the embedding segment is located between the current collector and the active material layer along the thickness direction, and the connecting segment is connected between the embedding segment and the first portion along the width direction.

7. The pole piece according to claim 6, characterized in that, In the width direction, the width of the embedded section ranges from 0.5 mm to 1 mm; and / or, in the width direction, the width of the connecting section ranges from 0.5 mm to 1 mm.

8. The pole piece according to claim 1, wherein, In the width direction, the width of the first part ranges from 3 mm to 8 mm.

9. The pole piece according to claim 1, wherein In the width direction, the width of the second portion ranges from 2 mm to 12 mm.

10. A battery device, characterized in that, It comprises a box body and a battery cell arranged inside the box body, and the battery cell comprises a pole piece as claimed in any one of claims 1 to 9.

11. A coating die, characterized in that, Used for coating the pole piece according to any one of claims 1 to 9, the coating die head has a material storage cavity inside, and the coating die head is provided with a first discharge port and a second discharge port respectively connected to the material storage cavity, the first discharge port is used for coating the first part of the protective layer, and the second discharge port is used for coating the second part of the protective layer; Wherein, along the transport direction of the electrode piece, the width of the first discharge port is greater than the width of the second discharge port.

12. The coating die according to claim 11, wherein The coating die head is also provided with a thinning outlet connected with the first outlet, and the thinning outlet is located on a side of the first outlet away from the second outlet along the width direction of the electrode piece; Wherein, along the transport direction of the electrode piece, the width of the thinning outlet is smaller than the width of the first discharge outlet.

13. The coating die according to claim 11, wherein The material storage chamber comprises a first sub-chamber and a second sub-chamber which are independent of each other, the first sub-chamber is communicated with the first discharge port, and the second sub-chamber is communicated with the second discharge port.

14. The coating die according to claim 13, characterized in that, Along the transport direction of the pole piece, the depth of the first sub-cavity ranges from 0.3 mm to 0.8 mm; and / or, along the transport direction of the pole piece, the depth of the second sub-cavity ranges from 0.4 mm to 1 mm.

15. The coating die according to claim 11, characterized in that, The coating die head includes an upper die head and a lower die head that jointly enclose to form the material storage cavity. The upper die head has a first upper lip and a second upper lip, and the lower die head has a first lower lip and a second lower lip. A first discharge port is formed at an interval between the first upper lip and the first lower lip, and a second discharge port is formed at an interval between the second upper lip and the second lower lip. Wherein, along the thickness direction of the electrode sheet, the first upper lip is set to be retracted away from the electrode sheet relative to the first lower lip, and the second upper lip is set to be retracted away from the electrode sheet relative to the second lower lip.

16. The coating die according to claim 15, characterized in that, The retraction range between the first upper lip and the first lower lip is 50 μm to 100 μm; and / or, the retraction range between the second upper lip and the second lower lip is 30 μm to 60 μm.

17. A coating device, characterized in that, It includes at least one first die head, and the first die head is the coating die head according to any one of claims 11-16.

18. The coating device according to claim 17, characterized in that, The coating device includes a conveying roller and a first support roller that are used for conveying the electrode sheet and are sequentially arranged along the conveying direction of the electrode sheet. Each of the first die heads corresponds to the first support roller one by one, and is respectively arranged on opposite sides of the electrode sheet along the thickness direction of the electrode sheet. The first support roller is used to provide a pressing force against the electrode sheet to the corresponding first die head.

19. The coating device according to claim 18, wherein, The coating device further includes a second die head and a second support roller that are respectively arranged on opposite sides of the electrode sheet along the thickness direction. The second support roller is used to provide a pressing force against the electrode sheet to the second die head. The second die head is used for coating the active material layer, and the second die head is located on at least one side of all the first die heads along the conveying direction of the electrode sheet.

20. The coating device according to claim 19, characterized in that, The coating device further includes an oven, and the oven is arranged downstream of the first die head and the second die head along the conveying direction of the electrode sheet.

21. The coating device according to claim 17, characterized in that, The coating device further includes a first control valve, a second control valve, a first pipeline, and a second pipeline. The first pipeline is communicated with the first discharge port, and the first control valve is arranged on the first pipeline and is used to control the on-off of the first pipeline; the second pipeline is communicated with the second discharge port, and the second control valve is arranged on the second pipeline and is used to control the on-off of the second pipeline.

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