Systems and methods for battery electrode fabrication

Abstract

An exemplary battery electrode, as well as systems and methods for fabricating the battery electrode, are provided. The electrode includes a conductive substrate defining a first surface and a second surface. The electrode includes a pattern of active material coating formed on at least one of the first or second surfaces of the conductive substrate. The pattern includes coated and uncoated areas formed by depositing an active material dry powder on at least one of the first or second surfaces of the conductive substrate by electrostatic spray deposition while the conductive substrate is moving, and selectively removing at least a portion of the active material dry powder from at least one of the first or second surfaces of the conductive substrate using a powder removal assembly to create uncoated areas of the pattern.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 430,478, filed December 6, 2022. The entire contents of the aforementioned provisional application are incorporated herein by reference. [Background technology]

[0002] There are various types of batteries in the industry for various applications. Generally, lithium-ion (Li-ion) batteries have become the predominant type of battery used in portable consumer electronics and electric vehicles. Fabricating a Li-ion battery involves numerous steps, each of which can affect the quality of the battery itself as well as the costs associated with manufacturing the battery. A conventional manufacturing process generally involves forming an electrode slurry by mixing an active material, a conductive additive, and a binder in an organic solvent, which is then applied to a metal foil material. Once applied to the foil material, the solvent dries or volatilizes, leaving the electrode active material mixture adhered to the surface of the metal foil material. In some instances, the solvent can be hazardous and require additional steps to deal with / dispose of, which increases the overall cost of the manufacturing process. Therefore, the cost of removing the solvent from the material applied to the metal foil involves an additional step, which also increases the overall cost of the manufacturing process.

[0003] Alternative manufacturing techniques used in the industry include electrostatic spray deposition (ESD), which is a solvent-free manufacturing process for electrode coatings in Li-ion batteries (see, e.g., B. Ludwig et al., Solvent-Free Manufacturing of Electrodes for Lithium-ion Batteries, Sci. Rep. 6, Article No. 23150, doi:10.1038 / srep23150 (2016)); M. Wang et al., The Influence of Polyvinylidene Fluoride (PVDF) Binder Properties on LiNi 0.33 Co 0.33 Mn 0.33 O2 (NMC) Electrodes Made by a Dry-Powder-Coating Process, J. Electrochem. Soc., Vol. 166, No. 10, A2151 (2019); H. Abe et al., Electrostatic Spray Deposition for Fabrication of Li-ion Batteries, Transactions of JWRI, Vol. 44, No. 2 (2015); and U.S. Patent No. 10,547,044. Rather than relying on a solvent mixture, the ESD process uses a powder of the electrode active material mixture, which is applied to a metal foil material. By eliminating the solvent from the mixture and the drying step from the manufacturing process, the overall process is simplified and more economical, making it a viable alternative for large-scale manufacturing. Solventless electrode coating technology is an attractive alternative to conventional manufacturing, particularly because it significantly reduces energy consumption in the manufacturing process and therefore battery manufacturing costs.

[0004] In electrode manufacturing, web handling concepts and principles are critical in producing a satisfactory product that is within the desired requirements and of the correct geometry. This is as true for ESD processes as it is for conventional slurry casting processes. Figure 1 shows a general outline of a conventional dry powder ESD coating system 10, highlighting the features of the web handling system. The central portion of the system 10 is the web 12 itself, also known in the industry as a current collector, foil, or substrate, having two sides (e.g., side A—top side and side B—bottom side). Web 12 passes continuously along direction 16 through coating chamber 14, where it undergoes an ESD process that applies an active material mixture (not shown) to web 12. Web 12 then passes between calender rolls 18 and 20 to densify the active material mixture coating on web 12. Finally, web 12 is wound onto a core at a rewind station, slit, and prepared for assembly into a Li-ion battery. The direction 16 in which the web 12 travels is commonly known in the industry as the Machine Direction (MD), and the orthogonal axis 22 is known as the Cross Direction (CD).

[0005] The formation of an electrode by the ESD coating system 10 generally results in at least one uncoated area along which a conductive tab can be welded to the electrode for assembly into a battery. However, because the active material powder is applied to the web 12, the location of the uncoated area is typically limited. For example, in conventional slurry-cast electrode manufacturing, the formation of these types of uncoated areas can be achieved by controlling the deposition of the slurry onto the web using a slot die. In such conventional processes, the slurry has the appropriate viscosity to precisely coat the web in the desired coating area while avoiding the edge tab area. To reduce the risk of capacitance mismatch between the cathode and anode, which can result in reduced cycle life or internal shorts, a sharp edge between the active material and the edge tab is generally formed. In dry ESD processes, the powder cannot be delivered in a controlled manner because the momentum and trajectory of the dry particles can easily be altered by external forces such as drag and / or electromagnetic fields. The inherent process differences between wet slurry and dry powder make the slurry-cast electrode manufacturing solution inapplicable to this problem. Therefore, the desired location and number of uncoated areas in the ESD process are limited.

[0006] The entire web converting industry has not provided a readily available solution to the limitations of conventional slurry cast electrode manufacturing processes or conventional ESD processes. Several methods exist by which coatings are controlled or removed from a web. However, the goal of these conventional means is to control the thickness and uniformity of the coating by metrology or by using blades. These options do not lend themselves to introducing or creating patterns in the coating that are not uniform in thickness across the width of the web (e.g., uncoated areas between coated areas). Current solutions in the industry generally apply to water- or liquid-based coating materials. There are few web handling applications in which dry powders are applied onto a moving web. The nature of dry powders presents new challenges that are not addressed by slurry casting and the current web handling industry. Summary of the Invention

[0007] According to an embodiment of the present disclosure, an exemplary system for fabricating battery electrodes is provided. The system can be used to produce electrodes having a specific pattern of active material coated areas and uncoated areas with a sharp edge between the two areas. According to an embodiment of the present disclosure, an exemplary battery electrode is provided. The electrode includes a conductive substrate defining a first surface and an opposing second surface. The electrode includes a pattern of active material coating formed on at least one of the first surface or the second surface of the conductive substrate. The pattern includes coated areas and uncoated areas. The pattern of coated and uncoated areas is formed by depositing active material dry powder on at least one of the first surface or the second surface of the conductive substrate by electrostatic spray deposition while the conductive substrate is moving, selectively removing at least a portion of the active material dry powder from at least one of the first surface or the second surface of the conductive substrate using a powder removal assembly to create uncoated areas of the pattern, and bonding the active material dry powder to at least one of the first surface or the second surface of the conductive substrate to create coated areas of the pattern.

[0008] In some embodiments, the conductive substrate can be an aluminum foil substrate. In some embodiments, the first and second surfaces of the conductive substrate can be substantially planar or flat. In some embodiments, the pattern of coated and uncoated areas can be formed by simultaneously depositing active material dry powder on both the first and second surfaces of the conductive substrate by electrostatic spray deposition, and simultaneously selectively removing at least a portion of the active material dry powder from both the first and second surfaces of the conductive substrate using a powder removal assembly to create uncoated areas of the pattern on both the first and second surfaces.

[0009] In some embodiments, the powder removal assembly can include a wiping mechanism configured to remove at least a portion of the active material dry powder from at least one of the first surface or the second surface of the conductive substrate. In some embodiments, the powder removal assembly can include a masking mechanism configured to cover areas of the conductive substrate corresponding to uncoated areas of the pattern. In some embodiments, the pattern can include uncoated areas in a cross-direction of the conductive substrate. In some embodiments, the powder removal assembly can include a wiping mechanism configured to disturb or move at least a portion of the active material dry powder from at least one of the first surface or the second surface of the conductive substrate, and can further include a vacuum configured to remove the disturbed or moved active material dry powder.

[0010] According to an embodiment of the present disclosure, an exemplary system for battery electrode fabrication is provided. The system includes a coating assembly configured to deposit active material dry powder on at least one of a first surface or an opposing second surface of a conductive substrate by electrostatic spray deposition while the conductive substrate moves or passes through or under the coating assembly. The system includes a powder removal assembly configured to selectively remove at least a portion of the active material dry powder from at least one of the first surface or the second surface of the conductive substrate to create a pattern of active material dry powder having coated and uncoated areas. The system includes a bonding assembly configured to bond the active material dry powder to at least one of the first surface or the second surface of the conductive substrate.

[0011] In some embodiments, the conductive substrate can be an aluminum foil substrate. In some embodiments, the pattern can include uncoated areas oriented along a cross direction of the conductive substrate. In some embodiments, the pattern can include uncoated areas oriented along a machine direction of the conductive substrate. In some embodiments, the powder removal assembly can include a masking mechanism integrated into the coating chamber. In some embodiments, the powder removal assembly can include a wiping mechanism disposed distally from the coating chamber. In some embodiments, the powder removal assembly can include both a masking mechanism integrated into the coating chamber and a wiping mechanism disposed distally from the coating chamber.

[0012] In some embodiments, the coating assembly can be configured to simultaneously deposit active material dry powder on both the first surface and the second surface of the conductive substrate, and the powder removal assembly can be configured to simultaneously selectively remove at least a portion of the active material dry powder from both the first surface and the second surface of the conductive substrate to produce a pattern of active material dry powder having coated areas and uncoated areas on both the first surface and the second surface.

[0013] In some embodiments, the powder removal assembly can be a wiping mechanism including a vacuum with a nozzle disposed above at least one of the first surface or the second surface of the conductive substrate and configured to selectively remove the active material dry powder to form uncoated areas of the pattern. In some embodiments, the powder removal assembly can be a wiping mechanism including an angled ramp configured to direct the active material dry powder away from the conductive substrate to form the uncoated areas of the pattern. In some embodiments, the powder removal assembly can include a wiping mechanism including a ramp configured to disturb or move at least a portion of the active material dry powder from the conductive substrate, and further include a vacuum configured to remove the disturbed or moved active material dry powder. In some embodiments, the powder removal assembly can be a wiping mechanism including a rotary slitter configured to form slits in the active material dry powder to define edges of the uncoated areas to be formed in the active material dry powder. In some embodiments, the power removal assembly can be a wiping mechanism including a conveyor system having one or more belts configured to contact and remove the active material dry powder from the conductive substrate.

[0014] According to an embodiment of the present disclosure, an exemplary method for fabricating a battery electrode is provided. The method includes continuously passing a conductive substrate through or under a coating assembly to deposit an active material dry powder on at least one of a first surface or a second surface of the conductive substrate by electrostatic spray deposition while the conductive substrate is moving. The method includes selectively removing at least a portion of the active material dry powder from at least one of the first surface or the second surface of the conductive substrate using a powder removal assembly to create a pattern of active material dry powder having coated and uncoated areas. The method also includes bonding the active material dry powder to at least one of the first surface or the second surface of the conductive substrate using a bonding assembly.

[0015] Any combination and / or permutation of the embodiments is contemplated. Other objects and features will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely as an illustration and not as a definition of the limits of the present disclosure. [Brief explanation of the drawings]

[0016] To assist those skilled in the art in making and using a system for battery electrode fabrication, reference is made to the accompanying figures.

[0017] [Figure 1] 1 is a diagram of a conventional electrostatic spray deposition (ESD) system. [Figure 2] 1 is a diagram of an electrode geometry formed by an exemplary system for battery electrode fabrication using an ESD process. [Figure 3] 1 is a diagram of an electrode geometry formed by an exemplary system for battery fabrication using an ESD process. [Figure 4] FIG. 1 is a diagram of an exemplary system for battery electrode fabrication using an ESD process, including a powder removal assembly. [Figure 5] FIG. 1 is a diagram of an exemplary system for battery electrode fabrication using an ESD process, including a powder removal assembly that uses a wiping mechanism to produce an uncoated pattern along the machine direction (MD). [Figure 6] FIG. 1 is a diagram of an exemplary system for battery electrode fabrication using an ESD process, including a powder removal assembly that uses a wiping mechanism to produce an uncoated pattern along the cross direction (CD). [Figure 7] FIG. 1 is a diagram of an exemplary system for battery electrode fabrication using an ESD process, including a powder removal assembly that uses a vacuum mechanism to produce an uncoated pattern along the machine direction (MD). [Figure 8] FIG. 1 is a diagram of an exemplary system for battery electrode fabrication using an ESD process, including a powder removal assembly that uses a ramp mechanism to produce an uncoated pattern along the machine direction (MD). [Figure 9] FIG. 1 is a diagram of an exemplary system for battery electrode fabrication using an ESD process, including a powder removal assembly that uses a slitter or rotary blade mechanism to produce an uncoated pattern along the machine direction (MD). [Figure 10] FIG. 1 is a diagram of an exemplary system for battery electrode fabrication using an ESD process, including a powder removal assembly that uses a continuous conveyor mechanism to produce uncoated patterns along the machine direction (MD). [Figure 11] FIG. 1 is a diagram of an exemplary system for battery electrode fabrication using an ESD process, including a powder removal assembly that uses a masking mechanism to produce an uncoated pattern along the machine direction (MD). [Figure 12] FIG. 1 is a diagram of an exemplary system for battery electrode fabrication using an ESD process, including a powder removal assembly that uses a conveyor mask mechanism to produce an uncoated pattern along the machine direction (MD). [Figure 13] FIG. 1 is a diagram of an exemplary system for battery electrode fabrication using an ESD process, including a powder removal assembly that uses a stationary mask mechanism to produce an uncoated pattern along the machine direction (MD). [Figure 14] FIG. 1 is a diagram of an exemplary system for battery electrode fabrication using an ESD process, with the web oriented vertically. [Figure 15] FIG. 1 is a diagram of an exemplary system for battery electrode fabrication using an ESD process, including a powder removal assembly that produces an uncoated pattern along the machine direction (MD) on the bottom or B-side of a web. [Figure 16] FIG. 1 is a diagram of an exemplary system for battery electrode fabrication using an ESD process, including a powder removal assembly that simultaneously produces uncoated patterns along the machine direction (MD) on both the top and bottom (A-side and B-side) of a web. [Figure 17] FIG. 17 is a diagrammatic view of the bottom or B-side of an electrode formed by the exemplary system for battery electrode fabrication of FIGS. 15 and 16. [Figure 18]FIG. 1 is a diagram of an exemplary system for battery electrode fabrication using an ESD process having a powder removal assembly that includes both a wiping mechanism and a masking mechanism. [Figure 19] FIG. 1 is a diagram of an exemplary system for battery electrode fabrication using an ESD process, including a powder removal assembly that uses wiping and vacuum mechanisms to produce an uncoated pattern along the machine direction (MD). [Figure 20] FIG. 20 is a diagram of an exemplary system for fabricating the battery electrode of FIG. 19. [Figure 21] FIG. 1 is a diagram of an exemplary system for battery electrode fabrication using an ESD process, including a powder removal assembly that uses wiping and vacuum mechanisms and adjustable force on the blades to produce an uncoated pattern along the machine direction (MD). DETAILED DESCRIPTION OF THE INVENTION

[0018] No conventional process, mechanism, or combination of both adequately addresses the unique characteristics of particles electrostatically attached to a grounded conductive web when producing a pattern coating. Electrostatically charged, deposited particles generally generate an attractive "image" force on the conductive substrate based on the potential difference between the particle's surface charge relative to the grounded substrate and the strength and direction of the electromagnetic field lines along which the particle travels. Some of the fundamental characteristics include the time dependence of charge dissipation, which leads to a decrease in electrostatic image attraction, the total charge a particle can hold, and distortion of field lines due to phenomena such as the Faraday cage effect. Image attraction temporarily bonds charged particles to a grounded substrate. Image attraction is generally not strong in terms of binding strength, and therefore, the particle's bond to the substrate surface can be easily removed by mechanical wiping, which produces the uncoated coating pattern described herein. Because the ESD coating process involves spraying dry powder onto a conductive web, a masking mechanism allows for the generation of an uncoated coating pattern. Such a masking mechanism has not been used to develop pattern coating in a continuous coating assembly. (See, for example, Lee et al., Binder-assisted electrostatic spray deposition of LiCoO2 and graphite films on coplanar interdigitated electrodes for flexible / wearable lithium-ion batteries, Journal of Power Sources, Volume 472, pp. 228573 (October 1, 2020)).

[0019] The exemplary system discussed herein provides a means for responding to the unique characteristics of particles electrostatically attached to a conductive web and forming a unique pattern in the coating of the conductive web during an ESD process. In particular, the system provides a means for fabricating electrodes for incorporation into Li-ion batteries. The system includes a powder removal assembly and / or a guide assembly (referred to herein as a powder removal assembly) that selectively removes powder from a web to create a desired pattern of coated and uncoated areas on the web. The powder removal assembly can remove powder applied to the web, guide / redirect powder applied to the web, or a combination thereof. Thus, the powder removal assembly can perform wiping and / or masking, as discussed herein. This allows for customization of the location and number of edge tab areas or welded tab areas formed on the web. The system makes the electrode coating process simpler and more flexible, enabling unique customizable options in electrode manufacturing.

[0020] In particular, to meet the functional requirements of the electrode after the ESD process is complete, the final product must exhibit certain key geometric shapes. Figures 2 and 3 provide diagrammatic representations of electrode geometries (referred to herein as uncoated coating patterns) formed by an exemplary ESD system (discussed below). As shown in Figure 2, electrode 50 includes a web 52 (e.g., a conductive substrate, current collector, etc.) and an active material coating 54 applied to web 52. Active material coating 54 occupies most of the surface area of ​​web 52. The application of coating 54 shown in Figure 2 includes edge tab regions 56-60 (e.g., weld tab regions). These regions 56-60 can be used in a battery assembly to weld conductive tabs to electrode 50, thereby electrically incorporating electrode 50 within a battery. Regions 56-60 can be formed on both sides of coating 54 (e.g., regions 56 and 58) and / or in an interior area of ​​electrode 50 (e.g., region 60). Uncoated regions 56-60 are formed along the machine direction (MD). FIG. 3 shows a substantially similar electrode 70, but with edge tab regions 72 formed in the cross direction (CD). The exemplary system allows for the formation of multiple uncoated regions in web 52, including one or more interior regions similar to region 60 and / or region 70. The location and number of uncoated regions can be customized based on the desired location of the conductive tabs. The introduction of one or more edge tab regions allows the electrode to be slit into multiple strips, improving production capacity. In some embodiments, the system can be configured to form uncoated coating patterns oriented solely in the machine direction (MD), solely in the cross direction (CD), or both.

[0021] Thus, the present system provides flexibility and customization in creating weld or edge tab areas during electrode fabrication by ESD techniques on a moving conductive web. The system ensures that the weld or edge tab areas are created without introducing defects into the coating material that could degrade the performance of the finished electrode. The resulting weld or edge tab areas are free of coating material. Furthermore, the system does not introduce defects into the web (e.g., foil substrate) while forming the weld or edge tab areas, as such defects could potentially degrade the web's ability to successfully complete downstream processing. In some embodiments, the system can operate continuously at normal operating speeds for web formation. In some embodiments, the system's operation can be adjusted to selectively create uncoated areas on the web or selectively enable full web coverage. The system accommodates the specific behavior of electrostatically deposited particles, allowing for the reuse of uncoated powder, if any. In particular, any powder removed from the web surface prior to bonding can be collected and reused for further coating of the same or another web.

[0022] FIG. 4 is a diagram of an exemplary system 100 for battery fabrication using an ESD process. The system 100 includes a web 102 traveling along a direction 104 (e.g., a machine direction) for coating. In some embodiments, the web 102 can be in the form of an aluminum foil substrate. The system 100 can include a roller 106 at a proximal end of the assembly and a roller 108 at a distal end of the assembly. Both rollers 106, 108 can be disposed below and in direct contact with the web 102 to maintain the web 102 in a substantially taught configuration as it undergoes the coating process. In some embodiments, additional rollers can be positioned below and / or above the web 102 to ensure that the web 102 is maintained in a desired orientation for coating. As shown in FIG. 4, in some embodiments, the web 102 can be maintained in a substantially parallel or transverse orientation to a horizontal surface (e.g., a floor, etc.). In some embodiments, the web 102 can be maintained in a substantially vertical / perpendicular or transverse orientation to a horizontal surface, as shown in FIG. 14. In some embodiments, the web 102 can be maintained in a non-parallel or non-perpendicular orientation to the horizontal plane, for example, at any relative angle between a parallel orientation and a perpendicular orientation.

[0023] The system 100 includes a coating assembly 110 (e.g., a coating chamber) configured to apply a dry powder coating to one or more surfaces of the web 102. For example, the web 102 can include a top surface (e.g., surface A or side A, facing up in FIG. 4 ) and an opposing bottom surface (e.g., surface B or side B, facing down in FIG. 4 ). The coating assembly 110 can be configured to apply a dry powder coating to the top surface, the bottom surface, or both. In some embodiments, the coating assembly 110 can be used to apply a dry powder coating to one surface and then to apply a dry powder coating to the opposite surface. In some embodiments, the coating assembly 110 can be used to apply a dry powder coating to both surfaces simultaneously. Thus, it should be understood that any description herein relating to applying a dry powder coating to one surface of the web 102 can also be used to apply a dry powder coating to the opposite surface of the web 102.

[0024] The coating assembly 110 can be positioned distally from the roller 106 to ensure that the continuously moving web 102 is in a horizontal orientation (or any desired orientation) before dry powder is applied to the upper surface of the web 102. The coating assembly 110 can apply powder from one or more powder applicators such that electrostatically charged powder particles are deposited on the grounded, conductive web 102. For example, in some embodiments, the coating assembly 110 can be positioned distally of the roller 106 (e.g., from the central axis of the roller 106). In some embodiments, the coating assembly 110 can be in the form of multiple spray heads 112 positioned over the web 102 and configured to release dry powder 114 onto the web 102 for application to the upper surface (or any surface) of the web 102. In some embodiments, the coating assembly 110 can include a single spray head 112 or multiple spray heads 112. In some embodiments, coating assembly 110 can be in the form of a roller that dispenses powder onto the surface of web 102, an air stream that carries powder in a controlled manner onto the surface of web 102, or the like. In some embodiments, alternative dry powder coating application configurations can be used.

[0025] System 100 includes a powder removal assembly 118 distal to coating assembly 110 that can be selectively activated to remove dry powder 114 from defined areas of web 102 to create a pattern of coated and uncoated areas on a surface (e.g., a top surface, a bottom surface, or both) of web 102. In some embodiments, powder removal assembly 118 can be incorporated into coating assembly 110. In some embodiments, powder removal assembly 118 can be spaced distally from coating assembly 110, as shown in FIG. 4 . Because the bond between web 102 and dry powder 114 is not strong, merely sufficient to maintain the placement of dry powder 114 on web 102 until later processing stages, powder removal assembly 118 can simply remove dry powder 114 from desired areas of web 102 to create a desired coated / uncoated pattern along the surface of web 102. The powder removal assembly 118 is disposed above the surface of the web 102 and can include various internal mechanisms and / or assemblies for removing the dry powder 114 from the web 102, examples of which are discussed below.

[0026] In some embodiments, the powder removal assembly 118 can be continuously operated to continuously create one or more uncoated regions of the web 102. In some embodiments, the powder removal assembly 118 can be selectively operated between an operative state and a non-operative state to selectively create one or more uncoated regions of the web 102. The powder removal assembly 118 removes dry powder 114 in desired areas such that those uncoated areas or regions are completely free of dry powder 114, leaving the surrounding areas uniformly coated with dry powder 114. The uncoated pattern can be formed in the machine direction, the cross direction, or both.

[0027] After removing the dry powder 114 from the desired areas to create a pattern of coated and uncoated areas on the web 102, the web 102 continues along the direction 104 to a hot press assembly (e.g., a bonding assembly) formed by a hot roller 120 disposed above the surface of the web 102 and a roller 122 (e.g., a roll-to-roll roller) disposed below the web 102. In some embodiments, the roller 122 can be hot or cold. In some embodiments, the web 102 can first pass through a heated chamber before entering the hot press assembly formed by the rollers 120, 122. The hot press assembly is disposed distally from the powder removal assembly 118. The rollers 120, 122 can be calender rolls that use heat from the roller 120 to press the dry powder 114 onto the web 102 to densify the active material coating on the web 102. In particular, the heat applied by roller 120 can soften and / or melt the binder in powder 114 to bond active material coating 124 to the upper surface of web 102. The force imparted by rollers 120, 122 onto web 102 can be adjusted by a central controller and / or at rollers 120, 122. In some embodiments, the location of roller 122 can remain fixed, and roller 120 can be moved farther or closer to roller 122 to adjust the pressure imparted to web 102 for bonding of dry powder 114.

[0028] After passing through the hot press assembly, the active material coating 124 is strongly bonded to the upper surface of the web 102. While FIG. 4 shows the web 102 with a central region coated with the coating 124, it should be understood that by using the powder removal assembly 118, one or more central regions can be left uncoated, and the bonded coating 124 will have the same pattern as the pattern produced after the web 102 passes through or under the powder removal assembly 118 (e.g., the pattern of the electrodes 50, 70 in FIG. 2 or FIG. 3 or other uncoated / coated pattern). After bonding, the web 102 continues along direction 104 toward and over rollers 108 at the distal end of the system 100. At this stage in the fabrication process, the web 102 can be wound onto a core at a rewind station, slit, and assembled into a Li-ion battery.

[0029] The powder removal assembly 118 of the system 100 shown in FIG. 4 can take various forms capable of selectively removing dry powder 114 from the surface of the web 102 to achieve a desired coated / uncoated pattern bonded to the web 102. For example, the assembly 118 can take the form of a wiping mechanism and / or a masking mechanism. Thus, the assembly 118 can create an uncoated pattern using a wiping mechanism alone, a masking mechanism alone, or a combination of a wiping mechanism and a masking mechanism. In some embodiments, a vacuum assembly can be used in combination with a wiping mechanism to remove the dry powder 114 from the web 102. In embodiments including a masking mechanism, the powder removal assembly 118 is incorporated into and operates within the coating assembly 110 to selectively remove the dry powder 114 while the web 102 is being coated. This is achieved by masking the desired edge tab area from the coating process so that the web 102 is not coated in that area. As discussed herein, the masking mechanism can be in the form of a conveyor mask and / or a stationary mask. Figures 5-17 illustrate system embodiments having different embodiments of the powder removal assembly. The systems can be substantially similar in structure and / or function to system 100 of Figure 4, except for the differences noted herein. Accordingly, the same reference numbers are used to refer to the same structures.

[0030] 5 illustrates a system 150 that includes a powder removal assembly in the form of a wiping mechanism 152. The wiping mechanism 152 is disposed after the coating assembly 110 and operates after the web 102 has been coated with dry powder 114. This is accomplished by wiping the dry coating powder 114 from the desired edge tab area after coating is completed and the web 102 has moved to the powder removal assembly 118. In some embodiments, the wiping mechanism 152 can be positioned across the web 102 in an orientation substantially perpendicular to the direction of web 102 travel 104. In some embodiments, as illustrated by system 200 in FIG. 6, the wiping mechanism 202 can be positioned across the web 102 in an orientation that is not perpendicular to the direction of web 102 travel 104. As discussed herein, the wiping mechanisms 152, 202 can be in the form of vacuums, ramps, slitters, conveyors, and / or rotators that wipe the powder 114 from the surface of the web 102 as the web 102 passes through and / or under the wiping mechanisms 152, 202. In the orientation of FIG. 5, the wiping mechanisms 152 can form uncoated regions 154, 156 along the edges of the web 102 and an inner uncoated region 158 in the central area of ​​the web 102, each oriented along the machine direction. In the orientation of FIG. 6, the wiping mechanisms 202 can form uncoated regions 204 spaced apart across the web 102 and oriented perpendicular to the machine direction. In the embodiment of FIG. 6, the wiping mechanisms 202 can include a wiping structure 206 moving along a direction 208 to wipe the powder 114 from the surface of the web 102.

[0031] 6, wiping mechanism 202 is configured to create an uncoated area 204 perpendicular to the machine direction. Wiping structure 206, which may include any of the wiping embodiments discussed herein, traverses web 102 at an angle α relative to the machine direction, which angle α is selected based on Equation 1 below:

number

[0032] In some embodiments, the wiping mechanism can be in the form of a vacuum 252, as shown in system 250 of FIG. 7. In such embodiments, the vacuum 252, having a specific nozzle geometry, can be positioned at a predetermined height or an adjustable height above the surface of the web 102. Coupled with the correct electrostatic voltage (selected based on the magnitude of the image attraction) that provides sufficient image attraction to hold the coating 114 on the web 102, but weak enough to allow the vacuum 252 to locally remove the coating 114, the vacuum 252 removes material from the edge tab region 256, leaving the desired coating 114 intact. A powder collection duct structure 254 extending from the vacuum 252 can lead to a chamber for collecting the removed powder 114 for recycling and / or reuse. In some embodiments, the vacuum 252 can be replaced by or coupled with a blower, air knife, or similar structure for precise removal of the coating 114. The nozzle shape can be selected or designed to create an appropriate flow field, particularly to remove only the powder in the edge tab region 256.

[0033] In some embodiments, the wiping mechanism can be in the form of one or more ramps 302, as shown in system 300 of FIG. 8. In such embodiments, the wipers of the ramps 302 can be stationary wipers that rely on angled surfaces to move the powder 114 from the web 102 at desired or predetermined locations to form the edge tab regions 304. In such embodiments, the ramps 302 have surfaces that are oriented at a given / fixed angle relative to the direction 104 of motion of the web 102, for example, at a given rake angle of up to 90° relative to the direction 104. In some embodiments, the rake angle can be approximately 45°. The ramps 302 can be positioned such that the ramps 302 contact the web 102 and extend into the web 102 at the desired width of the edge tab regions 304. The angle of the surfaces can be such that the coating material 114 is directed toward the edge of the web 102, given the direction 104 of motion of the web 102.

[0034] In some embodiments, the wiping mechanism can be in the form of one or more lamps 802 (e.g., wiping blades, etc.) combined with one or more vacuums 804, as shown in system 800 of FIGS. 19 and 20 . In some embodiments, lamps 802 and / or vacuum 804 can be substantially similar in structure and / or function to vacuum 252 and lamps 302 of FIGS. 7 and 8 . System 800 generally includes a vertical support structure 806 to which a beam 808 is pivotally connected by fasteners 810. Fasteners 810 define a pivot point or axis for beam 808 relative to structure 806. One end of beam 808 is connected to a compression spring 812, the opposite end of which is connected to structure 806. The connection between spring 812 and structure 806 is above the connection of fasteners 810. The opposite end of beam 808 (relative to spring 812) is coupled to a wiping assembly. The wiping assembly includes a wiping ramp 802 disposed distally to a vacuum 804 (e.g., a vacuum tube). Thus, vacuum 804 is disposed directly in front of ramp 802. In some embodiments, only the open end of vacuum 804 can provide suction. In some embodiments, the length of the distal end of vacuum 804's tube can include suction openings and / or slots along the length of the tube (e.g., a distance substantially equal to the width of ramp 802, so that suction occurs directly in front of ramp 802).

[0035] 19 and 20, the system 800 is configured to wipe active material 814 from the surface of the web 816 to form a left edge tab 818 of the continuous web 816 as the web 816 moves in a direction 820. While the system 800 is shown forming a left edge tab 818, it should be understood that a mirrored configuration can also be used to form a right edge tab of the electrode. In some embodiments, a combination of both left and right assemblies can be located in the center of the web to form a center edge tab. In some embodiments, a perpendicularly oriented lamp 802 can be positioned in the center of the web to form a center edge tab. In operation, the wiping blade (i.e., the lamp 802) disturbs the active material 814 at the exact location where the edge tab 818 is desired. The spring 810 maintains a downward force on the beam 808, which provides the downward force of the wiping assembly to the web surface to disturb, move, or wipe the active material 814. The force exerted by spring 810 is selected to ensure that substantial disturbance to the powder occurs without damaging the foil substrate. The disturbed powder collects in a small pile in front of lamp 802, and vacuum 804 continuously removes the powder as it collects. Vacuum 804 is optimized to exclusively remove the disturbed powder without affecting the surrounding powder, ensuring a substantially uniform line along the formed edge tab 818.

[0036] In some embodiments, the wiping mechanism of FIGS. 19 and 20 can include an adjustable spring 852, as shown in system 850 of FIG. 21. System 850 can be substantially similar in structure and / or function to system 800, except for the differences noted herein. The vertical support structure can be in the form of mounting brackets 854, 856, with bracket 854 extending vertically and bracket 856 connected to bracket 854 and extending perpendicularly therefrom. Brackets 854, 856 can be connected to a support beam 858 to stabilize system 850. The bottom of bracket 856 can include a mounting flange 860 extending perpendicularly and spaced apart therefrom. Mounting flange 860 is spaced apart to pivotally accommodate beam 862 therebetween. Beam 862 can be attached using fasteners 864, which define a pivot point for beam 862 relative to mounting flange 860.

[0037] One end 866 of beam 862 is connected to cable 868, which in turn connects to spring 852. The opposite end of spring 852 is connected to bracket 854. In some embodiments, spring 852 can be connected to bracket 854 via, for example, turnbuckle 870. Opposite end 872 of beam 862 includes a wiping assembly, i.e., ramp 874 and vacuum 876. System 850 operates similarly to system 800, with ramp 874 agitating the active material coating and vacuum 876 collecting the agitated active material to form tabs. Turnbuckle 870 can be adjusted to optimize the force applied by spring 852, which in turn adjusts the force applied to the web surface by ramp 874. In some embodiments, force adjustment can be automated by replacing turnbuckle 870 with a spool attached to a servo motor. Winding or unwinding the spool using a servo motor increases or decreases the downward force on the ramp 874. In some embodiments, the ramp and vacuum assembly can be formed from separate components (such as system 800 of FIGS. 19 and 20). In some embodiments, the vacuum 876 and ramp 874 can be combined into a single component, as shown in FIG. 21. In particular, the body of the vacuum 876 serves as a mount for the ramp 874, ensuring precise alignment between the opening of the vacuum 876 and the edge of the ramp 874.

[0038] While the lamps 802, 874 are used to remove all of the active material coating at a desired location along the web surface, in some embodiments, the system can be configured to remove only a partial thickness of active material coating at a particular location along the web surface. For example, the bottom-most edge of the lamp is set at a predetermined fixed height from the surface of the web (e.g., approximately 10-100 μm, inclusive; 20-100 μm, inclusive; 30-100 μm, inclusive; 40-100 μm, inclusive; 50-100 μm, inclusive; 60-100 μm, inclusive; 70-100 μm, inclusive; 80-100 μm, inclusive; 90-100 μm, inclusive; 10-90 μm, inclusive; 120-140 μm, inclusive). The ranges are: 10-80 μm, 10-70 μm inclusive, 10-60 μm inclusive, 10-50 μm inclusive, 10-40 μm inclusive, 10-30 μm inclusive, 10-20 μm inclusive, 20-90 μm inclusive, 30-80 μm inclusive, 40-70 μm inclusive, 50-60 μm inclusive, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, etc. The lamp is positioned at the desired edge tab formation location.

[0039] As the coated substrate passes under the lamp, the thickness of the coated active material is reduced at the location of the wiping blade. However, only a partial thickness of the active material is removed, and the remaining thickness of the web passes under the lamp and leaves it. In some embodiments, the thickness of the active material can be reduced by an alternative assembly, such as counter-rotating vacuum rollers. The electrode then passes through a calender system (as described above with respect to system 150). After the calendering process, areas of the electrode with a thinner coating have significantly reduced adhesion to the web due to reduced load from the calender rollers (i.e., less or no contact with the calender roll, resulting in less force on the active material). In areas of the web with a thicker coating of active material, the calender roll creates stronger adhesion to the web. The entire electrode is then exposed to another material removal system, such as compressed air, a vacuum, a wiping blade, or a combination thereof, which can remove the less-adhered powder to form the desired edge tab region. Thus, partial reduction in the thickness of the active material in each area of ​​the web can be used to create edge tab regions, and the loss of adhesion can be used in a subsequent process to remove the unadhered material to form the edge tab regions.

[0040] In some embodiments, the wiping mechanism can take the form of one or more rotary blades or slitters 352, as shown in system 350 of FIG. 9. In such embodiments, the slitter 352 can include a thin blade or rotary blade that slits the powder 114. In such embodiments, the blade seats on the web 102 and slits the coating 114 at the desired location where the coating 114 meets the tab at the edge 354. Only enough downward force is applied by the slitter 352 at the blade to slit the coating 114 and not the web 102, thereby preventing damage to the web 102 itself. This sets the exact edge 354 relative to where the tab begins. A vacuum can be positioned distal or downward from the slitter 352 to remove the powder 114 separated by the blade of the slitter 354 (e.g., from the edge 354 to the outer edge of the web 102). In doing so, the slitter 352 can be used to identify and form a precise edge 354, along which the uncoated area is formed by another mechanism.

[0041] In some embodiments, the wiping mechanism can be in the form of a conveyor system having one or more belt-based conveyor wipers 402, as shown in system 400 in FIG. 10 . In some embodiments, the conveyor system can be in the form of perpendicular or parallel wiping belts 402. In such embodiments, the conveyor belt system can travel perpendicular or parallel to the direction 104 of web 102 movement. The coating on the belt can be a low-friction material capable of picking up powder 114, such as a high-density, short-bristle brush or felt material that holds the powder 114 within the fibers. The belt extends into the web 102 for the desired width of the edge tab region 404. A vacuum 406 collects the removed powder 416 and thoroughly cleans the belt surface on the return leg before the belt again contacts the web 102. In embodiments with parallel belts, the belts can travel in the same direction as the web 102 or in the opposite direction to the web 102. 10 , the conveyor system can include multiple rollers 408, 410, 412 that maintain a belt (e.g., wiper 402) under tension and in either a clockwise or counterclockwise direction along direction 414. In doing so, the belt collects a predetermined amount of powder 114 from web 102 and lifts the removed powder 416 along the belt surface, where it is collected using vacuum 406, with the cleaned belt continuing in direction 414 to remove additional powder 114 from web 102 in a continuous motion. A powder collection duct structure 418 extends from vacuum 406 to collect the removed powder 416 in a chamber for recycling and / or reuse.

[0042] 11, the powder removal mechanism can be a masking mechanism 452 incorporated into and operative within the coating assembly 110 to selectively remove dry powder 114 while the moving web 102 is being continuously coated. Such powder 114 removal can be achieved by masking desired edge tab areas from the coating process so that the web 102 is never coated in those areas. As discussed herein, the masking mechanism 452 can be in the form of a conveyor mask and / or a stationary mask.

[0043] In some embodiments, the masking mechanism can be in the form of a vacuum-assisted conveyor mask, as shown in system 500 of FIG. 12. In such embodiments, a conveyor belt 502 can continuously rotate in contact with the surface of the web 102. The surface or coating of the belt 502 can be low-friction or can include features that assist in lifting and removing the powder 506 from the web 102 to form an uncoated edge tab area 508. To form the edge tab area 508, the belt 502 is continuously rotated along a direction 504 to remove the powder 506, and a vacuum 510 can be used to remove the powder 506 from the belt 502 so that the cleaned belt 502 can be used again. A duct structure 512 can be used to remove the collected powder 506 for reuse and / or recycling. Such a system 500 allows the coated area 514 to remain untouched while an uncoated pattern is formed on the web 102.

[0044] In some embodiments, the masking mechanism can be in the form of a vacuum-assisted stationary mask, as shown in system 550 of FIG. 13. In such an embodiment, a strip-like plate 552 can be used to cover the width of the desired edge tab area 554 inside the coating chamber 110. A vacuum system (similar to the vacuum systems discussed herein with respect to other embodiments) can be directed such that powder 556 that falls onto the mask is continuously removed by the vacuum system so that the powder does not accumulate on the mask. Such a system allows the coated area 558 to remain untouched while the uncoated pattern is formed on the web 102.

[0045] Although the systems discussed herein are shown with the web 102 oriented and moving in a direction 104 parallel to the floor with the coating 114 on top of the web 102, it should be understood that the web 102 can be oriented at any angle between 0° and 90°, inclusive, relative to the floor. For example, the system 600 of Figure 14 can be substantially similar to the system 150 of Figure 5, except that the overall system 600 is oriented vertically. However, it should be understood that other angles between 0° and 90°, inclusive, for the overall system and / or the web 102 can also be used.

[0046] While the systems discussed herein show the web 102 being coated exclusively along one surface (e.g., the top surface), in some embodiments, the system can be configured to sequentially or simultaneously apply powder to one or both surfaces of the web 102 to generate a coating pattern. For example, FIG. 15 shows a system 650 including a coating assembly 652 disposed adjacent to the bottom surface of the web 102 so that the web 102 can be coated from the bottom side rather than the top side. In such an embodiment, a powder removal assembly 654 can also be disposed along the bottom of the web 102. The web 102 shown in FIG. 15 was first coated along one surface and then flipped over to coat the opposite surface and generate an uncoated pattern. As another example, FIG. 16 shows a system 700 including a coating assembly 702 disposed above the top surface of the web 102 and a coating assembly 704 disposed adjacent to the bottom surface of the web 102 so that both surfaces of the web 102 can be simultaneously coated. In such an embodiment, system 700 still includes a first powder removal assembly 706 disposed above the top surface of web 102 and a second powder removal assembly 708 disposed adjacent the bottom surface of web 102 so that uncoated patterns can be simultaneously formed on both sides of web 102. Figure 17 shows the bottom surface of web 102, with uncoated areas 154, 156, 158 formed thereon. In some embodiments, system 700 can be used to form the same uncoated area pattern on both sides of web 102, or can be used to form different uncoated area patterns on the top and bottom surfaces of web 102, depending on manufacturing guidelines.

[0047] The masking and / or wiping mechanisms discussed herein can be used to recover the removed dry powder 114 for recycling and reuse for further coating of the same or a different web 102. In some embodiments, one or more of the masking and / or wiping mechanisms can be combined to produce an uncoated coating pattern on a battery electrode. For example, FIG. 18 shows a system 750 including a masking mechanism 752 integrated into the coating assembly 110 and a wiping mechanism 754 positioned distally from the coating assembly 110. Thus, the system 750 enables a combined masking and wiping operation to produce an uncoated pattern on the web 102. In some embodiments, the masking mechanism 752 can be used to produce outer strips of uncoated areas 154, 156, and the wiping mechanism 754 can be used to produce inner strips of uncoated areas 158. However, it should be understood that any combination of wiping and masking can be used during electrode production. For example, in some embodiments, a masking mechanism 752 can be used to produce the majority of the uncoated area, and a wiping mechanism 754 can be used to refine the formed uncoated area to improve the accuracy of the resulting pattern.

[0048] It is to be expressly noted that while exemplary embodiments have been described herein, these embodiments should not be construed as limiting, and additions and modifications to those expressly described herein are also included within the scope of the present invention. Furthermore, it is to be understood that the features of the various embodiments described herein are not mutually exclusive and can exist in various combinations or sequences, even if such combinations and sequences are not expressly set forth herein, without departing from the spirit and scope of the present invention.

Claims

1. An electrode for a battery, comprising: a conductive substrate defining a first surface and an opposing second surface; a pattern of an active material coating formed on at least one of the first surface or the second surface of the conductive substrate, the pattern including a coated area and an uncoated area; Equipped with The pattern of the coated and uncoated areas is depositing an active material dry powder on at least one of the first surface or the second surface of the conductive substrate by electrostatic spray deposition while the conductive substrate is moving; selectively removing at least a portion of the active material dry powder from at least one of the first surface or the second surface of the conductive substrate using a powder removal assembly to create the uncoated areas of the pattern; Binding the active material dry powder to at least one of the first surface or the second surface of the conductive substrate to create the coated areas of the pattern. An electrode is formed by this.

2. The electrode of claim 1 , wherein the conductive substrate is an aluminum foil substrate.

3. The electrode of claim 1 , wherein the first and second surfaces of the conductive substrate are substantially planar or flat.

4. 2. The electrode of claim 1, wherein the pattern of coated and uncoated areas is formed by simultaneously depositing the active material dry powder on both the first surface and the second surface of the conductive substrate by electrostatic spray deposition, and simultaneously selectively removing at least the portion of the active material dry powder from both the first surface and the second surface of the conductive substrate using the powder removal assembly to create the uncoated areas of the pattern on both the first surface and the second surface.

5. 10. The electrode of claim 1, wherein the powder removal assembly comprises a wiping mechanism configured to remove at least the portion of the active material dry powder from at least one of the first surface or the second surface of the conductive substrate.

6. 10. The electrode of claim 1, wherein the powder removal assembly includes a wiping mechanism configured to disturb or move at least a portion of the active material dry powder from at least one of the first surface or the second surface of the conductive substrate, and further includes a vacuum configured to remove the disturbed or moved active material dry powder.

7. 10. The electrode of claim 1, wherein the powder removal assembly includes a masking mechanism configured to cover areas of the conductive substrate corresponding to the uncoated areas of the pattern.

8. The electrode of claim 1 , wherein the pattern includes the uncoated areas in a cross direction of the conductive substrate.

9. a coating assembly configured to deposit an active material dry powder on at least one of a first surface or an opposing second surface of a conductive substrate by electrostatic spray deposition while the conductive substrate moves or passes through or under the coating assembly; a powder removal assembly configured to selectively remove at least a portion of the active material dry powder from at least one of the first surface or the second surface of the conductive substrate to create a pattern of the active material dry powder having coated areas and uncoated areas; a bonding assembly configured to bond the active material dry powder to at least one of the first surface or the second surface of the conductive substrate; A system for fabricating a battery electrode, comprising:

10. The system of claim 9 , wherein the conductive substrate is an aluminum foil substrate.

11. The system of claim 9 , wherein the pattern includes the uncoated areas oriented along a cross direction of the conductive substrate.

12. The system of claim 9 , wherein the pattern includes the uncoated areas oriented along a machine direction of the conductive substrate.

13. The system of claim 9 , wherein the powder removal assembly includes a masking mechanism integrated into the coating chamber.

14. 10. The system of claim 9, wherein the powder removal assembly includes a wiping mechanism disposed distally from the coating chamber.

15. 10. The system of claim 9, wherein the powder removal assembly includes both a masking mechanism integrated into the coating chamber and a wiping mechanism disposed distally from the coating chamber.

16. 10. The system of claim 9, wherein the coating assembly is configured to simultaneously deposit the active material dry powder on both the first surface and the second surface of the conductive substrate, and the powder removal assembly is configured to simultaneously selectively remove at least the portion of the active material dry powder from both the first surface and the second surface of the conductive substrate to create the pattern of the active material dry powder having coated areas and uncoated areas on both the first surface and the second surface.

17. 10. The system of claim 9, wherein the powder removal assembly is a wiping mechanism including a vacuum including a nozzle disposed above at least one of the first surface or the second surface of the conductive substrate and configured to selectively remove the active material dry powder to form the uncoated areas of the pattern.

18. 10. The system of claim 9, wherein the powder removal assembly is a wiping mechanism including an angled ramp configured to direct the active material dry powder away from the conductive substrate to form the uncoated areas of the pattern.

19. 10. The system of claim 9, wherein the powder removal assembly includes a wiping mechanism including a ramp configured to disturb or move at least a portion of the active material dry powder from the conductive substrate, and further includes a vacuum configured to remove the disturbed or moved active material dry powder.

20. 10. The system of claim 9, wherein the powder removal assembly is a wiping mechanism including a rotary slitter configured to form a slit in the active material dry powder to designate an edge of the uncoated area formed in the active material dry powder.

21. 10. The system of claim 9, wherein the power removal assembly is a wiping mechanism including a conveyor system having one or more belts configured to contact and remove the active material dry powder from the conductive substrate.

22. continuously passing the conductive substrate through or under a coating assembly to deposit an active material dry powder on at least one of a first surface or a second surface of the conductive substrate by electrostatic spray deposition while the conductive substrate is moving; selectively removing at least a portion of the active material dry powder from at least one of the first surface or the second surface of the conductive substrate using a powder removal assembly to create a pattern of the active material dry powder having coated areas and uncoated areas; bonding the active material dry powder to at least one of the first surface or the second surface of the conductive substrate using a bonding assembly; A method for producing a battery electrode, comprising:

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