Gasket for coating positive electrode of sodium ion battery

Abstract

The utility model relates to a gasket for coating a positive electrode of a sodium ion battery. The gasket comprises a transverse plate, the side baffles are arranged on one side edge of the transverse plate and extend from the side edges of the transverse plate; the at least one splitter plate extends from the side edge of the transverse plate and is positioned between the pair of side baffles so as to form at least two drainage areas; the thin cutting plate extends from the side edge of the transverse plate and is located in the drainage area, the thickness of the thin cutting plate is equal to that of the splitter plate, the end, away from the transverse plate, of the thin cutting plate is provided with a thin cutting part, the thin cutting part is provided with a plane section and inclined plane sections, and the inclined plane sections are symmetrically arranged on the two sides of the plane section; the guiding device is used for guiding slurry to form a thinning area with gradually-changed thickness in a pole piece coating area. On the premise of not increasing the manufacturing cost of the gasket and the production cost of the battery cell, the phenomenon of edge sodium precipitation is solved, and meanwhile, the cycle life of the battery cell is prolonged because the loss of reversible capacity is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of positive electrode coating gaskets, in particular to a gasket used for positive electrode coating of sodium ion batteries. Background Art

[0002] Electrode coating technology is a critical step in the manufacturing of all-tab battery cells, directly impacting the overall performance of the cell. In traditional processes, a coating gasket ensures that the slurry is evenly applied to the electrode coil, forming a coating area, with the two sides naturally extending into the foil area. The coating area is then divided into two by slitting, forming the positive and negative electrode sheets. In the manufacture of all-tab battery cells, the positive and negative electrode sheets and separators are wound or stacked in a specific sequence, with the negative electrode coating area wider than the positive electrode coating area to achieve full coverage and optimize energy storage efficiency. However, existing technologies have some problems: after slitting, the coating area maintains a uniform thickness at the cut end, while the side closest to the foil area gradually thins, forming a skived area. When the positive and negative electrode sheets are wound and assembled, the skived area of the negative electrode corresponds to the cut end of the positive electrode with normal thickness. Due to the reduced thickness of the negative electrode in this area, the ratio of the negative electrode's unit area capacity to the positive electrode's unit area capacity is lower than the designed NP value of the cell. During battery cell charging, sodium precipitation (sodium edge precipitation) is prone to occur in areas with unbalanced NP values. This not only reduces the reversible capacity of the battery cell but also increases safety risks. Therefore, developing a new positive electrode coating gasket that effectively prevents sodium edge precipitation during charging after the slitting and winding of the produced positive electrode coils, thus ensuring high performance and safety, is a pressing issue. Utility Model Content

[0003] In response to the problems existing in the prior art, the purpose of the present utility model is to provide a gasket for coating the positive electrode of a sodium ion battery, comprising a horizontal plate, a side baffle, a diverter plate and a thinning plate. By configuring the thinning plate, a thinning area is formed at the cut end of the positive electrode winding material area. Without increasing the manufacturing cost of the gasket and the production cost of the battery cell, the phenomenon of sodium precipitation at the edge is solved. At the same time, the cycle life of the battery cell is increased by reducing the loss of reversible capacity.

[0004] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0005] 20. The foldable battery according to claim 19, wherein the plurality of side baffles are located at a position adjacent to the cross-plate and extending from the side of the cross-plate to define a boundary of a coating area; at least one diverter plate extending from the side of the cross-plate and located between the pair of side baffles to form at least two drainage areas for guiding slurry; and at least one thinning plate extending from the side of the cross-plate and located within the drainage area. The thinning plate has a thickness equal to that of the diverter plate, the thinning plate divides the drainage area into a first sub-drainage area and a second sub-drainage area, and the thinning plate has a thinning portion at an end away from the cross-plate, the thinning portion having a planar section and an inclined section symmetrically arranged on both sides of the planar section, which is used to guide the slurry to form a thinning area with a gradually varying thickness on the electrode winding material area.

[0006] Furthermore, the ratio of the length to the width of the inclined surface segment is in the range of 1.5-2.

[0007] Furthermore, the length of the plane segment is 1-2 mm.

[0008] Furthermore, the side baffle has a bent portion at the end away from the transverse plate, and the bent portion extends a certain distance toward the thinning plate, wherein the outer corner of the bent portion has an inclined section, and the ratio of the length to the width of the inclined section is in the range of 1.5-2.

[0009] Furthermore, the thinned portion is flush with the end of the side baffle away from the transverse plate.

[0010] Furthermore, the number of the diverter plate is one, and the diverter plate is located between the pair of side baffles and forms two drainage areas. The number of the thinning plates is two, and the two thinning plates are respectively arranged in the two drainage areas, wherein the spacing between the thinning plate and the side baffle is equal to the spacing between the thinning plate and the diverter plate.

[0011] Furthermore, the thickness of the skived plate is equal to the thickness of the side baffle.

[0012] Furthermore, the thickness of the transverse plate is 0.8 mm to 1.2 mm; the thickness of the side baffle is 0.8 mm to 1.2 mm; the thickness of the diverter plate is 0.8 mm to 1.2 mm; and the thickness of the skived plate is 0.8 mm to 1.2 mm.

[0013] Furthermore, the side baffle, the diverter plate and the skived plate are integrally formed.

[0014] Furthermore, a plurality of positioning holes are provided on the transverse plate at certain intervals.

[0015] The utility model has the following advantages:

[0016] The utility model is a gasket for coating the positive electrode of a sodium ion battery. The structure is sophisticated and includes a horizontal plate, a side baffle, a diverter plate and a skiving plate. The positive electrode coil produced by adding a skiving plate to the gasket can form a skiving zone in the middle of the positive electrode coating area. After subsequent slitting and other processing steps, the resulting positive electrode sheet shows skiving zones on both sides of the coating area. This ensures that when the positive electrode sheet is wound to form a bare battery cell, the positions corresponding to the positive and negative electrode coating areas at both ends of the battery cell will not have the problem of a small NP value. Therefore, during the charging process of the battery cell, the phenomenon of sodium precipitation at the edge can be effectively avoided, thereby reducing the loss of reversible capacity, reducing safety hazards, and improving the overall performance and safety of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the three-dimensional structure of the gasket used for coating the positive electrode of a sodium ion battery according to the present invention.

[0018] Figure 2 This is a front view of the gasket for coating the positive electrode of a sodium ion battery according to the present invention.

[0019] Figure 3 yes Figure 2 A partial enlarged view of point A.

[0020] Figure 4 yes Figure 2 A local enlarged view of point B.

[0021] Figure 5 This is a top view of an existing electrode coil after coating but not cut.

[0022] Figure 6 This is a top view of a conventional electrode coil after coating and slitting.

[0023] Figure 7 It is a cross-sectional view of the existing positive electrode sheet, separator and negative electrode sheet.

[0024] Figure 8 It is a cross-sectional view of the positive electrode sheet, the separator and the negative electrode sheet of the present invention.

[0025] Figure 9 This is a cross-sectional view of a conventional electrode coil after coating.

[0026] Figure 10 This is a cross-sectional view of the electrode coil of the present invention after coating.

[0027] Among them, 1 is a horizontal plate, 101 is a positioning hole, 2 is a side baffle, 201 is a bending portion, 201a is an inclined section, 3 is a diverter plate, 4 is a thinning plate, 401 is a thinning portion, 401a is a plane section, 401b is an inclined section, 5 is a drainage area, 501 is a first sub-drainage area, 502 is a second sub-drainage area, 6 is an electrode coil, 601 is a coating area, 602 is a foil area, 603 is a thinning area, 7 is a positive electrode sheet, 8 is a negative electrode sheet, and 9 is a diaphragm. DETAILED DESCRIPTION

[0028] The following description is essentially only exemplary and is not intended to limit the present invention, its application, or use. It will be further understood that the terms "comprise" and / or "comprising" specify the existence of the features, wholes, steps, operations, elements and / or parts described when used in this specification, but do not exclude the existence of one or more other features, wholes, steps, operations, elements, parts and / or their groups or add one or more other features, wholes, steps, operations, elements, parts and / or their groups. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. It will be understood that when an element, component and / or part is referred to as "connected to another element, component and / or part", it can be directly connected to another element, component and / or part, or there can be an intermediate element. It will be understood that although the terms "first", "second" and the like can be used to describe various elements, components and / or parts in this article, these elements, components and / or parts should not be limited by these terms. These terms are only used to distinguish an element, component or part from another element, component or part. Therefore, the first element, component or part discussed below can be referred to as the second element, component or part without departing from the teachings of the present invention. Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the relevant field and / or the context of this specification, and will not be interpreted in an idealized or overly formal sense unless explicitly defined as such herein.

[0029] It should be understood that, in order to clearly show the contents therein, the drawings herein are not drawn to scale, and the same or similar reference numerals indicate the same or similar components or parts. In addition, it should be understood that any embodiments described in this application and the technical features included therein can be combined with each other.

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0031] like Figure 1 and Figure 2 As shown, a gasket for coating the positive electrode of a sodium ion battery includes a transverse plate 1, a side baffle 2, a diverter plate 3 and a skived plate 4.

[0032] like Figure 1 and Figure 2 As shown, the horizontal plate 1, serving as the basic structure of the gasket, is rectangular in shape. The X direction is the length of the horizontal plate 1. The length of the horizontal plate 1 can be adjusted according to the size of the coating area and the specific dimensions of the die. The horizontal plate 1 is provided with a plurality of positioning holes 101 at regular intervals. The positioning holes 101 are used to secure the gasket to the die.

[0033] like Figure 1 and Figure 2 As shown, a pair of side baffles 2 are arranged at one side of the transverse plate 1 and extend from the side of the transverse plate 1 to define the boundary of the coating area, effectively prevent the slurry from overflowing, and ensure precise control of the coating area, wherein the pair of side baffles 2 are symmetrically arranged at the two ends of one side of the transverse plate 1 and extend a certain length from their ends along the width direction of the transverse plate 1.

[0034] like Figure 1 and Figure 2 As shown, at least one diverter plate 3 extends from the side of the transverse plate 1 and is located between a pair of side baffles 2 to form at least two drainage areas 5 for guiding the slurry, wherein the diverter plate 3 and the side baffle 2 are both arranged on the same side of the transverse plate 1, and the diverter plate 3 and the side baffle 2 extend along the width direction of the transverse plate 1 to the same length, that is, the end of the diverter plate 3 is flush with the end of the side baffle 2, so that a drainage area 5 can be formed between them, and the opening formed at their ends is the coating port. The drainage area 5 serves as a guiding channel for the flow of the slurry, ensuring that the slurry can flow to the coating port. The end of the diverter plate 3 corresponds to the foil area 602 of the electrode coil 6, which effectively prevents the slurry from leaking to the non-coating area and ensures the coating quality.

[0035] like Figure 1 and Figure 2As shown, at least one skived plate 4 extends from the side of the transverse plate 1 and is located within the drainage area 5. The thickness of the skived plate 4 is equal to that of the diverter plate 3 and the side baffle 2. The skived plate 4 divides the drainage area 5 into a first sub-drainage area 501 and a second sub-drainage area 502. The end of the skived plate 4 away from the transverse plate 1 has a skived portion 401. The skived portion 401 comprises a planar section 401a and symmetrically arranged inclined sections 401b on either side of the planar section 401a. The skived portion 401 is used to guide the slurry to form a skived area 603 with a gradually varying thickness on the coating area 601 of the electrode coil 6, thereby optimizing the coating distribution in the coating area 601 of the electrode coil 6. The skived portion 401 is flush with the end of the side baffle 2 away from the transverse plate 1. The thickness of the horizontal plate 1 is 0.8mm-1.2mm; the thickness of the side baffle 2 is 0.8mm-1.2mm; the thickness of the diverter plate 3 is 0.8mm-1.2mm; and the thickness of the skived plate 4 is 0.8mm-1.2mm. The equal thickness of each component can reduce stress concentration and deformation caused by thickness differences. In addition, during the coating process, the slurry generates a certain amount of heat, which makes the thermal conductivity between the components more balanced. This helps to promptly dissipate the heat generated by the slurry to the surrounding environment, avoiding local overheating that adversely affects the coating quality and battery performance.

[0036] Among them, the side baffle 2, the diverter plate 3 and the thinning plate 4 are integrally formed. Among them, the width of the thinning plate 4 is smaller than the width of the diverter plate 3, and the coating area 601 coated by the first sub-drainage area 501 and the second sub-drainage area 502 are connected to each other at the thinning part 401, which not only ensures the continuity of the coating, but also realizes the gradual transition of the thickness. Among them, the gasket is arranged in the coating die head, and the coating die head includes a first die head and a second die head arranged up and down. The gasket is located in the gap between the first die head and the second die head, so that the slurry can enter from the drainage area 5 and flow out from the coating port. The position of the coating port corresponds to the coating area 601 of the electrode coil 6. Due to the barrier effect of the thinning plate 4, the slurry flows out from the first sub-drainage area 501 and the second sub-drainage area 502 respectively and is evenly coated on the coating area 601 of the electrode coil 6. Under the action of the thinning portion 401 of the thinning plate 4 , the coating area 601 of the electrode coil 6 forms a thinning area 603 with a gradually varying thickness along the coating direction.

[0037] like Figure 2 and Figure 3As shown, the ratio of the length to width of the inclined surface segment 401b ranges from 1.5 to 2, where the length of the inclined surface segment 401b is a and the width is b, with 1.5 ≤ a / b ≤ 2. This not only takes into account the flow characteristics of the slurry, but also the requirements for coating uniformity and efficiency. The length of the flat surface segment 401a is 1-2 mm. The inclined surface segment 401b is chamfered at specific angles and ratios, allowing the slurry to gradually decelerate and evenly distribute as it flows through the inclined surface segment 401b, thereby forming a gradient coating thickness at a specific location in the coating area (i.e., the skived zone 603). This gradient coating is crucial for improving battery performance because it helps reduce stress concentration in the coating, thereby increasing the battery's cycle stability and lifespan. By controlling the length-to-width ratio of the inclined surface segment 401b, the flow speed and direction of the slurry in the skived zone 603 can be adjusted. A longer inclined surface segment 401b provides a longer deceleration path, allowing the slurry to transition more smoothly into the skived zone 603, thereby reducing the risk of splashing and leakage. At the same time, the appropriate ratio also helps maintain the laminar flow of the slurry, avoiding the adverse effects of turbulence on coating quality. The length of the flat section 401a is set to 1-2 mm. As the length of the flat section 401a changes, the distance between the two inclined sections 401b can also be adjusted accordingly. This makes the thinning area of the thinning zone 603 a controllable variable and can be optimized according to the specific requirements of the battery and the parameters of the coating process. By adjusting the thinning area, the thickness distribution and uniformity of the coating can be further controlled, thereby improving the performance and consistency of the battery.

[0038] like Figure 2 and Figure 4 As shown, the end of the side baffle 2 away from the cross plate 1 has a bent portion 201, which extends a certain distance toward the skived plate 4. The outer corner of the bent portion 201 has an inclined section 201a. The ratio of the length to the width of the inclined section 201a ranges from 1.5 to 2. The length of the inclined section 201a is c, and the width is d, with 1.5≤c / d≤2. The provision of the inclined section 201a allows the slurry to gradually change direction as it flows through this area, slowing the flow rate and transitioning more smoothly to the coating area 601 of the electrode coil 6. This helps reduce slurry splashing and leakage, while improving the uniformity and quality of the coating.

[0039] like Figure 1 and Figure 2As shown, there is one diverter plate 3, which is located between a pair of side baffles 2 and forms two drainage areas 5. There are two skiving plates 4, which are respectively arranged in the two drainage areas 5, wherein the spacing d1 between the skiving plate 4 and the side baffles 2 is equal to the spacing d2 between the skiving plate 4 and the diverter plate 3. The equidistant arrangement helps to achieve uniform distribution and flow control of the slurry in the drainage areas 5, thereby reducing coating defects caused by uneven flow rates. Of course, the number of diverter plates 3 can also be set to two, three, five, etc. For example, there are two diverter plates 3, and three drainage areas 5 are formed between the two diverter plates 3 and between the diverter plates 3 and the side baffles 2. There are three skiving plates 4, and the three skiving plates 4 are respectively located in the three drainage areas 5. That is, one skiving plate 4 is arranged between the two diverter plates 3, and the other two skiving plates 4 are respectively arranged between the diverter plate 3 and the side baffles 2.

[0040] like Figure 5 and Figure 6 As shown in the figure, the top view of the existing electrode sheet after coating and before slitting is shown. Before slitting, the electrode coil 6 has a coating area 601 and foil areas 602 located on both sides of the coating area 601. When entering the slitting process, the electrode coil 6 is cut into two coils along the center line of the coating area 601, and one side of the coating area 601 has a foil area 602. Figure 7 and Figure 9 , which respectively show the cross-sectional views of the existing positive electrode sheet 7, separator 9 and negative electrode sheet 8, as well as the cross-sectional view of the coated electrode coil 6 before slitting. It can be seen that before slitting, the coating area 601 is a continuous, complete plane of the same thickness. A thinning area 603 is naturally formed at the junction of the coating area 601 and the foil area 602. After slitting, the cut end of the coating area 601 is in a right angle shape, and then wound into the positive electrode sheet 7, separator 9 and negative electrode sheet 8. The cut end of the positive electrode corresponds to the thinning area 603 of the negative electrode, and the cut end of the negative electrode corresponds to the thinning area 603 of the positive electrode. This results in the ratio of the negative electrode unit area capacity to the positive electrode unit area capacity being lower than the NP value of the battery cell design. During the battery cell charging process, the area with unbalanced NP values is prone to sodium precipitation. Continue to refer to Figure 8 and Figure 10, which respectively show the electrode coil 6 after coating with the gasket of the present invention, a cross-sectional view of the electrode coil 6 after being cut and wound to form a positive electrode sheet 7, a separator 9 and a negative electrode sheet 8, and a cross-sectional view of the coated electrode coil 6 before cutting. It can be seen that the coating area 601 is divided into two areas of equal thickness, and a thinning area 603 is formed between the two areas by a thinning plate 4. After the thinning area 603 is cut, the cut end of the coating area 601 has a thinning area 603, and then it is wound into a positive electrode sheet 7, a separator 9 and a negative electrode sheet 8. The thinning area 603 of the positive electrode corresponds to the thinning area 603 of the negative electrode. In this way, the positions corresponding to the positive and negative electrode coating areas 601 at both ends of the battery cell will not have the problem of small NP value, and the phenomenon of sodium precipitation at the edge can also be effectively avoided.

[0041] Among them, after the positive electrode sheet 7 was cut and coated with the traditional gasket, a large amount of sodium was clearly deposited on its edge after the charging process. However, after the positive electrode sheet 7 was cut and coated with the present gasket, no sodium deposition was found on its edge after the charging process.

[0042] The method of using the utility model is as follows:

[0043] Install the gasket in the die head, align and fix it with the die head using the positioning hole 101 on the horizontal plate 1 to ensure that the gasket is stable and does not shake. Turn on the coater, adjust to the preset coating speed and pressure, introduce the slurry into the die head, and the slurry passes through the restriction of the side baffle 2 and flows into the drainage area 5 separated by the diverter plate 3. Then, through the obstruction of the thinning plate 4, the slurry flows out from the coating ports corresponding to the first sub-drainage area 501 and the second sub-drainage area 502 and is coated on the coating area 601 on one side of the electrode coil 6. When the slurry flows through the thinning plate 4, it is guided by the thinning portion 401, and a thinning area 603 with a gradient thickness can be formed on the coating area 601 on one side of the electrode coil 6. Turn the other side of the electrode coil 6 over and repeat the above coating operation to form a thinning area 603 with a gradient thickness on the coating area 601 on the other side of the electrode coil 6, so that the thinning areas 603 on the upper and lower sides of the electrode coil 6 correspond to each other. In this way, there are thinning areas 603 on both sides of the coating area 601 after cutting.

[0044] In general, the gasket for coating the positive electrode of a sodium ion battery of the present invention has a sophisticated structure, including a horizontal plate, a side baffle, a diverter plate and a thinning plate. The positive electrode coil produced by adding a thinning plate to the gasket can form a thinning zone in the middle of the positive electrode coating area. After subsequent slitting and other processing steps, the resulting positive electrode sheet shows a thinning zone on both sides of the coating area. This ensures that when the positive electrode sheet is wound to form a bare battery cell, the positions corresponding to the positive and negative electrode coating areas at both ends of the battery cell will not have the problem of a small NP value. Therefore, during the charging process of the battery cell, the phenomenon of sodium precipitation at the edge can be effectively avoided, thereby reducing the loss of reversible capacity, reducing safety hazards, and improving the overall performance and safety of the battery.

[0045] The above embodiments are preferred implementation methods of the present invention, but the implementation methods of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A gasket for coating a positive electrode of a sodium ion battery, characterized in that: include: horizontal board; a pair of side baffles, the pair of side baffles being arranged at one side of the transverse plate and extending from the side of the transverse plate to define a boundary of a coating area; at least one diverter plate extending from a side of the transverse plate and positioned between the pair of side baffles to form at least two drainage areas for guiding the slurry; At least one thinning plate, which extends from the side of the transverse plate and is located in the drainage area, wherein the thickness of the thinning plate is equal to the thickness of the diverter plate, and the thinning plate divides the drainage area into a first sub-drainage area and a second sub-drainage area, and the end of the thinning plate away from the transverse plate has a thinning portion, and the thinning portion has a plane section and inclined sections arranged symmetrically on both sides of the plane section, which is used to guide the slurry to form a thinning area with a gradually varying thickness on the electrode winding material area.

2. A gasket for coating a positive electrode of a sodium ion battery according to claim 1, characterized in that: The ratio of the length to the width of the inclined surface section is in the range of 1.5-2.

3. A gasket for coating a positive electrode of a sodium ion battery according to claim 1, characterized in that: The length of the planar segment is 1-2 mm.

4. The gasket for coating the positive electrode of a sodium ion battery according to claim 1, characterized in that: The side baffle has a bent portion at the end away from the transverse plate, and the bent portion extends a certain distance toward the thinning plate, wherein the outer corner of the bent portion has an inclined section, and the ratio of the length to the width of the inclined section is in the range of 1.5-2.

5. The gasket for coating the positive electrode of a sodium ion battery according to claim 1, characterized in that: The thinned portion is flush with an end portion of the side baffle away from the transverse plate.

6. The gasket for coating the positive electrode of a sodium ion battery according to claim 1, characterized in that: There is one diverter plate, which is located between the pair of side baffles and forms two drainage areas. There are two thinning plates, which are respectively arranged in the two drainage areas, wherein the distance between the thinning plate and the side baffle is equal to the distance between the thinning plate and the diverter plate.

7. The gasket for coating the positive electrode of a sodium ion battery according to claim 1, characterized in that: The thickness of the skived plate is equal to the thickness of the side baffle.

8. The gasket for coating the positive electrode of a sodium ion battery according to claim 1, characterized in that: The thickness of the transverse plate is 0.8mm-1.2mm; the thickness of the side baffle is 0.8mm-1.2mm; the thickness of the diverter plate is 0.8mm-1.2mm; and the thickness of the skived plate is 0.8mm-1.2mm.

9. The gasket for coating the positive electrode of a sodium ion battery according to claim 1, characterized in that: The side baffle, the diverter plate and the skived plate are integrally formed.

10. The gasket for coating the positive electrode of a sodium ion battery according to claim 1, characterized in that: The transverse plate is provided with a plurality of positioning holes at regular intervals.

Images