Coating device, coating method, and battery production line

Abstract

A coating device, a coating method, and a battery production line, relating to the technical field of batteries. The coating device is used for coating a base material (20) with functional layers (30, 40), and in the thickness direction of the base material (20), the base material (20) comprises a first surface and a second surface which are opposite to each other. The coating device comprises a first coating roller (11), a second coating roller (12), and a first driving member (13); the first coating roller (11) is used for coating the first surface with a first functional layer (30); along the web travel direction of the base material (20), the second coating roller (12) is arranged at the downstream or upstream of the first coating roller (11) and is used for coating the second surface with a second functional layer (40); and the first driving member (13) is connected to the first coating roller (11) and is used for driving the first coating roller (11) to reciprocate in the axial direction.

Description

Coating device, coating method and battery production line

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202410439188.3, filed on April 12, 2024, entitled “Coating device, coating method and battery production line”, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the technical field of batteries, in particular to a coating device, a coating method and a battery production line. BACKGROUND

[0004] Energy saving and emission reduction is 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 energy-saving and environmentally friendly advantages. For electric vehicles, battery technology is an important factor for their development.

[0005] In the manufacturing process of the battery, the reliability of the battery is a problem that cannot be ignored. Therefore, how to improve the quality of the electrode assembly of the battery, improve the quality and performance of the battery, is a technical problem that needs to be solved in the battery technology.

[0006] SUMMARY

[0007] The purpose of the present application is to solve the above problems, provide a coating device, a coating method and a battery production line, which can effectively solve the technical problem of obvious drumming of the substrate after coating and winding, and can effectively improve the quality of the electrode assembly of the battery during the production of the battery, thereby improving the quality and performance of the battery.

[0008] In a first aspect, the present application provides a coating device for coating a functional layer on a substrate, the substrate including opposite first and second surfaces along a thickness direction of the substrate. The coating device includes a first coating roller for coating a first functional layer on the first surface, a second coating roller disposed downstream or upstream of the first coating roller along a running direction of the substrate for coating a second functional layer on the second surface, and a first driving member connected to the first coating roller for driving the first coating roller to reciprocate along an axial direction.

[0009] In the technical solutions of the embodiments of the present application, the second coating roller is arranged downstream or upstream of the first coating roller in the conveying direction of the base material, that is, the positions of the first coating roller and the second coating roller can be set according to requirements. In some embodiments, the base material can pass through the first coating roller and the second coating roller in sequence when conveying, and the first functional layer coating on the first surface and the second functional layer coating on the second surface are performed in sequence. In other embodiments, the base material can pass through the second coating roller and the first coating roller in sequence when conveying, and the second functional layer coating on the second surface and the first functional layer coating on the first surface are performed in sequence.

[0010] On the one hand, the first coating roller and the second coating roller are each provided with a coating structure that can bond paste. When the first coating roller and the second coating roller rotate around their axes and contact the surface of the base material, the paste bonded in the coating structure of the first coating roller and the second coating roller can be coated onto the surface of the base material. The first functional layer is coated on the first surface of the base material by the first coating roller, and the second functional layer is coated on the second surface of the base material by the second coating roller. In the width direction of the base material, the coating range of the first coating roller and the second coating roller is less than the width of the base material, that is, the first coating roller and the second coating roller are used to coat materials with certain functions on the front and back surfaces of the base material in a local manner, thereby meeting the functional requirements of the base material.

[0011] On the other hand, due to the characteristics of the coating process, the thickness of the edge of the coated functional layer is slightly greater than the thickness of the middle part of the functional layer, and the functional layer forms a thick edge. If the first coating roller and the second coating roller only rotate in the axial direction, and the coating structure of the first coating roller and the coating structure of the second coating roller always face each other, then the thick edges of the first functional layer and the second functional layer will face and overlap in the thickness direction of the base material, and then the thick edge overlapping parts of the multiple turns of the base material will again perform thickness overlapping on the corresponding radial cross section of the coiled material after the base material is wound and arranged, so that the coiled material after coiling is obviously drummed, which not only affects the subsequent production process, but also affects the overall flatness of the base material. The base material is easily deformed in the width direction and has an arc, etc. When the base material is the base material of the pole piece of the battery, it will affect the quality and performance of the finished battery.

[0012] Therefore, in order to solve the above problems found, the first driving part is arranged to drive the first coating roller to move reciprocatingly along the axial direction, so that the first coating roller can rotate around the axial direction and move reciprocatingly along the axial direction at the same time, and then the edge of the coating structure of the first coating roller and the edge of the coating structure of the second coating roller can be staggered. After the coating is completed, along the thickness direction of the substrate, since the edge of the first functional layer and the edge of the second functional layer are not completely projected and overlapped, the thickness superposition of the thick edge of the first functional layer and the thick edge of the second functional layer when formed on the substrate can be effectively solved. In addition, along the width direction of the substrate, since the relative position between the thick edge of the first functional layer and the thick edge of the second functional layer changes, the axial reciprocating movement of the first coating roller can be periodic or non-periodic, but as the substrate is wound, the positions of the thick edges of the first functional layer on the multiple turns of the substrate can be at least partially staggered and will not all overlap and superimpose on the same radial section, and then the obvious drum problem existing after the substrate is coated and wound can be effectively solved.

[0013] It should be noted that in the state that the second coating roller only rotates around the axis, along the width direction of the substrate, the position of the thick edge of the second functional layer formed on the substrate is always unchanged, and after the substrate is wound, it will still be superimposed on the same radial section, but since the first coating roller moves reciprocatingly along the axial direction, along the thickness direction of the substrate, for the thick edge of the second functional layer, some parts of the first surface correspond to no first functional layer, some parts are superimposed with the thick edge of the first functional layer, and some parts are superimposed with the non-thick edge part of the first functional layer, instead of the thick edge of the first functional layer always being superimposed with the thick edge of the second functional layer in thickness. Since there is no thickness superposition and various thickness superposition modes, after the substrate is wound, the thickness difference of different parts of the substrate can be utilized to finally effectively improve the condition of the thick edge thickness superposition on the same radial section, and then the obvious drum problem existing after the substrate is coated and wound can be effectively solved.

[0014] In summary, the present scheme can obviously improve the local drum condition of the substrate after the coating is completed and wound into a roll, and the flatness of the substrate can be obviously improved, especially when used for the production of battery pole pieces, which is beneficial to improve the overall quality of the pole pieces of the electrode assembly, and then improve the quality and performance of the battery.

[0015] In addition, the conventional arrangement is that the axial direction of the first coating roller and the axial direction of the second coating roller are both perpendicular to the conveying direction of the substrate. The reciprocating movement refers to moving back and forth between an initial position and a preset position, for example, one-sided reciprocating movement at the initial position, which requires moving back and forth between the extreme position on one side and the initial position; for example, two-sided reciprocating movement at the initial position, which requires moving from the initial position to one of the extreme positions on the two sides, moving back and forth between the two extreme positions, and then returning to the initial position or not returning to the initial position. However, the first movement needs to start from the initial position, that is, the initial position needs to be returned before the coating starts.

[0016] In some embodiments, the coating device further comprises a second driving member connected to the second coating roller for driving the second coating roller to reciprocate in the axial direction.

[0017] In the technical scheme of the embodiments of the present application, the coating device is further provided with a second driving member for driving the second coating roller to reciprocate in the axial direction, so that the position of the thick edge of the second functional layer coated by the second coating roller on the substrate can also be changed. With the winding of the substrate, the positions of the thick edges of the first functional layer on the multiple turns of the substrate can be staggered, and they will not all overlap and add up on the same radial section. Similarly, the positions of the thick edges of the second functional layer can also be staggered, and they will not all overlap and add up on the same radial section. Thus, the problem of obvious bulging after the coating and winding of the substrate can be effectively solved.

[0018] It should be noted that the thick edge of the first functional layer and the thick edge of the second functional layer can also be completely overlapped in the thickness direction of the substrate. Although the thick edge of the first functional layer and the thick edge of the second functional layer always overlap at this time, since the first coating roller and the second coating roller both reciprocate in the axial direction, the position of the thick edge of the first functional layer on the substrate changes in the thickness direction of the substrate, and the position of the thick edge of the second functional layer on the substrate also changes. Then, with the winding of the substrate, the positions of the thick edges of the first functional layer between the multiple turns of the substrate can be at least partially staggered, and they will not all overlap and add up on the same radial section. The thickness difference between different parts of the substrate after the coating of the first functional layer and the second functional layer can be utilized, and thus the problem of obvious bulging after the coating and winding of the substrate can be effectively solved.

[0019] That is, as long as at least the first coating roller reciprocates in the axial direction, the technical effect of effectively improving the condition of overlapping thick edge thickness on the same radial section after the winding of the substrate can be achieved, and thus the problem of obvious bulging after the coating and winding of the substrate can be effectively solved.

[0020] In some embodiments, the first coating roller is a gravure roller or a microgravure roller; and the second coating roller is a gravure roller or a microgravure roller.

[0021] In the technical solution of the embodiment of the application, the coating structure is a screen area etched on the surface of the gravure roll or microgravure roll. The screen area is generally a plurality of screen holes or grooves with the same depth, used for accommodating the coating paste to be coated, and the coating paste can be adhered in the screen. The prepared paste-like thick paste is uniformly coated on the specific area of the substrate through the screen area. During coating, the thickness consistency of each coating position needs to be ensured and the coating thickness needs to be controlled within the tolerance range required by the process.

[0022] The difference between the gravure roll and the microgravure roll is that, on the one hand, during use, the gravure roll needs to be pressed against the substrate by a back pressure roll to realize the surface contact between the screen area and the substrate, while the microgravure roll does not need a back pressure roll. The microgravure roll is a reverse and contact type coating method, that is, the rotation direction of the microgravure roll is opposite to the material feeding direction of the substrate, and the substrate does not need to be directly pressed against the microgravure roll by a back pressure roll. On the other hand, generally, the roll diameter of the microgravure roll is smaller, or the size of the screen on the microgravure roll is smaller, and the processing and forming difficulty is greater than that of the gravure roll.

[0023] For example, commonly, the gravure roll is a metal roll, and the screen area thereof is also a metal material, and the size of the screen hole / groove thereon is larger; while the microgravure roll sprays ceramic material on the roll surface and then etches the screen by laser, and the size of the screen hole of the screen is smaller.

[0024] During the coating process, in order to reduce the possibility that the screen roll interferes with other areas to cause the substrate to have concave and convex points, a stepped screen roll is generally selected, for example, a microgravure roll. The microgravure roll generally includes a roll shaft and a protruding part arranged on the circumference of the roll shaft and protruding from the surface of the roll shaft. The screen for bonding the paste is arranged on the circumferential surface of the protruding part.

[0025] In order to realize coating, other structures of the coating device not mentioned can refer to related technologies. For example, the coating device can further include a first liquid storage tank, the first coating roll is rotatable relative to the first liquid storage tank and partially located in the first liquid storage tank, the surface of the substrate is tangent to the surface of the first coating roll, and the first functional layer is coated by rotating the first coating roll to dip and coat. In this way, as the first coating roll rotates, the first coating roll can dip the paste of the first functional layer in the first liquid storage tank and print and coat it to the first coating area. For another example, the coating device can further include a second liquid storage tank corresponding to the second coating roll; for another example, the coating device can further include a unwinding assembly, a winding assembly, a drying assembly for drying the functional layer, and the like. Details are not described herein.

[0026] In a second aspect, a coating method is provided, including the following steps:

[0027] The first functional layer is coated on the first surface of the substrate by the first coating roll; and the second functional layer is coated on the second surface of the substrate by the second coating roll;

[0028] wherein the first coating roller is driven to reciprocate along the axial direction while coating the first functional layer.

[0029] The technical scheme of the embodiment of the present application is consistent with the technical effect of the coating device described above. When the first coating roller and the second coating roller rotate around the axial direction and contact the surface of the substrate, the adhesive in the coating structure of the first coating roller can be coated onto the surface of the substrate. The first functional layer is coated on the first surface of the substrate by the first coating roller, and the second functional layer is coated on the second surface of the substrate by the second coating roller. Along the width direction of the substrate, the coating range of the first coating roller and the second coating roller is smaller than the width of the substrate, that is, the material with a certain function is coated on the front surface and the back surface of the local substrate, thereby meeting the functional requirements of the substrate.

[0030] By driving the first coating roller to reciprocate along the axial direction while coating the first functional layer by driving the first coating roller to rotate around the axial direction, the edge of the coating structure of the first coating roller and the edge of the coating structure of the second coating roller can be staggered. After coating, along the thickness direction of the substrate, since the edge of the first functional layer and the edge of the second functional layer are not completely projected and overlapped, the thickness overlap of the thick edge of the first functional layer and the thick edge of the second functional layer formed on the substrate can be effectively solved. In addition, along the width direction of the substrate, since the relative position between the thick edge of the first functional layer and the thick edge of the second functional layer changes, the axial reciprocation of the first coating roller can be periodic or non-periodic. However, as the substrate is wound, the positions of the thick edges of the first functional layer on multiple turns of the substrate can at least partially stagger, and will not all overlap and stack on the same radial section, thereby effectively solving the obvious bulging problem existing after the substrate is coated and wound.

[0031] In the state that the second coating roller only rotates around the axial line, along the width direction of the substrate, the position of the thick edge of the second functional layer formed on the substrate is always the same, and it will still be stacked on the same radial section after the substrate is wound. However, since the first coating roller reciprocates along the axial direction during the coating of the first functional layer, along the thickness direction of the substrate, for the thick edge of the second functional layer, some parts of the first surface correspond to no first functional layer, some parts are stacked with the thick edge of the first functional layer, and some parts are stacked with the non-thick edge part of the first functional layer, instead of the thick edge of the first functional layer always being stacked with the thick edge of the second functional layer in thickness. Since there is no thickness stacking and various thickness stacking modes, after the substrate is wound, the difference in thickness of different parts of the substrate can also effectively improve the condition of the thick edge thickness stacking on the same radial section, thereby effectively solving the obvious bulging problem existing after the substrate is coated and wound.

[0032] In conclusion, the coating method can obviously improve the local drumming of the substrate after coating and winding into a roll, and the flatness of the substrate can be obviously improved, especially when used in the production of battery pole pieces, which is beneficial to improve the overall quality of the pole pieces of the electrode assembly, and further improve the quality and performance of the battery.

[0033] In some embodiments, the coating method further comprises driving the second coating roller to reciprocate along the axial direction when coating the second functional layer.

[0034] In the technical solution of the embodiments of the present application, the second coating roller rotates around the axis while reciprocating along the axial direction, and the position of the thick edge of the second functional layer coated by the second coating roller on the substrate can also change. As the substrate is wound, the positions of the thick edges of the first functional layer on the multiple turns of the substrate can be staggered, and they will not all overlap on the same radial section. Similarly, the positions of the thick edges of the second functional layer can also be staggered, and they will not all overlap on the same radial section. Thus, the problem of obvious drumming after coating and winding of the substrate can be effectively solved.

[0035] In some embodiments, the frequency of the reciprocating movement of the first coating roller along the axial direction is the same as the frequency of the reciprocating movement of the second coating roller along the axial direction.

[0036] In the technical solution of the embodiments of the present application, the first coating roller reciprocates along the axial direction at a certain frequency, and the reciprocating movement of the first coating roller along the axial direction is periodic, not disordered. Similarly, the second coating roller also reciprocates along the axial direction at a certain frequency, and the reciprocating movement of the second coating roller along the axial direction is periodic, not disordered.

[0037] By controlling the frequency of the reciprocating movement of the first coating roller along the axial direction to be the same as the frequency of the reciprocating movement of the second coating roller along the axial direction, the period of the reciprocating movement of the first coating roller along the axial direction is consistent with the period of the reciprocating movement of the second coating roller along the axial direction, which can facilitate the beat control of the process.

[0038] In some embodiments, driving the first coating roller to reciprocate along the axial direction when coating the first functional layer specifically comprises:

[0039] Driving the first coating roller to reciprocate along the axial direction on the first side of the initial position.

[0040] In the technical solution of the embodiments of the present application, the reciprocating movement of the first coating roller along the axial direction is only between the initial position and the preset limit position on the first side, that is, the period of the reciprocating movement of the first coating roller along the axial direction is the time interval between the first coating roller starting to move and the first coating roller starting to move again from the initial position to the preset limit position on the first side.

[0041] In the coating of the first functional layer, by driving the first coating roller to reciprocate along the axial direction on the first side of the initial position of the first coating roller, the position of the edge of the first functional layer on the substrate is changed, the edge of the coating structure of the first coating roller and the edge of the coating structure of the second coating roller can be partially staggered, and after the coating is completed, due to the fact that the edge of the first functional layer and the edge of the second functional layer are not completely projected and overlapped, the thickness superposition of the thick edge of the first functional layer and the thick edge of the second functional layer formed on the substrate can be effectively solved. At the same time, with the winding of the substrate, the positions of the thick edges of the first functional layer on the multiple turns of the substrate can be at least partially staggered, and will not all be overlapped and superimposed on the same radial section, thereby effectively solving the obvious bulging problem existing after the substrate is coated and wound.

[0042] In some embodiments, the second coating roller is driven to reciprocate along the axial direction when the second functional layer is coated, specifically including:

[0043] The second coating roller is driven to reciprocate along the axial direction on the second side of the initial position of the second coating roller; the first side is opposite to the second side.

[0044] In the technical scheme of the embodiments of the present application, the axial reciprocation of the second coating roller is only between the initial position and the preset limit position on the second side, that is, the period of the axial reciprocation of the second coating roller at this time is the time interval between the front and back two times of movement of the second coating roller from the initial position to the preset limit position on the first side after starting to move.

[0045] By making the first coating roller only deviate to the first side and reciprocate, and making the second coating roller only deviate to the second side and reciprocate, the position of the edge of the first functional layer on the substrate is changed, and the position of the edge of the second functional layer on the substrate is also changed. At the same time, since the frequency of the axial reciprocation of the first coating roller is the same as the frequency of the axial reciprocation of the second coating roller, the first coating roller and the second coating roller always maintain the same pace of opposite moving directions, the edge of the coating structure of the first coating roller and the edge of the coating structure of the second coating roller can be partially staggered, thereby effectively solving the problem of drumming of the wound material after winding.

[0046] In some embodiments, the first coating roller is driven to reciprocate along the axial direction when the first functional layer is coated, specifically including:

[0047] The first coating roller is driven to reciprocate along the axial direction on the first side of the initial position of the first coating roller once, and then on the second side of the initial position of the first coating roller once, and the above movement is repeated.

[0048] In the technical solution of the embodiment of the application, the path of the axial reciprocating movement of the first coating roller in one cycle is: initial position-limit position on the first side-initial position-limit position on the second side-initial position, and the first coating roller repeatedly moves reciprocatingly according to the path, that is, the coating mode of double-side reciprocating movement.

[0049] At this time, it can be known through analysis that when the second coating roller is always at the initial position for coating the second functional layer, the first coating roller adopts double-side reciprocating movement, and for the thick edge of the second functional layer in the thickness direction of the substrate, some parts of the first surface region do not have the first functional layer, at this time, there is no thickness superposition, some parts are superposed with the thick edge of the first functional layer, and some parts are superposed with the non-thick edge part of the first functional layer, instead of that the thick edge of the first functional layer is always superposed with the thick edge of the second functional layer in thickness. Since there is no superposition of thickness and various superpositions of thickness between the first functional layer and the second functional layer, after the substrate is wound up, the difference in thickness of different parts of the substrate can be utilized, and finally the condition of thickness superposition of the thick edge on the same radial section can also be effectively improved, and then the obvious drum problem existing after the substrate is coated and wound up can be effectively solved.

[0050] In some embodiments, the second coating roller is driven to move reciprocatingly in the axial direction when the second functional layer is coated, and specifically includes:

[0051] The second coating roller is driven to move reciprocatingly in the axial direction once on the second side of the initial position and then move reciprocatingly in the axial direction once on the first side of the initial position, and the above movement is repeated.

[0052] In the technical solution of the embodiment of the application, similar to the axial reciprocating movement of the first coating roller, the path of the axial reciprocating movement of the second coating roller in one cycle is: initial position-limit position on the second side-initial position-limit position on the first side-initial position, and the second coating roller repeatedly moves reciprocatingly according to the path, that is, the coating mode of double-side reciprocating movement.

[0053] The positions of the edges of the first functional layer and the edges of the second functional layer on the substrate are both variable, and since the frequency of the axial reciprocating movement of the first coating roller is the same as the frequency of the axial reciprocating movement of the second coating roller, the first coating roller and the second coating roller always maintain the same pace in the opposite moving directions, the edges of the coating structure of the first coating roller and the edges of the coating structure of the second coating roller can be partially staggered, and then the problem of drum after winding can be effectively solved.

[0054] Meanwhile, through analysis, it can be known that, along the thickness direction of the substrate, for the thick edge of the second functional layer, some parts correspond to the area of the first surface without the first functional layer, at this time, there is no thickness superposition, some parts are superposed with the thick edge of the first functional layer, and some parts are superposed with the non-thick edge part of the first functional layer, instead of the thick edge of the first functional layer always being superposed with the thick edge of the second functional layer in thickness. Due to the existence of the non-superposition of the thickness of the first functional layer and the second functional layer and the possibility of various thickness superpositions, after the substrate is wound, the difference in thickness of different parts of the substrate can be utilized, and finally, the situation of the thick edge thickness superposition in the same radial cross section can also be effectively improved, and then the obvious rib problem existing after the substrate is coated and wound can be effectively solved.

[0055] In some embodiments, the coating method further comprises: controlling the running time of the substrate between the first coating roller and the second coating roller to be t;

[0056] According to the running direction of the substrate, the first coating roller and the second coating roller are controlled to move reciprocally along the axis in sequence, and the time difference of the reciprocally moving in sequence is t.

[0057] In the technical scheme of the embodiments of the present application, it can be understood that: taking the same area of the substrate as the reference, the area contacts the first coating roller, the first coating roller starts to move reciprocally along the axis as the timing starting point, after time t, the area starts to contact the second coating roller, and the second coating roller starts to move reciprocally along the axis at the same time.

[0058] When the speed of the substrate running is always constant, the running time of the substrate between the first coating roller and the second coating roller is t, and the material length of the substrate running from the first coating roller to the second coating roller can also be obtained. By making the time interval of the reciprocally moving of the first coating roller and the second coating roller also t, the part of the substrate contacted by the first coating roller when it starts to move transversely is consistent with the part of the substrate contacted by the second coating roller when it starts to move transversely, and then the coating starting point of the reciprocally moving of the first coating roller along the axis is consistent with the coating starting point of the reciprocally moving of the second coating roller along the axis.

[0059] It should be noted that the sequence of the first coating roller and the second coating roller is determined by the specific situation of the production line, and one of the first coating roller and the second coating roller located upstream moves reciprocally along the axis first, and one located downstream moves reciprocally along the axis later.

[0060] In some embodiments, the maximum offset distance of the first coating roller along the axis relative to its initial position is controlled to be L, and L≤5mm.

[0061] In the technical solution of the embodiments of the present application, theoretically, the preset coating area of the first surface corresponds to the range coated when the first coating roller is in the initial position, and similarly, the preset coating area of the second surface corresponds to the range coated when the second coating roller is in the initial position. Therefore, the coating area of the first coating roller deviating from the initial position along the axial direction is not the preset coating area. By controlling the maximum deviation distance of the first coating roller from the initial position along the axial direction to be no more than 5 mm, the problem of obvious drumming of the substrate after coating and winding can be effectively solved by improving the process, while the deviation of the coating range can be reduced, and the influence on the subsequent process and the final required performance of the substrate can be reduced.

[0062] It should be noted that the maximum deviation distance L of the first coating roller from the initial position along the axial direction refers to the maximum distance deviated from the initial position on one side. In some embodiments, when the first coating roller adopts a double-sided reciprocating movement scheme, the maximum deviation distance of the first coating roller on the first side and the second side should both be no more than 5 mm.

[0063] For example, in some embodiments, L can be selected from 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1.2 mm, 1.5 mm, 1.6 mm, 2 mm, 2.3 mm, 2.5 mm, 2.8 mm, 3 mm, 3.5 mm, 3.8 mm, 4 mm, 4.3 mm, 4.5 mm, 4.8 mm, 5 mm, etc.

[0064] In some embodiments, L≤0.5 mm.

[0065] In the technical solution of the embodiments of the present application, by controlling the maximum deviation distance L of the first coating roller from the initial position along the axial direction to be no more than 0.5 mm, the technical effect of effectively solving the problem of obvious drumming of the substrate after coating and winding can be achieved, and the influence on the preset area which does not need to be coated with the first functional layer and the second functional layer can be reduced. In particular, in some embodiments, other functional layers of other properties can be coated in the area adjacent to the first functional layer and the second functional layer.

[0066] For example, in some embodiments, L can be selected from 0.08 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.24 mm, 0.26 mm, 0.3 mm, 0.32 mm, 0.36 mm, 0.38 mm, 0.4 mm, 0.42 mm, 0.44 mm, 0.45 mm, 0.46 mm, 0.49 mm, 0.5 mm, etc.

[0067] In some embodiments, the first coating roller is driven to move reciprocally along the axial direction when coating the first functional layer, and specifically includes:

[0068] controlling the axial movement of the first coating roller at least once during movement of the first coating roller from the initial position to the limit position farthest from the initial position;

[0069] controlling the axial movement of the first coating roller at least once during movement of the first coating roller from the initial position to the limit position farthest from the initial position;

[0070] In the technical solution of the embodiments of the present application, the first coating roller is controlled to move at least once during movement of the first coating roller from the initial position to the limit position farthest from the initial position and / or during movement of the first coating roller from the limit position farthest from the initial position to the initial position. That is, the axial movement of at least one of the two processes of the first coating roller moving away from the initial position and returning to the initial position is intermittent and interval movement, rather than continuous movement. During the movement pause of the first coating roller, the substrate is still conveyed at the preset speed.

[0071] By reasonably setting the relationship between the distance of single movement of the first coating roller, the length of the substrate conveying corresponding to the single movement, the time of single pause, the length of the substrate conveying corresponding to the single pause, and other parameters, the thick edges of the first functional layer and the thick edges of the second functional layer on each coil of the substrate after winding can be effectively staggered, so that they will not only be stacked in thickness on the corresponding radial cross section, thereby effectively solving the obvious drum problem existing after the substrate coating is completed and wound.

[0072] In a third aspect, a battery production line is also provided, which comprises the coating device described above and is used for coating a functional layer on a substrate of a pole piece of a battery.

[0073] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0074] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be considered as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0075] FIG. 1 is a structural schematic diagram of a vehicle.

[0076] FIG. 2 is a structural schematic diagram of a battery.

[0077] FIG. 3 is a structural schematic diagram of a battery monomer.

[0078] Figure 4 is a schematic diagram of a coating device according to some embodiments of the present application.

[0079] Figure 5 is a schematic diagram of a coating range of a substrate by a coating device according to some embodiments of the present application at a time when both the first coating roller and the second coating roller are at the initial position.

[0080] Figure 6 is a schematic diagram of a coating range of a substrate by a coating device according to some embodiments of the present application at a time when the first coating roller is deviated from the initial position and the second coating roller is at the initial position.

[0081] Figure 7 is a schematic diagram of a first functional layer and a second functional layer coated by a coating device according to some embodiments of the present application in the state of Figure 6.

[0082] Figure 8 is a schematic diagram of a first functional layer and a second functional layer coated by a coating device according to some other embodiments of the present application in the state of Figure 6.

[0083] Figure 9 is a schematic diagram of a coating range of a substrate by a coating device according to some embodiments of the present application at a time when both the first coating roller and the second coating roller are deviated from the initial position and deviated to different sides.

[0084] Figure 10 is a schematic diagram of a first functional layer and a second functional layer coated by a coating device according to some embodiments of the present application in the state of Figure 9.

[0085] Figure 11 is a schematic diagram of a first functional layer and a second functional layer coated by a coating device according to some other embodiments of the present application in the state of Figure 9.

[0086] Figure 12 is a schematic diagram of a coating method according to some embodiments of the present application.

[0087] Figure 12 is a schematic diagram of a coating method according to some embodiments of the present application.

[0088] 10 - coating device; 11 - first coating roller; 12 - second coating roller; 13 - first driving member; 14 - second driving member; 15 - drying assembly.

[0089] 20 - substrate; 30 - first functional layer; 40 - second functional layer. DETAILED DESCRIPTION

[0090] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0091] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used in the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion. The terms "first", "second" and the like in the specification and claims of the present application and the above description of drawings are used to distinguish different objects, not to describe a particular order or primary and secondary relationship.

[0092] In the present application, the phrase "embodiments" means that the specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appears at various places in the specification does not necessarily all refer to the same embodiments, nor are they necessarily mutually exclusive or alternative embodiments to each other. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in the present application can be combined with other embodiments.

[0093] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mount", "connect", "connection", "attach" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be direct connection, or indirect connection through intermediate medium, or internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0094] In the description of the embodiments of the present application, the term "and / or" is only to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which means that there are three cases of A, A and B, and B. In addition, the character " / " in this paper generally represents that the front and rear associated objects are in an "or" relationship.

[0095] "Multiple" appearing in the present application means two or more (including two), and similarly, "multiple groups" means two or more groups (including two groups), and "multiple pieces" means two or more pieces (including two pieces).

[0096] In the present application, the battery referred to means a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in the present application can include a battery module or a battery pack, etc.

[0097] At present, from the development of market situation, the application of power battery is more and more widely. The power battery is not only applied to the energy storage power supply system of hydropower, thermal power, wind power and solar power station, but also widely applied to electric bicycles, electric motorcycles, electric vehicles and other electric vehicles, military equipment, aerospace and other fields. With the continuous expansion of the application field of power battery, the market demand is also increasing.

[0098] Coating is to coat a thin layer of coating material in liquid or powder form on the surface of fabric, paper, metal foil or plate, etc. In order to improve the electrical performance and safety performance of lithium ion battery, coating is an indispensable step in the production process of battery cell, and is also a key process directly affecting the safety, capacity, life and other performances of battery. In the production process of battery cell, the positive active material is coated on the positive current collector, and the negative active material is coated on the negative current collector. The coating process is to uniformly, continuously or intermittently coat the prepared paste-like thick slurry (positive active material or negative active material) on the substrate (positive current collector or negative current collector).

[0099] However, due to the characteristics of coating, the thickness of the edge of the functional layer coated is slightly larger than that of the middle part of the functional layer, and the functional layer forms a thick edge on the substrate. If the first coating roller and the second coating roller only rotate in the axial direction, and the coating structure of the first coating roller and the coating structure of the second coating roller always face each other, the thick edges of the first functional layer and the second functional layer will be opposite and superimposed in the thickness direction of the substrate, and then the thick edge superimposed part of the multiple turns of the substrate will be superimposed again in the corresponding radial cross section of the roll after the substrate is wound and set, so that the roll after winding is obviously drummed, which not only affects the subsequent production process, but also affects the overall flatness of the substrate. The substrate is easy to deform in the width direction, has an arc, etc. When the substrate is the substrate of the battery pole piece (such as aluminum foil, etc.), it will affect the quality and performance of the battery product.

[0100] Based on the above considerations, in order to solve the problem of obvious drumming after the substrate is coated with a functional layer and rolled up, a coating device, a coating method and a battery production line are designed. The coating device comprises a first coating roller, a second coating roller and a first driving member. The first coating roller is used to coat a first functional layer on a first surface of the substrate. The second coating roller is arranged downstream or upstream of the first coating roller along the conveying direction of the substrate and is used to coat a second functional layer on a second surface of the substrate. The first driving member is connected to the first coating roller and is used to drive the first coating roller to move back and forth along the axial direction. The first surface and the second surface are opposite along the thickness direction of the substrate.

[0101] The first coating roller moves back and forth along the axial direction under the driving of the first driving member, so that the first coating roller can move back and forth along the axial direction while rotating around its axial direction, and thus the edges of the coating structure of the first coating roller and the edges of the coating structure of the second coating roller can be staggered. After coating is completed, along the thickness direction of the substrate, since the edges of the first functional layer and the edges of the second functional layer are not completely projected and overlapped, the thickness superposition of the thick edges of the first functional layer and the thick edges of the second functional layer formed on the substrate can be effectively solved. In addition, along the width direction of the substrate, since the relative positions between the thick edges of the first functional layer and the thick edges of the second functional layer change, the back-and-forth movement of the first coating roller along the axial direction can be periodic or non-periodic, but as the substrate is rolled up, the positions of the thick edges of the first functional layer on multiple turns of the substrate can at least partially stagger, and will not all overlap and superimpose on the same radial section, thereby effectively solving the problem of obvious drumming after the substrate is coated and rolled up.

[0102] In order to solve the problem of thick edges of the functional layer relative to the middle part, the related art adopts the scheme of improving the structure of the coating roller, such as setting the screen lines of the gravure roller to have inconsistent depth sizes, so that the screen line depth of the part corresponding to the thick edge is smaller than the screen line depth of the part corresponding to the non-thick edge. However, this scheme has certain limitations and implementation difficulties in actual application, especially when applied to microgravure coating. Due to the structural characteristics of the microgravure roller and the arrangement requirements of the screen lines thereon, the part of the microgravure roller etched with screen lines is made of ceramic material, and the screen line density of the microgravure roller is much larger than that of the gravure roller. The manufacturing of the microgravure roller itself has certain processing difficulty, and on this basis, the difficulty of etching screen lines with different depths on the ceramic roller surface is further increased, and the problem of large etching position deviation is prone to occur. At the same time, due to the processing precision problem, either the thinning area is large, or it is difficult to thin and etch in the narrow edge area. In addition, after processing and manufacturing, the microgravure roller needs to be detected before being put into use to check whether the screen lines meet the requirements, which has great detection difficulty and low detection qualification rate of the microgravure roller. For different coating requirements, a new microgravure roller needs to be reprocessed and designed, which consumes time and effort and is not conducive to popularization and use.

[0103] Therefore, compared with the solution of the structure of the coating roller in the related art, the application provides a completely different technical solution by improving the process method. The application can be applied to the fields of micro-embossing coating and gravure coating, without changing the structure of the existing coating roller, that is, the coating structure on the first coating roller and the second coating roller is a conventional and uniform structure, that is, the existing gravure roller and micro-embossing roller with uniform mesh depth can be put into use to achieve the technical effect of solving the drum muscle, saving time and effort, and being widely applied.

[0104] The coating device disclosed in the embodiments of the application can be used in the production of the pole piece of the battery, and it should be noted that the battery in the application refers to a single physical module including one or more battery monomers to provide higher voltage and capacity. For example, the battery mentioned in the application can include a battery pack and the like. The battery can be used as a power supply or a power supply system of an electric device, so as to improve the overall performance of the battery and facilitate the promotion of the battery.

[0105] The electric device can be but is not limited to a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, and the like. Among them, the electric toy can include a fixed or mobile electric toy, for example, a game console, an electric car toy, an electric ship toy, and an electric plane toy, and the like, and the spacecraft can include an airplane, a rocket, a space shuttle, and a spacecraft, and the like.

[0106] The following embodiments are described by taking the electric device as a vehicle for convenience of description.

[0107] Please refer to FIG. 1, which is a structural schematic diagram of a vehicle 1000 provided by some embodiments of the application. The vehicle 1000 can be a fuel automobile, a gas automobile, or a new energy automobile, and the new energy automobile can be a pure electric automobile, a hybrid electric automobile, or a range extended automobile, and the like. The vehicle 1000 is internally provided with a battery 100, which can be arranged at the bottom, the head, or the tail of the vehicle 1000. The battery 100 can be used for power supply of the vehicle 1000, for example, the battery 100 can be used as an operating power supply of the vehicle 1000. The vehicle 1000 can further include a controller 300 and a motor 200, and the controller 300 is used to control the battery 100 to supply power to the motor 200, for example, to meet the working power demand of the vehicle 1000 during starting, navigation, and driving.

[0108] In some embodiments of the application, the battery 100 can not only be used as an operating power supply of the vehicle 1000, but also be used as a driving power supply of the vehicle 1000, instead of or partially instead of fuel or natural gas to provide driving power for the vehicle 1000.

[0109] Please refer to FIG. 2, which is an exploded view of the battery 100 according to some embodiments of the present application. The battery 100 includes a box 110 and a battery cell 120, which is accommodated in the box 110. The box 110 is configured to provide a space for accommodating the battery cell 120, and can have various structures. In some embodiments, the box 110 can include a first part 111 and a second part 112, which are coupled to each other to define a space for accommodating the battery cell 120. The second part 112 can be a hollow structure with one open end, and the first part 111 can be a plate structure, which is coupled to the open end of the second part 112 to define the space for accommodating the battery cell 120 together with the second part 112. Alternatively, the first part 111 and the second part 112 can both be hollow structures with one open end, and the open end of the first part 111 is coupled to the open end of the second part 112. Of course, the box 110 formed by the first part 111 and the second part 112 can have various shapes, such as a cylinder, a cuboid, etc.

[0110] In the battery 100, the battery cell 120 can be multiple, and the multiple battery cells 120 can be connected in series, in parallel, or in a mixed manner. The mixed manner means that the multiple battery cells 120 are connected in series and in parallel. The multiple battery cells 120 can be directly connected in series, in parallel, or in a mixed manner, and then the multiple battery cells 120 are accommodated in the box 110. Of course, the battery 100 can also be that the multiple battery cells 120 are connected in series, in parallel, or in a mixed manner to form a battery module, and then the multiple battery modules are connected in series, in parallel, or in a mixed manner to form a whole, which is accommodated in the box 110. The battery 100 can further include other structures, for example, the battery 100 can further include a busbar component for electrically connecting the multiple battery cells 120.

[0111] Each battery cell 120 can be a secondary battery or a primary battery, and can be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 120 can have a cylindrical shape, a flat shape, a cuboid shape, or other shapes.

[0112] As shown in FIG. 3, the battery cell 120 can include a housing, an electrode assembly 123, and an electrode terminal. The housing includes a case 121 and an end cap 122, and the case 121 has an opening, which is closed by the end cap 122 to isolate the internal environment of the battery cell 120 from the external environment.

[0113] The shell 121 is a component for fitting the end cover 122 to form an internal environment of the battery cell 120, wherein the formed internal environment can be used to accommodate the electrode assembly 123, electrolyte and other components. The shell 121 and the end cover 122 can be independent components. The shell 121 can be of various shapes and sizes. Specifically, the shape of the shell 121 can be determined according to the specific shape and size of the electrode assembly 123. The material of the shell 121 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0114] The end cover 122 refers to a component that covers the opening of the shell 121 to isolate the internal environment of the battery cell 120 from the external environment. Without limitation, the shape of the end cover 122 can be adapted to the shape of the shell 121 to fit the shell 121. Optionally, the end cover 122 can be made of a material with certain hardness and strength (such as aluminum alloy), so that the end cover 122 is not easily deformed when subjected to extrusion collision, so that the battery cell 120 can have higher structural strength, and the reliability can also be improved. The end cover 122 can be provided with functional components such as electrode terminals. The electrode terminals can be used to electrically connect with the electrode assembly 123 for outputting or inputting the electrical energy of the battery cell 120. The material of the end cover 122 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., which are not specially limited in the embodiments of the present application. In some embodiments, an insulating structure can also be provided on the inner side of the end cover 122, which can be used to isolate the electrical connection components in the shell 121 from the end cover 122 to reduce the risk of short circuit. Exemplarily, the insulating structure can be plastic, rubber, etc.

[0115] The electrode assembly 123 is a component in which electrochemical reactions occur in the battery cell 120. One or more electrode assemblies 123 can be contained in the shell 121. The electrode assembly 123 is mainly formed by winding or stacking the positive electrode sheet and the negative electrode sheet, and an isolation film is usually provided between the positive electrode sheet and the negative electrode sheet to separate the positive electrode sheet and the negative electrode sheet to reduce the risk of internal short circuit of the positive electrode sheet and the negative electrode sheet. The positive electrode sheet and the negative electrode sheet have a portion of active material constituting the main body of the electrode assembly 123, and a portion of the positive electrode sheet and the negative electrode sheet without active material each constitutes a tab. The positive tab and the negative tab can be located at one end of the main body or at two ends of the main body, respectively. During the charging and discharging process of the battery 100, the positive active material and the negative active material react with the electrolyte, and the tabs are connected to the electrode terminals to form a current loop. In addition, the electrode assembly 123 can be of a winding type structure or a stacking type structure.

[0116] In some embodiments, the battery cell 120 can also be provided with a pressure relief mechanism for relieving the internal pressure of the battery cell 120 when the internal pressure or temperature of the battery cell 120 reaches a threshold value.

[0117] According to some embodiments of the present application, FIG. 4 is a schematic diagram of the structure of the coating device 10 in the present application. As shown in FIG. 4, the present application provides a coating device 10 for coating a functional layer on a substrate 20. Along the thickness direction of the substrate 20, the substrate 20 includes opposite first and second surfaces.

[0118] The functional layer is a functional slurry coated on the surface of the substrate 20, which enables the substrate 20 to have a function consistent with its material properties. Depending on the type of slurry, it plays different roles on the surface of the substrate 20, and the coating range of the functional layer is also selected according to the required function, i.e. it can partially cover the surface of the substrate 20, or it can completely cover the surface of the substrate 20. For example, the functional layer can be a primer slurry or an insulating slurry or other functional slurry. There are many optional functional layers, and in the field of batteries 100, common ones include primer layers, active material layers, insulating layers, etc.

[0119] Specifically, the primer slurry includes a functional material, a binder and a conductive agent, the binder can be selected from at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene and butadiene-styrene rubber, and the conductive agent can be selected from at least one of carbon black, carbon fiber, carbon nanotube, graphite, graphene, metal powder, composite conductive material and conductive ceramic powder.

[0120] Specifically, the insulating glue is at least one of oil-based epoxy resin, bismaleimide resin, water-based polyvinylidene fluoride and polyimide. The insulating coating is a metal oxide particle coating, and the material components thereof specifically include metal oxide particles, polyvinylidene fluoride and N-methyl pyrrolidone. The metal oxide particles can be selected from aluminum oxide, titanium dioxide, zinc oxide, magnesium oxide and combinations thereof.

[0121] Specifically, the active material layer includes at least one of lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium nickelate, lithium nickel manganese oxide and lithium manganese iron nickelate. The active material is divided into positive active material and negative active material, i.e. the positive active material is used in the active material slurry of the positive electrode sheet, and the negative active material is used in the active material slurry of the negative electrode sheet.

[0122] Generally, the substrate 20 is of regular structure, and the first and second surfaces of the commonly seen regular-shaped substrate 20 are opposite, and along the width direction of the substrate 20, the two edges of the first surface and the two edges of the second surface correspondingly project and coincide. In the case of a special-shaped substrate 20, the first and second surfaces thereof can be staggered.

[0123] The coating device 10 comprises a first coating roller 11 for coating the first functional layer 30 on the first surface of the substrate 20.

[0124] The first coating roller 11 is a component with a coating structure for coating the slurry of the first functional layer 30 on the first surface of the substrate 20.

[0125] The coating device 10 further comprises a second coating roller 12, which is arranged downstream or upstream of the first coating roller 11 along the conveying direction of the substrate 20, for coating the second functional layer 40 on the second surface of the substrate 20.

[0126] The second coating roller 12 is a component with a coating structure for coating the slurry of the second functional layer 40 on the first surface of the substrate 20.

[0127] The second coating roller 12 is arranged downstream or upstream of the first coating roller 11 along the conveying direction of the substrate 20, i.e. the positions of the first coating roller 11 and the second coating roller 12 can be set as required. In some embodiments, the substrate 20 can pass through the first coating roller 11 and the second coating roller 12 in sequence when being conveyed, and the first functional layer 30 on the first surface and the second functional layer 40 on the second surface can be coated in sequence. In other embodiments, the substrate 20 can pass through the second coating roller 12 and the first coating roller 11 in sequence when being conveyed, and the second functional layer 40 on the second surface and the first functional layer 30 on the first surface can be coated in sequence.

[0128] The first coating roller 11 and the second coating roller 12 are both provided with a coating structure capable of bonding the slurry. When the first coating roller 11 and the second coating roller 12 rotate around their axes and contact the surface of the substrate 20, the slurry bonded in the coating structure can be coated onto the surface of the substrate 20. The first functional layer 30 on the first surface of the substrate 20 is coated by the first coating roller 11, and the second functional layer 40 on the second surface of the substrate 20 is coated by the second coating roller 12. Along the width direction of the substrate 20, the coating range of the first coating roller 11 and the second coating roller 12 is smaller than the width of the substrate 20, i.e. the first coating roller 11 and the second coating roller 12 are used to coat the front surface and the back surface of the local part of the substrate 20 with a certain functional material, thereby meeting the functional requirements of the substrate 20.

[0129] When the substrate 20 of the electrode plate of the battery 100 is coated, the first functional layer 30 and the second functional layer 40 are the same slurry, such as both being insulating materials or both being active materials that can be used for reaction with electrolyte, since they are used to coat the front surface and the back surface of the same area. In other fields, the functions of the first surface and the second surface of the substrate 20 can be different, and the specific materials of the first functional layer 30 and the second functional layer 40 can be selected as required, i.e. the materials and functions of the slurry of the first functional layer 30 and the second functional layer 40 can be the same or different.

[0130] The coating device 10 further comprises a first driving member 13 connected to the first coating roller 11 for driving the first coating roller 11 to reciprocate along the axial direction.

[0131] The first driving member 13 is a component capable of driving the first coating roller 11 to reciprocate along the axial direction, and can be any linear transmission mechanism, such as a servo motor transmission mechanism, a gear and rack transmission mechanism, a ball screw transmission mechanism, a hydraulic transmission mechanism, a push rod transmission mechanism, a screw pair transmission mechanism, etc.

[0132] Due to the characteristics of the coating process, the thickness of the edge of the coated functional layer will be slightly larger than the thickness of the middle part of the functional layer, and the functional layer will form a thick edge. If the first coating roller 11 and the second coating roller 12 only rotate along the axial direction, and the coating structure of the first coating roller 11 and the coating structure of the second coating roller 12 are always opposite, then the thick edges of the first functional layer 30 and the thick edges of the second functional layer 40 will be opposite and superimposed in the thickness direction of the substrate 20, and then after the substrate 20 is wound and arranged, the thick edge superimposed parts of the multiple turns of the substrate 20 will again be superimposed in thickness on the corresponding radial cross section of the roll, so that the roll after winding is obviously drummed, not only affecting the subsequent production process, but also affecting the overall flatness of the substrate 20, the substrate 20 is easily deformed in the width direction and has an arc, etc., and when the substrate 20 is the substrate 20 of the pole piece of the battery 100, it will affect the quality and performance of the finished battery 100.

[0133] Therefore, in order to solve the above-mentioned problems found, the present scheme sets the first driving member 13 for driving the first coating roller 11 to reciprocate along the axial direction, so that the first coating roller 11 can not only rotate around its axial direction, but also reciprocate along the axial direction, and then the edges of the coating structure of the first coating roller 11 and the edges of the coating structure of the second coating roller 12 can be staggered. After coating, in the thickness direction of the substrate 20, since the edges of the first functional layer 30 and the edges of the second functional layer 40 are not completely projected and overlapped, the thickness superimposition of the thick edges of the first functional layer 30 and the thick edges of the second functional layer 40 when formed on the substrate 20 can be effectively solved. In addition, in the width direction of the substrate 20, the relative positions between the thick edges of the first functional layer 30 and the thick edges of the second functional layer 40 are changed, the axial reciprocation of the first coating roller 11 can be periodic or non-periodic, but as the substrate 20 is wound, the positions of the thick edges of the first functional layer 30 on the multiple turns of the substrate 20 can be at least partially staggered, not all overlapped and superimposed on the same radial cross section, and then the obvious drumming problem existing after the substrate 20 is coated and wound can be effectively solved.

[0134] It should be noted that, as shown in FIGS. 5 and 6, the first coating roller 11 is driven by the first driving member 13, repeatedly switches between the initial position and the position deviated from the initial position in the axial direction, and the second coating roller 12 is always located at the initial position. FIG. 5 shows the state in which the coating structure of the first coating roller 11 and the coating structure of the second coating roller 12 are located at the initial position and face each other, and FIG. 6 shows the state in which the first coating roller 11 is deviated and misaligned with the second coating roller 12. The dashed line in FIG. 6 represents the schematic of the first coating roller 11 at the initial position. In the state in which the second coating roller 12 only rotates around the axis, the position of the thick edge of the second functional layer 40 formed on the substrate 20 along the width direction of the substrate 20 is always unchanged, and the thick edge of the second functional layer 40 is still superimposed on the same radial cross section after the substrate 20 is wound. However, since the first coating roller 11 reciprocally moves in the axial direction, along the thickness direction of the substrate 20, some parts of the thick edge of the second functional layer 40 correspond to the part of the first surface without the first functional layer 30, some parts are superimposed with the thick edge of the first functional layer 30, and some parts are superimposed with the non-thick edge part of the first functional layer 30, instead of the thick edge of the first functional layer 30 always being superimposed with the thick edge of the second functional layer 40. As shown in FIGS. 7 and 8, the solid line in FIGS. 7 and 8 represents the edge of the first functional layer 30, and the dashed line in FIGS. 7 and 8 represents the edge of the second functional layer 40. At this time, the superposition of the thickness at the edge only occurs at the edge of the projection overlapping part closest to the center of the coating area. Since there is no superposition of the thickness and various ways of superposition of the thickness, after the substrate 20 is wound, the difference in the thickness of different parts of the substrate 20 can be utilized to effectively improve the superposition of the thickness of the thick edge on the same radial cross section, and thus the problem of obvious bulging after the substrate 20 is coated and wound can be effectively solved.

[0135] In the related art, the first coating roller 11 and the second coating roller 12 are both arranged to be fixed in the axial direction. Analysis shows that, after coating is completed, the thick edges of the first functional layer 30 and the second functional layer 40 are completely projected and overlapped, and the positions of the thick edges on the substrate 20 are fixed. After the substrate 20 is wound, the thick edges will continue to be overlapped in the radial cross section for multiple turns, which will eventually cause the wound material to be obviously drummed. If the coating area of the first coating roller 11 and the coating area of the second coating roller 12 are only offset, but the coating scheme is still fixed in the axial direction, although the thick edges of the first functional layer 30 and the second functional layer 40 are offset, the positions of the thick edges on the substrate 20 are still unchanged. Therefore, after winding, the thick edges will still continue to be overlapped in the radial cross section, that is, the corresponding technical problem still exists. Only the overlapping of the thick edges of the first functional layer 30 and the second functional layer 40 is changed to the overlapping of the thickness of the thick edge of the first functional layer 30 and the non-thick edge area of the second functional layer 40 opposite to the first functional layer 30, and the overlapping of the thickness of the thick edge of the second functional layer 40 and the non-thick edge area of the first functional layer 30 opposite to the second functional layer 40. After winding, the wound material will still be obviously drummed.

[0136] In summary, compared with the technical solution of the related art, the present application does not consider improving the coating structure and arrangement position of the first coating roller 11 and the second coating roller 12. Essentially, the coating roller that has been put into use on the existing production line and will form obvious drumming after winding can still be applied. The present application can obviously improve the local drumming of the substrate 20 after coating and winding into a wound material. The flatness of the substrate 20 can be obviously improved. Especially when used for producing the electrode sheet of the battery 100, it is beneficial to improve the overall quality of the electrode sheet of the electrode assembly 123, thereby improving the quality and performance of the battery 100.

[0137] In addition, the conventional arrangement is that the axial direction of the first coating roller 11 and the axial direction of the second coating roller 12 are both perpendicular to the running direction of the substrate 20. Reciprocating movement means moving back and forth between the initial position and the preset position. For example, it can be one-way reciprocating movement at the initial position. It needs to move back and forth between the limit position on one side and the initial position. At this time, the projection relationship between the coated first functional layer 30 and the second functional layer 40 is shown in FIG. 7. For another example, it can also be two-way reciprocating movement at the initial position. It needs to move from the initial position to one of the limit positions, and then move back and forth between the two limit positions. Finally, it can return to the initial position or not. However, it needs to start from the initial position for the first time, that is, it needs to return to the initial position before starting coating. At this time, the projection relationship between the coated first functional layer 30 and the second functional layer 40 is shown in FIG. 8.

[0138] According to some embodiments of the present application, the coating device 10 further comprises a second driving member 14 connected to the second coating roller 12 for driving the second coating roller 12 to move reciprocally along the axial direction.

[0139] The second driving member 14 is a member capable of driving the second coating roller 12 to move reciprocally along the axial direction, which can be any linear transmission mechanism, such as a servo motor transmission mechanism, a gear and rack transmission mechanism, a ball screw transmission mechanism, a hydraulic transmission mechanism, a push rod transmission mechanism, a screw pair transmission mechanism, etc.

[0140] In the above technical solution, the coating device 10 is further provided with the second driving member 14 for driving the second coating roller 12 to move reciprocally along the axial direction, so that the position of the thick edge of the second functional layer 40 coated by the second coating roller 12 on the substrate 20 can also be changed. With the winding of the substrate 20, the positions of the thick edges of the first functional layers 30 on the multiple turns of the substrate 20 can be staggered with each other, and none of them will overlap and stack on the same radial section. Similarly, the positions of the thick edges of the second functional layers 40 can also be staggered with each other, and none of them will overlap and stack on the same radial section. Thus, the problem of obvious bulging after the coating and winding of the substrate 20 can be effectively solved.

[0141] As shown in FIG. 9, the first coating roller 11 and the second coating roller 12 can be offset towards different sides when coating the same region of the substrate 20, so that the thick edge of the first functional layer 30 and the thick edge of the second functional layer 40 can be staggered and partially interlaced. In some embodiments, the first coating roller 11 and the second coating roller 12 can move reciprocally on the first side and the second side of the initial position respectively. At this time, the first functional layer 30 and the second functional layer 40 formed by coating are shown in FIG. 10, in which the solid line is the edge of the first functional layer 30, and the dashed line is the edge of the second functional layer 40. In some embodiments, the first coating roller 11 and the second coating roller 12 can move reciprocally on the first side and the second side of the initial position. At this time, the first functional layer 30 and the second functional layer 40 formed by coating are shown in FIG. 11, in which the solid line is the edge of the first functional layer 30, and the dashed line is the edge of the second functional layer 40.

[0142] It should be noted that in the thickness direction of the substrate 20, the thick edge of the first functional layer 30 and the thick edge of the second functional layer 40 can also be projected to completely coincide, although at this time the thick edge of the first functional layer 30 and the thick edge of the second functional layer 40 are always superimposed, but since the first coating roller 11 and the second coating roller 12 are both reciprocatingly moved along the axial direction, the position of the thick edge of the first functional layer 30 on the substrate 20 is changed along the thickness direction of the substrate 20, and the position of the thick edge of the second functional layer 40 on the substrate 20 is also changed. Then, as the substrate 20 is wound, the positions of the thick edges of the first functional layer 30 between multiple turns of the substrate 20 can be at least partially staggered, and will not all be superimposed on the same radial cross section, so that the thickness difference between different parts of the substrate 20 after the substrate 20 is coated with the first functional layer 30 and the second functional layer 40 can be utilized, and the problem of obvious bulging after the substrate 20 is coated and wound can also be effectively solved.

[0143] That is, as long as at least the first coating roller 11 is reciprocatingly moved in the axial direction, the technical effect of effectively improving the condition of the superimposition of the thickness of the thick edge on the same radial cross section after the substrate 20 is wound can be achieved, and the problem of obvious bulging after the substrate 20 is coated and wound can also be effectively solved.

[0144] According to some embodiments of the present application, the first coating roller 11 is a gravure roller or a microgravure roller; and the second coating roller 12 is a gravure roller or a microgravure roller.

[0145] In the technical solution of the embodiments of the present application, the coating structure is a screen area etched on the surface of the gravure roller or the microgravure roller. The screen area is generally a plurality of screen holes or grooves with the same depth, which is used to accommodate the coating slurry to be coated, and the coating slurry can be adhered in the screen. The prepared paste-like thick slurry is uniformly coated on the specific area of the substrate 20 through the screen area. The thickness consistency of each coating position needs to be ensured during coating, and the coating thickness needs to be controlled within the tolerance range required by the process.

[0146] The difference between the gravure roller and the microgravure roller is that, on the one hand, the gravure roller needs to be pressed against the substrate 20 by a back pressure roller to realize the contact between the screen area and the surface of the substrate 20, while the microgravure roller does not need a back pressure roller. The microgravure coating method is a reverse and contact type coating method, that is, the rotation direction of the microgravure roller is opposite to the feeding direction of the substrate 20, and the substrate 20 does not need to be directly pressed against the microgravure roller by a back pressure roller. On the other hand, generally, the diameter of the microgravure roller is smaller, or the size of the screen on the microgravure roller is smaller, and the processing difficulty is greater than that of the gravure roller.

[0147] For example, commonly, the gravure roller is a metal roller, and the screen area thereof is also a metal material, and the size of the screen hole / groove thereon is larger; while the microgravure roller sprays ceramic material on the surface thereof and then etches the screen by laser, and the size of the screen hole of the screen is smaller.

[0148] In the coating process, in order to reduce the possibility of the substrate 20 generating concave and convex points caused by the interference of the anilox roll with other areas, a stepped anilox roll, for example, a micro gravure roll, is generally selected. The micro gravure roll generally includes a roll shaft and a protruding part arranged circumferentially on the roll shaft and protruding from the surface of the roll shaft. The anilox for bonding the paste is arranged on the circumferential surface of the protruding part.

[0149] There can be only one coating area on the first coating roll 11 and the second coating roll 12, or there can be two or more coating areas arranged axially at intervals, so as to improve the production efficiency of the production line, and a plurality of functional layers can be obtained by one coating operation. The uncoated area can provide operation space for subsequent processing procedures (such as coating the required functional layer on the uncoated area in the next time, or cutting the substrate 20).

[0150] In order to realize coating, other structures of the coating device 10 not mentioned can refer to related technologies. For example, the coating device 10 can further include a first liquid storage tank, the first coating roll 11 is rotatable relative to the first liquid storage tank and partially located in the first liquid storage tank, the surface of the substrate 20 is tangent to the surface of the first coating roll 11, and the first functional layer 30 is coated by rotating the first coating roll 11 to dip and coat. In this way, as the first coating roll 11 rotates, the first coating roll 11 can dip the paste of the first functional layer 30 in the first liquid storage tank and print and coat it to the first coating area. For another example, the coating device 10 can further include a second liquid storage tank corresponding to the second coating roll 12; for another example, the coating device 10 can further include a unwinding assembly, a winding assembly, a drying assembly 15 for drying the functional layer, and the like. Details are not described herein.

[0151] In some embodiments, the drying assembly 15 can be arranged between the first coating roll 11 and the second coating roll 12, and the process can be that after the first functional layer 30 is coated, the substrate 20 enters the drying assembly 15, the drying assembly 15 dries the first functional layer 30, then the substrate 20 is conveyed to the second coating roll 12 to coat the second functional layer 40, and then the substrate 20 coated with the second functional layer 40 enters the drying assembly 15 again, and the drying assembly 15 dries the second functional layer 40.

[0152] In some embodiments, the drying assembly 15 can be arranged downstream of the first coating roll 11 and the second coating roll 12, and the process can be that the substrate 20 is conveyed to the first coating roll 11 to coat the first functional layer 30, then the substrate 20 is conveyed to the second coating roll 12 to coat the second functional layer 40, and then the substrate 20 coated with the first functional layer 30 and the second functional layer 40 enters the drying assembly 15, and the drying assembly 15 simultaneously dries the first functional layer 30 and the second functional layer 40.

[0153] It should be noted that the first coating roller 11 and the second coating roller 12 are a coating assembly, and at least the first coating roller 11 can be reciprocated along the axial direction by the first driving member 13 while coating. Then when there is a need for other functional layers, one or more coating assemblies can be additionally arranged, as long as at least one coating roller in each coating assembly can rotate around the axis and reciprocate along the axial direction while coating the functional layer, like the first coating roller 11.

[0154] According to some embodiments of the present application, the present application also provides a coating method. FIG. 12 shows a flowchart of some embodiments when the first coating roller 11 is arranged upstream of the second coating roller 12.

[0155] The present application provides a coating method, comprising the following steps:

[0156] The first functional layer 30 is coated on the first surface of the substrate 20 by the first coating roller 11, and the second functional layer 40 is coated on the second surface of the substrate 20 by the second coating roller 12.

[0157] Wherein, the first coating roller 11 is driven to reciprocate along the axial direction when coating the first functional layer 30.

[0158] In the above technical solution, the technical effects of the coating device 10 are consistent. When the first coating roller 11 and the second coating roller 12 rotate around the axis and contact the surface of the substrate 20, the adhesive in the coating structure of the first coating roller 11 and the second coating roller 12 can be coated on the surface of the substrate 20. The first functional layer 30 is coated on the first surface of the substrate 20 by the first coating roller 11, and the second functional layer 40 is coated on the second surface of the substrate 20 by the second coating roller 12. Along the width direction of the substrate 20, the coating range of the first coating roller 11 and the second coating roller 12 is smaller than the width of the substrate 20, that is, the material with certain function is coated on the front and back surfaces of the substrate 20, thereby meeting the functional requirements of the substrate 20.

[0159] As shown in FIGS. 5 and 6, by driving the first coating roller 11 to rotate around the axis to coat the first functional layer 30 while driving the first coating roller 11 to reciprocate along the axis, the edges of the coating structure of the first coating roller 11 and the edges of the coating structure of the second coating roller 12 can be staggered. After coating is completed, along the thickness direction of the substrate 20, since the edges of the first functional layer 30 and the edges of the second functional layer 40 are not completely projected to coincide, the thickness overlap of the thick edges of the first functional layer 30 and the thick edges of the second functional layer 40 when formed on the substrate 20 can be effectively solved. In addition, along the width direction of the substrate 20, since the relative positions between the thick edges of the first functional layer 30 and the thick edges of the second functional layer 40 are variable, the axial reciprocation of the first coating roller 11 can be periodic or aperiodic, but as the substrate 20 is wound, the positions of the thick edges of the first functional layer 30 on the multiple turns of the substrate 20 can at least partially stagger, and will not all overlap on the same radial section, thereby effectively solving the problem of obvious bulging after the substrate 20 is coated and wound.

[0160] In the state where the second coating roller 12 only rotates around the axis, along the width direction of the substrate 20, the positions where the thick edges of the second functional layer 40 are formed on the substrate 20 are always the same, and after the substrate 20 is wound, the thick edges will still overlap on the same radial section, but since the first coating roller 11 reciprocates along the axis during coating of the first functional layer 30, along the thickness direction of the substrate 20, for the thick edges of the second functional layer 40, some parts correspond to parts of the first surface without the first functional layer 30, some parts overlap with the thick edges of the first functional layer 30, and some parts overlap with the non-thick edge parts of the first functional layer 30, instead of the thick edges of the first functional layer 30 always overlapping with the thick edges of the second functional layer 40 in thickness. Since there is no overlap in thickness and various ways of overlapping in thickness, after the substrate 20 is wound, the differences in thickness of different parts of the substrate 20 can be utilized to finally effectively improve the situation of overlapping in thickness of the thick edges on the same radial section, thereby effectively solving the problem of obvious bulging after the substrate 20 is coated and wound.

[0161] In summary, the coating method can significantly improve the local bulging of the substrate 20 after coating is completed and the substrate 20 is wound into a roll, and the flatness of the substrate 20 can be significantly improved, especially when used for production of the electrode sheet of the battery 100, which is conducive to improving the overall quality of the electrode sheet of the electrode assembly 123, thereby improving the quality and performance of the battery 100.

[0162] According to some embodiments of the present application, the coating method further comprises driving the second coating roller 12 to reciprocate along the axis when coating the second functional layer 40.

[0163] In the above technical solution, the second coating roller 12 rotates around the axis while reciprocating along the axis, and the position of the thick edge of the second functional layer 40 coated by the second coating roller 12 on the substrate 20 can also be changed. As the substrate 20 is wound, the positions of the thick edges of the first functional layer 30 on the multiple turns of the substrate 20 can be staggered, and they will not all overlap on the same radial section. Similarly, the positions of the thick edges of the second functional layer 40 can also be staggered, and they will not all overlap on the same radial section. Thus, the problem of obvious bulging after the substrate 20 is coated and wound can be effectively solved.

[0164] According to some embodiments of the present application, the frequency of the axial reciprocating movement of the first coating roller 11 is the same as the frequency of the axial reciprocating movement of the second coating roller 12.

[0165] In the above technical solution, the first coating roller 11 reciprocates along the axis at a certain frequency. Thus, the axial reciprocating movement of the first coating roller 11 is periodic and not disordered. Similarly, the second coating roller 12 also reciprocates along the axis at a certain frequency. Thus, the axial reciprocating movement of the second coating roller 12 is periodic and not disordered.

[0166] By controlling the frequency of the axial reciprocating movement of the first coating roller 11 to be the same as the frequency of the axial reciprocating movement of the second coating roller 12, the period of the axial reciprocating movement of the first coating roller 11 can be consistent with the period of the axial reciprocating movement of the second coating roller 12, which can facilitate the beat control of the process.

[0167] According to some embodiments of the present application, the first coating roller 11 is driven to reciprocate along the axis when the first functional layer 30 is coated, and the method specifically comprises:

[0168] The first coating roller 11 is driven to reciprocate along the axis on the first side of the initial position.

[0169] In the above technical solution, the axial reciprocating movement of the first coating roller 11 is only between the initial position and the preset limit position on the first side. That is, the period of the axial reciprocating movement of the first coating roller 11 is the time interval between the first coating roller 11 moving from the initial position to the preset limit position on the first side twice.

[0170] When the first functional layer 30 is coated, the first coating roller 11 is driven to reciprocate along the axial direction on the first side of the initial position, so that the position of the edge of the first functional layer 30 on the substrate 20 is variable, the edge of the coating structure of the first coating roller 11 and the edge of the coating structure of the second coating roller 12 can be partially staggered, and after the coating is completed, due to the fact that the edge of the first functional layer 30 and the edge of the second functional layer 40 are not completely projected and coincided, the thickness superposition of the thick edge of the first functional layer 30 and the thick edge of the second functional layer 40 formed on the substrate 20 can be effectively solved. At the same time, with the winding of the substrate 20, the positions of the thick edges of the first functional layer 30 on the multiple turns of the substrate 20 can be at least partially staggered and will not be completely overlapped and superimposed on the same radial section, thereby effectively solving the obvious bulging problem existing after the substrate 20 is coated and wound.

[0171] According to some embodiments of the present application, the second coating roller 12 is driven to reciprocate along the axial direction when the second functional layer 40 is coated, specifically including:

[0172] The second coating roller 12 is driven to reciprocate along the axial direction on the second side of the initial position; the first side is opposite to the second side.

[0173] In the above technical solution, the axial reciprocation of the second coating roller 12 is only between the initial position and the preset limit position on the second side, that is, the period of the axial reciprocation of the second coating roller 12 at this time is the time interval between the first time and the second time when the second coating roller 12 moves from the initial position to the preset limit position on the first side.

[0174] By making the first coating roller 11 only deviate to the first side and reciprocate, and making the second coating roller 12 only deviate to the second side and reciprocate, the position of the edge of the first functional layer 30 on the substrate 20 is variable, and the position of the edge of the second functional layer 40 on the substrate 20 is also variable. At the same time, since the frequency of the axial reciprocation of the first coating roller 11 is the same as the frequency of the axial reciprocation of the second coating roller 12, the first coating roller 11 and the second coating roller 12 always maintain the same pace with opposite moving directions, the edge of the coating structure of the first coating roller 11 and the edge of the coating structure of the second coating roller 12 can be partially staggered, thereby effectively solving the problem of drum bulging after winding.

[0175] According to some embodiments of the present application, the first coating roller 11 is driven to reciprocate along the axial direction when the first functional layer 30 is coated, specifically including:

[0176] The first coating roller 11 is driven to reciprocate along the axial direction on the first side of the initial position once and on the second side of the initial position once, and the above movement is repeated.

[0177] In the technical solution, the axial reciprocating movement path of the first coating roller 11 in one cycle is: initial position-limit position on the first side-initial position-limit position on the second side-initial position, and the first coating roller 11 repeats the reciprocating movement according to the path, that is, a coating method of double-side reciprocating movement.

[0178] At this time, through analysis, it can be known that when the second coating roller 12 is always at the initial position for coating the second functional layer 40, the first coating roller 11 adopts double-side reciprocating movement, and for the thick edge of the second functional layer 40 in the thickness direction of the substrate 20, some parts of the first functional layer 30 correspond to the region of the first surface, at this time, there is no thickness superposition, some parts are superimposed with the thick edge of the first functional layer 30, and some parts are superimposed with the non-thick edge part of the first functional layer 30, instead of the thick edge of the first functional layer 30 always being superimposed with the thick edge of the second functional layer 40 in thickness. Since the first functional layer 30 and the second functional layer 40 exist in the non-superposition of thickness and the possibility of multiple thickness superpositions, after the substrate 20 is wound, the difference in thickness of different parts of the substrate 20 can be utilized, and finally the condition of the thick edge thickness superposition on the same radial cross section can also be effectively improved, and then the obvious drum problem existing after the substrate 20 is coated and wound can be effectively solved.

[0179] According to some embodiments of the present application, the second coating roller 12 is driven to reciprocate along the axial direction when coating the second functional layer 40, specifically including:

[0180] The second coating roller 12 is driven to reciprocate along the axial direction once on the second side of the initial position and once on the first side of the initial position, and the above movement is repeated.

[0181] In the technical solution, similar to the axial reciprocating movement of the first coating roller 11, the axial reciprocating movement path of the second coating roller 12 in one cycle is: initial position-limit position on the second side-initial position-limit position on the first side-initial position, and the second coating roller 12 repeats the reciprocating movement according to the path, that is, a coating method of double-side reciprocating movement.

[0182] The positions of the edges of the first functional layer 30 and the edges of the second functional layer 40 on the substrate 20 are both variable, and since the frequency of the axial reciprocating movement of the first coating roller 11 is the same as the frequency of the axial reciprocating movement of the second coating roller 12, the first coating roller 11 and the second coating roller 12 always maintain the same pace in the opposite movement direction, the edges of the coating structure of the first coating roller 11 and the edges of the coating structure of the second coating roller 12 can be partially staggered, and then the problem of drum after winding can be effectively solved.

[0183] Meanwhile, it can be known through analysis that, along the thickness direction of the base material 20, for the thick edge of the second functional layer 40, some parts correspond to the area of the first surface without the first functional layer 30, at this time there is no thickness superposition, some parts are superposed with the thick edge of the first functional layer 30, and some parts are superposed with the non-thick edge part of the first functional layer 30, instead of the thick edge of the first functional layer 30 always being superposed with the thick edge of the second functional layer 40 in thickness. Due to the existence of the non-superposition of the thickness of the first functional layer 30 and the second functional layer 40 and the possibility of various thickness superpositions, after the base material 20 is wound, the difference in thickness of different parts of the base material 20 can be utilized, and finally the situation of the thick edge thickness superposition in the same radial cross section can also be effectively improved, and then the obvious rib problem existing after the base material 20 is coated and wound can be effectively solved.

[0184] According to some embodiments of the present application, the coating method further comprises: controlling the running time of the base material 20 between the first coating roller 11 and the second coating roller 12 to be t;

[0185] According to the running direction of the base material 20, the first coating roller 11 and the second coating roller 12 are controlled to move reciprocally along the axis in sequence, and the time difference of the reciprocally moving in sequence is t.

[0186] In the above technical solution, it can be understood that: taking the same area of the base material 20 as a reference, the area contacts the first coating roller 11, the first coating roller 11 starts to move reciprocally along the axis as the timing starting point, after time t, the area starts to contact the second coating roller 12, and the second coating roller 12 starts to move reciprocally along the axis at the same time of contacting the area.

[0187] When the speed of the base material 20 running is always constant, the running time of the base material 20 between the first coating roller 11 and the second coating roller 12 is t, and the material length of the base material 20 running from the first coating roller 11 to the second coating roller 12 can be obtained. By making the time interval of the first coating roller 11 and the second coating roller 12 moving reciprocally along the axis also t, the part of the base material 20 contacted by the first coating roller 11 when starting to move transversely is consistent with the part of the base material 20 contacted by the second coating roller 12 when starting to move transversely, and then the coating starting point of the first coating roller 11 moving reciprocally along the axis is consistent with the coating starting point of the second coating roller 12 moving reciprocally along the axis.

[0188] It should be noted that the sequence of the first coating roller 11 and the second coating roller 12 is determined by the specific situation of the production line, and one of the first coating roller 11 and the second coating roller 12 located upstream moves reciprocally along the axis first, and the other one located downstream moves reciprocally along the axis later.

[0189] According to some embodiments of the present application, the maximum offset distance of the first coating roller 11 along the axis relative to its initial position is controlled to be L, and L≤5mm.

[0190] In the above technical solution, theoretically, the preset coating area of the first surface corresponds to the range coated when the first coating roller 11 is in the initial position. Similarly, the preset coating area of the second surface corresponds to the range coated when the second coating roller 12 is in the initial position. Therefore, the coating area of the first coating roller 11 deviating from the initial position in the axial direction is not the pre-planned coating area. By controlling the maximum deviation distance of the first coating roller 11 from the initial position in the axial direction to be no more than 5 mm, the problem of obvious drumming of the substrate 20 after coating and winding can be effectively solved by improving the process, while the deviation of the coating range can be reduced, and the influence on the subsequent process and the final required performance of the substrate 20 can be reduced.

[0191] It should be noted that the maximum deviation distance L of the first coating roller 11 from the initial position in the axial direction refers to the maximum deviation distance from the initial position on one side. In some embodiments, when the first coating roller 11 adopts a double-sided reciprocating movement scheme, the maximum deviation distance on the first side and the second side should both be no more than 5 mm.

[0192] For example, in some embodiments, L can be selected from 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1.2 mm, 1.5 mm, 1.6 mm, 2 mm, 2.3 mm, 2.5 mm, 2.8 mm, 3 mm, 3.5 mm, 3.8 mm, 4 mm, 4.3 mm, 4.5 mm, 4.8 mm, 5 mm, etc.

[0193] According to some embodiments of the present application, L≤0.5 mm.

[0194] In the above technical solution, by controlling the maximum deviation distance L of the first coating roller 11 from the initial position in the axial direction to be no more than 0.5 mm, the technical effect of effectively solving the problem of obvious drumming of the substrate 20 after coating and winding can be achieved, and the influence on the preset area which does not need to be coated with the first functional layer 30 and the second functional layer 40 can be reduced. In particular, in some embodiments, other functional layers of other properties can be coated in the area adjacent to the first functional layer 30 and the second functional layer 40.

[0195] For example, in some embodiments, L can be selected from 0.08 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.24 mm, 0.26 mm, 0.3 mm, 0.32 mm, 0.36 mm, 0.38 mm, 0.4 mm, 0.42 mm, 0.44 mm, 0.45 mm, 0.46 mm, 0.49 mm, 0.5 mm, etc.

[0196] According to some embodiments of the present application, the first coating roller 11 is driven to reciprocate along the axial direction when coating the first functional layer 30, specifically including:

[0197] During the movement of the first coating roller 11 from the initial position to the extreme position farthest from the initial position, the axial movement of the first coating roller 11 is controlled to at least pause once.

[0198] And / or, during the movement of the first coating roller 11 from the extreme position farthest from the initial position to the initial position, the axial movement of the first coating roller 11 is controlled to at least pause once.

[0199] In the above technical solution, during the reciprocating movement of the first coating roller 11, the axial movement of the first coating roller 11 is controlled to at least pause once during the movement of the first coating roller 11 from the initial position to the extreme position farthest from the initial position, and / or during the movement of the first coating roller 11 from the extreme position farthest from the initial position to the initial position. That is, at least one of the axial movement of the first coating roller 11 from the initial position and back to the initial position adopts an intermittent, interval movement, rather than a continuous movement. During the movement pause of the first coating roller 11, the substrate 20 is still conveyed at a predetermined speed.

[0200] By reasonably setting the relationship between the distance of single movement of the first coating roller 11, the length of the substrate 20 corresponding to the single movement, the time of single pause, the length of the substrate 20 corresponding to the single pause, and other parameters, the thick edges of the first functional layer 30 and the thick edges of the second functional layer 40 on each coil of the substrate 20 after winding can be effectively staggered, so that they will not only be stacked in thickness on the corresponding radial cross section, thereby effectively solving the obvious drum problem existing after the substrate 20 is coated and wound.

[0201] On this basis, according to some embodiments of the present application, in order to control the rhythm of the first coating roller 11 and the second coating roller 12 to be consistent, the axial movement of the first coating roller 11 and the second coating roller 12 is controlled to be pause movement, that is, at least pause once during the unidirectional movement, and the pause times of the first coating roller 11 and the second coating roller 12 and the distance of single movement are consistent.

[0202] According to some embodiments of the present application, the first coating roller 11 is driven to reciprocate along the axial direction when coating the first functional layer 30, which can also be that, during the movement of the first coating roller 11 from the initial position to the extreme position farthest from the initial position, the first driving member 13 drives the first coating roller 11 to continuously move axially, that is, without pausing in the middle. The unidirectional movement of the second coating roller 12 is consistent with the first coating roller 11, which is also a movement direction without pausing in the middle.

[0203] According to some embodiments of the present application, the present application also provides a battery 100 production line comprising the coating device 10 described above, the coating device 10 being used for coating the functional layer on the substrate 20 of the electrode sheet of the battery 100.

[0204] The following takes the first coating roller 11 and the second coating roller 12 as micro-concave rollers, the first coating roller 11 being located upstream of the second coating roller 12, and the coated substrate 20 being an aluminum foil as an example to introduce the coating process of the present application in two specific examples. The width of a single coating area on the micro-concave roller is 10 mm, and the total width of the aluminum foil is 1 m. The parameter settings of the first coating roller 11 and the second coating roller 12 remain consistent, and the parameters are defined as follows:

[0205] Lx: the distance of a single movement of the micro-concave roller when moving along the axial direction;

[0206] La: the substrate 20 running length corresponding to a single movement of the micro-concave roller;

[0207] 3) Ld: the substrate 20 running length corresponding to the pause time of the adjacent two single movements of the micro-concave roller, i.e., the substrate 20 running length corresponding to the pause time of the adjacent two single movements of the micro-concave roller after the completion of a single movement of the micro-concave roller;

[0208] 4) L: the maximum offset distance of the micro-concave roller along the axial direction with the base point being the initial position of the micro-concave roller;

[0209] 5) Lp: the substrate 20 length required for the substrate 20 to run from the first coating roller 11 to the second coating roller 12;

[0210] Parameter setting requirements: Lx≤L; Ld≥0.

[0211] Example 1: only the first coating roller 11 reciprocally moves along the axial direction:

[0212] 1) Coating starts, the coating area of the first coating roller 11 at the initial position is aligned with the coating area of the second coating roller 12, the first coating roller 11 starts to move for the first time from the initial position along the first side of the axial direction, the moving distance is Lx, Lx≤1 mm, for example, Lx is 0.2 mm, and at the same time, the substrate 20 running length during this movement is La, 0.1 m≤La≤1000 m.

[0213] 2) After the completion of the first movement, the first coating roller 11 stops moving, and the substrate 20 runs for Ld, Ld≤200 m, for example, Ld is 20 m, during the stop of the first coating roller 11.

[0214] 3) The first coating roller 11 moves again along the first side of the axial direction, and when the first coating roller 11 completes the second movement, the substrate 20 still has a length of La. When the first coating roller 11 completes the second movement, the first coating roller 11 stops moving again. After the substrate 20 moves again by a length of Ld, the first coating roller 11 moves again. This process is repeated until the first coating roller 11 moves to the first side by a maximum offset distance L, and the first coating roller 11 starts moving in the opposite direction to return to the initial position. L≤5mm, for example, 0.5mm.

[0215] 4) The first coating roller 11 repeatedly moves to and from the first side of the initial position in the manner described above, or periodically moves to and from the first side and the second side of the initial position, until the coating is completed.

[0216] In Example 2, both the first coating roller 11 and the second coating roller 12 move to and from the axial direction:

[0217] 1) The coating starts, the film coating area of the first coating roller 11 at the initial position and the film coating area of the second coating roller 12 at the initial position are aligned, the first coating roller 11 only moves to and from the first side, for example, the left side of the initial position, and the second coating roller 12 moves to and from the second side, for example, the right side of the initial position, which is opposite to the movement area of the first coating roller 11.

[0218] 2) The first coating roller 11 starts moving from the initial position to the left side by a distance of Lx, Lx≤1mm, for example, Lx can be 0.2mm. At the same time, during this movement, the substrate 20 moves by a length of La, 0.1m≤La≤1000m, for example, 20m. Taking the start of the first movement of the first coating roller 11 as the reference point, when the substrate 20 moves by a length of Lp, the second coating roller 12 starts moving in the opposite direction of the first coating roller 11 by a distance of Lx, so that the starting point of the coating of the first coating roller 11 is consistent with the starting point of the coating of the second coating roller 12.

[0219] 3) After the first movement of the first coating roller 11 is completed, the first coating roller 11 stops moving, and during the movement stop of the first coating roller 11, the substrate 20 moves by a length of Ld, Ld≤200m, for example, Ld is 20m. Similarly, after the first movement of the second coating roller 12 is completed, the second coating roller 12 stops moving, and during the movement stop of the second coating roller 12, the substrate 20 moves by a length of Ld, Ld≤0-200m, for example, Ld is 20m.

[0220] 4) the first coating roller 11 and the second coating roller 12 start the second movement respectively, and during the second movement, the substrate 20 runs a length of L; after the second movement is completed, the first coating roller 11 and the second coating roller 12 stop the lateral movement respectively, and after the substrate 20 runs a length of Ld, the first coating roller 11 and the second coating roller 12 start the third movement again, and the process is repeated;

[0221] 5) until the maximum offset position or the initial position is reached, the first coating roller 11 and the second coating roller 12 start the reverse movement respectively.

[0222] The coating device 10, the coating method and the battery 100 production line according to the embodiments of the present application can effectively solve the technical problem of the obvious drumming of the substrate 20 after coating and winding, and can effectively improve the quality of the electrode assembly 123 of the battery 100 when used for the production of the battery 100, thereby improving the quality and performance of the battery 100.

[0223] Although the present application has been described with reference to the preferred embodiments, various modifications can be made to it without departing from the scope of the present application, and equivalent components can be substituted therefor. In particular, the technical features mentioned in each embodiment can be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A coating device for coating a functional layer on a substrate, wherein the substrate comprises a first surface and a second surface opposite to each other along the thickness direction of the substrate, characterized in that: The coating device includes: a first coating roller for coating the first surface with a first functional layer; A second coating roller is provided downstream or upstream of the first coating roller along the substrate's conveying direction, and is used to coat the second surface with a second functional layer; The first driving member is connected to the first coating roller and is used for driving the first coating roller to move back and forth along the axial direction.

2. The coating device according to claim 1, wherein The coating device also includes: The second driving member is connected to the second coating roller and is used for driving the second coating roller to move back and forth along the axial direction.

3. The coating device according to claim 1 or 2, characterized in that The first coating roller is a gravure roller or a micro gravure roller; the second coating roller is a gravure roller or a micro gravure roller.

4. A coating method, characterized in that: The following steps are involved: Coating a first functional layer on a first surface of the substrate by a first coating roller; coating a second functional layer on a second surface of the substrate by a second coating roller; When coating the first functional layer, the first coating roller is driven to reciprocate along the axial direction.

5. The coating method according to claim 4, wherein The coating method also includes: When coating the second functional layer, the second coating roller is driven to reciprocate in the axial direction.

6. The coating method according to claim 5, wherein The frequency of the first coating roller's axial reciprocating movement is controlled to be the same as the frequency of the second coating roller's axial reciprocating movement.

7. The coating method according to claim 6, wherein Driving the first coating roller to reciprocate along the axial direction when coating the first functional layer specifically includes: The first coating roller is driven to reciprocate along the axial direction at a first side of its initial position.

8. The coating method according to claim 7, wherein Driving the second coating roller to reciprocate along the axial direction when coating the second functional layer specifically includes: The second coating roller is driven to reciprocate along the axial direction at a second side of its initial position; the first side is opposite to the second side.

9. The coating method according to claim 6, wherein Driving the first coating roller to reciprocate along the axial direction when coating the first functional layer specifically includes: The first coating roller is driven to reciprocate once on a first side of its initial position and then to reciprocate once on a second side of its initial position along the axial direction, and the above movement is repeated; the first side is opposite to the second side.

10. The coating method according to claim 9, wherein Driving the second coating roller to reciprocate along the axial direction when coating the second functional layer specifically includes: The second coating roller is driven to reciprocate once on the second side of its initial position in the axial direction, and then to reciprocate once on the first side of its initial position, and the above movements are repeated.

11. The coating method according to any one of claims 5 to 10, characterized in that: The coating method also includes: Controlling the substrate running time between the first coating roller and the second coating roller to be t; According to the running direction of the substrate, the first coating roller and the second coating roller are controlled to move back and forth in the axial direction in sequence, and the time difference between the two movements in the axial direction is controlled to be t.

12. The coating method according to any one of claims 4 to 11, characterized in that The maximum offset distance of the first coating roller relative to its initial position in the axial direction is controlled to be L, where L is less than or equal to 5 mm.

13. The coating method according to claim 12, wherein L≤0.5mm.

14. The coating method according to any one of claims 4 to 13, wherein: Driving the first coating roller to reciprocate along the axial direction when coating the first functional layer specifically includes: During the process of the first coating roller moving from the initial position to the limit position farthest from the initial position, controlling the axial movement of the first coating roller to pause at least once; And / or, in the process of the first coating roller moving from the extreme position farthest from the initial position to the initial position, the axial movement of the first coating roller is controlled to pause at least once.

15. A battery production line, characterized in that: The coating device comprises the coating device according to any one of claims 1 to 3, and is used for coating a functional layer on a substrate of a battery pole piece.

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