Coating roller assembly, coating method, electrode sheet and battery

Abstract

The present application discloses a coating roller assembly, which is used for coating an electrode sheet of a battery. The coating roller assembly comprises: a coating roller; and coating portions which are provided around the coating roller, wherein the coating portions comprise a first coating portion, a second coating portion and a third coating portion; the first coating portion is configured to form a first coating layer portion, the second coating portion is configured to form a second coating layer portion, and the third coating portion is configured to form a third coating layer portion between the first coating layer portion and the second coating layer portion. The present application further discloses a coating method for using the coating roller assembly to coat an electrode sheet of a battery, an electrode sheet obtained by means of the coating roller assembly or the coating method, and a battery comprising the electrode sheet.

Description

Coating roller assembly, coating method, pole piece and battery Technical Field

[0001] The present application relates to the field of batteries, and in particular to a coating roller assembly, a coating method for coating a battery pole piece using the coating roller assembly, a pole piece obtained by the coating roller assembly or the coating method, and a battery including the pole piece. Background Art

[0002] Energy conservation and emission reduction are key to the sustainable development of the automotive industry. Electric vehicles, due to their energy-saving and environmentally friendly advantages, have become an important component of the sustainable development of the automotive industry. For electric vehicles, battery technology is a key factor in their development.

[0003] During actual use, various factors may cause lithium deposition in the battery's electrodes, deteriorating battery performance and safety. Therefore, there is a need in the art for technologies that can suppress this lithium deposition phenomenon.

[0004] Summary of the Invention

[0005] In view of the above problems, the present application provides a coating roller assembly that can improve or inhibit lithium deposition in the middle of a battery, a coating method for coating the battery pole piece using the coating roller assembly, and a battery obtained by the coating roller assembly or the coating method.

[0006] In a first aspect, the present application provides a coating roller assembly for coating a battery electrode, the coating roller assembly comprising:

[0007] coating roller; and

[0008] a coating portion, the coating portion being disposed around the coating roller;

[0009] wherein the coating part comprises a first coating part, a second coating part and a third coating part; and

[0010] The first coating portion is configured to form a first coating portion, the second coating portion is configured to form a second coating portion, and the third coating portion is configured to form a third coating portion between the first coating portion and the second coating portion.

[0011] By adopting at least a first coating portion, a second coating portion, and a third coating portion, when coating the battery pole piece, differentiated coating can be performed, that is, a coating layer including at least three coating portions is formed on the pole piece. By controlling or adjusting the coating parameters of the first coating portion, the second coating portion, and the third coating portion, such as the coating depth, the slurry conductivity, etc., the characteristics of each coating portion can be controlled or adjusted. For example, each coating portion can have a different diaphragm resistance, and the diaphragm resistance of the middle coating portion can be made greater than the diaphragm resistance of the side coating portions on both sides, thereby reducing the current density in the middle portion, improving lithium deposition in the middle of the battery cell, and improving the cycle performance and safety performance of the battery cell.

[0012] In some embodiments of the coating roller assembly, the coating roller includes at least a first coating roller and a second coating roller;

[0013] wherein the coating portion is disposed around the first coating roller and the second coating roller, respectively; and

[0014] Two of the first coating part, the second coating part, and the third coating part are provided on the first coating roller, and the other one of the first coating part, the second coating part, and the third coating part is provided on the second coating roller.

[0015] In some embodiments of the coating roller assembly, the first coating section and the second coating section are disposed on the first coating roller and define a spacer therebetween, and the third coating section is disposed on the second coating roller and positioned to correspond to the spacer. Any suitable combination of the three coating sections and the two coating rollers may be employed to flexibly meet actual production and design requirements.

[0016] In some embodiments of the coating roller assembly, the first coating portion, the second coating portion, and the third coating portion define a total coating width, wherein the coating width of the first coating portion is one-third of the total coating width, the coating width of the second coating portion is one-third of the total coating width, and the coating width of the third coating portion is slightly larger than one-third of the total coating width.

[0017] In some embodiments of the coating roller assembly, a coating width of the third coating portion is 0.5% to 2% greater than one-third of the total coating width.

[0018] In this case, an overlapping region may be formed between the third coating portion and the first and second coating portions, so as to form a complete coating on the electrode sheet of the battery.

[0019] In some embodiments of the coating roller assembly, the first coating portion, the second coating portion, and the third coating portion are disposed side by side on the coating roller, with the third coating portion being between the first coating portion and the second coating portion.

[0020] In some embodiments of the coating roller assembly, the first coating portion, the second coating portion, and the third coating portion define a total coating width, wherein the coating width of the first coating portion is slightly less than one-third of the total coating width, the coating width of the second coating portion is slightly less than one-third of the total coating width, and the coating width of the third coating portion is slightly less than one-third of the total coating width.

[0021] In some embodiments of the coating roller assembly, the coating width of the first coating portion is 0.5% to 2% smaller than one-third of the total coating width, the coating width of the second coating portion is 0.5% to 2% smaller than one-third of the total coating width, and the coating width of the third coating portion is 0.5% to 2% smaller than one-third of the total coating width.

[0022] In some embodiments of the coating roller assembly, a first gap is defined between the first coating portion and the third coating portion, and / or a second gap is defined between the second coating portion and the third coating portion.

[0023] In some embodiments of the coating roller assembly, the width of the first gap is the same as the width of the second gap.

[0024] The coating widths of the first coating part, the second coating part and the third coating part are all less than one-third of the total coating width, so that the first coating part, the second coating part and the third coating part can be separated from each other, which can prevent interference between the various coating parts when attaching the slurry and avoid mixing between different slurries.

[0025] In some embodiments of the coating roller assembly, the conductivity of the slurry coated by the first coating portion is the same as the conductivity of the slurry coated by the second coating portion.

[0026] In some embodiments of the coating roller assembly, the conductivity of the slurry applied by the third coating portion is less than the conductivity of the slurry applied by the first coating portion and the conductivity of the slurry applied by the second coating portion.

[0027] In some embodiments of the coating roller assembly, the conductive carbon content of the slurry coated by the first coating portion is 40% to 50%, the conductive carbon content of the slurry coated by the second coating portion is 40% to 50%, and the conductive carbon content of the slurry coated by the third coating portion is 5% to 20%.

[0028] In this case, the sheet resistance of the third coating portion formed on the electrode sheet by the third coating portion can be greater than the sheet resistance of the first coating portion formed on the electrode sheet by the first coating portion and the sheet resistance of the second coating portion formed on the electrode sheet by the second coating portion. This can adjust the internal current density distribution of the battery, reduce the current density in the central portion, improve lithium deposition in the central portion of the battery, and enhance the battery's cycling performance and safety.

[0029] In some embodiments of the coating roller assembly, a coating depth of the first coating portion is the same as a coating depth of the second coating portion.

[0030] In some embodiments of the coating roller assembly, a coating depth of the third coating portion is greater than a coating depth of the first coating portion and a coating depth of the second coating portion.

[0031] In some embodiments of the coating roller assembly, a coating depth of the third coating portion is 1.1 to 6.2 times greater than a coating depth of the first coating portion and / or a coating depth of the second coating portion.

[0032] Similarly, in this case, the sheet resistance of the third coating portion formed on the electrode piece by the third coating portion can be greater than the sheet resistance of the first coating portion formed on the electrode piece by the first coating portion and the sheet resistance of the second coating portion formed on the electrode piece by the second coating portion. This can adjust the internal current density distribution of the battery, reduce the current density in the middle portion, improve lithium deposition in the middle portion of the battery, and enhance the battery's cycle performance and safety.

[0033] In some embodiments of the coating roller assembly, the coating roller is a gravure roller.

[0034] In a second aspect, the present application provides a method for coating a battery electrode using the coating roller assembly described above, the method comprising the following steps:

[0035] Immersing the coating roller assembly into a material tank so that the first coating part, the second coating part, and the third coating part are respectively attached with slurry from corresponding material tanks;

[0036] The coating roller assembly is used to coat the electrode sheet, with the first coating portion forming a first coating portion on the electrode sheet, the second coating portion forming a second coating portion on the electrode sheet, and the third coating portion forming a third coating portion on the electrode sheet, wherein the third coating portion is located between the first coating portion and the second coating portion. The sheet resistance of the central coating portion thus formed can be greater than that of the side coating portions, thereby adjusting the internal current density distribution of the battery, reducing the current density in the central portion, improving lithium deposition in the central portion of the battery, and improving the battery's cycling performance and safety.

[0037] In some embodiments of the method, the method includes the following steps: coating one side of the pole piece with the coating roller assembly, and coating the other side of the pole piece with the coating roller assembly.

[0038] In some embodiments of the method, the method includes the following steps: after coating the pole piece with the coating roller assembly to form a coating, pressing the coating. By pressing the coating, the middle coating portion and the side coating portions can be expanded to their respective sides and contact each other, thereby ultimately forming a complete coating.

[0039] In a third aspect, the present application provides a pole piece, comprising a coating formed using the coating roller assembly or the method described above. Specifically, the pole piece comprises a coating, the coating comprising a first coating portion, a second coating portion, and a third coating portion, wherein the third coating portion is located between the first coating portion and the second coating portion.

[0040] In some embodiments of the pole piece, the first coating portion is formed by a first coating portion of the coating roller assembly, the second coating portion is formed by a second coating portion of the coating roller assembly, and the third coating portion is formed by a third coating portion of the coating roller assembly.

[0041] In some embodiments of the pole piece, the diaphragm resistance of the third coating portion formed on the pole piece by the third coating portion is greater than the diaphragm resistance of the first coating portion formed on the pole piece by the first coating portion and the diaphragm resistance of the second coating portion formed on the pole piece by the second coating portion.

[0042] In some embodiments of the pole piece, the diaphragm resistance of the third coating portion formed on the pole piece by the third coating portion is 1.1 to 6.2 times the diaphragm resistance of the first coating portion formed on the pole piece by the first coating portion and the diaphragm resistance of the second coating portion formed on the pole piece by the second coating portion.

[0043] In some embodiments of the pole piece, the conductivity of the first coating portion formed on the pole piece by the first coating portion is the same as the conductivity of the second coating portion formed on the pole piece by the second coating portion.

[0044] In some embodiments of the pole piece, the conductivity of the third coating portion formed on the pole piece by the third coating portion is less than the conductivity of the first coating portion formed on the pole piece by the first coating portion and the conductivity of the second coating portion formed on the pole piece by the second coating portion.

[0045] In some embodiments of the pole piece, the conductive carbon content of the first coating portion formed on the pole piece by the first coating portion is 40% to 50%, the conductive carbon content of the second coating portion formed on the pole piece by the second coating portion is 40% to 50%, and the conductive carbon content of the third coating portion formed on the pole piece by the third coating portion is 5% to 20%.

[0046] In some embodiments of the pole piece, a thickness of a first coating portion formed on the pole piece by the first coating portion is the same as a thickness of a second coating portion formed on the pole piece by the second coating portion.

[0047] In some embodiments of the pole piece, the thickness of the third coating portion formed on the pole piece by the third coating portion is greater than the thickness of the first coating portion formed on the pole piece by the first coating portion and the thickness of the second coating portion formed on the pole piece by the second coating portion.

[0048] In some embodiments of the pole piece, the thickness of the third coating portion formed on the pole piece by the third coating portion is 1.1 to 6.2 times the thickness of the first coating portion formed on the pole piece by the first coating portion and / or the thickness of the second coating portion formed on the pole piece by the second coating portion.

[0049] In a fourth aspect, the present application provides a battery comprising the electrode as described above.

[0050] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0052] FIG1 is a perspective view of a coating roller assembly according to some embodiments of the present application;

[0053] FIG2 is a perspective view of a first coating roller and a corresponding coating portion of the coating roller assembly shown in FIG1 ;

[0054] FIG3 is a cross-sectional view of the first coating roller and the corresponding coating portion of the coating roller assembly shown in FIG1 ;

[0055] FIG4 is a perspective view of a second coating roller and a corresponding coating portion of the coating roller assembly shown in FIG1 ;

[0056] FIG5 is a cross-sectional view of the second coating roller and the corresponding coating portion of the coating roller assembly shown in FIG1 ;

[0057] FIG6 is a perspective view of a coating roller assembly according to other embodiments of the present application;

[0058] FIG7 is a cross-sectional view of the coating roller assembly shown in FIG6; and

[0059] FIG8 is a perspective view of the coating roller assembly shown in FIG6, also showing a trough corresponding to the coating portion.

[0060] The figure numbers in the specific embodiment are as follows: Coating roller assembly 3; Coating roller 30; Longitudinal axis 300; Outer circumference 330; First gap 332; Second gap 334; First coating roller 32; First longitudinal axis 320; First outer circumference 322; Spacer 324; Second coating roller 34; Second longitudinal axis 340; Second outer circumference 342; Coating portion 36; First coating portion 362; Second coating portion 364; Third coating portion 366; Material trough 40; First material trough 402; Second material trough 404; Third material trough 406. DETAILED DESCRIPTION

[0061] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0062] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0063] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0064] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0065] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0066] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0067] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0068] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0069] Currently, market developments indicate that power batteries are becoming increasingly widely used. They are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace. As power battery applications continue to expand, market demand is also growing.

[0070] However, batteries face many problems in these applications, such as lithium plating. Lithium plating is a relatively common problem in batteries, significantly impacting their performance, safety, and service life. Therefore, it is necessary to suppress the occurrence of lithium plating in batteries.

[0071] There are many factors that can cause lithium deposition in batteries. After in-depth mechanistic research and multiple experimental analyses, the inventors of this application discovered that during actual battery use, the expansion force and temperature at different locations may vary. Such differences can cause the current density in the middle of the large surface of the electrode to be higher, exceeding the lithium deposition limit, which can lead to lithium deposition in the middle area of ​​the electrode, deteriorating the performance and safety of the battery.

[0072] To this end, this application considers solving the problem of lithium deposition in the middle of the battery electrode by reducing the current density in the middle of the electrode. Specifically, when applying the slurry to the battery electrode through a coating roller, a differentiated coating method is adopted, that is, different coatings are applied to different positions on the electrode to increase the membrane resistance in the middle of the electrode, thereby reducing the current density in the middle, improving lithium deposition in the middle of the battery cell, and improving the cycling performance and safety performance of the battery cell.

[0073] Specifically, multiple coating sections can be formed on a coating roller. By varying the coating parameters of each coating section, the relative sheet resistance differences between different locations on the electrode sheet can be generated or altered, thereby increasing the sheet resistance in the center of the electrode sheet and reducing the current density in the center. For example, different coating sections can be coated with slurries of varying conductivity, resulting in a coating with varying sheet resistance at different locations on the electrode sheet. Alternatively, different coating sections can be applied at varying depths, similarly resulting in a coating with varying sheet resistance at different locations on the electrode sheet.

[0074] The coating roller assembly and its use method disclosed in the embodiments of this application are used to coat a battery electrode, forming a coating on one or both sides of the electrode. Using the coating roller assembly and its use method disclosed in the embodiments of this application can reduce the current density in the central portion of the battery, improve lithium deposition in the central portion, and enhance the battery's cycling performance and safety.

[0075] The battery formed by the coating roller assembly and the method of using the same disclosed in the embodiments of the present application can be used as a power source for electrical devices, which may include but are not limited to mobile phones, tablets, laptops, electric toys, power tools, battery-powered vehicles, electric vehicles, ships, spacecraft, etc. Among them, electric toys may include fixed or mobile electric toys, such as game consoles, electric vehicle toys, electric ship toys, and electric airplane toys, etc., and spacecraft may include airplanes, rockets, space shuttles, and spacecraft, etc.

[0076] According to some embodiments of the present application, referring to Figures 1-8, which respectively show perspective and cross-sectional views of a coating roller assembly 3 according to the present application, the coating roller assembly 3 is used to coat a battery electrode to form a coating on one or both sides of the electrode.

[0077] According to the present application, a coating roller assembly 3 is provided for coating a battery electrode. The coating roller assembly 3 includes a coating roller 30 and a coating section 36 disposed around the coating roller 30. The coating section 36 includes a first coating section 362, a second coating section 364, and a third coating section 366. The first coating section 362 is configured to form a first coating section, the second coating section 364 is configured to form a second coating section, and the third coating section 366 is configured to form a third coating section between the first and second coating sections.

[0078] Specifically, the coating roller assembly 3 according to the present application may include a coating roller 30, which may have, for example, a roughly cylindrical shape to facilitate roller coating of the pole piece. Accordingly, the coating roller 30 defines an outer circumference 320. The number of coating rollers 30 may be selected according to the needs of the actual application, for example, two coating rollers (as shown in the embodiments of Figures 1-5), one coating roller (as shown in the embodiments of Figures 6-8), or any other suitable number of coating rollers. Each coating roller may have its own longitudinal axis, which is an axis passing through the center of the cylinder and extending in the axial direction of the cylinder.

[0079] The coating roller assembly 3 according to the present application may further include a coating portion 36 , which may be disposed around the outer circumference 320 of the coating roller 30 , such that as the coating roller 30 rolls on the pole piece, the coating portion 36 can coat the slurry onto the pole piece.

[0080] The "coating portion" described herein is a component provided on a coating roller for applying the slurry to the pole piece of the battery, and is also generally referred to as a coating area. The coating portion can be connected to the coating roller in a variety of ways. For example, the coating portion can be formed integrally with the coating roller, for example, by machining the coating roller to form the coating portion. Alternatively, the coating portion can also be fixedly attached to the coating roller. When the coating roller is used to coat the pole piece, the coating roller and the coating portion can be immersed in a material tank so that the slurry in the material tank adheres to the coating portion, and when the coating roller rolls on the pole piece of the battery, the coating portion applies the slurry attached thereto to the pole piece to form a coating on the pole piece.

[0081] According to some embodiments of the present application, the coating roller assembly 3 may include multiple coating sections, such as at least a first coating section 362, a second coating section 364, and a third coating section 366. These coating sections cooperate with each other to coat the battery electrode. The number of coating sections may be determined based on actual application needs; for example, the coating roller assembly 3 may include more than three coating sections.

[0082] The first coating portion 362 can be configured to form a first coating portion, the second coating portion 364 can be configured to form a second coating portion, and the third coating portion 366 can be configured to form a third coating portion located between the first coating portion and the second coating portion. For example, the first coating portion 362 and the second coating portion 364 can be configured to form side coating portions on both sides of the battery's electrode, and the third coating portion 366 can be configured to form a middle coating portion in the middle of the battery's electrode, such that the middle coating portion is located between the side coating portions. The battery's electrode is typically a long, strip-shaped sheet extending along its length or longitudinal direction. The above-mentioned "both sides of the battery's electrode" and "the middle of the battery's electrode" refer to the width direction or transverse direction of the electrode perpendicular to the length or longitudinal direction, that is, the two sides and the middle of the electrode along the width direction. The formed side coating portions extend along the length of the electrode sheet on both sides of the battery electrode sheet, and the formed middle coating portion extends along the length of the electrode sheet in the middle of the battery electrode sheet, so that the coating formed on the battery electrode sheet by the coating roller assembly 3 includes three coating portions extending along the length of the electrode sheet and arranged side by side. The side coating portions on both sides can extend to the edge of the electrode sheet in the width direction or can be spaced apart from the edge of the electrode sheet.

[0083] In the illustrated embodiment, three coating portions 362, 364 and 364 are shown, however, those skilled in the art will appreciate that more than three coating portions may be employed without departing from the spirit and scope of the present application, so that the coating formed on the battery electrode can include more than three coating portions extending along the length of the electrode and arranged side by side.

[0084] By adopting at least a first coating portion 362, a second coating portion 364 and a third coating portion 366, when coating the battery electrode, differentiated coating can be performed, that is, a coating comprising at least three coating portions is formed on the electrode. By controlling or adjusting the coating parameters of the first coating portion 362, the second coating portion 364 and the third coating portion 366, such as coating depth, slurry conductivity, etc., the characteristics of each coating portion can be controlled or adjusted, for example, so that each coating portion has a different diaphragm resistance. In some embodiments, the diaphragm resistance of the middle coating portion can be made greater than the diaphragm resistance of the side coating portions on both sides, thereby reducing the current density in the middle, improving lithium deposition in the middle of the battery cell, and improving the cycle performance and safety performance of the battery cell.

[0085] According to some embodiments of the present application, as shown in Figures 1-5, the coating roller 30 includes at least a first coating roller 32 and a second coating roller 34. The coating portion 36 is respectively arranged around the first coating roller 32 and the second coating roller 34. Two of the first coating portion 362, the second coating portion 364, and the third coating portion 366 are arranged on the first coating roller 32, and the other of the first coating portion 362, the second coating portion 364, and the third coating portion 366 is arranged on the second coating roller 34.

[0086] Specifically, the coating roller assembly 3 may include at least two coating rollers, such as a first coating roller 32 and a second coating roller 34. The first coating roller 32 and the second coating roller 34 may be separated from each other and may coat the battery's pole pieces separately or successively. Each coating roller may have approximately the same shape, for example, the first coating roller 32 and the second coating roller 34 may both have a substantially cylindrical shape to facilitate roller coating of the pole pieces. Accordingly, the first coating roller 32 may define a first outer circumference 322, and the second coating roller 34 may define a second outer circumference 342. In addition, each coating roller may have its own longitudinal axis, that is, the first coating roller 32 has a first longitudinal axis 320, and the second coating roller 34 has a second longitudinal axis 340, and the first longitudinal axis 320 and the second longitudinal axis 340 are axes passing through the center of the cylinder and extending in the axial direction of the cylinder, as shown in Figures 1-5.

[0087] As shown in Figures 3 and 5, the first coating roller 32 can have a width W1 measured along the first longitudinal axis 320 (this dimension corresponds to the width of the coating to be formed on the electrode sheet and is therefore defined herein as the width). Similarly, the second coating roller 34 can have a width W2 measured along the second longitudinal axis 340. The width W1 of the first coating roller 32 and the width W2 of the second coating roller 34 can be the same, for example, 800 mm, but can also be different.

[0088] The first coating portion 362, the second coating portion 364, and the third coating portion 366 are respectively disposed around the first outer circumference 322 of the first coating roller 32 and the second outer circumference 342 of the second coating roller 34. Specifically, two of the first coating portion 362, the second coating portion 364, and the third coating portion 366 may be disposed on the first outer circumference 322 of the first coating roller 32, and the other of the first coating portion 362, the second coating portion 364, and the third coating portion 366 may be disposed on the second outer circumference 342 of the second coating roller 34. For example, the first coating portion 362 and the second coating portion 364 may be disposed on the first coating roller 32, and the third coating portion 366 may be disposed on the second coating roller 34. Alternatively, the first coating portion 362 and the third coating portion 366 may be disposed on the first coating roller 32, and the second coating portion 364 may be disposed on the second coating roller 34. Alternatively, the second coating part 364 and the third coating part 366 are provided on the first coating roller 32 , and the first coating part 362 is provided on the second coating roller 34 .

[0089] The three coating sections and the two coating rollers can be combined in any suitable manner to flexibly meet actual production and design requirements. In other embodiments, the coating roller assembly 3 may include more than two coating rollers, for example, three coating rollers, with each coating section being provided on a corresponding coating roller. The number of coating sections can be equal to or greater than the number of coating rollers, such that each coating roller is provided with at least one coating section.

[0090] According to some embodiments of the present application, the first coating portion 362 and the second coating portion 364 are disposed on the first coating roller 32 and define a spaced area 324 therebetween, and the third coating portion 366 is disposed on the second coating roller 34 and positioned to correspond to the spaced area 324 .

[0091] 2-3 , the first coating portion 362 and the second coating portion 364 may be disposed on the first outer circumference 322 of the first coating roller 32 and may be spaced apart from each other so as to define a spacer 324 between the first coating portion 362 and the second coating portion 364. When both the first coating portion 362 and the second coating portion 364 are disposed on the first coating roller 32, when coating a battery electrode, as the first coating roller 32 rolls on the electrode, first and second coating portions are formed on the battery electrode via the first coating portion 362 and the second coating portion 364.

[0092] As shown in Figures 4-5, the third coating portion 366 can be disposed on the second outer circumference 342 of the second coating roller 34. When coating the battery electrode, as the second coating roller 34 rolls on the electrode, a third coating portion is formed on the battery electrode via the third coating portion 366. According to the embodiment shown in Figures 4-5, the third coating portion 366 can be positioned to correspond to the spacer 324. The third coating portion 366 corresponding to the spacer 324 means that the position of the third coating portion 366 on the second coating roller 34 is roughly equivalent to the position of the spacer 324 on the first coating roller 32. For example, when the first coating roller 32 and the second coating roller 34 are aligned with each other, the third coating portion 366 and the spacer 324 are also aligned with each other.

[0093] Generally, it is desirable that the side coating portions on both sides of a battery electrode have the same characteristics. Therefore, disposing the first coating portion 362 and the second coating portion 364 forming the side coating portions on the first coating roller 32 can reduce operational complexity. For example, the first coating portion 362 and the second coating portion 364 can be coated with the same slurry from the same material tank, rather than having to obtain slurry from different material tanks for the first coating portion 362 and the second coating portion 364. Disposing the third coating portion 366 to correspond to the spacer 324 also facilitates alignment during coating, allowing the middle coating portion to be more ideally positioned between the side coating portions.

[0094] According to some embodiments of the present application, the first coating portion 362, the second coating portion 364 and the third coating portion 366 define a total coating width, wherein the coating width of the first coating portion 362 is one-third of the total coating width, the coating width of the second coating portion 364 is one-third of the total coating width, and the coating width of the third coating portion 366 is greater than one-third of the total coating width.

[0095] According to some embodiments of the present application, the coating width of the third coating portion 366 is 0.5% to 2% greater than one third of the total coating width.

[0096] Specifically, the first coating portion 362, the second coating portion 364, and the third coating portion 366 define a total coating width W. T . Total coating width W T It is the dimension along the longitudinal axis of the coating roller, corresponding to the width of the coating layer finally formed on the electrode of the battery by the coating roller assembly 3 .

[0097] As shown in FIG. 3 , the first coating portion 362 defines a coating width W along the first longitudinal axis 320 of the first coating roller 32 . L , the coating width W L The dimension of the first coating portion 362 measured along the first longitudinal axis 320 of the first coating roller 32 (i.e., the width dimension of the first coating portion 362) is roughly equivalent to the width of the first coating portion formed on the pole piece by the first coating portion 362. L The total coating width W T One third of .

[0098] Likewise, the second coating portion 364 defines a coating width W along the first longitudinal axis 320 of the first coating roller 32. R , the coating width W R The dimension of the second coating portion 364 measured along the first longitudinal axis 320 of the first coating roller 32 (i.e., the width dimension of the second coating portion 364) is roughly equivalent to the width of the second coating portion formed on the pole piece by the second coating portion 364. R The total coating width W T One third of .

[0099] The spacing region 324 between the first coating portion 362 and the second coating portion 364 defines a width W measured along the first longitudinal axis 320 of the first coating roller 32. S , the width W S It can also be the total coating width W T Thus, the coating width W of the first coating portion 362 is L , coating width W of the second coating portion 364 R and the width W of the spacer 324 S The sum is equal to the total coating width W T , as shown in Figure 3.

[0100] As shown in FIG. 5 , the third coating portion 366 defines a coating width W along the second longitudinal axis 340 of the second coating roller 34 . M , the coating width W MThe dimension of the third coating portion 366 measured along the second longitudinal axis 340 of the second coating roller 34 (i.e., the width dimension of the third coating portion 366) is roughly equivalent to the width of the third coating portion formed on the pole piece by the third coating portion 366. M Can be slightly larger than the total coating width W T Here, “slightly larger than” may refer to the coating width W of the third coating portion 366. M Ratio to total coating width W T For example, the coating width W of the third coating portion 366 is 0.5% to 2%. M The total coating width W T One third plus 2 mm.

[0101] In one embodiment, the total coating width W T It can be, for example, 600 mm. Accordingly, the coating width W of the first coating portion 362 is L The coating width W of the second coating portion 364 is 200 mm. R The width W of the spacer 324 is 200 mm. S The coating width W of the third coating portion 366 is 200 mm, as shown in FIG3 . M It is slightly larger than 200 mm, for example, it may be 202 mm, as shown in FIG5 .

[0102] Coating width W of the first coating portion 362 L The coating width W of the second coating portion 364 is R The width of the first coating portion formed by the first coating portion 362 on the electrode piece is the same as the width of the second coating portion formed by the second coating portion 364 on the electrode piece. M Slightly larger than the coating width W of the first coating portion 362 L and the coating width W of the second coating portion 364 R , so that the width of the third coating portion formed on the electrode piece by the third coating portion 366 can be slightly larger than the width of the first coating portion formed on the electrode piece by the first coating portion 362 and the width of the second coating portion formed on the electrode piece by the second coating portion 364. As a result, an overlapping area can be formed between the middle coating portion and the side coating portions, so as to form a complete coating on the battery electrode piece.

[0103] According to some other embodiments of the present application, the first coating part 362 , the second coating part 364 and the third coating part 366 are disposed side by side on the coating roller 30 , and the third coating part 366 is located between the first coating part 362 and the second coating part 364 .

[0104] Specifically, as shown in Figures 6-7, the coating roller assembly 3 may include a single coating roller 30. In this case, the first coating portion 362, the second coating portion 364, and the third coating portion 366 may be arranged side by side on the outer circumference 320 of the coating roller 30, so that the third coating portion 366 is between the first coating portion 362 and the second coating portion 364. The single coating roller 30 may have a generally cylindrical shape to facilitate roller coating of the electrode sheet. The coating roller 30 may have a longitudinal axis 300, which is an axis passing through the center of the cylinder and extending in the axial direction of the cylinder, as shown in Figures 6-7. In addition, the coating roller 30 may have a width W measured along the longitudinal axis 300. In one embodiment, the width W may be, for example, 800 mm.

[0105] The coating roller assembly 3 adopts a single coating roller 30, which can simplify the structure and reduce costs. At the same time, since the single coating roller 30 still has a first coating part 362, a second coating part 364 and a third coating part 366, the purpose of this application can also be achieved. Differentiated coating is applied to the battery pole pieces through multiple coating parts to control or adjust the diaphragm resistance of the middle coating part to reduce the current density in the middle, improve lithium deposition in the middle of the battery cell, and improve the cycle performance and safety performance of the battery cell.

[0106] According to some other embodiments of the present application, the first coating portion 362, the second coating portion 364 and the third coating portion 366 define a total coating width, wherein the coating width of the first coating portion 362 is less than one-third of the total coating width, the coating width of the second coating portion 364 is less than one-third of the total coating width, and the coating width of the third coating portion 366 is less than one-third of the total coating width.

[0107] According to other embodiments of the present application, the coating width of the first coating portion 362 is 0.5% to 2% smaller than one-third of the total coating width, the coating width of the second coating portion 364 is 0.5% to 2% smaller than one-third of the total coating width, and the coating width of the third coating portion 366 is 0.5% to 2% smaller than one-third of the total coating width.

[0108] Specifically, as shown in FIG. 7 , the first coating portion 362 , the second coating portion 364 and the third coating portion 366 define a total coating width W T . Total coating width W T It is the dimension along the longitudinal axis 300 of the coating roller 30 , corresponding to the width of the coating layer ultimately formed by the coating roller assembly 3 on the electrode of the battery.

[0109] As shown in FIG. 7 , the first coating portion 362 defines a coating width W along the longitudinal axis 300 of the coating roller 30 . L , the coating width W LThe width W of the first coating portion 362 is approximately equal to the dimension of the first coating portion 362 measured along the longitudinal axis 300 of the coating roller 30 (ie, the width dimension of the first coating portion 362 ), corresponding to the width of the first coating portion formed on the electrode by the first coating portion 362 . L Can be slightly smaller than the total coating width W T Here, “slightly less than” may refer to the coating width W of the first coating portion 362. L Ratio to total coating width W T For example, the coating width W of the first coating portion 362 is 0.5% to 2%. L The total coating width W T One third minus 2 mm.

[0110] The second coating portion 364 defines a coating width W along the longitudinal axis 300 of the coating roller 30. R , the coating width W R The coating width W is roughly equivalent to the dimension of the second coating portion 364 measured along the longitudinal axis 300 of the coating roller 30 (ie, the width dimension of the second coating portion 364), corresponding to the width of the second coating portion formed by the second coating portion 364 on the pole piece. R Can be slightly smaller than the total coating width W T Here, “slightly less than” may refer to the coating width W of the second coating portion 364. R Ratio to total coating width W T For example, the coating width W of the second coating portion 364 is 0.5% to 2% smaller than the third coating width W. R The total coating width W T One third minus 2 mm.

[0111] Likewise, the third coating portion 366 defines a coating width W along the longitudinal axis 300 of the coating roller 30. M , the coating width W M The width W of the third coating portion 366 is approximately equal to the dimension of the third coating portion 366 measured along the longitudinal axis 300 of the coating roller 30 (ie, the width dimension of the third coating portion 366 ), corresponding to the width of the third coating portion formed on the electrode piece by the third coating portion 366 . M Can be slightly smaller than the total coating width W T Here, “slightly less than” may refer to the coating width W of the third coating portion 366. M Ratio to total coating width W T For example, the coating width W of the third coating portion 366 is 0.5% to 2% smaller. M The total coating width W T One third minus 2 mm.

[0112] The coating widths of the first coating portion 362, the second coating portion 364, and the third coating portion 366 are all smaller than the total coating width W. T One third of the coating portion 362, the second coating portion 364 and the third coating portion 366 can be separated from each other, which can prevent interference between the coating portions when the slurry is attached and avoid mixing between different slurries.

[0113] In one embodiment, the coating width W of the first coating portion 362 is L , coating width W of the second coating portion 364 R and the coating width W of the third coating portion 366 M They may be the same so that the width of the first coating portion formed by the first coating portion 362 on the pole piece, the width of the second coating portion formed by the second coating portion 364 on the pole piece, and the width of the third coating portion formed by the third coating portion 366 on the pole piece are the same.

[0114] In one embodiment, the total coating width W T It can be, for example, 600 mm. Accordingly, the coating width W of the first coating portion 362 is L Less than 200 mm, for example, 198 mm, the coating width W of the second coating portion 364 R Less than 200 mm, for example, 198 mm, the coating width W of the third coating portion 366 M Less than 200 mm, for example, 198 mm, as shown in FIG7 .

[0115] According to some other embodiments of the present application, a first gap 332 is included between the first coating portion 362 and the third coating portion 366 , and / or a second gap 334 is included between the second coating portion 364 and the third coating portion 366 .

[0116] According to some other embodiments of the present application, the width of the first gap 332 is the same as the width of the second gap 334 .

[0117] Specifically, the coating widths of the first coating portion 362, the second coating portion 364, and the third coating portion 366 are all smaller than the total coating width W. T One third of the coating roller 30, therefore, when the first coating portion 362, the second coating portion 364 and the third coating portion 366 are arranged side by side on the outer circumference 320 of the coating roller 30, a first gap 332 can be defined between the first coating portion 362 and the third coating portion 366, and / or a second gap 334 can be defined between the second coating portion 364 and the third coating portion 366, as shown in FIG. 7 .

[0118] The first gap 332 may have a width G along the longitudinal axis 300 of the coating roller 30. L , the second gap 334 may have a width G along the longitudinal axis 300 of the coating roller 30 R In one embodiment, the width G L and width G R Of course, those skilled in the art will understand that the width G L and width G R It can also be different.

[0119] The coating width W of the first coating portion 362 L , coating width W of the second coating portion 364 R and the coating width W of the third coating portion 366 M When the width is 198 mm, the width G L It can be, for example, 3 mm, with a width G R It may also be, for example, 3 mm, as shown in FIG7 .

[0120] The first coating portion 362 , the second coating portion 364 and the third coating portion 366 are evenly separated from each other, which can help avoid mixing between different slurries and facilitate the formation of each coating portion.

[0121] According to some embodiments of the present application, the conductivity of the slurry applied by the first coating part 362 is the same as the conductivity of the slurry applied by the second coating part 364 .

[0122] Specifically, the conductivity of the slurry applied by the first coating portion 362 can be the same as the conductivity of the slurry applied by the second coating portion 364, so that the first coating portion formed on the electrode by the first coating portion 362 and the second coating portion formed on the electrode by the second coating portion 364 can have the same diaphragm resistance. In one embodiment, the first coating portion 362 and the second coating portion 364 can apply the same slurry. When the first coating portion 362 and the second coating portion 364 are arranged on the outer circumference 322 of the first coating roller 32, the first coating portion 362 and the second coating portion 364 can share the same material tank, reducing the number of operating steps and lowering costs.

[0123] According to some embodiments of the present application, the conductivity of the slurry applied by the third coating part 366 is lower than the conductivity of the slurry applied by the first coating part 362 and the conductivity of the slurry applied by the second coating part 364 .

[0124] Specifically, the conductivity of the slurry applied by the third coating portion 366 can be lower than the conductivity of the slurry applied by the first coating portion 362 and the conductivity of the slurry applied by the second coating portion 364. This allows the third coating portion formed on the electrode by the third coating portion 366 to have a sheet resistance greater than the sheet resistance of the first coating portion formed on the electrode by the first coating portion 362 and the sheet resistance of the second coating portion formed on the electrode by the second coating portion 364. This can adjust the internal current density distribution of the battery, reduce the current density in the middle, improve lithium deposition in the middle of the battery, and enhance the battery's cycle performance and safety.

[0125] According to some embodiments of the present application, the conductive carbon content of the slurry coated by the first coating part 362 is 40% to 50%, the conductive carbon content of the slurry coated by the second coating part 364 is 40% to 50%, and the conductive carbon content of the slurry coated by the third coating part 366 is 5% to 20%.

[0126] Specifically, the conductive carbon content of the slurry applied by the first coating part 362 can be 40% to 50%, and accordingly, the conductive carbon content of the slurry applied by the second coating part 364 can be 40% to 50%. In this case, the conductive carbon content of the slurry applied by the third coating part 366 can be 5% to 20%. In this case, the first coating part formed on the electrode by the first coating part 362 and the second coating part formed on the electrode by the second coating part 364 can have the same sheet resistance, while the third coating part formed on the electrode by the third coating part 366 can have a sheet resistance greater than the sheet resistance of the first coating part formed on the electrode by the first coating part 362 and the sheet resistance of the second coating part formed on the electrode by the second coating part 364. In addition, through the design of the above-mentioned conductive carbon content, the ratio of the diaphragm resistance of the third coating part formed by the third coating part 366 on the pole piece to the diaphragm resistance of the first coating part formed by the first coating part 362 on the pole piece can be within the range of 1.1 to 6.2, and / or the ratio of the diaphragm resistance of the third coating part formed by the third coating part 366 on the pole piece to the diaphragm resistance of the second coating part formed by the second coating part 364 on the pole piece can be within the range of 1.1 to 6.2.

[0127] According to some embodiments of the present application, the coating depth of the first coating portion 362 and the coating depth of the second coating portion 364 can be the same. The coating depth can correspond to the dimension of the coating portion along the radial direction perpendicular to the longitudinal axis of the coating roller, and corresponds to the thickness of the coating portion formed by each coating portion on the electrode of the battery. The coating depth of the first coating portion 362 is the same as the coating depth of the second coating portion 364, so that the first coating portion formed on the electrode by the first coating portion 362 and the second coating portion formed on the electrode by the second coating portion 364 can have the same sheet resistance. In one embodiment, the coating depth of the first coating portion 362 can be, for example, 28 microns, and the coating depth of the second coating portion 364 can also be, for example, 28 microns.

[0128] According to some embodiments of the present application, the coating depth of the third coating portion 366 can be greater than the coating depth of the first coating portion 362 and the coating depth of the second coating portion 364, so that the sheet resistance of the third coating portion formed by the third coating portion 366 on the electrode can be greater than the sheet resistance of the first coating portion formed by the first coating portion 362 on the electrode and the sheet resistance of the second coating portion formed by the second coating portion 364 on the electrode. In this way, the internal current density distribution of the battery can be adjusted, the current density in the middle can be reduced, the lithium plating phenomenon in the middle of the battery can be improved, and the cycle performance and safety performance of the battery can be improved. In one embodiment, the coating depth of the third coating portion 366 can be, for example, 56 microns.

[0129] Specifically, the coating depth of third coating portion 366 can be 1.1 to 6.2 times the coating depth of first coating portion 362 and / or the coating depth of second coating portion 364. In this case, the ratio of the sheet resistance of the third coating portion formed on the electrode by third coating portion 366 to the sheet resistance of the first coating portion formed on the electrode by first coating portion 362 can be within a range of 1.1 to 6.2, and / or the ratio of the sheet resistance of the third coating portion formed on the electrode by third coating portion 366 to the sheet resistance of the second coating portion formed on the electrode by second coating portion 364 can be within a range of 1.1 to 6.2. For example, as described above, the coating depths of first coating portion 362 and second coating portion 364 can both be 28 microns, while the coating depth of third coating portion 366 can be 56 microns, for example.

[0130] By controlling, adjusting and designing the coating parameters of the first coating part 362, the second coating part 364 and the third coating part 366, such as the conductivity of the coated slurry, the coating depth, etc., the relationship between the sheet resistance of the third coating part formed on the electrode by the third coating part 366 and the sheet resistance of the first coating part formed on the electrode by the first coating part 362 and the sheet resistance of the second coating part formed on the electrode by the second coating part 364 can be controlled and adjusted, thereby adjusting the internal current density distribution of the battery, reducing the current density in the middle, improving the lithium deposition phenomenon in the middle of the battery, and improving the cycle performance and safety performance of the battery. The above-mentioned limitations on the coating parameters of the first coating part 362, the second coating part 364 and the third coating part 366 can be applied to all embodiments of the present application, that is, whether it includes a single coating roller or multiple coating rollers, and whether the number of coating parts is three or more.

[0131] Furthermore, the coating parameters can be adjusted individually or in combination. For example, the conductivity of the slurry applied by the first coating section 362, the second coating section 364, and the third coating section 366 can be individually controlled, adjusted, and designed to achieve a desired relationship between the sheet resistance of the middle coating section and the sheet resistance of the side coating sections. The coating depths of the first coating section 362, the second coating section 364, and the third coating section 366 can be individually controlled, adjusted, and designed to achieve a desired relationship between the sheet resistance of the middle coating section and the sheet resistance of the side coating sections. Alternatively, the two can be combined, i.e., the coating depths of the first coating section 362, the second coating section 364, and the third coating section 366 and the conductivity of the applied slurry can be simultaneously controlled, adjusted, and designed to achieve a desired relationship between the sheet resistance of the middle coating section and the sheet resistance of the side coating sections.

[0132] According to some embodiments of the present application, the coating roller 30 may be a gravure roller, thereby applying gravure coating, such as micro-gravure coating, to the battery electrode. Specifically, a single coating roller 30 may be a gravure roller. In the case of multiple coating rollers, the first coating roller 32 may be a gravure roller, and the second coating roller 34 may also be a gravure roller.

[0133] According to some embodiments of the present application, the present application further provides a method for coating a battery electrode using the above-mentioned coating roller assembly 3, comprising: immersing the coating roller assembly 3 in a material tank, so that the first coating portion 362, the second coating portion 364, and the third coating portion 366 are respectively attached with slurry from the corresponding material tank; using the coating roller assembly 3 to coat the electrode, forming a first coating portion on the electrode by the first coating portion 362, forming a second coating portion on the electrode by the second coating portion 364, and forming a third coating portion on the electrode by the third coating portion 366. The third coating portion is located between the first coating portion and the second coating portion.

[0134] Specifically, the method includes the following steps.

[0135] The coating roller assembly 3 is immersed in the material tank, so that the first coating part 362, the second coating part 364 and the third coating part 366 are respectively attached with slurry from the corresponding material tanks.

[0136] When including a first coating roller 32 and a second coating roller 34, they can be immersed in separate tanks. For example, they can be immersed in different tanks so that the first coating portion 362, the second coating portion 364, and the third coating portion 366 are coated with slurries of different conductivity. For example, the first coating portion 362 and the second coating portion 364 are coated with slurry of higher conductivity, while the third coating portion 366 is coated with slurry of lower conductivity. In addition, in a scheme where differential coating is achieved by controlling the coating depth, the rollers can be immersed in the same or different tanks.

[0137] In the case of a single coating roller 30, the coating roller assembly 3 can be directly immersed in a trough. In this case, the trough can be a combination of multiple troughs. As shown in Figure 8, the trough 40 can include a first trough 402, a second trough 404, and a third trough 406. The first trough 402 corresponds to the first coating portion 362, the second trough 404 corresponds to the second coating portion 364, and the third trough 406 corresponds to the third coating portion 366. This allows the first coating portion 362 to be attached with slurry from the first trough 402, the second coating portion 364 to be attached with slurry from the second trough 404, and the third coating portion 366 to be attached with slurry from the third trough 406. The first trough 402, the second trough 404, and the third trough 406 can contain slurries with different electrical conductivities. For example, the first trough 402 and the second trough 404 can contain slurries with higher electrical conductivity, while the third trough 406 can contain slurries with lower electrical conductivity. Furthermore, in a solution where differential coating is achieved by controlling coating depth, the first tank 402 , the second tank 404 , and the third tank 406 may contain slurries having the same or different electrical conductivities.

[0138] After the slurry is applied to the first coating section 362, the second coating section 364, and the third coating section 366, the electrode sheet is coated using the coating roller assembly 3. The first and second coating sections 362 and 364 form the first and second coating sections on the electrode sheet, and the third coating section 366 forms the third coating section on the electrode sheet, so that the third coating section is located between the first and second coating sections. The sheet resistance of the third coating section formed in this way can be greater than the sheet resistance of the first and second coating sections, thereby adjusting the internal current density distribution of the battery, reducing the current density in the middle, improving the lithium deposition phenomenon in the middle of the battery, and improving the battery's cycle performance and safety performance.

[0139] According to some embodiments of the present application, the coating roller assembly 3 can be used to coat one side of the electrode piece, and the coating roller assembly 3 can be used to coat the other side of the electrode piece, that is, the coating roller assembly 3 can be used to coat both sides of the electrode piece. In the case of including a first coating roller 32 and a second coating roller 34, the first coating roller 32 and the second coating roller 34 are both used to coat one side of the electrode piece, and then coat the other side of the electrode piece.

[0140] According to some embodiments of the present application, after the electrode is coated with the coating roller assembly 3 to form a coating, the coating is pressed. In the case of a single coating roller 30, as described above, the coating widths of the first coating portion 362, the second coating portion 364, and the third coating portion 366 are all less than the total coating width W. T Therefore, a first gap 332 can be defined between the first coating portion 362 and the third coating portion 366, and / or a second gap 334 can be defined between the second coating portion 364 and the third coating portion 366. In this case, there will be a certain gap or interval between the third coating portion formed on the pole piece by the third coating portion 366 and the first coating portion formed on the pole piece by the first coating portion 362 and the second coating portion formed on the pole piece by the second coating portion 364, that is, the middle coating portion and the side coating portion may not be in contact. By pressing the coating, the middle coating portion and the side coating portion can be expanded to their respective sides and in contact with each other, so as to eventually form a complete coating.

[0141] According to some embodiments of the present application, the present application further provides a pole piece, which includes a coating formed using the coating roller assembly 3 described above or the method described above. Specifically, the pole piece includes a coating, which includes a first coating portion, a second coating portion, and a third coating portion, wherein the third coating portion is located between the first coating portion and the second coating portion.

[0142] As described above, the first coating portion may be formed by the first coating portion 362 of the coating roller assembly 3 , the second coating portion may be formed by the second coating portion 364 of the coating roller assembly 3 , and the third coating portion may be formed by the third coating portion 366 of the coating roller assembly 3 .

[0143] In some embodiments, the diaphragm resistance of the third coating portion formed on the pole piece by the third coating portion 366 can be greater than the diaphragm resistance of the first coating portion formed on the pole piece by the first coating portion 362 and the diaphragm resistance of the second coating portion formed on the pole piece by the second coating portion 364, thereby adjusting the internal current density distribution of the battery, reducing the current density in the middle, improving the lithium plating phenomenon in the middle of the battery, and improving the cycle performance and safety performance of the battery.

[0144] Specifically, the diaphragm resistance of the third coating portion formed on the pole piece by the third coating portion 366 can be 1.1 to 6.2 times the diaphragm resistance of the first coating portion formed on the pole piece by the first coating portion 362 and the diaphragm resistance of the second coating portion formed on the pole piece by the second coating portion 364.

[0145] In some embodiments, the conductivity of the first coating portion formed on the pole piece by the first coating portion 362 and the conductivity of the second coating portion formed on the pole piece by the second coating portion 364 may be the same.

[0146] In some embodiments, the conductivity of the third coating portion formed on the pole piece by the third coating portion 366 can be less than the conductivity of the first coating portion formed on the pole piece by the first coating portion 362 and the conductivity of the second coating portion formed on the pole piece by the second coating portion 364.

[0147] Specifically, the conductive carbon content of the first coating portion formed on the pole piece by the first coating portion 362 can be 40% to 50%, the conductive carbon content of the second coating portion formed on the pole piece by the second coating portion 364 can be 40% to 50%, and the conductive carbon content of the third coating portion formed on the pole piece by the third coating portion 366 can be 5% to 20%.

[0148] In some embodiments, the thickness of the first coating portion formed on the pole piece by the first coating portion 362 and the thickness of the second coating portion formed on the pole piece by the second coating portion 364 may be the same.

[0149] In some embodiments, the thickness of the third coating portion formed on the pole piece by the third coating portion 366 can be greater than the thickness of the first coating portion formed on the pole piece by the first coating portion 362 and the thickness of the second coating portion formed on the pole piece by the second coating portion 364.

[0150] Specifically, the thickness of the third coating portion formed on the pole piece by the third coating portion 366 can be 1.1 to 6.2 times the thickness of the first coating portion formed on the pole piece by the first coating portion 362 and / or the thickness of the second coating portion formed on the pole piece by the second coating portion 364.

[0151] According to some embodiments of the present application, the present application also provides a battery comprising the pole piece as described above.

[0152] Based on the above embodiment, compared with the comparative example, the results are as follows:

[0153] It can be seen that when the diaphragm resistance of the third coating part formed on the electrode by the third coating part 366 is 1.1 to 6.2 times the diaphragm resistance of the first and second coating parts formed on the electrode by the first coating part 362 and the second coating part 364, the occurrence of lithium deposition in the middle can be avoided, while if this ratio is too high or too low, lithium deposition in the middle may occur.

[0154] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A coating roller assembly (3) for coating a battery electrode, characterized in that: The coating roller assembly (3) comprises: a coating roller (30); and a coating portion (36), the coating portion (36) being arranged around the coating roller (30); wherein the coating portion (36) includes a first coating portion (362), a second coating portion (364) and a third coating portion (366); and The first coating portion (362) is configured to form a first coating portion, the second coating portion (364) is configured to form a second coating portion, and the third coating portion (366) is configured to form a third coating portion between the first coating portion and the second coating portion.

2. The coating roller assembly (3) according to claim 1, characterized in that: The coating roller (30) comprises at least a first coating roller (32) and a second coating roller (34); wherein the coating portion (36) is disposed around the first coating roller (32) and the second coating roller (34) respectively; and Wherein two of the first coating part (362), the second coating part (364) and the third coating part (366) are arranged on the first coating roller (32), and the other one of the first coating part (362), the second coating part (364) and the third coating part (366) is arranged on the second coating roller (34).

3. The coating roller assembly (3) according to claim 2, characterized in that: The first coating portion (362) and the second coating portion (364) are disposed on the first coating roller (32) and define a spacing area (324) between the first coating portion (362) and the second coating portion (364), and the third coating portion (366) is disposed on the second coating roller (34) and positioned to correspond to the spacing area (324).

4. The coating roller assembly (3) according to claim 2 or 3, characterized in that: The first coating portion (362), the second coating portion (364) and the third coating portion (366) define a total coating width, wherein the coating width of the first coating portion (362) is one third of the total coating width, the coating width of the second coating portion (364) is one third of the total coating width, and the coating width of the third coating portion (366) is greater than one third of the total coating width.

5. The coating roller assembly (3) according to claim 4, characterized in that: The coating width of the third coating portion (366) is 0.5% to 2% larger than one third of the total coating width.

6. The coating roller assembly (3) according to claim 1, characterized in that: The first coating part (362), the second coating part (364) and the third coating part (366) are arranged side by side on the coating roller (30), and the third coating part (366) is located between the first coating part (362) and the second coating part (364).

7. The coating roller assembly (3) according to claim 6, characterized in that: The first coating portion (362), the second coating portion (364) and the third coating portion (366) define a total coating width, wherein the coating width of the first coating portion (362) is less than one third of the total coating width, the coating width of the second coating portion (364) is less than one third of the total coating width, and the coating width of the third coating portion (366) is less than one third of the total coating width.

8. The coating roller assembly (3) according to claim 7, characterized in that: The coating width of the first coating portion (362) is 0.5% to 2% smaller than one third of the total coating width, the coating width of the second coating portion (364) is 0.5% to 2% smaller than one third of the total coating width, and the coating width of the third coating portion (366) is 0.5% to 2% smaller than one third of the total coating width.

9. The coating roller assembly (3) according to any one of claims 6 to 8, characterized in that: A first gap (332) is included between the first coating portion (362) and the third coating portion (366), and / or a second gap (334) is included between the second coating portion (364) and the third coating portion (366).

10. The coating roller assembly (3) according to claim 9, characterized in that: The width of the first gap (332) is the same as the width of the second gap (334).

11. The coating roller assembly (3) according to any one of claims 1 to 10, characterized in that: The conductivity of the slurry applied by the first coating part (362) is the same as the conductivity of the slurry applied by the second coating part (364).

12. The coating roller assembly (3) according to any one of claims 1 to 11, characterized in that: The conductivity of the slurry applied by the third coating part (366) is smaller than the conductivity of the slurry applied by the first coating part (362) and the conductivity of the slurry applied by the second coating part (364).

13. The coating roller assembly (3) according to any one of claims 1 to 12, characterized in that: The conductive carbon content of the slurry coated by the first coating part (362) is 40% to 50%, the conductive carbon content of the slurry coated by the second coating part (364) is 40% to 50%, and the conductive carbon content of the slurry coated by the third coating part (366) is 5% to 20%.

14. The coating roller assembly (3) according to any one of claims 1 to 13, characterized in that: The coating depth of the first coating portion (362) is the same as the coating depth of the second coating portion (364).

15. The coating roller assembly (3) according to any one of claims 1 to 14, characterized in that: The coating depth of the third coating portion (366) is greater than the coating depth of the first coating portion (362) and the coating depth of the second coating portion (364).

16. The coating roller assembly (3) according to any one of claims 1 to 15, characterized in that: The coating depth of the third coating portion (366) is 1.1 to 6.2 times the coating depth of the first coating portion (362) and / or the coating depth of the second coating portion (364).

17. The coating roller assembly (3) according to any one of claims 1 to 16, characterized in that: The coating roller (30) is a gravure roller.

18. A method for coating a battery pole piece using a coating roller assembly (3) according to any one of claims 1 to 17, characterized in that: The method comprises the following steps: Immersing the coating roller assembly (3) into a material tank, so that the first coating part (362), the second coating part (364) and the third coating part (366) are respectively attached with slurry from the corresponding material tanks; The pole piece is coated using the coating roller assembly (3), a first coating portion is formed on the pole piece by the first coating portion (362), a second coating portion is formed on the pole piece by the second coating portion (364), and a third coating portion is formed on the pole piece by the third coating portion (366), wherein the third coating portion is located between the first coating portion and the second coating portion.

19. The method according to claim 18, characterized in that The method comprises the following steps: using the coating roller assembly (3) to coat one side of the pole piece, and using the coating roller assembly (3) to coat the other side of the pole piece.

20. The method according to claim 18 or 19, characterized in that The method comprises the following steps: after coating the pole piece with the coating roller assembly (3) to form a coating layer, the coating layer is pressed.

21. A pole piece, characterized in that: The pole piece includes a coating, and the coating includes a first coating portion, a second coating portion, and a third coating portion, wherein the third coating portion is between the first coating portion and the second coating portion.

22. The pole piece according to claim 21, characterized in that: The coating is formed by a coating roller assembly (3), wherein the first coating portion is formed by a first coating portion (362) of the coating roller assembly (3), the second coating portion is formed by a second coating portion (364) of the coating roller assembly (3), and the third coating portion is formed by a third coating portion (366) of the coating roller assembly (3).

23. The pole piece according to claim 21 or 22, characterized in that: The sheet resistance of the third coating portion is greater than the sheet resistance of the first coating portion and the sheet resistance of the second coating portion.

24. The pole piece according to any one of claims 21 to 23, characterized in that: The sheet resistance of the third coating portion is 1.1 to 6.2 times the sheet resistance of the first coating portion, and is 1.1 to 6.2 times the sheet resistance of the second coating portion.

25. The pole piece according to any one of claims 21 to 24, characterized in that: The electrical conductivity of the first coating portion is the same as the electrical conductivity of the second coating portion.

26. A pole piece according to any one of claims 21 to 25, characterized in that: The electrical conductivity of the third coating portion is smaller than the electrical conductivity of the first coating portion and the electrical conductivity of the second coating portion.

27. A pole piece according to any one of claims 21 to 26, characterized in that: The conductive carbon content of the first coating portion is 40% to 50%, the conductive carbon content of the second coating portion is 40% to 50%, and the conductive carbon content of the third coating portion is 5% to 20%.

28. A pole piece according to any one of claims 21 to 27, characterized in that: The thickness of the first coating portion is the same as the thickness of the second coating portion.

29. A pole piece according to any one of claims 21 to 28, characterized in that: The thickness of the third coating portion is greater than the thickness of the first coating portion and the thickness of the second coating portion.

30. A pole piece according to any one of claims 21 to 29, characterized in that: The thickness of the third coating portion is 1.1 to 6.2 times the thickness of the first coating portion and / or the thickness of the second coating portion.

31. A battery comprising a pole piece according to any one of claims 21-30.

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