Passivation of flexible substrates

Abstract

In one embodiment, a flexible substrate processing system is provided that includes: a collection hub; a calendering apparatus having a first calender roller and a second calender roller; and a passivation apparatus having an interior region, wherein the collection hub is configured to rotate and assist in transporting the flexible substrate through the interior region of the passivation apparatus after the flexible substrate passes between the first calender roller and the second calender roller, and the passivation apparatus has an interior region including one or more UV lamps configured to direct ultraviolet (UV) radiation toward the flexible substrate as it is transported through the interior region of the passivation apparatus.

Description

[Technical Field]

[0001] SUMMARY OF THE DISCLOSURE Embodiments of the present disclosure generally relate to an apparatus and method for passivating films on flexible substrates, such as passivating lithium films disposed on flexible substrates used in roll-to-roll applications. [Background technology]

[0002] Flexible substrates can be used in the manufacture of electrodes for lithium-ion batteries. Various materials, such as one or more of copper, silicon, and graphite, can be used for lithium-ion battery cathodes. Prelithiation is a technique in which lithium is added to a lithium-ion battery electrode (e.g., the cathode) to prevent the loss of lithium ions, which act as charge carriers, during use of the lithium-ion battery. This prevention of lithium ion loss can improve the service life of lithium-ion batteries by reducing the loss of performance that can occur as the battery ages.

[0003] Although lithium can be deposited directly onto a flexible substrate that serves as the cathode, this process can often be damaging to the material (e.g., copper) used as the cathode. Therefore, one method is to deposit a lithium film onto a flexible carrier (e.g., PET) surface and then transfer the lithium film from the flexible carrier to the flexible substrate that serves as the cathode.

[0004] Although prelithiation of a flexible substrate that serves as a cathode can improve the performance of lithium-ion batteries, prelithiated cathodes do not completely solve the performance problems associated with lithium ion loss. Thus, there is a need for improved methods and equipment that can further mitigate the performance problems associated with lithium ion loss in lithium-ion batteries. Summary of the Invention

[0005] In one embodiment, a flexible substrate processing system is provided that includes: a collection hub; a calendering apparatus having a first calender roller and a second calender roller; and a passivation apparatus having an interior region, wherein the collection hub is configured to rotate and assist in transporting the flexible substrate through the interior region of the passivation apparatus after the flexible substrate passes between the first calender roller and the second calender roller, and the passivation apparatus has an interior region including one or more UV lamps configured to direct ultraviolet (UV) radiation toward the flexible substrate as it is transported through the interior region of the passivation apparatus.

[0006] In another embodiment, a flexible substrate processing system is provided that includes: a collection hub; a calendering apparatus including a first calender roller and a second calender roller; and a passivation apparatus having an interior region, wherein the collection hub is configured to rotate and assist in transporting the flexible substrate through the interior region of the passivation apparatus after the flexible substrate has passed between the first calender roller and the second calender roller, and the passivation apparatus has an interior region including one or more plasma generating devices configured to generate and provide plasma to the interior region of the passivation apparatus as the flexible substrate is transported through the interior region of the passivation apparatus.

[0007] In another embodiment, a flexible substrate processing system is provided that includes: a collection hub; a calendering apparatus including a first calender roller and a second calender roller; and a passivation apparatus having an interior region, wherein the collection hub is configured to rotate and assist in transporting the flexible substrate through the interior region of the passivation apparatus after the flexible substrate has passed between the first calender roller and the second calender roller, and the passivation apparatus has an interior region including one or more plasma generating devices configured to generate and provide plasma to the interior region of the passivation apparatus as the flexible substrate is transported through the interior region of the passivation apparatus.

[0008] So that the above features of the present disclosure can be understood in detail, a more particular description of the present disclosure briefly summarized above can be had by reference to several embodiments illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only exemplary embodiments and therefore should not be considered as limiting the scope thereof, which may admit of other equally substantial embodiments. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional side view of a flexible substrate processing system according to one embodiment. [Figure 2A] 2 is a cross-sectional side view of a first type of passivation device shown in FIG. 1, according to one embodiment. [Figure 2B] FIG. 2 is a top schematic view of an alternative passivation apparatus according to one embodiment. [Figure 2C] 2 is a cross-sectional side view of a second type of passivation device shown in FIG. 1 according to one embodiment. [Figure 3] 2 is a process flow diagram of a method for transferring a lithium film to a flexible substrate and passivating the surface of the lithium film using the processing system of FIG. 1 , according to one embodiment. [Figure 4] FIG. 10 is a cross-sectional side view of a flexible substrate processing system according to another embodiment. [Figure 5] FIG. 10 is a cross-sectional side view of a flexible substrate processing system according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] For ease of understanding, the same reference numerals will be used, where possible, to refer to identical elements that are common to multiple figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

[0011] Embodiments of the present disclosure generally relate to flexible substrate processing systems including one or more passivation devices for treating the most recently exposed surface of a film located on a flexible substrate. One exemplary application of the processing systems and methods provided herein includes passivating the surface of a lithium film that can be used as part of an electrode in a lithium-ion battery. For example, a lithium film can be transferred from a flexible carrier (e.g., a polymer-based carrier) and a flexible substrate (e.g., a flexible copper substrate) to a flexible substrate by passing the flexible carrier and the flexible substrate through a calendering device and then peeling the flexible carrier off. With the lithium film transferred to the flexible substrate, a new surface of the lithium film is exposed to the surrounding environment when the flexible carrier is peeled off from the flexible substrate. This newly exposed surface can then be transported through a passivation device along with the flexible substrate to prevent the newly exposed surface from reacting with the surrounding environment, which could adversely affect the performance of the lithium film in a lithium-ion battery. For example, reactions between lithium and nitrogen can adversely affect the performance of using a lithium film on the cathode surface of a lithium-ion battery.

[0012] The passivation apparatus can supply one or more gases (e.g., CO) to form a passivation film on the newly exposed surface of the lithium film, thereby preventing the above-mentioned adverse reactions, such as reaction with nitrogen. As the passivation film forms, the available area for lithium to react with the ambient environment is consumed, and therefore, after the formation of the passivation film is complete, adverse reactions between the lithium film and components of the ambient environment (e.g., nitrogen) are prevented or significantly reduced. In some embodiments, the passivation film is also formed in a self-limiting manner, such that while the gas used to form the passivation film can react with lithium to form the passivation film, the gas does not continue to react with the passivation film and increase its thickness.

[0013] The passivation apparatus can include ultraviolet lamps or plasma generators to increase the rate of these passivation reactions between the supplied gas(es) (e.g., CO) and the newly exposed surface of the lithium film. While the following disclosure primarily describes passivating the recently exposed surface of a lithium film formed on a flexible substrate, the benefits of this disclosure can also apply to passivating the recently exposed surface of other films, such as films of other alkali metals or alloys containing alkali metals, transferred to any type of flexible substrate. More generally, the benefits can apply to situations in which a newly exposed surface is formed, specifically of a film formed of a highly reactive material such as lithium.

[0014] FIG. 1 shows a side cross-sectional view of a flexible substrate processing system 100 according to one embodiment. The processing system 100 includes equipment for transferring lithium films from the surfaces of a first flexible carrier 110 and a second flexible carrier 120 to each side of a flexible substrate 130, thereby enabling the flexible substrate 130 with the lithium films to be used as an electrode (e.g., a cathode) in a lithium-ion battery. The processing system 100 includes a calendaring apparatus 140 for transferring the lithium films from the surfaces of the flexible carriers 110 and 120 to the flexible substrate 130. The processing system 100 further includes a passivation apparatus 200A or 200C for passivating the newly exposed surface of the lithium film transferred to the flexible substrate 130. Additional details regarding the passivation apparatus 200A are described below with reference to FIG. 2A. Additional details regarding the passivation apparatus 200C are described below with reference to FIG. 2C.

[0015] The processing system 100 includes a first flexible carrier supply hub 115. A supply roll 111 of the first flexible carrier 110 is located on the first flexible carrier supply hub 115. In some embodiments, the first flexible carrier 110 can be formed of a polymer material such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), or a combination thereof. A lithium film (not shown in FIG. 1 ) is located on a lower surface 110L of the first flexible carrier 110, such that the lithium film faces the upper surface 130U of the flexible substrate 130 as the first flexible carrier 110 and flexible substrate 130 are transported through the calendering device 140. After being transferred to the flexible substrate 130, the lithium film is shown as lithium film 201 in FIGS. 2A and 2C . The upper surface 130U of the flexible substrate 130 is opposite the lower surface 130L of the flexible substrate 130. The upper surface 130U is also referred to as the first surface or first side of the flexible substrate 130, and the lower surface is also referred to as the second surface or second side of the flexible substrate 130.

[0016] The processing system 100 includes a second flexible carrier supply hub 125. A supply roll 121 of the second flexible carrier 120 is located on the second flexible carrier supply hub 125. In some embodiments, the second flexible carrier 120 can be formed of the same material (e.g., PET) as the first flexible carrier 110. A lithium film (not shown in FIG. 1 ) is located on an upper surface 120U of the second flexible carrier 120, such that the lithium film faces a lower surface 130L of the flexible substrate 130 as the second flexible carrier 120 and flexible substrate 130 are transported through the calendering device 140. After being transferred to the flexible substrate 130, the lithium film is shown as lithium film 202 in FIGS. 2A and 2C .

[0017] In some embodiments, the lithium films on the surfaces of the first support 110 and the second support 120 can be formed of lithium metal, another alkali metal, or an alloy containing an alkali metal.

[0018] The processing system 100 includes a flexible substrate supply hub 135. A supply roll 131 of flexible substrate 130 is located on the flexible substrate supply hub 135. In some embodiments, the flexible substrate 130 can be formed from one or more of copper, graphite, silicon, silicon graphite, silicon oxide graphite, silicon, metallized plastic, or other materials.

[0019] The processing system 100 further includes a calendering device 140. The calendering device 140 includes a first calender roller 141 and a second calender roller 142. The first flexible carrier 110, the second flexible carrier 120, and the flexible substrate 130 are arranged to be transported along a path extending between the first calender roller 141 and the second calender roller 142. The flexible substrate 130 is located between the first flexible carrier 110 and the second flexible carrier 120 when the first flexible carrier 110, the second flexible carrier 120, and the flexible substrate 130 are transported between the first calender roller 141 and the second calender roller 142. The calender rollers 141, 142 apply a high amount of pressure to the carriers 110, 120 and the flexible substrate 130, causing the lithium film on the surface of each of the carriers 110, 120 to transfer to the flexible substrate 130. In some embodiments, a release layer is disposed on the surface of each of the flexible carriers 110, 120, between the corresponding flexible carrier 110, 120 and the lithium film on the surface of the flexible carrier. In some embodiments, the release layer can be formed of siloxane.

[0020] The processing system 100 includes a first flexible carrier collection hub 116. A collection roll 112 of the first flexible carrier 110 is located on the surface of the first flexible carrier collection hub 116. When the first flexible carrier 110 is wound onto the first flexible carrier collection hub 116, the lithium film is no longer on the surface of the first flexible carrier 110 because the lithium film that was previously on the surface of the first flexible carrier 110 has been transferred to the surface of the flexible substrate 130 by the calendering device 140.

[0021] The processing system 100 includes a second flexible carrier collection hub 126. The collection roll 122 of the second flexible carrier 120 is located on the surface of the second flexible carrier collection hub 126. When the second flexible carrier 120 is wound onto the second flexible carrier collection hub 126, the lithium film is no longer on the surface of the second flexible carrier 120 because the lithium film that was previously on the surface of the second flexible carrier 120 has been transferred to the surface of the flexible substrate 130 by the calendering device 140.

[0022] The processing system 100 includes a flexible substrate collection hub 136. A collection roll 132 of a flexible substrate 130 is positioned on the surface of the flexible substrate collection hub 136. The flexible substrate 130 includes a lithium film on each of an upper surface 130U and a lower surface 130L of the flexible substrate 130. These lithium films have been transferred from the respective carriers 110, 120 to the surface of the flexible substrate 130 by a calendering device 140.

[0023] The processing system 100 further includes a plurality of rollers 181-188. In some embodiments, each of the rollers 181-188 can be a driven roller. The rollers 181-188 can assist in providing proper tension and redirecting the flexible carriers 110, 120 and the flexible substrate 130 as they move through various portions of the processing system 100. Some of the rollers 181-188 can also assist in moving the carriers 110, 120 closer or farther apart relative to the flexible substrate 130. For example, the second roller 182 and the third roller 183 assist in bringing the carriers 110, 120 into contact with the flexible substrate 130 before the carriers 110, 120 and the flexible substrate 130 are transported through the calendering device 140. Additionally, fourth roller 184 and fifth roller 185 provide areas where tension can be applied to carriers 110, 120 to peel them from flexible substrate 130. In some embodiments, one or more of rollers 181-188 can be, instead of rollers, rods such as metal rods that can apply tension to the carrier or flexible substrate while it moves.

[0024] In some embodiments, the passivators 200A, 200C are positioned within a short distance from the rollers 184, 185 to reduce the duration between when the surface of the lithium film is exposed by stripping the flexible carrier 110, 120 and when the newly exposed surface of the lithium film is passivated by the corresponding passivator 200A, 200C. In some embodiments, the corresponding passivator 200A, 200C can be located within two feet, such as within one foot, such as within six inches, of the roller 184, 185. Similarly, in some embodiments, the corresponding passivator 200A, 200C can be located within two feet, such as within one foot, such as within six inches, of the calender rollers 141, 142.

[0025] Additionally, in some embodiments, rollers 184, 185 can be located in a regulated atmosphere, such as a nitrogen-free atmosphere, an atmosphere without any significant amounts of inert gases or other gases, or an atmosphere including one or more gases, such as carbon dioxide, supplied to the interior region of passivation apparatus 200A, 200C, but without any gases known to adversely affect the performance of lithium films, such as nitrogen. In one embodiment, rollers 184, 185 and corresponding passivation apparatus 200A, 200C are housed within the same enclosure having the regulated atmosphere described above, thereby ensuring that the newly exposed lithium surfaces are never exposed to an unregulated atmosphere, such as a nitrogen-containing atmosphere. In some embodiments, each portion of processing system 100 is in a regulated atmosphere, such as a nitrogen-free environment.

[0026] The processing system 100 may further include actuators (not shown) configured to rotate each of the hubs 115, 116, 125, 126, 135, 136 to transport the carriers 120, 120 and flexible substrates 130 from the corresponding supply hubs 115, 125, 135 through the calendering apparatus 140 to the corresponding collection hubs 116, 126, 136. The processing system 100 may further include one or more actuators (not shown) for rotating the calender rollers 141, 142 of the calendering apparatus 140. The rotational speed of the actuators may be adjusted to control the rate at which the flexible substrates 130 and flexible carriers 110, 120 are transported through the processing system 100.

[0027] In the processing system 100, the flexible substrate 130 is transported along a path from a supply roll 131 supported by a supply hub 135, past the first roller 181, between the second roller 182 and the third roller 183, between the calender rollers 141, 142, between the fourth roller 184 and the fifth roller 185, through the passivators 200A, 200C, past the eighth roller 188, and to the recovery roll 132 around the recovery hub 136. The recovery hub 136 is configured to rotate and assist in transporting the flexible substrate 130 through the interior regions of the corresponding passivators 200A, 200C after the flexible substrate 130 has passed between the first calender roller 141 and the second calender roller 142. Similarly, the retrieval hubs 116,126 are configured to rotate and assist in transporting the flexible carrier along a path between the supply hubs 115,125 and the retrieval hubs 116,126.

[0028] Processing system 100 may also include a controller 105 for controlling the processes performed by processing system 100. Controller 105 may be any type of controller used in industrial settings, such as a programmable logic controller (PLC). Controller 105 includes a processor 107, memory 106, and input / output (I / O) circuitry 108. Controller 105 may further include one or more of the following components typically found in controllers for semiconductor equipment: one or more power supplies, a clock, communication components (e.g., a network interface card), and a user interface.

[0029] Memory 106 may include non-transitory memory, which may be used to store programs and settings, as described below. Memory 106 may include one or more readily available types of memory, such as read-only memory (ROM) (e.g., electrically erasable programmable read-only memory (EEPROM)), flash memory, floppy disk, hard disk, or random access memory (RAM) (e.g., non-volatile random access memory (NVRAM)).

[0030] The processor 107 is configured to execute various programs stored in the memory 106, such as a program configured to execute the method 3000 described below with reference to FIG. 3. While executing these programs, the controller 105 can communicate with I / O devices through the I / O circuitry 108. For example, while executing these programs and communicating through the I / O circuitry 108, the controller 105 can control outputs (e.g., actuators connected to the different hubs and the calendering apparatus 140). The memory 106 can further include various operational settings used to control the processing system 100. For example, the settings can include speed settings for actuators coupled to the hubs and settings for controlling the passivators 200A, 200C described below.

[0031] FIG. 2A shows a side cross-sectional view of the passivation apparatus 200A shown in FIG. 1 , according to one embodiment. In FIG. 2A , an upper lithium film 201 (first lithium film) is located on an upper surface 130U of the flexible substrate 130, and a lower lithium film 202 (second lithium film) is located on a lower surface 130L of the flexible substrate 130. The flexible substrate 130 and the lithium films 201, 202 can be transported by the passivation apparatus 200A in direction D toward the collection hub 136 (see FIG. 1 ). The upper lithium film 201 includes an outer surface 203. The lower lithium film 202 includes an outer surface 204. The outer surfaces 203, 204 are exposed when the first flexible carrier 110 and the second flexible carrier 120 are transported through the calendering apparatus 140, pass through rollers 184, 185 (see FIG. 1 ), and are then peeled off from the flexible substrate 130.

[0032] The newly exposed surfaces 203, 204 of the lithium films 201, 202 may begin to react with the surrounding environment, for example, by reacting with nitrogen in the atmosphere if the environment is not a regulated atmosphere as described above. This reaction with nitrogen reduces the benefits of prelithiating electrodes (e.g., cathodes) for lithium-ion batteries. To address this issue, one or more different gases (e.g., CO) are supplied to passivation apparatus 200A (FIG. 2A), 200C (FIG. 2C) to passivate these newly exposed surfaces 203, 204. These one or more different gases (e.g., CO) undergo a passivating reaction with the lithium on surfaces 203, 204, thereby passivating these surfaces 203, 204 and preventing or significantly mitigating further undesirable reactions of the lithium films 201, 202 with components (e.g., nitrogen) in the unregulated atmosphere.

[0033] In some embodiments, carbon dioxide (CO) is supplied to the corresponding passivation apparatus 200A, 200C along with one or more of argon (Ar), hydrogen (H), oxygen (O), and water vapor to form a passivation film of lithium carbonate (LiCO). In other embodiments, sulfur hexafluoride (SF) is supplied to the corresponding passivation apparatus 200A, 200C along with one or more of argon (Ar), hydrogen (H), oxygen (O), and water vapor to form a passivation film of lithium fluoride (LiF) or lithium sulfur hexafluoride (LiCO). X The lithium film 201, 202 forms a passivation film (e.g., SF6). Other gases that can be used to form a passivation film on the lithium surface include carbon monoxide (CO), carbon tetrafluoride (CF4), ammonia (NH3), and other oxide, fluoride, and chloride gases. The thickness of the passivation film formed on the lithium surface can be from about 1 nm to about 1000 nm, such as from about 10 nm to about 500 nm. In some embodiments, the lithium films 201, 202 can have a thickness of from about 1 micron to about 100 microns, such as about 10 microns.

[0034] Passivation apparatus 200A includes a housing 215 disposed around interior region 208. Housing 215 includes an upper housing 215U and a lower housing 215L. Flexible substrate 130 having lithium films 201, 202 thereon is transported through interior region 208 as flexible substrate 130 moves toward collection hub 136. Interior region 208 includes upper cavity 208U above flexible substrate 130 and lower cavity 208L below flexible substrate 130.

[0035] In some embodiments, passivation apparatus 200A further includes a plurality of seals 251-254. Seals 251-254 can be formed of a compressible material. Seals 251-254 can be used to maintain a separate environment within interior region 208 relative to the environment surrounding passivation apparatus 200A. For example, interior region 208 can have various concentrations of gases and a different temperature and / or pressure relative to the environment surrounding passivation apparatus 200A.

[0036] In some embodiments, seals 251-254 can be omitted, and a pressure differential between interior region 208 and the surrounding environment can be used. For example, in one embodiment, the pressure in interior region 208 is greater than the pressure of the surrounding environment, thereby preventing nitrogen and other undesirable gases from entering interior region 208 of passivation apparatus 200A. In some embodiments, air knives, using, for example, an inert gas or other gas (e.g., CO), can be used at the inlet and outlet of the interior region to prevent gases in interior region 208 from mixing with gases in the surrounding environment.

[0037] A first sealing portion 251 is located between the upper housing 215U and the flexible substrate 130 at the entrance to the interior region 208 of the passivation apparatus 200A. A second sealing portion 252 is located between the lower housing 215L and the flexible substrate 130 at the entrance to the interior region 208 of the passivation apparatus 200A. A third sealing portion 253 is located between the upper housing 215U and the flexible substrate 130 at the exit from the interior region 208 of the passivation apparatus 200A. A fourth sealing portion 254 is located between the lower housing 215L and the flexible substrate 130 at the exit from the interior region 208 of the passivation apparatus 200A. In some embodiments, the upper housing 215U or the lower housing 215L can be configured to move, for example vertically, to more easily position a new flexible substrate 130 within the interior region 208, and to adjust the pressure of the sealing portions 251-254 on the flexible substrate 130 or the distance between the sealing portions 251-254 and the flexible substrate 130 during processing.

[0038] Upper housing 215U includes gas inlet port 231U near the entrance to upper cavity 208U and gas outlet port 241U near the exit from upper cavity 208U. Lower housing 215L includes gas inlet port 231L near the entrance to lower cavity 208L and gas outlet port 241L near the exit from lower cavity 208L. Gas inlet ports 231U and 231L can be coupled to gas sources 230A and 230B. In some embodiments, gas sources 230A and 230B can be a single gas source. Gas outlet ports 241U and 241L can be coupled to exhaust pumps 240A and 240B. In some embodiments, exhaust pumps 240A and 240B can be a single exhaust pump.

[0039] The passivation apparatus 200A further includes a plurality of ultraviolet (UV) lamps 210. Five UV lamps 210 are located within the upper housing 215U. Five UV lamps 210 are located within the lower housing 215U. Each of the UV lamps 210 can be connected to a power source (not shown), and power to the UV lamps 210 can be controlled by the controller 105 (FIG. 1). The passivation apparatus 200A includes an upper window 260U located within the upper housing 215U between the UV lamps 210 and the upper interior region 208U. The passivation apparatus 200A includes a lower window 260L located within the lower housing 215L between the UV lamps 210 and the lower interior region 208L. The windows 260U and 260L can be formed of a UV-transmitting material, such as quartz. In some embodiments, the UV lamps 210 can be located within corresponding interior regions 208U and 208L.

[0040] The UV lamps 210 in the upper housing 215U can direct UV energy into the upper cavity 208U to increase the rate of the passivation reaction between the upper lithium film 201 and one or more gases (e.g., CO) supplied to the upper interior region 208U from the gas source 230A. Similarly, the UV lamps 210 in the lower housing 215L can direct UV energy into the lower cavity 208L to increase the rate of the passivation reaction between the lower lithium film 202 and one or more gases (e.g., CO) supplied to the lower interior region 208L from the gas source 230B. The increased rate of the passivation reaction at the exposed lithium surfaces 203, 204 by the UV energy allows a sufficient portion of the surfaces 203, 204 to be effectively passivated before the flexible substrate 130 exits the passivation apparatus 200A. In some embodiments, the UV lamps 210 can emit UV radiation having wavelengths from about 100 nm to about 270 nm, such as from about 185 nm to about 254 nm. Wavelengths in these ranges can dissociate gases supplied to the passivation apparatus 200A. For example, UV radiation within these wavelengths can split carbon dioxide (CO) into CO and O, which may be more reactive than the originally supplied CO. Similarly, these wavelengths can split water (HO) and oxygen (O) into H and OH, and O and O, respectively, which may also be more reactive than the originally supplied water vapor or oxygen.

[0041] FIG. 2B is a top schematic view of an alternative passivation apparatus 200A′ according to one embodiment. Passivation apparatus 200A′ is identical to passivation apparatus 200A, except that it includes a different arrangement of components for supplying and exhausting one or more gases to and from interior regions 208U and 208L. FIG. 2B illustrates the arrangement of these components in the XY plane. The following describes the position of these components in the Z direction. Additionally referring to FIG. 2A, lamp 210 is located within housing 215U, while flexible substrate 130, gas supply line 232, and exhaust line 242 are located within upper interior region 208U.

[0042] Although Figure 2B is described as a top view with components for supplying and exhausting gas to the upper interior region 208U of Figure 2A, this description is also applicable to a bottom view of the lower interior region 208L. The upper housing 215U is shown as transparent so that the relative positions of the various components can be shown. The flexible substrate 130 is shown in dashed lines inside the passivation apparatus 200A' to indicate that it extends below the supply and exhaust lines and below the UV lamps 210.

[0043] Passivation apparatus 200A′ includes supply gas lines 232 disposed along three sides of interior region 208U to supply one or more gases (e.g., CO) from gas source 230A to interior region 208U at the inlet of interior region 208U and along the sides of flexible substrate 130 as flexible substrate 130 moves toward the outlet of interior region 208U. Supply gas lines 232 include a plurality of perforations 235 configured to supply one or more gases to various locations within upper interior region 208U. In some embodiments, supply gas lines 232 can further include sections extending in the Y direction within region 211 between UV lamps 210, such that one or more gases can also be supplied to upper interior region 208U at these locations. Additionally, although only a single row of perforations 235 is shown, in some embodiments, gas lines 232 can also include perforations 235 at various locations in the Z direction. For example, in some embodiments, the gas line 232 may include a section having a showerhead-like arrangement with perforations 235 distributed throughout the XZ or YZ plane, where the perforations are distributed in the Z direction (e.g., from the top of the interior region 208 to the bottom of the interior region 208) across most of the available space in the XZ or YZ plane. Further, in some embodiments, the perforations 235 may be oriented downward toward the flexible substrate 130.

[0044] The passivation apparatus 200A′ further includes an exhaust gas line 242 that extends across an area near the exit from the upper interior region 208U. The exhaust gas line 242 includes a plurality of perforations 245 configured to exhaust one or more gases across the width of the flexible substrate 130 in the Y direction near the exit from the upper interior region 208U.

[0045] 2C illustrates a cross-sectional side view of the passivation apparatus 200C shown in FIG. 1, according to one embodiment. Passivation apparatus 200C is identical to passivation apparatus 200A, except that it is configured to provide plasma P into the interior region instead of UV energy to increase the rate of the intended reaction between the lithium film and plasma species (e.g., CO radicals).

[0046] The housing and interior region of passivation apparatus 200C are different (e.g., different shape and / or size) from housing 215 and interior region 208 of passivation apparatus 200A described above. Passivation apparatus 200C includes an upper housing 285U and a lower housing 285L. Passivation apparatus 200C includes an upper interior region 288U and a lower interior region 288L. Upper interior region 288U is located between upper housing 285U and the upper surface of flexible substrate 130. Lower interior region 288L is located between lower housing 285L and the lower surface of flexible substrate 130.

[0047] The passivation apparatus 200C can include multiple plasma generators 270, each capable of generating a capacitively coupled plasma. While five plasma generators 270 are shown within the upper and lower housings 285U and 285L, other embodiments may include more or fewer plasma generators 270. Furthermore, the plasma generators 270 are only one example for providing plasma to the interior region containing the flexible substrate 130; many other types of plasma generators, such as various types of capacitively coupled plasma generators or inductively coupled plasma generators (e.g., with different electrode configurations and / or energy sources other than RF energy, such as microwave energy), can be used. In other embodiments, a remote plasma source can be used to provide plasma to the interior region containing the flexible substrate 130.

[0048] Each plasma generating device 270 is configured to generate a plasma P of one or more gases (e.g., CO) supplied from gas sources 230A and 230B. Each plasma generating device 270 includes a first electrode 271, a second electrode 272, a connection plate 273, and an interior region 275. The first electrode 271 of each plasma generating device 270 can be connected to one of radio frequency (RF) power sources 265A and 265B. The second electrode 272 of each plasma generating device 270 can be connected to electrical ground. To avoid cluttering the drawing, only one connection between the electrodes 271 and 272 is shown on each side of the flexible substrate 130. In some embodiments, the electrodes 271 and 272 can be spaced apart from each other by about 0.25 mm to about 10 mm, such as about 1 mm, in the X direction. In some embodiments, the ends of the electrodes 271, 272 closest to the flexible substrate 130 can be spaced apart from the flexible substrate 130 by about 1 mm to about 10 mm, such as about 4 mm.

[0049] A connecting plate 273 extends between the first electrode 271 and the second electrode 272 of each plasma generation device 270. The connecting plate 273 can be formed of or coated with a dielectric material. Further, in some embodiments, the electrodes 271, 272 can be coated with a dielectric material. In addition, each plasma generation device 270 can also include plates (not visible in FIG. 2C ) that extend in the X direction to enclose the interior region 275 on four sides. In some embodiments, these additional plates extending in the X direction can be formed of or coated with a dielectric material, while in other embodiments, these additional plates extending in the X direction can be a pair of electrodes similar to the electrodes 271, 272.

[0050] The plasma P generated by the plasma generating devices then flows from the interior region 275 of each plasma generating device 270 toward the flexible substrate 130, allowing the plasma species (e.g., CO radicals) to react with the corresponding lithium films 201, 202 on each side of the flexible substrate 130. The plasma P increases the rate of the passivation reaction at the exposed lithium surfaces 203, 204, thereby effectively passivating a sufficient portion of the surfaces 203, 204 before the flexible substrate 130 exits the passivation device 200C.

[0051] Although the passivation devices 200A, 200C are generally described as passivating the surface of lithium films, the passivation devices 200A, 200C can also be used to passivate the surface of other films, such as films formed from various alkali metals or alloys containing at least one alkali metal.

[0052] Figure 3 is a process flow diagram of a method 3000 for transferring a lithium film to a flexible substrate 130 surface and passivating the surface of the lithium film using the processing system of Figure 1, according to one embodiment. Passivation of the lithium film can be performed using passivation apparatus 200A of Figure 2A or passivation apparatus 200C of Figure 2C. Method 3000 will be described with reference to Figures 1, 2A-2C, and 3.

[0053] The method begins at block 3002. In block 3002, the processing system 100 begins transporting the flexible carriers 110, 120 and sections of the flexible substrate 130 from the corresponding supply hubs 115, 125, 135 towards the calendering device 140.

[0054] In block 3004, the lithium films 201, 202 are transferred from the flexible carriers 110, 120 to the flexible substrate 130 by the calendering apparatus 140. The first lithium film 201 is transferred from the first flexible carrier 110 to the upper surface 130U of the flexible substrate 130 by the calendering apparatus 140. The second lithium film 202 is transferred from the second flexible carrier 120 to the lower surface 130L of the flexible substrate 130 by the calendering apparatus 140.

[0055] In block 3006, the flexible carriers 110, 120 are peeled from the flexible substrate 130 as they are transported past rollers 184, 185 as shown in FIG. 1. In some embodiments, a release layer is disposed on the surface of each of the flexible carriers 110, 120 to aid in peeling the lithium films 201, 202 from each of the flexible carriers 110, 120. Each of the flexible carriers 110, 120 is then transported to a respective collection hub 116, 126.

[0056] In block 3008, the flexible substrate 130 and the newly transferred lithium films 201, 202 are transported into one of the passivation apparatuses 200A, 200C, and the newly exposed surfaces 203, 204 of these lithium films 201, 202 are passivated in the corresponding passivation apparatus 200A, 200C.

[0057] In one embodiment of block 3008 using passivation apparatus 200A (FIG. 2A), one or more gases (e.g., CO) are supplied from one or more gas sources 230A, 230B into upper interior region 208U and lower interior region 208L. UV energy is directed into interior regions 208U, 208L to increase the rate of the passivation reaction between lithium films 201, 202 and the gas activated by the UV energy. The activated gas, energized by UV energy from UV lamp 210, effectively passivates lithium films 201, 202 on flexible substrate 130 by the time the films 201, 202 and flexible substrate 130 exit passivation apparatus 200B.

[0058] In another embodiment of block 3008 using passivation apparatus 200C (FIG. 2C), one or more gases (e.g., CO) are supplied into the interior region 275 of each plasma generating device 270. RF power is supplied from corresponding RF power sources 265A, 265B to electrodes 271, 272 of each plasma generating device 270 to generate plasma P within the interior region 275 of each plasma generating device 270. The plasma P, including plasma species (e.g., CO ions and radicals), then flows toward the corresponding lithium films 201, 202, reacting with the lithium to passivate their respective surfaces 203, 204. The plasma effectively passivates the lithium films 201, 202 on the flexible substrate 130 by the time the films 201, 202 and flexible substrate 130 exit the passivation apparatus 200C.

[0059] In block 3010, the passivated lithium films 201, 202 on the flexible substrate 130 are transported to a collection hub 136. Because the surfaces 203, 204 of the lithium films 201, 202 on the flexible substrate 130 are passivated, the lithium films 201, 202 can remain exposed to ambient environments, e.g., nitrogen-containing environments, for significantly longer periods of time without their performance being significantly affected when ultimately used as part of an electrode (e.g., cathode) in a lithium-ion battery, compared to an otherwise similar lithium film without a passivated surface. Furthermore, passivation of the lithium films 201, 202 improves the performance of the lithium films 201, 202 when used as part of an electrode (e.g., cathode) in a lithium-ion battery.

[0060] FIG. 4 shows a side cross-sectional view of a flexible substrate processing system 400 according to one embodiment. The flexible substrate processing system 400 is identical to the flexible substrate processing system 100 of FIG. 1 except that the flexible substrate processing system 400 includes one of the passivation apparatuses 200A, 200C as part of a flexible substrate retrieval apparatus 430. The retrieval apparatus 430 includes the same flexible substrate retrieval hub 136 as the flexible substrate processing system 100 (FIG. 1). The retrieval hub 136 reels the flexible substrate roll 132 around the retrieval hub 136 after the flexible substrate has been transported through the passivation apparatuses 200A, 200C. The retrieval apparatus 430 includes a roller 488 to assist in applying appropriate tension to the flexible substrate 130 as it is reeled around the retrieval hub 136.

[0061] In some embodiments, the flexible substrate recovery apparatus 430 can include a housing 431. In some of these embodiments, the housing 431 can operate at a higher pressure than the surrounding environment to prevent gases from the atmosphere (e.g., nitrogen) that can have a negative effect on the lithium films 201, 202 (see, e.g., FIG. 2A) from interacting with the lithium films 201, 202 within the housing 431. In some of these embodiments, the housing 431 can be pressurized with an inert gas (e.g., argon) or gases known to not adversely affect the performance of the lithium films, such as oxygen and carbon dioxide. The entrance to the housing 431 can be immediately after the flexible carriers 110, 120 are peeled off to reduce the time the surfaces of the lithium films 201, 202 (see, e.g., FIG. 2A) are exposed before entering the controlled environment of the housing 431. In some embodiments, the interior of the housing 431 can also be temperature controlled to control the temperature of the flexible substrate 130 and roll 132. In some embodiments, the hub 136 can be temperature controlled to maintain the flexible substrate roll 132 at a specific temperature. Including one of the passivation apparatuses 200A, 200C as part of one flexible substrate recovery apparatus 430 may make it easier to add a passivation apparatus to an existing installation.

[0062] In the processing system 400, the flexible substrate 130 is transported along a path from a supply roll 131 supported by a supply hub 135, past the first roller 181, between the second roller 182 and the third roller 183, between the calender rollers 141, 142, between the fourth roller 184 and the fifth roller 185, through the passivators 200A, 200C, past the eighth roller 488, and to the collection roll 132 around the collection hub 136. In some embodiments, the passivators 200A, 200C can be located between the rollers 488 and the collection hub 136.

[0063] 5 shows a cross-sectional side view of a flexible substrate processing system 500 according to one embodiment. The flexible substrate processing system 500 is identical to the flexible substrate processing system 100 of FIG. 1, except that the flexible substrate processing system 500 includes three passivation apparatuses 200A1, 200A2, and 200C instead of only one of the passivation apparatuses 200A and 200C. An exemplary arrangement of three passivation apparatuses is described below, although other arrangements, such as placing the passivation apparatus 200C before one or more of the other passivation apparatuses 200A1 and 200A2, can also be used.

[0064] The first passivation device 200A1 and the second passivation device 200A2 are each one of the passivation devices 200A (see FIGS. 2A and 2B) that can direct UV energy into the interior regions 208U and 208L. The first passivation device 200A1 can be used to clean the lithium films 201 and 202. For example, after the lithium films 201 and 202 are peeled from the flexible carriers 110 and 120, some residual materials (e.g., hydrocarbon materials) from the flexible carriers 110 and 120 or elsewhere may remain on the surfaces 203 and 204 of the lithium films 201 and 202. To help remove this residual material, the passivation device 200A1 can direct UV energy from UV lamps 210 to an inert gas (e.g., argon) in the corresponding interior regions 208U and 208L to activate the inert gas. The inert gas may be supplied from one or more gas sources 230A, 230B.

[0065] The second passivation apparatus 200A2 can be used to form a passivation film on the surface of the lithium films 201, 202. The second passivation apparatus 200A2 can direct UV energy from UV lamps 210 to one or more reactive gases (e.g., CO) in the interior regions 208U, 208L to activate the one or more reactive gases. Activating these one or more gases with UV energy increases the rate at which the gases react with the lithium films 201, 202 to form the passivation film. The one or more reactive gases can be supplied from one or more gas sources 230A, 230B.

[0066] The third passivation apparatus 200C can be used to form an additional passivation film on the surface of the lithium films 201, 202 or to increase the thickness of the passivation film initiated by the second passivation apparatus 200A2. Referring to FIG. 2C, the third passivation apparatus 200C is configured to generate a plasma P from one or more gases supplied from one or more gas sources 230A, 230B to the interior region 275 of the plasma generation apparatus 270. The plasma P, including plasma species (e.g., CO ions and radicals), then flows toward the corresponding lithium films 201, 202 and reacts with the lithium to further passivate the lithium films 201, 202.

[0067] The use of three passivation apparatuses 200A1, 200A2, and 200C in the processing system 500 can form a more effective passivation film on the surface of the lithium film. For example, the first passivation apparatus 200A1 can remove residual material that may not otherwise be removed by the other passivation apparatuses. This residual material can eventually flake off, exposing unpassivated lithium, which could then undergo undesirable reactions with, for example, nitrogen, that would adversely affect the performance of the lithium film when used as part of a cathode in a lithium-ion battery. Furthermore, in some embodiments, the use of two passivation apparatuses 200A2 and 200C can form a more effective passivation film or two passivation films with improved passivation properties compared to a single passivation film formed by only one of the passivation apparatuses 200A2 and 200C. For example, in one embodiment, a first gas (e.g., CO) can be supplied to passivation apparatus 200A2, and a second gas (e.g., CF) can be supplied to passivation apparatus 200C. As another example, the plasma P formed by passivation apparatus 200C may be more effective at filling small voids in the passivation film formed by passivation apparatus 200A2. Thus, passivation apparatus 200C configured to generate plasma P can be used to fill remaining voids in the passivation film formed by second passivation apparatus 200A2.

[0068] In the processing system 500, the flexible substrate 130 is transported along a path from a supply roll 131 supported by a supply hub 135, through the first roller 181, between the second roller 182 and the third roller 183, between the calendar rollers 141, 142, between the fourth roller 184 and the fifth roller 185, through the passivation device 200A1, through the passivation device 200A2, through the passivation device 200C, through the eighth roller 188 and to the recovery roll 132 around the recovery hub 136.

[0069] While the above description is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof, the scope of which is defined by the claims that follow.

Claims

1. Collection hubs and a calendering device including a first calender roller and a second calender roller; a passivation apparatus having an interior region, wherein the collection hub is configured to rotate and assist in transporting the flexible substrate through the interior region of the passivation apparatus after the flexible substrate passes between the first calender roller and the second calender roller, the passivation apparatus having an interior region including one or more UV lamps configured to direct ultraviolet (UV) radiation toward the flexible substrate as it is transported through the interior region of the passivation apparatus; A flexible substrate processing system comprising:

2. 10. The flexible substrate processing system of claim 1, wherein the passivation apparatus further comprises one or more gas inlets configured to direct gas toward the flexible substrate as the flexible substrate is transported through an interior region of the passivation apparatus.

3. the one or more gas inlets include a first gas inlet and a second gas inlet; the first gas inlet is configured to direct gas to a first portion of the interior region on a first side of the flexible substrate as the flexible substrate is transported through the interior region of the passivation apparatus; the second gas inlet is configured to direct gas to a second portion of the interior region on a second side of the flexible substrate opposite the first side as the flexible substrate is transported through the interior region of the passivation apparatus; The flexible substrate processing system according to claim 2 .

4. the one or more UV lamps include a first UV lamp and a second UV lamp; the first UV lamp is configured to direct UV energy to a first portion of the interior region on a first side of the flexible substrate as the flexible substrate is conveyed through the interior region of the passivation apparatus; the second UV lamp is configured to direct UV energy to a second portion of the interior region on a second side of the flexible substrate as the flexible substrate is conveyed through the interior region of the passivation apparatus; The flexible substrate processing system according to claim 3 .

5. the one or more UV lamps include a first UV lamp and a second UV lamp; the first UV lamp is configured to direct UV energy to a first portion of the interior region on a first side of the flexible substrate as the flexible substrate is conveyed through the interior region of the passivation apparatus; the second UV lamp is configured to direct UV energy to a second portion of the interior region on a second side of the flexible substrate opposite the first side as the flexible substrate is transported through the interior region of the passivation apparatus; The flexible substrate processing system according to claim 1 .

6. 10. The flexible substrate processing system of claim 1, further comprising a first roller located between the calendering device and the passivation device, the first roller configured to assist in peeling the first flexible carrier from the flexible substrate before the flexible substrate enters the passivation device.

7. 7. The flexible substrate processing system of claim 6, further comprising a second roller located between the calendering device and the passivation device, the second roller configured to assist in peeling the second flexible carrier from the flexible substrate before the flexible substrate enters the passivation device.

8. 7. The flexible substrate processing system of claim 6, wherein the passivator is located less than one foot from the first roller.

9. 10. The flexible substrate processing system of claim 1, wherein the passivation device is located less than one foot from the calendering device.

10. Collection hubs and a calendering device including a first calender roller and a second calender roller; a passivation apparatus having an interior region, wherein the collection hub is configured to rotate and assist in transporting the flexible substrate through the interior region of the passivation apparatus after the flexible substrate passes between the first calender roller and the second calender roller, the passivation apparatus having an interior region including one or more plasma generating devices configured to generate and provide plasma to the interior region of the passivation apparatus as the flexible substrate is transported through the interior region of the passivation apparatus; A flexible substrate processing system comprising:

11. The flexible substrate processing system according to claim 10 , wherein the plasma generating device comprises a first electrode and a second electrode.

12. 12. The flexible substrate processing system of claim 11, wherein the first electrode is coupled to a radio frequency power source and the second electrode is coupled to electrical ground.

13. the one or more plasma generation devices include a first plasma generation device and a second plasma generation device; a first plasma generating device configured to direct plasma generated by the first plasma generating device to a first portion of the interior region on a first side of the flexible substrate when the flexible substrate is transported through the interior region of the passivation device; a second plasma generating device configured to direct plasma generated by the second plasma generating device to a second portion of the interior region on a second side of the flexible substrate while the flexible substrate is being transported through the interior region of the passivation device; The flexible substrate processing system according to claim 10.

14. 11. The flexible substrate processing system of claim 10, further comprising a first roller located between the calendering device and the passivation device, the first roller configured to assist in peeling the first flexible carrier from the flexible substrate before the flexible substrate enters the passivation device.

15. 15. The flexible substrate processing system of claim 14, further comprising a second roller located between the calendering device and the passivation device, the second roller configured to assist in peeling the second flexible carrier from the flexible substrate before the flexible substrate enters the passivation device.

16. 15. The flexible substrate processing system of claim 14, wherein the passivation device is located less than one foot from the first roller.

17. 11. The flexible substrate processing system of claim 10, wherein the passivation device is located less than one foot from the calendering device.

18. Collection hubs and a calendering device including a first calender roller and a second calender roller; a first passivation apparatus having an interior region, wherein the collection hub is configured to rotate and assist in transporting the flexible substrate through the interior region of the first passivation apparatus after the flexible substrate passes between the first calender roller and the second calender roller, the first passivation apparatus having an interior region including one or more UV lamps configured to direct ultraviolet (UV) radiation toward the flexible substrate as it is transported through the interior region of the first passivation apparatus; a second passivation apparatus having an interior region, wherein the collection hub is configured to rotate and assist in transporting the flexible substrate through the interior region of the second passivation apparatus after the flexible substrate has passed between the first calender roller and the second calender roller, the passivation apparatus having an interior region including one or more plasma generating devices configured to generate and provide plasma to the interior region of the second passivation apparatus as the flexible substrate is transported through the interior region of the second passivation apparatus; A flexible substrate processing system comprising:

19. the collection hub is configured to assist in transporting the flexible substrate along a path from the calendering device through an interior region of the first passivation device, through an interior region of the second passivation device, and to the collection hub; The first passivation device is installed on the path between the calendering device and the second passivation device; 20. The flexible substrate processing system of claim 18.

20. a third passivation apparatus having an interior region, wherein the collection hub is configured to rotate and assist in transporting the flexible substrate through the interior region of the third passivation apparatus after the flexible substrate exits the interior region of the first passivation apparatus, the third passivation apparatus further comprising an interior region including one or more UV lamps configured to direct ultraviolet (UV) radiation toward the flexible substrate as it is transported through the interior region of the third passivation apparatus; the first passivation device is coupled to a first gas source configured to supply one or more inert gases to an interior region of the first passivation device; the third passivation device is coupled to a second gas source configured to supply one or more reactive gases to an interior region of the third passivation device; 20. The flexible substrate processing system of claim 18.

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