Flexible substrate passivation

Abstract

In one embodiment, there is provided a flexible substrate processing system comprising: a pick-and-place center; a rolling unit including a first roller and a second roller; and a passivation unit having an interior space, the pick-and-place center configured to rotate after the flexible substrate passes through the first roller and the second roller and to assist in feeding the flexible substrate through the interior space of the passivation unit, the passivation unit including one or more ultraviolet (UV) lamps configured to emit light to the flexible substrate when the flexible substrate passes through the interior space of the passivation unit. UV radiation is directed towards the flexible substrate.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure generally relate to apparatuses and methods for passivating a top layer on a flexible substrate, such as passivating a lithium layer on a flexible substrate for roll-to-roll applications. BACKGROUND

[0002] Flexible substrates can be used to manufacture electrodes for lithium ion batteries. Different materials can be used for the anode of a lithium ion battery, such as one or more of copper, silicon, and graphite. Pre-lithiation is a technique that adds lithium to the electrodes (e.g., anodes) of a lithium ion battery to prevent loss of lithium ions that act as charge carriers when the lithium ion battery is used. Preventing loss of lithium ions can improve the effective useful life of a lithium ion battery by reducing performance loss that can occur during the aging process of the battery.

[0003] Although lithium can be deposited directly on a flexible substrate that serves as an anode, this process tends to cause damage to the material (e.g., copper) that serves as the anode. As such, one approach is to deposit a lithium film onto a flexible carrier (e.g., PET) and then transfer the lithium film from the flexible carrier to the flexible substrate that serves as the anode.

[0004] Although pre-lithiation of a flexible substrate that serves as an anode can improve the performance of a lithium ion battery, pre-lithiated anodes have not fully solved performance issues related to loss of lithium ions. As such, there is a pressing need for improved methods and apparatuses to further reduce performance issues related to loss of lithium ions in lithium ion batteries. SUMMARY

[0005] In one embodiment, a flexible substrate processing system is provided, including: a pick-and-place center; a roller unit including a first roller and a second roller; and a passivation unit having an interior space, the pick-and-place center configured to rotate and assist in feeding a flexible substrate through the interior space of the passivation unit after the flexible substrate passes between the first roller and the second roller, the passivation unit including one or more ultraviolet (UV) lamps configured to direct UV radiation toward the flexible substrate as the flexible substrate is fed through the interior space of the passivation unit.

[0006] In another embodiment, a flexible substrate processing system is provided, including: a pick-and-place center; a roller unit including a first roller and a second roller; and a passivation unit having an interior space, the pick-and-place center configured to rotate and assist in feeding a flexible substrate through the interior space of the passivation unit after the flexible substrate passes between the first roller and the second roller, the passivation unit including one or more plasma generation units configured to generate and provide plasma to the interior space of the passivation unit as the flexible substrate is fed through the interior space of the passivation unit.

[0007] In another embodiment, a flexible substrate processing system is provided, comprising: a pick-and-place center; a roller unit comprising a first roller and a second roller; and a passivation unit having an interior space, the pick-and-place center configured to rotate and assist in feeding a flexible substrate through the interior space of the passivation unit after the flexible substrate passes between the first roller and the second roller, the passivation unit comprising one or more plasma generating units configured to generate and provide plasma to the interior space of the passivation unit as the flexible substrate passes through the interior space of the passivation unit. BRIEF DESCRIPTION OF DRAWINGS

[0008] For the features of the disclosure described above to be understood in detail, a more particular description will be made, reference being had to the accompanying drawings, wherein like numerals designate like elements in the several figures. It is to be noted, however, that the drawings only show exemplary embodiments and are therefore not to be considered limiting of its scope, as the scope of the disclosure can encompass other equally effective embodiments.

[0009] Figure 1 A side cross-sectional view of a flexible substrate processing system is shown in accordance with one embodiment.

[0010] Figure 2A A side cross-sectional view of a first passivation unit is shown in accordance with one embodiment, as shown in Figure 1 .

[0011] Figure 2B A top view of an alternative passivation unit is shown in accordance with one embodiment.

[0012] Figure 2C A side cross-sectional view of a second passivation unit is shown in accordance with one embodiment, as shown in Figure 1 .

[0013] Figure 3 is a process flow diagram of a processing system using Figure 1 to transfer lithium films to a flexible substrate and to passivate the surfaces of the lithium films in accordance with one embodiment.

[0014] Figure 4 A side cross-sectional view of a flexible substrate processing system is shown in accordance with another embodiment.

[0015] Figure 5 A side cross-sectional view of a flexible substrate processing system is shown in accordance with another embodiment.

[0016] To facilitate the understanding of this disclosure, like reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that the components and features of the embodiments can be beneficially incorporated in other embodiments without further recitation. DETAILED DESCRIPTION

[0017] Embodiments of the present disclosure generally relate to flexible substrate processing systems including one or more passivation units to treat a newly exposed surface of a film located on a flexible substrate. One exemplary use of the processing systems and methods provided in the present disclosure includes passivation 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 onto a flexible substrate by passing a flexible carrier (e.g., a polymer-based carrier) and a flexible substrate (e.g., a flexible copper substrate) through a roller unit, and then tearing the flexible carrier away. When the lithium film is transferred onto the flexible substrate, a new surface of the lithium film is exposed as the flexible carrier is torn away from the flexible substrate. This newly exposed surface can then be passed through a passivation unit along with the flexible substrate to prevent reactions from occurring with the surrounding environment that can negatively impact the performance of the lithium film in a lithium-ion battery. For example, reactions between lithium and nitrogen can negatively impact the performance of a lithium film used on an anode in a lithium-ion battery.

[0018] The passivation unit can supply one or more gases (e.g., C02) to form a passivation layer on the newly exposed surface of the lithium film that prevents the aforementioned negative reactions from occurring, such as reactions with nitrogen. As the passivation layer is formed, sites available for lithium to react with the environment are consumed, so after the formation of the passivation layer is complete, negative reactions between the lithium film and components in the environment (e.g., nitrogen) will be prevented or significantly reduced. In certain embodiments, the formation of the passivation layer also occurs in a self-limiting manner, so while the gas used to form the passivation layer can react with the lithium to form the passivation layer, the gas does not continue to react with the passivation layer to increase the thickness of the passivation layer.

[0019] The passivation unit can include an ultraviolet lamp or a plasma generator to increase the rate of the passivation reaction between the one or more supplied gases (e.g., C02) and the newly exposed surface of the lithium film. While the following disclosure primarily describes passivation of a newly exposed surface of a lithium film formed on a flexible substrate, the benefits of this disclosure can also be applied to passivation of newly exposed surfaces of other films, such as other alkali metals or alloy films containing alkali metals, and can be transferred to any type of flexible substrate. More generally, these benefits are particularly applicable when a new film surface is exposed that is formed from a highly reactive material, such as lithium.

[0020] Figure 1A side cross-sectional view of a flexible substrate processing system 100 is shown according to one embodiment. The processing system 100 includes equipment to transfer lithium film to first and second flexible carriers 110, 120 on both sides of a flexible substrate 130 so that the flexible substrate 130 with lithium film thereon can be used as an electrode (e.g., an anode) in a lithium ion battery. The processing system 100 includes a roll unit 140 to transfer lithium film from the flexible carriers 110, 120 to the flexible substrate 130. The processing system 100 also includes a passivation unit 200A or a passivation unit 200C to passivate newly exposed surfaces of the lithium film transferred to the flexible substrate 130. Details of the passivation unit 200A are described below with reference to Figure 2A Details of the passivation unit 200C are described below with reference to Figure 2C

[0021] The processing system 100 includes a first flexible carrier supply center 115. A supply spool 111 of the first flexible carrier 110 is disposed on the first flexible carrier supply center 115. In some embodiments, the first flexible carrier 110 can be made of a polymeric material such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), or a combination thereof. A lithium film (not shown in Figure 1 is positioned on a lower side 110L of the first flexible carrier 110 so that the lithium film faces an upper surface 130U of the flexible substrate 130 when the first flexible carrier 110 and the flexible substrate 130 are conveyed in the roll unit 140. The lithium film is shown as lithium film 201 after being transferred to the flexible substrate 130 in Figure 2A and 2C The upper surface 130U of the flexible substrate 130 is on an opposite side of the flexible substrate 130 from the lower surface 130L. The upper surface 130U is also referred to as a first surface or a first side of the flexible substrate 130, while the lower surface is referred to as a second surface or a second side of the flexible substrate 130.

[0022] The processing system 100 includes a second flexible carrier supply center 125. A supply spool 121 of the second flexible carrier 120 is disposed on the second flexible carrier supply center 125. In some embodiments, the second flexible carrier 120 can be made of the same material as the first flexible carrier 110 (e.g., PET). A lithium film (not shown in Figure 1 is positioned on an upper side 120U of the second flexible carrier 120 so that the lithium film faces the lower surface 130L of the flexible substrate 130 when the second flexible carrier 120 and the flexible substrate 130 are conveyed in the roll unit 140. The lithium film is shown as lithium film 202 after being transferred to the flexible substrate 130 in Figure 2A and 2C

[0023] ​​In certain embodiments, the lithium film on the first carrier 110 and the second carrier 120 can be composed of lithium metal, other alkali metals, or alloys containing alkali metals.

[0024] The processing system 100 includes a flexible substrate supply center 135. A supply spool 131 of the flexible substrate 130 is placed on the flexible substrate supply center 135. In certain embodiments, the flexible substrate 130 can be composed of one or more of copper, graphite, silicon, silicon graphite, silicon oxide graphite, silicon, metallized plastic, or other materials.

[0025] The processing system 100 further includes a roll unit 140. The roll unit 140 includes a first roll 141 and a second roll 142. The first flexible carrier 110, the second flexible carrier 120, and the flexible substrate 130 are arranged to be fed along a path between the first roll 141 and the second roll 142. When the first flexible carrier 110, the second flexible carrier 120, and the flexible substrate 130 are fed between the first roll 141 and the second roll 142, the flexible substrate 130 is positioned between the first flexible carrier 110 and the second flexible carrier 120. The roll rolls 141, 142 apply high strength pressure to the carriers 110, 120 and the flexible substrate 130, causing the lithium film on each carrier 110, 120 to be transferred onto the flexible substrate 130. In certain embodiments, a release layer is disposed on each flexible carrier 110, 120, between the corresponding flexible carrier 110, 120 and the lithium film on the flexible carrier. In certain embodiments, the release layer can be composed of siloxane.

[0026] The processing system 100 includes a first flexible carrier take-off center 116. The take-off roll 112 of the first flexible carrier 110 is positioned on the first flexible carrier take-off center 116. When the first flexible carrier 110 is wound onto the first flexible carrier take-off center 116, the lithium film is no longer on the first flexible carrier 110 because the lithium film that was originally on the first flexible carrier 110 has been transferred onto the flexible substrate 130 by the roll unit 140.

[0027] The processing system 100 includes a second flexible carrier take-off center 126. The take-off roll 122 of the second flexible carrier 120 is positioned on the second flexible carrier take-off center 126. When the second flexible carrier 120 is wound onto the second flexible carrier take-off center 126, the lithium film is no longer on the second flexible carrier 120 because the lithium film that was originally on the second flexible carrier 120 has been transferred onto the flexible substrate 130 by the roll unit 140.

[0028] The processing system 100 includes a flexible substrate handling center 136. The handling rollers 132 of the flexible substrate 130 are positioned on the flexible substrate handling center 136. The upper surface 130U and the lower surface 130L of the flexible substrate 130 each include a lithium film. These lithium films are transferred from the respective carriers 110, 120 to the flexible substrate 130 by the roll-off unit 140.

[0029] The processing system 100 further includes a plurality of rollers 181-188. In some embodiments, each roller 181-188 can be a passive roller. The rollers 181-188 can assist in applying appropriate tension to the flexible carriers 110, 120 and the flexible substrate 130 during movement of each carrier 110, 120 in different portions of the processing system 100, and assist in changing the direction of movement of each carrier 110, 120 and the flexible substrate 130. Some rollers 181-188 can also assist in moving the carriers 110, 120 closer to or further from the flexible substrate 130. For example, the second and third rollers 182, 183 assist in bringing the carriers 110, 120 into contact with the flexible substrate 130 prior to the carriers 110, 120 and the flexible substrate 130 passing through the roll-off unit 140. In addition, the fourth and fifth rollers 184, 185 provide an area where tension can be applied to the carriers 110, 120 to peel them away from the flexible substrate 130. In some embodiments, one or more rollers 181-188 can be replaced by a rod, such as a metal rod, that can apply tension to the carriers or the flexible substrate during movement thereof.

[0030] In some embodiments, the passivation units 200A, 200C are positioned within a short distance of the rollers 184, 185 to reduce the time that the lithium film surface is exposed to the passivation applied by the corresponding passivation unit 200A, 200C after the flexible carrier 110, 120 is peeled away. In some embodiments, the corresponding passivation unit 200A, 200C can be positioned within two feet, such as within one foot, such as within six inches, of the rollers 184, 185. Similarly, in some embodiments, the corresponding passivation unit 200A, 200C can be positioned within two feet, such as within one foot, such as within six inches, of the rollers 141, 142.

[0031] Further, in some embodiments, the rollers 184, 185 can be placed in a controlled atmosphere, such as an atmosphere that does not include nitrogen, an inert gas atmosphere that does not have significant other gases, or an atmosphere that includes one or more gases provided into the interior space of the passivation units 200A, 200C, such as carbon dioxide, without including gases known to negatively affect the performance of lithium films, such as nitrogen. In one embodiment, the rollers 184, 185 and corresponding passivation units 200A, 200C are housed in a common housing having a controlled atmosphere as described above to ensure that newly exposed lithium surfaces are not exposed to uncontrolled atmospheres, such as atmospheres that include nitrogen. In some embodiments, each portion of the processing system 100 is located in a controlled atmosphere, such as an environment that does not include nitrogen.

[0032] The processing system 100 can further include actuators (not shown) configured to rotate each of the pick-and-place centers 115, 116, 125, 126, 135, 136 so that the carriers 110, 120 and the flexible substrate 130 can be transported from the corresponding supply pick-and-place centers 115, 125, 135 through the rolling units 140 and to the corresponding pick-and-place centers 116, 126, 136. The processing system 100 can further include one or more actuators (not shown) configured to rotate the rollers 141, 142 of the rolling units 140. The speed of rotation of the actuators can be adjusted to control the speed of the flexible substrate 130 and the flexible carriers 110, 120 through the processing system 100.

[0033] In the processing system 100, the flexible substrate 130 is transported along a path from the supply spool 131 supported by the supply center 135, through the first roller 181, between the second and third rollers 182, 183, between the rolling rollers 141, 142, between the fourth and fifth rollers 184, 185, through the passivation units 200A, 200C, through the eighth roller 188, and to the pick-and-place roller 132 around the pick-and-place center 136. The pick-and-place center 136 is configured to rotate and assist in the transport of the flexible substrate 130 through the interior space of the corresponding passivation units 200A, 200C after the flexible substrate 130 passes between the first roller 141 and the second roller 142. Likewise, the pick-and-place centers 116, 126 are configured to rotate and assist in the transport of the flexible carriers along the path between the supply centers 115, 125 and the pick-and-place centers 116, 126.

[0034] The processing system 100 may also include a controller 105 for controlling the processes performed by the processing system 100. The controller 105 may be any type of controller suitable for industrial environments, such as a programmable logic controller (PLC). The controller 105 includes a processor 107, a memory 106, and input / output (I / O) circuitry 108. The controller 105 may also include one or more of the following components (not shown): power supplies, clocks, communication components (e.g., network adapters), and user interfaces typically found in semiconductor device controllers.

[0035] Memory 106 may include non-transient memory. The non-transient memory may be used to store the programs and settings described below. Memory 106 may include one or more common memory types, such as read-only memory (ROM) (e.g., electrically erasable programmable read-only memory (EEPROM), flash memory, disk, hard disk) or random access memory (RAM) (e.g., non-volatile random access memory (NVRAM)).

[0036] Processor 107 is configured to execute various programs stored in memory 106, such as those described below. Figure 3 The method 3000 is a program. During the execution of these programs, the controller 105 can communicate with I / O devices via I / O circuitry 108. For example, during the execution of these programs and communication via I / O circuitry 108, the controller 105 can control outputs (e.g., actuators connected to different pick-and-place centers and rolling units 140). The memory 106 may also contain various operational settings for controlling the processing system 100. For example, these settings may include speed settings for actuators connected to the pick-and-place centers, and settings for controlling the passivation units 200A and 200C described below.

[0037] Figure 2A A side cross-sectional view of a passivation unit 200A according to one embodiment is shown. Figure 2A In the middle section, the upper lithium film 201 (first lithium film) is located on the upper surface 130U of the flexible substrate 130, and the lower lithium film 202 (second lithium film) is located on the lower surface 130L of the flexible substrate 130. The flexible substrate 130 and the lithium films 201 and 202 can be conveyed along direction D through the passivation unit 200A and toward the pick-and-place center 136 (see...). Figure 1 The upper lithium film 201 includes an outer surface 203. The lower lithium film 202 includes an outer surface 204. The flexible substrate 130 passes through the rolling unit 140 and rollers 184 and 185 (see...). Figure 1 After that, when the first flexible carrier 110 and the second flexible carrier 120 are peeled off, the outer surfaces 203 and 204 will be exposed.

[0038] The newly exposed surfaces 203, 204 of the lithium films 201, 202 can begin to react with the ambient environment, for example, with nitrogen in the atmosphere if the environment is not the controlled atmosphere described above. These reactions with nitrogen reduce the benefits of pre-lithiating the electrodes (e.g., anodes) of lithium-ion batteries. To address this problem, one or more different gases (e.g., CO2) are supplied to the passivation units 200A Figure 2A Figure 2C , 200C to passivate these newly exposed surfaces 203, 204. These one or more different gases (e.g., CO2) react with the lithium on the surfaces 203, 204 to passivate these surfaces 203, 204 to prevent or significantly reduce further undesirable reactions of the lithium films 201, 202 with components in the uncontrolled atmosphere (e.g., nitrogen).

[0039] In certain embodiments, carbon dioxide (CO2) is supplied to the respective passivation units 200A, 200C along with one or more of argon (Ar), hydrogen (H2), oxygen (O2), and water vapor to form a passivation layer of lithium carbonate (Li2CO3). In other embodiments, sulfur hexafluoride (SF6) is supplied to the respective passivation units 200A, 200C along with one or more of argon (Ar), hydrogen (H2), oxygen (O2), and water vapor to form a passivation layer of lithium fluoride (LiF) or lithium hexafluoride (Li x SF6). Other gases that can be used to form a passivation layer on a lithium surface include carbon monoxide (CO), carbon tetrafluoride (CF4), ammonia (NH3), and other oxide, fluoride, and chloride gases. The thickness of the passivation layer formed on the lithium surface can be from about 1 nm to about 1000 nm, for example, from about 10 nm to about 500 nm. In certain embodiments, the thickness of the lithium films 201, 202 can be from about 1 micron to about 100 microns, for example, about 10 microns.

[0040] The passivation units 200A include an enclosure 215 that surrounds an interior space 208. The enclosure 215 includes an upper portion 215U and a lower portion 215L. The flexible substrate 130 with the lithium films 201, 202 is fed through the interior space 208 while the flexible substrate 130 is moved toward the pick-and-place center 136. The interior space 208 includes an upper portion 208U above the flexible substrate 130 and a lower portion 208L below the flexible substrate 130.

[0041] ​In certain embodiments, the passivation unit 200A further includes a plurality of seals 251-254. The seals 251-254 can be made of a compressible material. The seals 251-254 can be used to maintain an independent environment of the interior space 208 with respect to the surrounding environment of the passivation unit 200A. For example, the gas concentration, temperature, and / or pressure of the interior space 208 can be different from the surrounding environment of the passivation unit 200A.

[0042] In certain embodiments, the seals 251-254 can be omitted, and a pressure difference between the interior space 208 and the surrounding environment can be utilized. For example, in one embodiment, the pressure of the interior space 208 is higher than the pressure of the surrounding environment to prevent nitrogen and other unwanted gases from entering the interior space 208 of the passivation unit 200A. In certain embodiments, a gas flow knife can be used at the inlet and outlet of the interior space, for example, using an inert gas or other gas (e.g., CO2) to prevent the gas in the interior space 208 from mixing with the gas in the surrounding environment.

[0043] The first seal 251 is located between the upper housing 215U and the flexible substrate 130 at the inlet of the interior space 208 of the passivation unit 200A. The second seal 252 is located between the lower housing 215L and the flexible substrate 130 at the inlet of the interior space 208 of the passivation unit 200A. The third seal 253 is located between the upper housing 215U and the flexible substrate 130 at the outlet of the interior space 208 of the passivation unit 200A. The fourth seal 254 is located between the lower housing 215L and the flexible substrate 130 at the outlet of the interior space 208 of the passivation unit 200A. In certain embodiments, the upper housing 215U or the lower housing 215L can be configured to move, for example, in a vertical direction, in order to be able to more easily place a new flexible substrate 130 in the interior space 208 and adjust the pressure of the seals 251-254 against the flexible substrate 130 or the distance between the seals 251-254 and the flexible substrate 130 during processing.

[0044] The upper enclosure 215U includes a gas inlet port 231U located near the entrance of the upper space 208U, and a gas outlet port 241U located near the exit of the upper space 208U. The lower enclosure 215L includes a gas inlet port 231L located near the entrance of the lower space 208L, and a gas outlet port 241L located near the exit of the lower space 208L. The gas inlet ports 231U, 231L can be connected to a gas source 230A, 230B. In some embodiments, the gas sources 230A, 230B can be a single gas source. The gas outlet ports 241U, 241L can be connected to an exhaust pump 240A, 240B. In some embodiments, the exhaust pumps 240A, 240B can be a single exhaust pump.

[0045] The passivation unit 200A further includes a plurality of ultraviolet (UV) lamps 210. Five UV lamps 210 are placed in the upper enclosure 215U. Five UV lamps 210 are placed in the lower enclosure 215L. Each UV lamp 210 can be connected to a power supply (not shown), and the power of the UV lamps 210 can be controlled by the controller 105 Figure 1 ) to control the power of the UV lamps 210. The passivation unit 200A includes an upper window 260U between the UV lamps 210 in the upper enclosure 215U and the upper interior space 208U. The passivation unit 200 includes a lower window 260L between the UV lamps 210 in the lower enclosure 215L and the lower interior space 208L. The windows 260U, 260L can be made of ultraviolet transparent material, such as quartz. In some embodiments, the UV lamps 210 can be placed in the corresponding interior spaces 208U, 208L.

[0046] The UV lamp 210 in the upper housing 215U can direct UV energy to the upper space 208U to increase the rate of passivation reaction between the upper lithium film 201 and one or more gases (e.g., CO2) supplied from the gas source 230A to the upper internal space 208U. Similarly, the UV lamp 210 in the lower housing 215L can direct UV energy to the lower space 208L to increase the rate of passivation reaction between the lower lithium film 202 and one or more gases (e.g., CO2) supplied from the gas source 230B to the lower internal space 208L. The increased passivation reaction rate on the exposed lithium surfaces 203, 204 provided by the UV energy allows a sufficient portion of the surfaces 203, 204 to be effectively passivated before the flexible substrate 130 leaves the passivation unit 200A. In some embodiments, the UV lamp 210 can emit UV radiation with wavelengths from about 100 nm to about 270 nm, for example from about 185 nm to about 254 nm. Wavelengths within these ranges can dissociate the gas supplied to the passivation unit 200A. For example, UV radiation in these wavelength ranges can decompose carbon dioxide (CO2) into CO and O, which is more reactive than the originally supplied CO2. Similarly, these wavelengths can also decompose water (H2O) into H and OH, and oxygen (O2) into O and O3, which is also more reactive than the originally supplied water vapor or oxygen.

[0047] Figure 2B A top schematic diagram of an alternative passivation unit 200A' is shown according to one embodiment. Passivation unit 200A' is the same as passivation unit 200A, except that passivation unit 200A' includes a different component configuration for supplying and discharging one or more gases to the internal spaces 208U, 208L. Figure 2B This describes the arrangement of these components in the XY plane. The following describes the positions of these components in the Z direction. (Reference) Figure 2A The lamp 210 is located in the housing 215U, while the flexible substrate 130, the gas supply line 232 and the exhaust line 242 are located in the upper internal space 208U.

[0048] Despite Figure 2B Described as a top-down view, showing the supply and exhaust gases to Figure 2A The components of the upper interior space 208U are shown, but the description also applies to the bottom view of the lower interior space 208L. The upper housing 215U is shown as transparent so that the relative positions of the different components can be shown. The flexible substrate 130 is shown in dashed lines in the passivation unit 200A', indicating that the flexible substrate 130 extends below the supply and discharge lines and the ultraviolet lamp 210.

[0049] The passivation unit 200A' includes gas supply lines 232 arranged along three sides of the interior space 208U to supply one or more gases (e.g., CO2) from the gas source 230A to the inlet of the interior space 208U, and to supply gas along the sides of the flexible substrate 130 as the flexible substrate 130 moves toward the outlet of the interior space 208U. The gas supply lines 232 include a plurality of perforations 235 configured to supply one or more gases to different locations within the upper interior space 208U. In some embodiments, the gas supply lines 232 may also include portions extending in the Y direction within the region 211 between the UV lamps 210 to supply one or more gases to the upper interior space 208U at these locations. Furthermore, although only one row of perforations 235 is shown, in some embodiments, the gas supply lines 232 may also include perforations 235 at different locations in the Z direction. For example, in some embodiments, the air supply line 232 may include a portion with a nozzle layout, and the perforations 235 are arranged in an XZ plane or a YZ plane, with the perforations aligned in the Z direction of most of the available space in said plane (e.g., from the top of the interior space 208 to the bottom of the interior space 208). Furthermore, in some embodiments, the perforations 235 may be aligned downwards toward the flexible substrate 130.

[0050] The passivation unit 200A' also includes exhaust lines 242 that extend near the outlet of the upper internal space 208U. The exhaust lines 242 include a plurality of perforations 245 that are configured to exhaust one or more gases in the Y direction along the width of the flexible substrate 130 near the outlet of the upper internal space 208U.

[0051] Figure 2C A side cross-sectional view of a passivation unit 200C according to one embodiment is shown, as follows. Figure 1 As shown. Passivation unit 200C is the same as passivation unit 200A, except that passivation unit 200C is configured to supply plasma P to the internal space instead of UV energy to improve the expected reaction rate between the lithium film and plasma material (e.g., CO2 radicals).

[0052] The outer shell and internal space of passivation unit 200C differ from the outer shell 215 and internal space 208 of passivation unit 200A described above (e.g., different shape and / or size). Passivation unit 200C includes an upper outer shell 285U and a lower outer shell 285L. Passivation unit 200C includes an upper internal space 288U and a lower internal space 288L. The upper internal space 288U is located between the upper outer shell 285U and the upper side of the flexible substrate 130. The lower internal space 288L is located between the lower outer shell 285L and the lower side of the flexible substrate 130.

[0053] The passivation unit 200C can include a plurality of plasma generation units 270, each of which can generate a capacitively coupled plasma. While five plasma generation units 270 are shown in the upper housing 285U and the lower housing 285L, other embodiments can include more or fewer plasma generation units 270. Moreover, the plasma generation units 270 are one example of providing plasma to the interior space including the flexible substrate 130, and many other types of plasma generation units can also be used, such as different types of capacitively coupled plasma generation units (e.g., different electrode and / or power supply (as opposed to RF energy, such as microwave energy) layouts) or inductively coupled plasma generation units. In other embodiments, a remote plasma source can be used to supply plasma to the interior space including the flexible substrate 130.

[0054] Each plasma generation unit 270 is configured to generate a plasma P of one or more gases (e.g., CO2) supplied by the gas sources 230A, 230B. Each plasma generation unit 270 includes a first electrode 271, a second electrode 272, a connection plate 273, and an interior space 275. The first electrode 271 of each plasma generation unit 270 can be connected to one of the radio frequency (RF) power supplies 265A, 265B. The second electrode 272 of each plasma generation unit 270 can be connected to electrical ground. To not clutter the figure, the connections of the electrodes 271 and 272 are only shown on either side of the flexible substrate 130. In certain embodiments, the spacing between the electrodes 271 and 272 in the X-direction is about 0.25 mm to about 10 mm, such as about 0.5 mm to about 5 mm, or about 1 mm. In certain embodiments, the spacing between the ends of the electrodes 271 and 272 proximate the flexible substrate 130 and the flexible substrate 130 is about 1 mm to about 10 mm, such as about 4 mm.

[0055] The connection plate 273 extends between the first electrode 271 and the second electrode 272 of each plasma generation unit 270. The connection plate 273 can be made of or coated with a dielectric material. Moreover, in certain embodiments, the electrodes 271, 272 can be coated with a dielectric material. Furthermore, each plasma generation unit 270 can also include a plate material (not visible in FIG. 2) extending in the X-direction such that the interior space 275 is surrounded by four sides. In certain embodiments, these additional plate materials extending in the X-direction can be made of or coated with a dielectric material, while in other embodiments, these additional plate materials extending in the X-direction can be a pair of electrodes similar to the electrodes 271, 272. Figure 2C

[0056] ​The plasma P generated by the plasma generation unit then flows from the internal space 275 of each plasma generation unit to the flexible substrate 130, so that the plasma material (e.g., CO2 radicals) can react with the corresponding lithium films 201, 202 on both sides of the flexible substrate 130. The plasma P increases the passivation reaction rate on the exposed lithium surfaces 203, 204, so that a sufficient portion of the surfaces 203, 204 can be effectively passivated before the flexible substrate 130 leaves the passivation unit 200C.

[0057] Although passivation units 200A and 200C are generally described as passivating the surface of lithium films, passivation units 200A and 200C can also be used to passivate the surface of other films, such as films formed of different alkali metals or alloys containing at least one alkali metal.

[0058] Figure 3 According to one embodiment, a lithium film is transferred to a flexible substrate 130 and used... Figure 1 The flowchart illustrates a method 3000 for passivating the surfaces of these lithium films using a processing system 100. The passivation of the lithium films can be achieved using... Figure 2A passivation unit 200A or Figure 2C The passivation unit 200C is used for execution. (See reference...) Figure 1 , 2A -2C and 3 describe method 3000.

[0059] The method begins at block 3002. In block 3002, the processing system 100 begins to transport sections of the flexible carriers 110, 120 and the flexible substrate 130 from the respective supply centers 115, 125, 135 to the rolling unit 140.

[0060] In block 3004, lithium films 201 and 202 are transferred from flexible carriers 110 and 120 to flexible substrate 130 by rolling unit 140. First lithium film 201 is transferred from first flexible carrier 110 to upper surface 130U of flexible substrate 130 by rolling unit 140. Second lithium film 202 is transferred from second flexible carrier 120 to lower surface 130L of flexible substrate 130 by rolling unit 140.

[0061] In block 3006, when the flexible carriers 110 and 120 pass through rollers 184 and 185, the flexible carriers 110 and 120 are peeled off from the flexible substrate 130, as shown below. Figure 1 As shown. In some embodiments, each flexible carrier 110, 120 is provided with a release layer to assist the release of lithium films 201, 202 from each flexible carrier 110, 120. Each flexible carrier 110, 120 is then sent to its respective pick-and-place center 116, 126.

[0062] In block 3008, the flexible substrate 130 and the newly transferred lithium films 201, 202 are advanced into the passivation units 200A, 200C, where the newly exposed surfaces 203, 204 of the lithium films 201, 202 are passivated.

[0063] In one embodiment of block 3008 using the passivation unit 200A Figure 2A one or more gases (e.g., CO2) are supplied to the upper interior space 208U and the lower interior space 208L from one or more gas sources 230A, 230B. UV energy is directed into the interior spaces 208U, 208L to increase the passivation reaction rate between the lithium films 201, 202 and the gas activated by the UV energy. The gas excited by the UV energy of the UV fixture 210 is effective to passivate the lithium films 201, 202 while the lithium films 201, 202 and the flexible substrate 130 are still within the passivation unit 200B.

[0064] In another embodiment of block 3008 using the passivation unit 200C Figure 2C one or more gases (e.g., CO2) are supplied to the interior space 275 of each plasma generation unit 270. RF power is supplied by the respective RF power sources 265A, 265B to the electrodes 271, 272 of each plasma generation unit 270 to generate a plasma P in the interior space 275 of each plasma generation unit 270. The plasma P, which includes plasma species (e.g., CO2 ions and radicals), then flows toward the respective lithium films 201, 202 and reacts with the lithium to passivate the respective surfaces 203, 204. The plasma is effective to passivate the lithium films 201, 202 on the flexible substrate 130 while the lithium films 201, 202 and the flexible substrate 130 are still within the passivation unit 200C.

[0065] In block 3010, the passivated lithium films 201, 202 on the flexible substrate 130 are advanced to the pick-and-place center 136. Because the surfaces 203, 204 of the lithium films 201, 202 on the flexible substrate 130 have been passivated, the lithium films 201, 202 can be exposed to the environment, such as an environment containing nitrogen, for a long period of time without significantly affecting the performance of the lithium films when used as electrodes (e.g., anodes) of lithium ion batteries in the future, as compared to similar lithium films that do not have passivated surfaces. Moreover, the passivation of the lithium films 201, 202 improves the performance of the lithium films when used as electrodes (e.g., anodes) of lithium ion batteries.

[0066] Figure 4 A side cross-sectional view of a flexible substrate processing system 400 is shown in accordance with one embodiment. The flexible substrate processing system 400 is similar to the flexible substrate processing system 100 Figure 1the flexible substrate handling system 100, the only difference is that the flexible substrate handling system 400 incorporates one of the passivation units 200A or 200C as part of the flexible substrate pick and place unit 430. The pick and place unit 430 includes the same flexible substrate pick and place center 136 as the flexible substrate handling system 100 Figure 1 After the flexible substrate passes through the passivation unit 200A or 200C, the pick and place center 136 winds the flexible substrate roll 132 on the pick and place center 136. The pick and place unit 430 also includes a roll 488 to assist in applying the proper tension to the flexible substrate 130 as it is wound on the pick and place center 136.

[0067] In some embodiments, the flexible substrate pick and place unit 430 can include an enclosure 431. In these embodiments, the enclosure 431 can operate at a higher pressure than the surrounding environment to prevent gases from the atmosphere (e.g., nitrogen) from negatively affecting the lithium film 201, 202 (see Figure 2A ) from coming into contact with the lithium film 201, 202 within the enclosure 431. In these embodiments, the enclosure 431 can be filled with an inert gas (e.g., argon) or a gas known not to negatively affect the performance of the lithium film, such as oxygen and carbon dioxide. The inlet of the enclosure 431 can be positioned after the flexible carrier 110, 120 is peeled away to reduce the amount of time the surface of the lithium film 201, 202 (see Figure 2A ) is exposed until it enters the controlled environment of the enclosure 431. In some embodiments, the interior of the enclosure 431 can also be temperature controlled to control the temperature of the flexible substrate 130 and the roll 132. In some embodiments, the center 136 can be temperature controlled to maintain the roll 132 of flexible substrate at a specified temperature. Incorporating the passivation unit 200A, 200C as part of the flexible substrate pick and place unit 430 can make it easier to add the passivation unit to existing equipment.

[0068] In the handling system 400, the flexible substrate 130 is transported along a path that starts at the supply roll 131 supported by the supply center 135, passes through the first roll 181, between the second and third rolls 182, 183, between the nip rolls 141, 142, between the fourth and fifth rolls 184, 185, through the passivation unit 200A, 200C, through the eighth roll 488, and to the pick and place roll 132 around the pick and place center 136. In some embodiments, the passivation unit 200A, 200C can also be positioned between the roll 488 and the pick and place center 136.

[0069] Figure 5 A side cross-sectional view of a flexible substrate handling system 500 is shown according to one embodiment. The flexible substrate handling system 500 is similar to Figure 1The flexible substrate processing system 500 is identical to the flexible substrate processing system 100 except that the flexible substrate processing system 500 includes three passivation units 200A1, 200A2, and 200C instead of just the passivation units 200A and 200C. An example arrangement of the three passivation units is provided below, but other arrangements can also be used, such as placing the passivation unit 200C before one or more of the other passivation units 200A1, 200A2.

[0070] The first and second passivation units 200A1, 200A2 are each one of the passivation units 200A (see Figure 2A , 2B ) and are configured to direct UV energy into the interior spaces 208U, 208L. The first passivation unit 200A1 can be used to clean the lithium films 201, 202. For example, after the lithium films 201, 202 are peeled off from the flexible carriers 110, 120, there can be some residual materials (e.g., hydrocarbons) left on the surfaces 203, 204 of the lithium films 201, 202. The passivation unit 200A1 can direct the UV energy from the UV fixtures 210 toward the inert gas (e.g., argon) in the corresponding interior space 208U, 208L to activate the inert gas to assist in removing these residual materials. The inert gas can come from one or more of the gas sources 230A, 230B.

[0071] The second passivation unit 200A2 can be used to form a passivation layer on the lithium films 201, 202. The second passivation unit 200A2 can direct the UV energy from the UV fixtures 210 toward one or more reactive gases (e.g., CO2) in the interior spaces 208U, 208L to activate these one or more reactive gases. These one or more gases, when activated by the UV energy, can increase the rate at which these gases react with the lithium films 201, 202 to form the passivation layer. The one or more reactive gases can come from one or more of the gas sources 230A, 230B.

[0072] The third passivation unit 200C can be used to form an additional passivation layer on the lithium films 201, 202 or to increase the thickness of the passivation layer started by the second passivation unit 200A2. Referring to Figure 2C , the third passivation unit 200C is configured to generate a plasma P from one or more gases supplied from one or more of the gas sources 230A, 230B and delivered to the interior space 275 of the plasma generation unit 270. The plasma P includes plasma species (e.g., CO2 ions and radicals) that then flow toward the corresponding lithium film 201, 202 and react with the lithium to further passivate the lithium film 201, 202.

[0073] By using three passivation units 200A1, 200A2, 200C in the processing system 500, a more effective passivation layer can be formed on the lithium film. For example, the first passivation unit 200A1 can remove residual materials that other passivation units can not be able to remove. These residual materials can eventually flake off and expose unpassivated lithium, which can lead to unwanted reactions, such as with nitrogen, which can negatively impact the performance of the lithium film as part of a lithium-ion battery anode. Further, in certain embodiments, using two passivation units 200A2, 200C can form a more effective passivation layer or two passivation layers that have improved passivation performance over a single passivation layer formed by only one of the passivation units 200A2, 200C. For example, in one embodiment, a first gas (e.g., carbon dioxide) can be supplied to the passivation unit 200A2, while a second gas (e.g., carbon tetrafluoride) can be supplied to the passivation unit 200C. As another example, the plasma P formed by the passivation unit 200C can be more advantageous in filling in small pores in the passivation layer formed by the passivation unit 200A2. Thus, the passivation unit 200C configured to generate the plasma P can be used to fill in remaining pores in the passivation layer formed by the second passivation unit 200A2.

[0074] In the processing system 500, the flexible substrate 130 travels along a path conveyed by the supply spool 131, which is supported by the supply center 135, past the first roller 181, between the second and third rollers 182, 183, between the nip rollers 141, 142, between the fourth and fifth rollers 184, 185, through the passivation unit 200A1, through the passivation unit 200A2, through the passivation unit 200C, past the eighth roller 188, and to the take-up spool 132 around the take-up center 136.

[0075] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments can be devised without departing from the basic scope thereof, the scope thereof being determined by the claims that follow.

Claims

1. A flexible substrate processing system comprising: a pick-and-place center; a roll unit including a first roll and a second roll; and a passivation unit having an interior space, the pick-and-place center configured to rotate and assist in feeding the flexible substrate through the interior space of the passivation unit after the flexible substrate passes between the first roll and the second roll, the passivation unit including one or more ultraviolet (UV) lamps configured to direct UV radiation toward the flexible substrate as the flexible substrate passes through the interior space of the passivation unit.

2. The flexible substrate processing system of claim 1, wherein the passivation unit further includes one or more gas inlets configured to direct gas toward the flexible substrate as the flexible substrate passes through the interior space of the passivation unit.

3. The flexible substrate processing system of claim 2, wherein 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 toward a first portion of the interior space on a first side of the flexible substrate as the flexible substrate passes through the interior space of the passivation unit, and the second gas inlet is configured to direct gas toward a second portion of the interior space on a second side of the flexible substrate opposite the first side as the flexible substrate passes through the interior space of the passivation unit.

4. The flexible substrate processing system of claim 3, wherein 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 toward the first portion of the interior space on the first side of the flexible substrate as the flexible substrate passes through the interior space of the passivation unit, and the second UV lamp is configured to direct UV energy toward the second portion of the interior space on the second side of the flexible substrate as the flexible substrate passes through the interior space of the passivation unit.

5. The flexible substrate processing system of claim 1, wherein 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 toward a first portion of the interior space on a first side of the flexible substrate as the flexible substrate passes through the interior space of the passivation unit, and the second UV lamp is configured to direct UV energy toward a second portion of the interior space on a second side of the flexible substrate opposite the first side as the flexible substrate passes through the interior space of the passivation unit.

6. The flexible substrate processing system of claim 1, further comprising a first roll positioned between the roll unit and the passivation unit, the first roll designed to assist in peeling a first flexible carrier from the flexible substrate prior to the flexible substrate entering the passivation unit. ​ 7. The flexible substrate processing system of claim 6, further comprising a second roller positioned between the roller unit and the passivation unit, wherein the second roller is configured to assist in peeling a second flexible carrier from the flexible substrate prior to the flexible substrate entering the passivation unit.

8. The flexible substrate processing system of claim 6, wherein the passivation unit is positioned less than one foot from the first roller.

9. The flexible substrate processing system of claim 1, wherein the passivation unit is positioned less than one foot from the roller unit.

10. A flexible substrate processing system, comprising: a pick-and-place center; a roller unit comprising a first roller and a second roller; and a passivation unit having an interior space, the pick-and-place center configured to rotate and assist in feeding a flexible substrate through the interior space of the passivation unit after the flexible substrate passes between the first roller and the second roller, the passivation unit comprising one or more plasma generating units configured to generate and provide plasma to the interior space of the passivation unit as the flexible substrate passes through the interior space of the passivation unit.

11. The flexible substrate processing system of claim 10, wherein the plasma generating units comprise a first electrode and a second electrode.

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

13. The flexible substrate processing system of claim 10, wherein the one or more plasma generating units comprise a first plasma generating unit and a second plasma generating unit, the first plasma generating unit is configured to direct plasma generated by the first plasma generating unit to a first portion of the interior space on the first side of the flexible substrate as the flexible substrate passes through the interior space of the passivation unit, and the second plasma generating unit is configured to direct plasma generated by the second plasma generating unit to a second portion of the interior space on the second side of the flexible substrate as the flexible substrate passes through the interior space of the passivation unit.

14. The flexible substrate processing system of claim 10, further comprising a first roller positioned between the roller unit and the passivation unit, wherein the first roller is designed to assist in peeling a first flexible carrier from the flexible substrate prior to the flexible substrate entering the passivation unit.

15. The flexible substrate processing system of claim 14, further comprising a second roller positioned between the roller unit and the passivation unit, the second roller configured to assist in peeling a second flexible carrier from the flexible substrate prior to the flexible substrate entering the passivation unit.

16. The flexible substrate processing system of claim 14, wherein the passivation unit is positioned less than one foot from the first roller. ​ 17. The flexible substrate processing system of claim 10, wherein the passivation unit is less than one foot from the roll unit.

18. A flexible substrate processing system, comprising: a pick-and-place center; a roll unit, the roll unit comprising a first roll and a second roll; a first passivation unit having an interior space, the pick-and-place center configured to rotate and assist in feeding the flexible substrate through the interior space of the first passivation unit after the flexible substrate passes between the first roll and the second roll, the first passivation unit comprising one or more ultraviolet (UV) lamps configured to direct UV radiation toward the flexible substrate as the flexible substrate passes through the interior space of the first passivation unit; and a second passivation unit having an interior space, the pick-and-place center configured to rotate and assist in feeding the flexible substrate through the interior space of the second passivation unit after the flexible substrate passes between the first roll and the second roll, the passivation unit comprising one or more plasma generation units configured to generate and provide plasma to the interior space of the second passivation unit as the flexible substrate passes through the interior space of the second passivation unit.

19. The flexible substrate processing system of claim 18, wherein the pick-and-place center is configured to assist in conveying the flexible substrate along a path from the roll unit, through the interior space of the first passivation unit, through the interior space of the second passivation unit, and back to the pick-and-place center; and the first passivation unit is located in the path between the roll unit and the second passivation unit.

20. The flexible substrate processing system of claim 18, further comprising a third passivation unit having an interior space, the pick-and-place center configured to rotate and assist in feeding the flexible substrate through the interior space of the third passivation unit after the flexible substrate exits the interior space of the first passivation unit, the third passivation unit comprising one or more ultraviolet (UV) lamps configured to direct UV radiation toward the flexible substrate as the flexible substrate passes through the interior space of the third passivation unit. the first passivation unit is connected to a first gas source configured to supply one or more inert gases to the interior space of the first passivation unit, and the third passivation unit is connected to a second gas source configured to supply one or more reactive gases to the interior space of the third passivation unit. ​

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