Coating roller assembly, coating method, pole piece and battery

Abstract

The invention discloses a coating roller assembly, which is used for coating a pole piece of a battery, and is characterized by comprising a coating roller, a coating roller, a coating device and a coating device, and a coating part, wherein the coating part is arranged around the coating roller; wherein the coating part comprises a first coating part, a second coating part and a third coating part; and wherein 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. The invention also discloses a coating method for coating the pole piece of the battery by using the coating roller assembly, the pole piece obtained by the coating roller assembly or the coating method, and the battery comprising the pole piece.

Description

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 the key to the sustainable development of the automobile industry. Electric vehicles have become an important part of the sustainable development of the automobile industry due to their advantages of energy conservation and environmental protection. For electric vehicles, battery technology is an important factor related to their development.

[0003] In actual application of batteries, various factors may cause lithium deposition in the battery pole piece, which deteriorates the battery performance and safety. Therefore, a technology capable of suppressing lithium deposition is needed in the art. Summary of the invention

[0004] 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 a battery electrode using the coating roller assembly, and a battery obtained by the coating roller assembly or the coating method.

[0005] In a first aspect, the present application provides a coating roller assembly for coating a pole piece of a battery, the coating roller assembly comprising:

[0006] coating roller; and

[0007] a coating part, the coating part being arranged around the coating roller;

[0008] wherein the coating part comprises a first coating part, a second coating part and a third coating part; and

[0009] 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.

[0010] By using at least the first coating part, the second coating part and the third coating part, when coating the pole piece of the battery, differential coating can be performed, that is, a coating including at least three coating parts is formed on the pole piece. By controlling or adjusting the coating parameters of the first coating part, the second coating part and the third coating part, such as coating depth, slurry conductivity, etc., the characteristics of each coating part can be controlled or adjusted, for example, each coating part has a different membrane resistance, and the membrane resistance of the middle coating part can be made greater than the membrane resistance of the side coating parts 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.

[0011] In some embodiments of the coating roller assembly, the coating roller includes at least a first coating roller and a second coating roller;

[0012] wherein the coating portion is disposed around the first coating roller and the second coating roller, respectively; and

[0013] Two of the first coating part, the second coating part and the third coating part are disposed on the first coating roller, and the other of the first coating part, the second coating part and the third coating part is disposed on the second coating roller.

[0014] In some embodiments of the coating roller assembly, the first coating part and the second coating part are arranged on the first coating roller and define a spacer area between the first coating part and the second coating part, and the third coating part is arranged on the second coating roller and positioned to correspond to the spacer area. Any suitable combination of the three coating parts and the two coating rollers can be adopted to flexibly meet the needs of actual production and design.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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, and the third coating portion is located between the first coating portion and the second coating portion.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] In some embodiments of the coating roller assembly, the width of the first gap is the same as the width of the second gap.

[0023] 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 coating parts when attaching the slurry and avoid mixing between different slurries.

[0024] 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.

[0025] In some embodiments of the coating roller assembly, the conductivity of the slurry coated by the third coating portion is less than the conductivity of the slurry coated by the first coating portion and the conductivity of the slurry coated by the second coating portion.

[0026] In some embodiments of the coating roller assembly, the conductive carbon content of the slurry coated by the first coating part is 40% to 50%, the conductive carbon content of the slurry coated by the second coating part is 40% to 50%, and the conductive carbon content of the slurry coated by the third coating part is 5% to 20%.

[0027] In this case, the sheet resistance of the third coating portion formed by the third coating portion on the pole piece can be greater than the sheet resistance of the first coating portion formed by the first coating portion on the pole piece and the sheet resistance of the second coating portion formed by the second coating portion on the pole piece. 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 deposition phenomenon in the middle of the battery can be improved, and the cycle performance and safety performance of the battery can be improved.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] Similarly, in this case, the third coating portion formed by the third coating portion on the pole piece may have a sheet resistance greater than the sheet resistance of the first coating portion formed by the first coating portion on the pole piece and the sheet resistance of the second coating portion formed by the second coating portion on the pole piece. 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 deposition phenomenon in the middle of the battery can be improved, and the cycle performance and safety performance of the battery can be improved.

[0032] In some embodiments of the coating roller assembly, the coating roller is a gravure roller.

[0033] In a second aspect, the present application provides a method for coating a battery electrode sheet using the coating roller assembly as described above, the method comprising the following steps:

[0034] 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 the corresponding material tanks;

[0035] The coating roller assembly is used to coat the pole piece, and the first coating part is used to form a first coating part on the pole piece, the second coating part is used to form a second coating part on the pole piece, and the third coating part is used to form a third coating part on the pole piece, wherein the third coating part is located between the first coating part and the second coating part. The membrane resistance of the middle coating part formed in this way can be greater than the membrane resistance of the side coating part, 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.

[0036] 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.

[0037] 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, the coating is pressed. By pressing the coating, the middle coating portion and the side coating portion can be extended to both sides of each other and contact each other to finally form a complete coating.

[0038] In a third aspect, the present application provides a pole piece, the pole piece comprising a coating formed by using the coating roller assembly as described above or the method as 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 between the first coating portion and the second coating portion.

[0039] 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.

[0040] 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.

[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 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.

[0042] 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.

[0043] 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.

[0044] 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%.

[0045] 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.

[0046] 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.

[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 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.

[0048] In a fourth aspect, the present application provides a battery comprising the pole piece as described above.

[0049] 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

[0050] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0051] Figure 1 is a perspective view of a coating roller assembly according to some embodiments of the present application;

[0052] Figure 2 for Figure 1 A perspective view of a first coating roller and a corresponding coating portion of the coating roller assembly is shown;

[0053] Figure 3 for Figure 1 A cross-sectional view of a first coating roller and a corresponding coating portion of the coating roller assembly shown;

[0054] Figure 4 for Figure 1 A perspective view of a second coating roller of the coating roller assembly and a corresponding coating portion is shown;

[0055] Figure 5 for Figure 1 A cross-sectional view of the second coating roller of the coating roller assembly and the corresponding coating portion;

[0056] Figure 6 is a perspective view of a coating roller assembly according to some other embodiments of the present application;

[0057] Figure 7 for Figure 6 A cross-sectional view of the coating roller assembly shown; and

[0058] Figure 8 for Figure 6 A perspective view of the coating roller assembly is shown, also showing the material channel corresponding to the coating section.

[0059] The reference numerals in the specific implementation manner are as follows:

[0060] Coating roller assembly 3;

[0061] Coating roller 30; longitudinal axis 300; outer circumference 330; first gap 332; second gap 334;

[0062] First coating roller 32; first longitudinal axis 320; first outer circumference 322; spacing region 324;

[0063] Second coating roller 34; second longitudinal axis 340; second outer circumference 342;

[0064] Coating portion 36; first coating portion 362; second coating portion 364; third coating portion 366;

[0065] Trough 40; first trough 402; second trough 404; third trough 406. DETAILED DESCRIPTION

[0066] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0067] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field 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" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0068] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0069] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0070] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0071] 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).

[0072] 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. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which 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 referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0073] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0074] At present, from the perspective of market development, the application of power batteries is becoming more and more extensive. 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 vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the continuous expansion of the application field of power batteries, the market demand is also constantly expanding.

[0075] However, there are many problems with batteries in these applications, such as lithium plating. Lithium plating is a relatively easy problem in batteries, which has a great impact on the performance, safety and service life of batteries. Therefore, it is necessary to suppress the occurrence of lithium plating in batteries.

[0076] There are many factors that lead to lithium deposition in batteries. After in-depth mechanism research and multiple experimental analyses, the inventors of this application found that in actual use of batteries, the expansion force and temperature at different positions may be different. Such differences may cause the current density in the middle of the large surface of the pole piece to be larger, so that it exceeds the lithium deposition limit, which may cause lithium deposition in the middle area of ​​the pole piece, deteriorating the performance and safety of the battery.

[0077] To this end, the present application considers solving the problem of lithium deposition in the middle of the battery pole piece by reducing the current density in the middle of the pole piece. Specifically, when applying slurry to the pole piece of the battery through a coating roller, differentiated coating is adopted, that is, different coating is performed for different positions on the pole piece, and the membrane resistance in the middle of the pole piece is increased, 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.

[0078] Specifically, multiple coating parts can be formed on the coating roller, and the relative diaphragm resistance difference between different positions of the pole piece can be generated or changed by changing the coating parameters of each coating part, so as to increase the diaphragm resistance at the middle position of the pole piece and reduce the current density in the middle. For example, different coating parts are attached with slurries with different conductivity, so that the coating coated on the pole piece has different diaphragm resistance at different positions. Alternatively, different coating parts use different coating depths, which also makes the coating coated on the pole piece have different diaphragm resistance at different positions.

[0079] The coating roller assembly and the use method thereof disclosed in the embodiment of the present application are used to coat the pole piece of the battery to form a coating on one side or both sides of the pole piece. The coating roller assembly and the use method thereof disclosed in the embodiment of the present application can reduce the current density in the middle of the battery, improve the lithium deposition in the middle of the battery, and improve the cycle performance and safety performance of the battery.

[0080] The battery formed by the coating roller assembly and the method of using the same disclosed in the embodiment of the present application can be used as a power source for an electric device, which can be, but is not limited to, a mobile phone, a tablet, a laptop, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, etc. Among them, the electric toy can include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc., and the spacecraft can include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0081] According to some embodiments of the present application, reference Figure 1-8 , which respectively show a perspective view and a cross-sectional view of a coating roller assembly 3 according to the present application. The coating roller assembly 3 is used to coat the pole piece of the battery to form a coating on one side or both sides of the pole piece.

[0082] According to the present application, a coating roller assembly 3 is provided for coating a pole piece of a battery. The coating roller assembly 3 includes: a coating roller 30; and a coating portion 36, which is arranged around the coating roller 30. The coating portion 36 includes a first coating portion 362, a second coating portion 364, and a third coating portion 366. 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.

[0083] Specifically, the coating roller assembly 3 according to the present application may include a coating roller 30, and the coating roller 30 may have, for example, a substantially cylindrical shape, so as to facilitate roller coating of the electrode 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 (such as Figure 1-5 ), a coating roller (such as Figure 6-8 ), or any other suitable number of coating rollers. Each coating roller may have a respective longitudinal axis, which is an axis passing through the center of the cylinder and extending in the axial direction of the cylinder.

[0084] 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 , so that as the coating roller 30 rolls on the pole piece, the coating portion 36 can coat the slurry onto the pole piece.

[0085] The "coating portion" described herein is a component disposed on a coating roller for applying the slurry to the pole piece of the battery, 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 on 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.

[0086] According to some embodiments of the present application, the coating roller assembly 3 may include multiple coating parts, such as at least a first coating part 362, a second coating part 364, and a third coating part 366, which cooperate with each other to coat the battery pole piece. The number of coating parts can be determined according to the needs of the actual application, for example, the coating roller assembly 3 may include more than three coating parts.

[0087] The first coating portion 362 may be configured to form a first coating portion, the second coating portion 364 may be configured to form a second coating portion, and the third coating portion 366 may be configured to form a third coating portion between the first coating portion and the second coating portion. For example, the first coating portion 362 and the second coating portion 364 may be configured to form side coating portions on both sides of the battery's pole piece, and the third coating portion 366 may be configured to form a middle coating portion in the middle of the battery's pole piece, so that the middle coating portion is located between the side coating portions. The battery's pole piece is usually a long strip extending along its length or longitudinal direction. The above-mentioned "both sides of the battery's pole piece" and "the middle of the battery's pole piece" are relative to the width direction or transverse direction of the pole piece perpendicular to the length direction or longitudinal direction, that is, on both sides and the middle of the pole piece along the width direction. The formed side coating portions extend along the length direction of the pole piece on both sides of the pole piece of the battery, and the formed middle coating portion extends along the length direction of the pole piece in the middle of the pole piece of the battery, so that the coating formed on the pole piece of the battery via the coating roller assembly 3 includes three coating portions extending along the length direction of the pole piece and arranged side by side. The side coating portions on both sides may extend to the edge of the pole piece in the width direction, or may be spaced apart from the edge of the pole piece.

[0088] 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 used without departing from the spirit and scope of the present application, so that the coating formed on the battery pole piece can include more than three coating portions extending along the length direction of the pole piece and arranged side by side.

[0089] By using at least the first coating part 362, the second coating part 364 and the third coating part 366, when coating the pole piece of the battery, differential coating can be performed, that is, a coating including at least three coating parts is formed on the pole piece. By controlling or adjusting the coating parameters of the first coating part 362, the second coating part 364 and the third coating part 366, such as coating depth, slurry conductivity, etc., the characteristics of each coating part can be controlled or adjusted, for example, each coating part has a different diaphragm resistance. In some embodiments, the diaphragm resistance of the middle coating part can be made greater than the diaphragm resistance of the side coating parts 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.

[0090] According to some embodiments of the present application, Figure 1-5As shown, the coating roller 30 includes at least a first coating roller 32 and a second coating roller 34. The coating portion 36 is disposed around the first coating roller 32 and the second coating roller 34, respectively. Two of the first coating portion 362, the second coating portion 364, and the third coating portion 366 are disposed 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 disposed on the second coating roller 34.

[0091] 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 pole pieces of the battery 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, so as 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 along the axial direction of the cylinder, such as Figure 1-5 shown.

[0092] like Figure 3 and Figure 5 As shown, the first coating roller 32 may have a width W1 measured along the first longitudinal axis 320 (which is defined as the width here because it actually corresponds to the width direction of the coating to be formed on the pole piece). Similarly, the second coating roller 34 may 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 may be the same, for example, both are 800 mm, but may also be different.

[0093] 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 are disposed on the first coating roller 32, and the third coating portion 366 is disposed on the second coating roller 34. Alternatively, the first coating portion 362 and the third coating portion 366 are disposed on the first coating roller 32, and the second coating portion 364 is disposed on the second coating roller 34. Alternatively, the second coating part 364 and the third coating part 366 are disposed on the first coating roller 32 , and the first coating part 362 is disposed on the second coating roller 34 .

[0094] The three coating parts and the two coating rollers may be combined in any suitable form to flexibly meet the needs of actual production and design. In other embodiments, the coating roller assembly 3 may include more than two coating rollers, for example, three coating rollers, and each coating part may be correspondingly arranged on a coating roller. The number of coating parts may be equal to or greater than the number of coating rollers, so that at least one coating part is arranged on each coating roller.

[0095] 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 spacing area 324 therebetween, and the third coating portion 366 is disposed on the second coating roller 34 and positioned to correspond to the spacing area 324 .

[0096] Specifically, Figure 2-3 As shown, 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 spacing area 324 between the first coating portion 362 and the second coating portion 364. In the case where both the first coating portion 362 and the second coating portion 364 are disposed on the first coating roller 32, when coating the pole piece of the battery, as the first coating roller 32 rolls on the pole piece, the first and second coating portions are formed on the pole piece of the battery via the first coating portion 362 and the second coating portion 364.

[0097] like Figure 4-5As shown, the third coating portion 366 can be disposed on the second outer circumference 342 of the second coating roller 34. When coating the pole piece of the battery, as the second coating roller 34 rolls on the pole piece, a third coating portion is formed on the pole piece of the battery via the third coating portion 366. Figure 4-5 In the illustrated embodiment, the third coating portion 366 can be positioned to correspond to the spaced area 324. The third coating portion 366 corresponding to the spaced area 324 means that the position of the third coating portion 366 on the second coating roller 34 is substantially equivalent to the position of the spaced area 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 spaced area 324 are also aligned with each other.

[0098] Generally, it is expected that the side coating portions on both sides of the battery pole piece have the same characteristics, so that the first coating portion 362 and the second coating portion 364 forming the side coating portion are arranged on the first coating roller 32 to reduce the complexity of the operation, for example, the first coating portion 362 and the second coating portion 364 can be attached with the same slurry from the same material tank, without having to obtain slurry from different material tanks for the first coating portion 362 and the second coating portion 364. The third coating portion 366 is arranged to correspond to the spacer 324, which is also conducive to alignment during coating, so that the middle coating portion can be more ideally located between the side coating portions.

[0099] 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.

[0100] 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.

[0101] 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 by the coating roller assembly 3 on the pole piece of the battery.

[0102] like Figure 3 As shown, 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 LThe coating width W is roughly equivalent to the dimension of the first coating portion 362 measured along the first longitudinal axis 320 of the first coating roller 32 (ie, the width dimension of the first coating portion 362), corresponding to the width of the first coating portion formed by the first coating portion 362 on the pole piece. L The total coating width W T one third of.

[0103] 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 coating width W is roughly equivalent to the dimension of the second coating portion 364 measured along the first longitudinal axis 320 of the first coating roller 32 (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 The total coating width W T one third of.

[0104] 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 The total coating width W can also be T Thus, the coating width W of the first coating portion 362 is L , the 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 ,like Figure 3 shown.

[0105] like Figure 5 As shown, 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 M The coating width W is roughly equivalent to the 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), corresponding to the width of the third coating portion formed by the third coating portion 366 on the pole piece. 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 TOne third plus 2 mm.

[0106] 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 is 200 mm, such as Figure 3 The coating width W of the third coating portion 366 is shown. M Slightly larger than 200 mm, for example, 202 mm, such as Figure 5 shown.

[0107] Coating width W of the first coating portion 362 L The coating width W of the second coating portion 364 is R The coating width W of the third coating portion 366 is the same as that of the first coating portion 362 formed on the electrode piece, so that the width of the first coating portion formed on the electrode piece by the first coating portion 362 is the same as the width of the second coating portion formed on the electrode piece by the second coating portion 364. 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 pole piece by the third coating portion 366 can be slightly larger than the width of the first coating portion formed on the pole piece by the first coating portion 362 and the width of the second coating portion formed on the pole piece by the second coating portion 364. Thus, an overlapping area can be formed between the middle coating portion and the side coating portion, so as to form a complete coating on the pole piece of the battery.

[0108] 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 .

[0109] Specifically, Figure 6-7 As shown, the coating roller assembly 3 may include a single coating roller 30, in which 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 pole piece. 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 FIG. Figure 6-7In addition, the coating roller 30 can have a width W measured along the longitudinal axis 300, and in one embodiment, the width W can be, for example, 800 mm.

[0110] 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 the present application can also be achieved. Through the multiple coating parts, the pole pieces of the battery are differentially coated, and the diaphragm resistance of the middle coating part is controlled or adjusted 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.

[0111] 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.

[0112] 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.

[0113] Specifically, Figure 7 As shown, 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 finally formed by the coating roller assembly 3 on the pole piece of the battery.

[0114] like Figure 7 As shown, 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 L The coating width W is roughly equivalent 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 by the first coating portion 362 on the pole piece. 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 WT 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.

[0115] 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 one third of the coating width W of the second coating portion 364. R The total coating width W T One third minus 2 mm.

[0116] 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 coating width W is roughly equivalent 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 by the third coating portion 366 on the pole piece. 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.

[0117] 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 attaching the slurry and avoid mixing between different slurries.

[0118] In one embodiment, the coating width W of the first coating portion 362 is L , the coating width W of the second coating portion 364 R and the coating width W of the third coating portion 366 M can 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.

[0119] 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, such as Figure 7 shown.

[0120] 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 .

[0121] 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 .

[0122] 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 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 may be defined between the first coating portion 362 and the third coating portion 366, and / or a second gap 334 may be defined between the second coating portion 364 and the third coating portion 366, as shown in FIG. Figure 7 shown.

[0123] 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 appreciate that the width GL and width G R It can also be different.

[0124] The coating width W of the first coating portion 362 L , the coating width W of the second coating portion 364 R and the coating width W of the third coating portion 366 M The width G is 198 mm. L It can be, for example, 3 mm, and the width G R It can also be, for example, 3 mm. Figure 7 shown.

[0125] 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.

[0126] 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 .

[0127] Specifically, 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 can be the same, so that the first coating part formed on the pole piece by the first coating part 362 and the second coating part formed on the pole piece by the second coating part 364 can have the same membrane resistance. In one embodiment, the first coating part 362 and the second coating part 364 can apply the same slurry. In the case where the first coating part 362 and the second coating part 364 are arranged on the outer circumference 322 of the first coating roller 32, the first coating part 362 and the second coating part 364 can share the same material tank, which reduces the operation steps and reduces the cost.

[0128] According to some embodiments of the present application, 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 .

[0129] Specifically, the conductivity of the slurry coated by the third coating part 366 can be less than the conductivity of the slurry coated by the first coating part 362 and the conductivity of the slurry coated by the second coating part 364, so that the membrane resistance of the third coating part formed by the third coating part 366 on the pole piece can be greater than the membrane resistance of the first coating part formed by the first coating part 362 on the pole piece and the membrane resistance of the second coating part formed by the second coating part 364 on the pole piece. 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 precipitation phenomenon in the middle of the battery can be improved, and the cycle performance and safety performance of the battery can be improved.

[0130] 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%.

[0131] Specifically, the conductive carbon content of the slurry applied by the first coating part 362 may be 40% to 50%, and correspondingly, the conductive carbon content of the slurry applied by the second coating part 364 may be 40% to 50%, and at this time, the conductive carbon content of the slurry applied by the third coating part 366 may be 5% to 20%. In this case, the first coating part formed on the pole piece by the first coating part 362 and the second coating part formed on the pole piece by the second coating part 364 may have the same diaphragm resistance, and the diaphragm resistance of the third coating part formed on the pole piece by the third coating part 366 may be greater than the diaphragm resistance of the first coating part formed on the pole piece by the first coating part 362 and the diaphragm resistance of the second coating part formed on the pole piece 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.

[0132] 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 may be the same. The coating depth may correspond to the dimension of the coating portion along the radial direction perpendicular to the longitudinal axis of the coating roller, corresponding to the thickness of the coating portion formed by each coating portion on the pole piece 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 pole piece by the first coating portion 362 and the second coating portion formed on the pole piece by the second coating portion 364 may have the same membrane resistance. In one embodiment, the coating depth of the first coating portion 362 may be, for example, 28 microns, and the coating depth of the second coating portion 364 may also be, for example, 28 microns.

[0133] 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 third coating portion formed by the third coating portion 366 on the pole piece has a diaphragm resistance that is greater than the diaphragm resistance of the first coating portion formed by the first coating portion 362 on the pole piece and the diaphragm resistance of the second coating portion formed by the second coating portion 364 on the pole piece. 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 precipitation 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.

[0134] Specifically, the coating depth of the third coating portion 366 can be 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. In this case, the ratio of the diaphragm resistance of the third coating portion formed on the pole piece by the third coating portion 366 to the diaphragm resistance of the first coating portion formed on the pole piece by the first coating portion 362 can be in the range of 1.1 to 6.2, and / or the ratio of the diaphragm resistance of the third coating portion formed on the pole piece by the third coating portion 366 to the diaphragm resistance of the second coating portion formed on the pole piece by the second coating portion 364 can be in the range of 1.1 to 6.2. For example, as described above, the coating depths of the first coating portion 362 and the second coating portion 364 can both be, for example, 28 microns, while the coating depth of the third coating portion 366 can be, for example, 56 microns.

[0135] 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 diaphragm resistance of the third coating part formed by the third coating part 366 on the pole piece and the diaphragm resistance of the first coating part formed by the first coating part 362 on the pole piece and the diaphragm resistance of the second coating part formed by the second coating part 364 on the pole piece 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 precipitation phenomenon in the middle of the battery, and improving the cycle performance and safety performance of the battery. The above-mentioned definition of 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 than three.

[0136] In addition, the adjustment of the coating parameters can be performed individually or in combination. For example, the conductivity of the slurry applied by the first coating part 362, the second coating part 364 and the third coating part 366 can be individually controlled, adjusted and designed to obtain the desired relationship between the diaphragm resistance of the middle coating part and the diaphragm resistance of the side coating part, and the coating depth of the first coating part 362, the second coating part 364 and the third coating part 366 can be individually controlled, adjusted and designed to obtain the desired relationship between the diaphragm resistance of the middle coating part and the diaphragm resistance of the side coating part. At the same time, the two can also be combined, that is, the coating depth of the first coating part 362, the second coating part 364 and the third coating part 366 and the conductivity of the applied slurry are simultaneously controlled, adjusted and designed to obtain the desired relationship between the diaphragm resistance of the middle coating part and the diaphragm resistance of the side coating part in combination.

[0137] According to some embodiments of the present application, the coating roller 30 may be a gravure roller, thereby gravure coating, such as micro-gravure coating, is applied to the pole piece of the battery. Specifically, a single coating roller 30 may be a gravure roller, and in the case of including 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.

[0138] According to some embodiments of the present application, the present application also provides a method for coating a battery pole piece using the above-mentioned coating roller assembly 3, comprising: immersing the coating roller assembly 3 in 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 tank; coating the pole piece using the coating roller assembly 3, forming a first coating part on the pole piece by the first coating part 362, forming a second coating part on the pole piece by the second coating part 364, and forming a third coating part on the pole piece by the third coating part 366. The third coating part is between the first coating part and the second coating part.

[0139] Specifically, the method includes the following steps.

[0140] 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.

[0141] In the case of including the first coating roller 32 and the second coating roller 34, they can be immersed in a material tank respectively. For example, they can be immersed in different material tanks so that the first coating part 362, the second coating part 364 and the third coating part 366 are attached with slurries of different conductivity, for example, the first coating part 362 and the second coating part 364 are attached with slurries of higher conductivity, while the third coating part 366 is attached with slurries of lower conductivity. In addition, in the scheme of achieving differentiated coating by controlling the coating depth, they can also be immersed in the same or different material tanks.

[0142] In the case of a single coating roller 30, the coating roller assembly 3 can be directly immersed in the material tank, and in this case, the material tank can be a combination of multiple material tanks. Figure 8 As shown, the material tank 40 may include a first material tank 402, a second material tank 404, and a third material tank 406. The first material tank 402 corresponds to the first coating portion 362, the second material tank 404 corresponds to the second coating portion 364, and the third material tank 406 corresponds to the third coating portion 366, so that the first coating portion 362 may be attached with slurry from the first material tank 402, the second coating portion 364 may be attached with slurry from the second material tank 404, and the third coating portion 366 may be attached with slurry from the third material tank 406. The first material tank 402, the second material tank 404, and the third material tank 406 may contain slurries with different electrical conductivity, for example, the first material tank 402 and the second material tank 404 may contain slurries with greater electrical conductivity, and the third material tank 406 may contain slurries with less electrical conductivity. Furthermore, in the scheme of achieving differential coating 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.

[0143] After the first coating part 362, the second coating part 364 and the third coating part 366 are attached with slurry, the pole piece is coated by the coating roller assembly 3, and the first and second coating parts are formed on the pole piece by the first coating part 362 and the second coating part 364, and the third coating part is formed on the pole piece by the third coating part 366, so that the third coating part is between the first and second coating parts. The membrane resistance of the third coating part formed in this way can be greater than the membrane resistance of the first and second coating parts, thereby adjusting the internal current density distribution of the battery, reducing the current density in the middle, improving the lithium precipitation phenomenon in the middle of the battery, and improving the cycle performance and safety performance of the battery.

[0144] According to some embodiments of the present application, the coating roller assembly 3 can be used to coat one side of the pole piece, and the coating roller assembly 3 can be used to coat the other side of the pole piece, that is, the coating roller assembly 3 can be used to coat the two sides of the pole piece respectively. In the case of including the first coating roller 32 and the second coating roller 34, the first coating roller 32 and the second coating roller 34 are both used to coat one side of the pole piece, and then coat the other side of the pole piece.

[0145] According to some embodiments of the present application, after the electrode piece is coated by 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 may be defined between the first coating portion 362 and the third coating portion 366, and / or a second gap 334 may 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 extended to their respective sides and contact each other to finally form a complete coating.

[0146] According to some embodiments of the present application, the present application further provides a pole piece, which includes a coating formed by using the coating roller assembly 3 as described above or the method as 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 between the first coating portion and the second coating portion.

[0147] 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 .

[0148] 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 deposition phenomenon in the middle of the battery, and improving the cycle performance and safety performance of the battery.

[0149] 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.

[0150] 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.

[0151] 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.

[0152] 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%.

[0153] 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.

[0154] In some embodiments, the thickness of the third coating portion formed on the pole piece by the third coating portion 366 may 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 .

[0155] 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.

[0156] According to some embodiments of the present application, the present application also provides a battery, which includes the pole piece as described above.

[0157] Based on the above embodiment, compared with the comparative example, the results are as follows:

[0158] plan Ratio of middle diaphragm resistance to diaphragm resistance on both sides Lithium precipitation in the central part Example 1 1.1 none Example 2 2.0 none Example 3 3.0 none Example 4 4.0 none Example 5 5.0 none Example 6 6.2 none Comparative Example 1 1.0 have Comparative Example 2 0.9 have Comparative Example 3 7.0 have

[0159] It can be seen that when the diaphragm resistance of the third coating part formed on the pole piece 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 pole piece 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.

[0160] 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 replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate 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 the pole piece is coated with the coating roller assembly (3) to form a coating, the coating 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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