A dry powder laydown tab manufacturing process based on a mother ribbon current collector

Abstract

The application relates to the technical field of lithium battery production and discloses a dry powder coating electrode tab manufacturing process based on a mother tape current collector, which comprises the following steps: mother tape current collector unwinding, coating of a pressure-sensitive adhesive layer, powder feeding and coating, primary scraping, secondary scraping, heating and glassing, primary pressing, edge material adsorption, secondary pressing and mother tape current collector winding, wherein the first scraper in the primary scraping process and the second scraper in the secondary scraping process are both arranged obliquely relative to the conveying direction of the mother tape current collector, and the oblique directions both extend from the inner side to the outer side of the mother tape current collector along the conveying direction. The electrode powder blocked by the scraper can autonomously roll to the outer side of the mother tape current collector along the oblique surface of the scraper. The dry powder coating electrode tab manufacturing process based on the mother tape current collector can dredge the excess powder through the obliquely arranged first scraper and second scraper, avoid accumulation, greatly improve the powder layer density consistency of the dry powder coating electrode tab and improve the uniformity of the electrochemical performance of the electrode tab.

Description

Technical Field

[0001] This invention relates to the field of lithium battery manufacturing technology, specifically to a dry powder coating electrode manufacturing process based on a master tape current collector. Background Technology

[0002] Lithium-ion battery electrode preparation is divided into wet coating and dry powder coating processes. Compared with traditional wet coating, dry powder coating does not require a large amount of organic solvents and has outstanding advantages such as low energy consumption, environmental friendliness, and simplified processes. It has gradually become one of the mainstream technologies for mass production of high-energy-density battery electrodes. The existing dry powder coated electrode manufacturing process generally includes continuous processes such as unwinding the master tape current collector, feeding and coating the electrode powder, leveling with a scraper, heat setting, rolling, and rewinding. Among these, leveling with a scraper is the core key process that determines the uniformity of the density of the electrode powder layer.

[0003] Currently, the scrapers used in the dry powder coating process in the industry are all straight scrapers arranged perpendicular to the conveying direction of the current collector, with the entire scraper spanning the effective coating area of ​​the current collector. When the current collector carrying electrode powder is continuously conveyed forward, the excess electrode powder will be intercepted and blocked by the vertical scraper. The powder cannot be dispersed to both sides and can only continue to roll and accumulate on the feed side of the scraper. As the conveying continues, the total amount of powder accumulated in front of the scraper gradually increases, and the weight of the accumulated powder itself continues to increase, which will continuously press down on the bottom powder. This causes the local surface density of the powder layer downstream of the scraper to continuously increase, resulting in uneven defects such as high density in the middle and low density at the edges, or gradual density changes along the conveying direction. This will directly cause differences in electrochemical performance such as electrode internal resistance and cycle stability, seriously affecting the consistency of electrochemical performance of battery products. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology and provide a dry powder coated electrode manufacturing process based on a master tape current collector that can guide excess powder to avoid accumulation, greatly improve the uniformity of powder layer density of dry powder coated electrode, and improve the uniformity of electrode electrochemical performance.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A manufacturing process for dry powder coated electrodes based on a master tape current collector includes the following steps: (S1) The unwinding mechanism unwinds the master tape current collector at a constant speed, so that the master tape current collector moves continuously along the preset conveying trajectory. (S2) Apply pressure-sensitive adhesive to the surface of the master tape current collector to form a pressure-sensitive adhesive layer, and form edge material areas on both sides of the pressure-sensitive adhesive layer; (S3) Electrode powder is fed and spread onto the surface of the current collector using a feeding mechanism; (S4) The electrode powder on the surface of the master tape current collector is initially leveled by the first scraper. The first scraper is arranged at an angle relative to the conveying direction of the master tape current collector. The first scraper extends at an angle from the inside of the pressure-sensitive adhesive layer to the outside of the edge material area along the conveying direction. When leveling, the electrode powder blocked by the first scraper on the surface of the master tape current collector rolls off the inclined surface of the first scraper toward the outside of the edge material area. After being leveled by the first scraper, the pressure-sensitive adhesive layer and the edge material area are covered with a powder layer with uniform surface density. (S5) The powder layer on the edge material area is scraped twice by the second scraper. The second scraper is arranged at an angle relative to the conveying direction of the master tape current collector. The second scraper extends at an angle from the inside of the edge material area to the outside of the edge material area along the conveying direction. When scraping, the electrode powder blocked by the second scraper on the edge material area rolls off the inclined surface of the second scraper toward the outside of the edge material area. After being scraped by the second scraper, the edge material area is covered with an edge material powder layer with a uniform surface density. (S6) The electrode powder that rolled off in steps (S4) and (S5) is adsorbed and collected by the first suction mechanism located outside the current collector of the main tape. (S7) The powder layer on the pressure-sensitive adhesive layer and the edge powder layer on the edge material area are heated by the heating mechanism. The powder layer and the edge powder layer undergo glass transition when heated, and the powder layer and the edge powder layer are initially shaped. (S8) The powder layer on the pressure-sensitive adhesive layer is initially pressed by a roller pressing mechanism; (S9) The edge material powder layer on the edge material area is adsorbed and collected by the second suction mechanism; (S10) The powder layer on the pressure-sensitive adhesive layer is pressed a second time by a roller pressing mechanism to obtain a single-sided electrode sheet; (S11) The single-sided electrode sheet is wound up at a constant speed by a winding mechanism.

[0006] As a further improvement to the above technical solution: In step (S1), after the master tape current collector is output by the unwinding mechanism, the master tape current collector is corrected by the first correction mechanism to ensure the accuracy of the master tape current collector entering the feeding mechanism.

[0007] In step (S3), the feeding width of the feeding mechanism is equal to the width of the pressure-sensitive adhesive layer.

[0008] In step (S4), the number of groups of first scrapers is set to N groups, and the gap size between the N groups of first scrapers and the surface of the mother tape current collector decreases in a gradient along the conveying direction.

[0009] In step (S5), the number of groups of the second scraper is set to N groups, and the gap size between the N groups of second scrapers and the surface of the mother tape current collector decreases in a gradient along the conveying direction.

[0010] In step (S8), the rollers of the roller pressing mechanism are heated to a preset temperature to perform initial heating and pressing on the powder layer on the pressure-sensitive adhesive layer.

[0011] In step (S10), the rollers of the roller pressing mechanism are heated to a preset temperature to perform secondary heating and pressing on the powder layer on the pressure-sensitive adhesive layer.

[0012] In step (S11), after the single-sided electrode sheet is output by the rolling mechanism, the single-sided electrode sheet is corrected by the second correction mechanism to ensure the accuracy of the single-sided electrode sheet entering the winding mechanism.

[0013] Compared with the prior art, the advantages of the present invention are as follows: The manufacturing process of the dry powder coated electrode based on the master tape current collector of the present invention includes unwinding the master tape current collector, coating with a pressure-sensitive adhesive layer, powder feeding and coating, initial leveling, secondary leveling, heating and vitrification, initial pressing, edge material adsorption, secondary pressing, and rewinding the master tape current collector. In the initial leveling process, a first scraper is positioned above the pressure-sensitive adhesive layer and the edge material area to level the powder on the surface of the master tape current collector, obtaining a powder layer. In the secondary leveling process, a second scraper is positioned above the edge material area to level the powder layer on the edge material area, obtaining an edge powder layer. Both the first and second scrapers are inclined relative to the conveying direction of the master tape current collector, and the inclination direction is along the conveying direction. Extending from the inside to the outside of the current collector, this design replaces the existing technology of vertically arranged straight scrapers. Electrode powder that is blocked by the first and second scrapers can roll off the outside of the current collector along the inclined surface of the scrapers. This fundamentally prevents the powder from continuously rolling and accumulating in front of the scrapers, effectively preventing the continuous increase in powder accumulation from causing a continuous increase in local surface density and resulting in uneven density of the electrode powder layer. This ensures that the overall surface density of the powder layer on the pressure-sensitive adhesive layer and the edge powder layer on the edge material area are uniform and stable, significantly improving the consistency of the powder layer density of the dry powder coated electrode and improving the uniformity of the electrode's electrochemical performance. Attached Figure Description

[0014] Figure 1 This is a schematic flowchart of the manufacturing process of the dry powder coated electrode sheet of the present invention.

[0015] Figure 2 This is a diagram showing the distribution of current collectors in the mother tape.

[0016] Figure 3 This is a schematic diagram of the structure of the first and second scrapers.

[0017] Legend: 100. Unwinding mechanism; 200. Feeding mechanism; 300. Scraping mechanism; 400. First suction mechanism; 500. Heating mechanism; 600. Roller pressing mechanism; 700. Second suction mechanism; 800. Winding mechanism; 900. First correction mechanism; 1000. Second correction mechanism; 1. Mother tape current collector; 101. Pressure-sensitive adhesive layer; 102. Edge material area; 2. First scraper; 3. Second scraper. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] like Figures 1 to 3 As shown, the dry powder coated electrode manufacturing process based on the master tape current collector in this embodiment includes the following steps: (S1) The unwinding mechanism 100 unwinds the master tape current collector at a uniform speed, so that the master tape current collector 1 moves continuously along the preset conveying trajectory. (S2) Apply pressure-sensitive adhesive to the surface of the master tape current collector 1 to form a pressure-sensitive adhesive layer 101, and form edge material areas 102 on both sides of the pressure-sensitive adhesive layer 101 respectively; (S3) Electrode powder is fed and spread onto the surface of the mother tape current collector 1 by the feeding mechanism 200; (S4) The electrode powder on the surface of the master tape current collector 1 is initially leveled by the first scraper 2. The first scraper 2 is arranged at an angle relative to the conveying direction of the master tape current collector 1. The first scraper 2 extends at an angle from the inside of the pressure-sensitive adhesive layer 101 to the outside of the edge material area 102 along the conveying direction. When leveling, the electrode powder blocked by the first scraper 2 on the surface of the master tape current collector 1 rolls off the inclined surface of the first scraper 2 toward the outside of the edge material area 102. After being leveled by the first scraper 2, the pressure-sensitive adhesive layer 101 and the edge material area 102 are covered with a powder layer with uniform surface density. (S5) The powder layer on the edge material area 102 is scraped twice by the second scraper 3. The second scraper 3 is arranged at an angle relative to the conveying direction of the main tape current collector 1. The second scraper 3 extends at an angle from the inside of the edge material area 102 to the outside of the edge material area 102 along the conveying direction. When scraping, the electrode powder blocked by the second scraper 3 on the edge material area 102 rolls off the inclined surface of the second scraper 3 toward the outside of the edge material area 102. After being scraped by the second scraper 3, the edge material area 102 is covered with an edge material powder layer with a uniform surface density. (S6) The electrode powder that rolled off in steps (S4) and (S5) is adsorbed and collected by the first suction mechanism 400 located outside the mother tape current collector 1. (S7) The powder layer on the pressure-sensitive adhesive layer 101 and the edge powder layer on the edge material area 102 are heated by the heating mechanism 500. The powder layer and the edge powder layer undergo glass transition when heated, and the powder layer and the edge powder layer are initially shaped. (S8) The powder layer on the pressure-sensitive adhesive layer 101 is initially pressed by the roller pressing mechanism 600; (S9) The edge material powder layer on the edge material area 102 is adsorbed and collected by the second suction mechanism 700; (S10) The powder layer on the pressure-sensitive adhesive layer 101 is pressed a second time by the roller pressing mechanism 600 to obtain a single-sided electrode sheet; (S11) The single-sided electrode sheet is wound up at a constant speed by the winding mechanism 800.

[0020] The manufacturing process of dry powder coated electrode based on master tape current collector includes unwinding of master tape current collector 1, coating with pressure-sensitive adhesive layer 101, powder feeding and coating, initial leveling, secondary leveling, heating and vitrification, initial pressing, edge material adsorption, secondary pressing, and rewinding of master tape current collector 1. In the initial leveling process, the first scraper 2 is positioned above the pressure-sensitive adhesive layer 101 and the edge material area 102 to level the powder on the surface of the master tape current collector 1, obtaining a powder layer. In the secondary leveling process, the second scraper 3 is positioned above the edge material area 102 to level the powder layer on the edge material area 102, obtaining an edge powder layer. Both the first scraper 2 and the second scraper 3 are inclined relative to the conveying direction of the master tape current collector 1, and the inclination direction... The scraper extends from the inside to the outside of the current collector 1 along the conveying direction, replacing the existing technology of vertically setting straight scrapers. The electrode powder that is blocked by the first scraper 2 and the second scraper 3 can roll off the outside of the current collector 1 along the inclined surface of the scraper. This avoids the powder from continuously rolling and accumulating in front of the scraper, effectively preventing the continuous increase of powder accumulation from causing a continuous increase in local surface density and resulting in uneven density of the electrode powder layer. This makes the overall surface density of the powder layer on the pressure-sensitive adhesive layer 101 and the edge powder layer on the edge material area 102 uniform and stable, greatly improving the consistency of the powder layer density of the dry powder coated electrode and improving the uniformity of the electrochemical performance of the electrode.

[0021] It should be noted that the first scraper 2 and the second scraper 3 are in Figure 1 The designation is "scraping mechanism 300", which means that the scraping mechanism 300 includes a first scraper 2 and a second scraper 3.

[0022] Preferably, in step (S1), after the master tape current collector 1 is output by the unwinding mechanism 100, it is corrected by the first correction mechanism 900 to ensure the accuracy of the master tape current collector 1 as it enters the feeding mechanism 200. In this embodiment, the unwinding mechanism 100 unwinds the wound master tape current collector 1 at a constant speed and tension. After the master tape current collector 1 is output from the unwinding mechanism 100, it first undergoes pre-correction by the first correction mechanism 900. The first correction mechanism 900 can adopt a photoelectric detection real-time correction structure to dynamically collect the lateral offset data of the master tape current collector 1 and automatically compensate for the offset, limiting the lateral offset error of the master tape current collector 1. This ensures that the master tape current collector 1 can enter the downstream feeding mechanism 200 in a precise position, avoiding problems such as powder displacement and electrode waste caused by the offset of the master tape current collector 1 from the source.

[0023] Preferably, in step (S3), the feeding width of the feeding mechanism 200 is equal to the width of the pressure-sensitive adhesive layer 101. In this embodiment, the powder used is a dry-mixed electrode powder, which includes battery active material, conductive agent and PVDF powder. Each component is uniformly mixed according to the process preset ratio. After correction, the master tape current collector 1 is transported to the bottom of the feeding mechanism 200. The feeding mechanism 200 continuously and quantitatively feeds the uniformly mixed dry powder material onto the surface of the master tape current collector 1 to complete the powder covering operation. The lateral feeding width of the feeding mechanism 200 is equal to the width of the pressure-sensitive adhesive layer 101, thereby dividing the edge material area 102. This design can limit the basic powder covering range from the source, reduce the problem of large-scale overflow, and reduce the working load of the subsequent edge suction mechanism.

[0024] Preferably, in step (S4), the number of groups of the first scraper 2 is set to N groups, and the gap size between the N groups of first scrapers 2 and the surface of the mother tape current collector 1 decreases in a gradient along the conveying direction. In this embodiment, assuming the feeding mechanism 200 feeds 500 micrometers of material to the surface of the main tape current collector 1, and the target thickness of the powder layer after the initial leveling process is 300 micrometers, if the number of sets of the first scraper 2 is set to two, the gap between the front first scraper 2 and the surface of the main tape current collector 1 is designed to be 400 micrometers, and the gap between the rear first scraper 2 and the surface of the main tape current collector 1 is designed to be 300 micrometers; if the number of sets of the first scraper 2 is set to four, the gap between the first set of the first scraper 2 and the surface of the main tape current collector 1 is designed to be 450 micrometers, the gap between the second set of the first scraper 2 and the surface of the main tape current collector 1 is designed to be 400 micrometers, the gap between the third set of the first scraper 2 and the surface of the main tape current collector 1 is designed to be 350 micrometers, the gap between the fourth set of the first scraper 2 and the surface of the main tape current collector 1 is designed to be 300 micrometers, and so on.

[0025] Preferably, in step (S5), the number of groups of second scrapers 3 is set to N groups, and the gap size between the N groups of second scrapers 3 and the surface of the main belt current collector 1 decreases gradually along the conveying direction. In this embodiment, assuming that the target thickness of the edge material powder layer on the edge material area 102 is 50 micrometers after the second leveling process, if the number of groups of second scrapers 3 is set to two, the gap between the front second scraper 3 and the surface of the main belt current collector 1 is designed to be 100 micrometers, the gap between the rear second scraper 3 and the surface of the main belt current collector 1 is designed to be 50 micrometers, and so on.

[0026] Preferably, in step (S8), the roller of the rolling mechanism 600 is heated to a preset temperature to perform initial heating and pressing on the powder layer on the pressure-sensitive adhesive layer 101. In this embodiment, the roller of the rolling mechanism 600 has an integrated heating component inside, which can heat to a preset constant temperature according to the characteristics of the electrode powder and the electrode process requirements. The initial rolling operation is completed under heating, which on the one hand can further heat the powder layer to undergo glass transition, improve the bonding force between the particles inside the powder, and on the other hand can promote the deep adhesion between the material inside the powder layer and the pressure-sensitive adhesive layer, thereby improving the overall structural stability of the powder layer.

[0027] It should be noted that, in this embodiment, assuming that the gap between the roller and the surface of the master tape current collector 1 is designed to be 250 micrometers in the initial heating and pressing process of the roller pressing mechanism 600, the roller will heat and press the powder layer with a thickness of 300 micrometers on the pressure-sensitive adhesive layer 101. The powder layer is tightly bonded to the pressure-sensitive adhesive layer 101, while the edge powder layer with a thickness of 50 micrometers on the edge material area 102 has not been heated and pressed and has not been bonded to the pressure-sensitive adhesive. Therefore, it is relatively loose and easy to fall off. At this time, the master tape current collector 1 is transported to the second suction mechanism 700, which adsorbs and collects the edge powder layer on the edge material area 102, refines the edge contour of the powder layer, and optimizes the edge forming effect of the electrode sheet.

[0028] Preferably, in step (S10), the rollers of the rolling mechanism 600 are heated to a preset temperature to perform secondary heating and pressing on the powder layer on the pressure-sensitive adhesive layer 101. In this embodiment, the two rollers of the rolling mechanism 600 are integrated with heating components, which can also be heated to a preset constant temperature according to the characteristics of the electrode powder and the electrode process requirements to complete the secondary rolling operation under heating. Assuming that the gap between the roller and the surface of the master tape current collector 1 is designed to be 200 micrometers in the secondary heating and pressing process, the roller will perform secondary heating and pressing on the powder layer with a thickness of 250 micrometers after the initial heating and pressing, so that the powder layer, the pressure-sensitive adhesive layer 101 and the master tape current collector 1 achieve high-strength composite.

[0029] Preferably, in step (S11), after the single-sided electrode sheet is output by the roller pressing mechanism 600, the second correction mechanism 1000 corrects the single-sided electrode sheet to ensure the accuracy of the single-sided electrode sheet's transport into the winding mechanism 800. In this embodiment, after the secondary heating and pressing process is completed, the single-sided electrode sheet is output from the roller pressing mechanism 600 and undergoes secondary correction by the second correction mechanism 1000. The second correction mechanism 1000 can adopt a photoelectric detection real-time correction structure to detect the transport trajectory of the single-sided electrode sheet in real time, correct the lateral displacement problem caused by the roller pressing force on the electrode sheet during the heating and pressing process, and ensure that the transport trajectory of the single-sided electrode sheet is accurate and stable. Finally, the winding mechanism 800 winds the single-sided electrode sheet at a uniform speed and constant tension to obtain a rolled finished electrode sheet, which facilitates subsequent processes such as powder coating, leveling, heating and pressing on the other side of the current collector 1 to obtain a double-sided electrode sheet.

[0030] The above description is merely a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. For those skilled in the art, improvements and modifications obtained without departing from the inventive concept should also be considered within the scope of protection of the present invention.

Claims

1. A manufacturing process for dry powder coated electrode sheets based on a master tape current collector, characterized in that, Includes the following steps: (S1) The unwinding mechanism unwinds the main tape current collector at a constant speed, so that the main tape current collector (1) moves continuously along the preset conveying trajectory. (S2) Apply pressure-sensitive adhesive to the surface of the master tape current collector (1) to form a pressure-sensitive adhesive layer (101), and form edge material areas (102) on both sides of the pressure-sensitive adhesive layer (101). (S3) Electrode powder is fed and spread onto the surface of the current collector (1) of the main tape through the feeding mechanism; (S4) The electrode powder on the surface of the master tape current collector (1) is initially leveled by the first scraper (2). The first scraper (2) is arranged at an angle relative to the conveying direction of the master tape current collector (1). The first scraper (2) extends at an angle from the inside of the pressure-sensitive adhesive layer (101) to the outside of the edge material area (102) along the conveying direction. When leveling, the electrode powder blocked by the first scraper (2) on the surface of the master tape current collector (1) rolls down along the inclined surface of the first scraper (2) toward the outside of the edge material area (102). After being leveled by the first scraper (2), the pressure-sensitive adhesive layer (101) and the edge material area (102) are covered with a powder layer with uniform surface density. (S5) The powder layer on the edge material area (102) is scraped twice by the second scraper (3). The second scraper (3) is arranged at an angle relative to the conveying direction of the master tape current collector (1). The second scraper (3) extends at an angle from the inside of the edge material area (102) to the outside of the edge material area (102) along the conveying direction. When scraping, the electrode powder blocked by the second scraper (3) on the edge material area (102) rolls down along the inclined surface of the second scraper (3) toward the outside of the edge material area (102). After being scraped by the second scraper (3), the edge material area (102) is covered with an edge material powder layer with uniform surface density. (S6) The electrode powder that rolled off in steps (S4) and (S5) is adsorbed and collected by the first suction mechanism located outside the current collector (1). (S7) The powder layer on the pressure-sensitive adhesive layer (101) and the edge powder layer on the edge material area (102) are heated by the heating mechanism. The powder layer and the edge powder layer undergo glass transition when heated, and the powder layer and the edge powder layer are initially shaped. (S8) The powder layer on the pressure-sensitive adhesive layer (101) is initially pressed by a roller pressing mechanism; (S9) The edge material powder layer on the edge material area (102) is adsorbed and collected by the second suction mechanism; (S10) The powder layer on the pressure-sensitive adhesive layer (101) is pressed twice by a roller pressing mechanism to obtain a single-sided electrode sheet; (S11) The single-sided electrode sheet is wound up at a constant speed by a winding mechanism.

2. The dry powder coated electrode manufacturing process based on the master tape current collector according to claim 1, characterized in that, In step (S1), after the master tape current collector (1) is output by the unwinding mechanism, the master tape current collector (1) is corrected by the first correction mechanism to ensure the accuracy of the conveying of the master tape current collector (1) into the feeding mechanism.

3. The dry powder coated electrode manufacturing process based on the master tape current collector according to claim 2, characterized in that, In step (S3), the feeding width of the feeding mechanism is equal to the width of the pressure-sensitive adhesive layer (101).

4. The dry powder coated electrode manufacturing process based on the master tape current collector according to claim 3, characterized in that, In step (S4), the number of groups of the first scraper (2) is set to N groups, and the gap size between the N groups of first scrapers (2) and the surface of the mother tape current collector (1) decreases in a gradient along the conveying direction.

5. The dry powder coated electrode manufacturing process based on the master tape current collector according to claim 4, characterized in that, In step (S5), the number of groups of the second scraper (3) is set to N groups, and the gap size between the N groups of second scrapers (3) and the surface of the mother tape current collector (1) decreases gradually along the conveying direction.

6. The dry powder coated electrode manufacturing process based on the master tape current collector according to claim 5, characterized in that, In step (S8), the rollers of the roller pressing mechanism are heated to a preset temperature to perform initial heating and pressing on the powder layer on the pressure-sensitive adhesive layer (101).

7. The dry powder coated electrode manufacturing process based on the master tape current collector according to claim 6, characterized in that, In step (S10), the rollers of the roller pressing mechanism are heated to a preset temperature to perform secondary heating and pressing on the powder layer on the pressure-sensitive adhesive layer (101).

8. The dry powder coated electrode manufacturing process based on the master tape current collector according to claim 7, characterized in that, In step (S11), after the single-sided electrode sheet is output by the rolling mechanism, the single-sided electrode sheet is corrected by the second correction mechanism to ensure the accuracy of the single-sided electrode sheet entering the winding mechanism.

Images