Film stacks for electronic devices and methods of forming

Abstract

Embodiments of the present disclosure generally relate to film stacks for electronic devices and to methods of forming. In an embodiment, a film stack is provided. The film stack includes a current collector layer, an alkali metal-containing layer disposed over the current collector layer, and a passivation layer disposed over the alkali metal-containing layer. In another embodiment, a method of forming a film stack is provided. The method includes removing materials from a first film stack disposed in a chamber, the first film stack comprising the materials disposed on a surface of an alkali metal-containing layer. The method further comprises passivating the exposed surface of the alkali metal-containing layer to form a second film stack, the second film stack comprising: the alkali metal-containing layer and a passivation layer disposed on the alkali metal-containing layer.

Description

FILM STACKS FOR ELECTRONIC DEVICES AND METHODS OF FORMINGBACKGROUNDField

[0001] Embodiments of the present disclosure generally relate to film stacks for electronic devices and to methods of forming film stacks.Description of the Related Art

[0002] Substrate independent direct transfer (SIDT) is a method to pre-lithiate anodes in energy storage devices in order to improve the life cycles of the batteries. In SIDT processes, lithium is first deposited on a support layer composed of one or more materials such as polyethylene terephthalate (PET), paper, or combinations thereof. The materials on the support layer are directly transferred to the anode for pre-l ith iation . A release layer enables transferring lithium and other materials off of the support layer and onto the anode.

[0003] Following SIDT, materials such as trace amounts of release layer remain on a surface of the lithium of the formed film stack. Such release layer materials, however, are not compatible with end uses such as electrochemical devices as the materials can impede ion or electronic transport. That is, the release layer chemistry may not be compatible with the end device (for example, a battery). For example, unwanted reactions of the release layer with gases (for example, H2O, O2, N2, etc.) during handling, shipping, and subsequent integration can impact device integration. As a result, SIDT is not utilized in the battery and capacitor industries, among other industries, as such industries require high-quality alkali metal films (for example, Li films) that can be used for device integration.

[0004] There is a need for new and improved film stacks for electronic devices and methods of forming film stacks.SUMMARY

[0005] Embodiments of the present disclosure generally relate to film stacks and to methods of forming film stacks. Film stacks described herein can be utilized with electronic devices.

[0006] In an embodiment is provided a film stack for an energy storage device. The film stack includes a current collector layer, an alkali metal-containing layer disposed over the current collector layer, and a passivation layer disposed over the alkali metalcontaining layer.

[0007] Implementations may include one or more of the following. The passivation layer of the film stack can have a thickness of about 1 nm to about 200 nm and / or an impedance of less than about 200 Q. The alkali metal-containing layer of the film stack can include lithium or sodium. The passivation layer of the film stack can include U2CO3, LiF, LixSFe, l_i2C2, LisN, l_i2O, LiAIC>2, Li-ZrO2, LiCI, LiBr, Li4TisOi2, or combinations thereof.

[0008] In another embodiment, an energy storage device is provided that includes an anode and a film stack described herein disposed over the anode.

[0009] In another embodiment, a method of forming a film stack for an energy storage device is provided. The method includes removing release layer materials from a surface of an alkali metal-containing layer of a first film stack disposed in a chamber. The method further includes passivating an exposed surface of the alkali metal-containing layer to form a second film stack, the second film stack comprising: the alkali metal-containing layer; and a passivation layer disposed on the alkali metalcontaining layer.

[0010] Implementations may include one or more of the following. The first film stack can be formed by SIDT. The passivation layer formed by the method can have a thickness of about 1 nm to about 200 nm and / or an impedance of less than about 200 Q. The removing of the release layer materials from the surface of the first film stack can include performing a plasma treatment, an ultraviolet light treatment, an ozone treatment, or combinations thereof on the first film stack to form a removal species from the release layer materials, and removing the removal species from the first film stack by a vacuum or a purge gas stream. The performing of the plasma treatment can include: flowing a plasma processing gas into the chamber, the plasma processing gas comprising H2O, H2, O2, CO2, CO, CF4, Ar, He, Ne, Kr, Xe, N2, or combinations thereof, exciting the plasma processing gas into reactive or activated species, and exposing the release layer materials to the reactive or activated species to form the removal species. The performance of the plasma treatment can include: forming a reactive or activated species from a plasma processing gas in a remote plasma generator, the plasma processing gas comprising H2O, H2, O2, CO2, CO, CF4, Ar, He, Ne, Kr, Xe, N2, or combinations thereof, flowing the reactive or activated species into the chamber from the remote plasma generator, and exposing the release layer materials to the reactive or activated species to form the removal species. The performance of the ultraviolet light treatment can include: flowing a processing gasinto the chamber, the processing gas comprising H2O, H2, O2, CO2, CO, CF4, Ar, He, Ne, Kr, Xe, N2, or combinations thereof, forming reactive or activated species from the processing gas by ultraviolet light, and exposing the release layer materials to the reactive or activated species. The passivation of the exposed surface of the alkali metal-containing layer to form the second film stack can include: treating the exposed surface of the alkali metal-containing layer with a reactive or activated species formed from a passivation processing gas; depositing the passivation layer by chemical vapor deposition, physical vapor deposition, or electron beam deposition, or combinations thereof. The treatment of the exposed surface of the alkali metal-containing layer with a reactive or activated species can include: forming the reactive or activated species from the passivation processing gas by plasma activation, ultraviolet activation, or combinations thereof; and exposing the exposed surface of the alkali metal-containing layer with the reactive or activated species to form the passivation layer. The passivation processing gas can include CO2, H2O, H2, O2, CO, CF4, or combinations thereof. The passivation processing gas can further include a non-reactive gas comprising Ar, He, Ne, Kr, Xe, N2, or combinations thereof. The passivation layer formed by the method can include U2CO3, LiF, LixSFe, l_i2C2, LisN, l_i2O, UAIO2, Li- ZrO2, LiCI, LiBr, Li4TisOi2, or combinations thereof.

[0011] In another embodiment, a method of forming a film stack for an energy storage device is provided. The method includes removing release layer materials from a surface of an alkali metal-containing layer of a first film stack, the first film stack formed by SIDT. The method further includes passivating the exposed surface of the alkali metal-containing layer to form a second film stack, the second film stack comprising the alkali metal-containing layer and a passivation layer disposed on the alkali metal-containing layer.

[0012] Implementations may include one or more of the following. The removal of the release layer materials from the surface of the alkali metal-containing layer can include: forming reactive or activated species from a processing gas by plasma activation, UV activation, or combinations thereof, exposing the release layer materials to the reactive or activated species to form a removal species, and removing the removal species from the first film stack by a vacuum or a purge gas stream. The passivation of the exposed surface of the alkali metal-containing layer to form the second film stack can include: treating the exposed surface of the alkali metalcontaining layer with a reactive or activated species formed from a passivationprocessing gas, depositing the passivation layer by chemical vapor deposition, physical vapor deposition, or electron beam deposition, or combinations thereof.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments of the disclosure and are therefore not to be considered limiting of scope, and may admit to other equally effective embodiments.

[0014] FIG. 1 shows a film stack according to at least one embodiment of the present disclosure.

[0015] FIG. 2A is a flowchart showing selected operations of a method of forming a film stack according to at least one embodiment of the present disclosure.

[0016] FIG. 2B is an illustration of film stacks during operations of the method of FIG. 2A according to at least one embodiment of the present disclosure.

[0017] FIG. 3 shows a side cross-sectional view of a flexible substrate processing system according to at least one embodiment of the present disclosure.

[0018] FIG. 4 shows a side cross-sectional view of a first type of passivation unit shown in FIG. 3 according to at least one embodiment of the present disclosure.

[0019] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.DETAILED DESCRIPTION

[0020] Embodiments of the present disclosure generally relate to film stacks for electronic devices and to methods of forming. Film stacks described herein can have superior device performance relative to conventional technologies. Methods described herein are reproducible and can yield uniform passivation layers. Further, embodiments described herein can enable streamlined material handling and integration and longer shelf life for the passivated film stacks (passivated film rolls) than conventional technologies.

[0021] Although embodiments of the present disclosure are described with respect to lithium, it is contemplated that embodiments described herein apply to other alkali metals, such as sodium.

[0022] FIG. 1 illustrates a schematic cross-sectional view of one implementation of a film stack 100. The film stack 100 can be a device or a portion of a device. The film stack 100 includes a current collector (CC) layer 102 having a bottom surface 102a and a top surface 102b. The film stack 100 further includes an alkali metalcontaining layer 104 (for example, a lithium-containing layer, a sodium-containing layer, a lithium alloy, or sodium alloy) having a bottom surface 104a disposed on the top surface 102b of the CC layer 102. The film stack 100 further includes a passivation layer 106 having a top surface 106b and a bottom surface 106a, the bottom surface 106a disposed on the top surface 104b of the alkali metal-containing layer 104.

[0023] The passivation layer 106 serves to, for example, protect the alkali metalcontaining layer 104 from unwanted reactions that can affect the performance of the film stack, when, for example, the film stack 100 is used as a battery (or a portion of a battery).

[0024] The passivation layer 106 disposed on the top surface 104b of the alkali metal-containing layer 104 can be an ultra-thin layer. A thickness of the passivation layer 106 can be greater than 0 nm, about 200 nm or less, or combinations thereof, such as from about 0.1 nm to about 200 nm, such as from about 1 nm to about 150 nm, such as from about 10 nm to about 100 nm, or from about 0.5 nm to about 50 nm, such as from about 1 nm to about 40 nm, such as from about 2 nm to about 30 nm, such as from about 3 nm to about 20 nm, such as from about 4 nm to about 10 nm, though other thicknesses are contemplated. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close- ended range.

[0025] In some embodiments, which can be combined with other embodiments, the passivation layer 106 can have an impedance (regardless of thickness) that is greater than 0 ohms (Q) about 500 O or less, or combinations thereof, such as less than about 450 Q, such as less than about 400 Q, such as less than about 350 Q, such as less than about 300 Q, such as less than about 250 Q, such as less than about 200 Q, such as less than about 150 Q, such as less than about 100 Q, such as less than about 75 Q, such as less than about 50 Q, though other values are contemplated. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range. In at least one example, the passivation layer 106 can have an impedance (regardless of thickness) that is about 100 Q or less, such as about 90 0 or less, such as about 80 O or less, such as about 70 O or less, such as about 60 O or less, such as about 50 O or less, such as about 40 O or less, such as about 30 O or less, such as about 20 O or less, such as about 10 Q or less. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range.

[0026] The passivation layer 106 can comprise, consist of, or consist essentially of an alkali metal or other metal (such as the alkali metal of the alkali metal-containing layer 104), reaction product(s) of an alkali metal or other metal with reagent(s), a remainder balance of reagent(s), or combinations thereof.

[0027] Illustrative, but non-limiting, examples of reagent(s) utilized for passivation can include carbon dioxide (CO2), carbon monoxide (CO), hydrogen (H2), oxygen (O2), water vapor, halogen-containing reagents (for example, sulfur hexafluoride (SFe), ammonia (NH3), chlorine-containing gases), among others.

[0028] As described above, the passivation layer 106 can comprise, consist essentially of, or consist of reaction product(s) of an alkali metal (or other metal) with one or more reagents reaction product(s) of an alkali metal or other metal with one or more reagents, a remainder balance of reagent(s), or combinations thereof. Reaction products can include carbonates, halides, oxides, or nitrides of metals; carbonates, halides, oxides, or nitrides of alkali metals, chalcogenides, or combinations thereof, among others. Illustrative, but non-limiting examples of reaction products that can form at least a part of passivation layer 106 can include lithium carbonate (Li2CO3), lithium fluoride (LiF), lithium sulfur hexafluoride (LixSFe, wherein x is a number from 0 to 1 ), lithium carbide (l_i2C2), AIOx, AIOOH, LisN, l_i2O, LiAIC>2, Li-ZrO2, chalcogenides (for example, Bi2Tes), halides (for example, LiX, wherein X = F, Cl, Br), Li4TisOi2, or combinations thereof, among others.

[0029] In some examples, CO2 is provided with one or more of argon (Ar), H2, O2, and water vapor to form a passivation layer 106 comprising U2CO3. In at least one embodiment, SFe is provided with one or more of Ar, H2, O2, and water vapor to form a passivation layer 106 comprising LiF and / or LixSFe. In some embodiments, CF4 plasma is provided to form a passivation layer 106 comprising LiF and / or Li2C2.

[0030] The passivation layer 106 can be characterized as having high purity. High purity in the context of the passivation layer 106 means that the composition of matterin the passivation layer 106 is greater than 99%. For example, if the passivation layer is targeted to be Li2CO3, the passivation layer will contain less than 1 % of elements other than Li, C, and 0. As another example, if the passivation layer is targeted to be LiF, the passivation layer will contain less than 1 % of elements other than Li and F. The high purity can be achieved by, for example, embodiments described herein.

[0031] The film stack 100 can be used in energy storage devices such as batteries. For example, an energy storage device can include an anode and the film stack 100 disposed over the anode.

[0032] Embodiments described herein also generally relate to methods of forming passivation layers. Generally, and in some embodiments which can be combined with other embodiments, methods described herein include cleaning a surface of an alkali metal-containing layer to remove materials from the surface, such as polymer release layers (for example, plastics, silicone, polymethylacrylate (PMA), polyethylene terephthalate (PET), etc.), organic materials, among other materials. The cleaned surface of the alkali metal-containing layer is then passivated.

[0033] The alkali metal-containing layer can be part of a film stack such as those made by substrate independent direct transfer (SIDT). SIDT is a method to pre-l ithiate (or pre-sodiate) anodes in energy storage devices in order to improve the life cycles of the batteries. These anodes can include, but are not limited to, graphite, silicon, silicon graphite, silicon oxide graphite, silicon, metalized plastic, and copper. In SIDT processes, lithium (or other alkali metal) is first deposited on a support layer composed of one or more materials such as polyethylene terephthalate (PET), paper, or combinations thereof. The materials on the support layer are directly transferred to the anode for pre-lithiation. A release layer enables transferring lithium and other materials off of the support layer and onto the anode.

[0034] Following SIDT, materials such as trace amounts of release layer may remain on a surface of the alkali metal-containing layer. Such materials, however are not compatible with end uses such as electrochemical devices as the materials can impede ion or electronic transport. That is, the release layer chemistry may not be compatible with the end device (for example, a battery). For example, unwanted reactions of the release layer with gases (for example, H2O, O2, N2, etc.) during handling, shipping, and subsequent integration can impact device integration. As a result, SIDT is not utilized in the battery and capacitor industries, among other industries as such industries require high-quality alkali metal films (for example, Lifilms) that can be used for device integration. Utilization of SIDT for such industries, however, can be beneficial because SIDT can: (1 ) enable wider substrate deposition and high throughput; (2) commodity plastic substrate is widely available; and (3) higher recyclability, streamline production independent of customer substrate and electrode pattern requirements, good Li edge control by lamination and build device stack thin film layers needed to augment functionality before SIDT, preferably under vacuum and same deposition system allow highest quality interface. In contrast, methods of depositing lithium by evaporation, molten lithium slot die, and molten lithium hot roll transfer, among others can be problematic for most substrates due to heat during deposition. SIDT transfer can remove any thermal issues related to the actual substrate.

[0035] As described herein, the inventors have found that a post-SIDT cleaning followed by passivation can achieve, for example, improved qualities of metal films for superior device performance.

[0036] FIG. 2A is a flowchart showing selected operations of a method 200 for forming a passivation layer 106 on an alkali metal-containing layer 104 according to at least one embodiment of the present disclosure. FIG. 2B is an illustration 250 of film stacks during operations of the method 200 according to at least one embodiment of the present disclosure.

[0037] The method 200 can be a continuous process where the film stack 260 is in continuous motion such that film stack 100 is formed continuously.

[0038] The method 200 begins with cleaning the film stack 260 to remove materials 208 from a surface (for example, top surface 104b) of the alkali metal-containing layer 104 at operation 205. The alkali metal-containing layer 104 is disposed on the top surface 102b of the CC layer 102. Materials 208 present on the surface of the alkali metal-containing layer 104 can include release layers, such as polymer release layers (for example, plastics, silicone (e.g. crosslinked polydimethylsiloxane), PMA, polyolefin, polyethylene terephthalate (PET), fluoropolymer, polyester, and ester acrylic acid copolymers, etc.), organic materials, components thereof, among other materials. The materials 208 present can be in trace amounts or larger than trace amounts.

[0039] The cleaning process of operation 205 can include performing a plasma treatment, an ultraviolet (UV) light treatment, an ozone treatment, or combinations thereof (indicated by arrows 254) on film stack 260 via a source 252 to form the filmstack 270. Here, the materials 208 (for example, resistive organic materials) can dissociate and / or react with reactive species in the surrounding environment during the cleaning. The dissociated materials or reaction products can be removed by a vacuum, a purge gas stream, or converted into materials compatible with other battery components with minimal impact on battery cell performance. That is, the cleaning process can serve to, for example, break down the materials 208 into, for example, gaseous species or other species that can be removed.

[0040] In some examples, the materials 208 can be those from PET release lines, such as silicone (e.g. crosslinked polydimethylsiloxane), fluoropolymer, polyolefin, polyester, and ester acrylic acid copolymers, among others described herein.

[0041] The cleaning process of operation 205 can be a continuous process where the film stack 260 is in continuous motion such that film stack 270 is formed continuously.

[0042] The plasma treatment of operation 205 can be performed in any suitable chamber such as a cleaning unit 400A (described below), such as a SmartWeb® chamber available from Applied Materials, Inc. of Santa Clara, California, though other chambers are contemplated. The cleaning unit 400A is interchangeably referred to herein as a chamber.

[0043] As an example of the plasma treatment process of operation 205, the film stack 260 having the materials 208 disposed thereon is disposed within a cleaning unit 400A. A temperature inside the cleaning unit can be about room temperature or from about 20°C to about 100°C, such as from about 20°C to about 60°C, such as from about 30°C to about 50°C, though other values are contemplated. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range. A pressure inside the cleaning unit can be from about 1x1 O’6Torr to about 1x1 O’2Torr (about 10 mTorr), such as from about 1x1 O’5Torr to about 1x1 O’3Torr (about 1 mTorr), though other values are contemplated. Any of the foregoing numbers can be used singly to describe an open- ended range or in combination to describe a close-ended range. In some examples, a plasma processing gas can be flowed into the cleaning unit 400A and excited into a plasma to bombard the materials 208 with ions and / or radicals of the plasma processing gas. The plasma processing gas can include H2O, H2, O2, CO2, CO, fluorocarbons (for example, CF4), Ar, He, Ne, Kr, Xe, N2, or combinations thereof. For example, Ar alone can be used. In some examples, Ar with H2O, Ar with H2, Ar withCO2, CO2 alone, CO alone, He alone, Ne alone, can be utilized. A gas flow rate of the plasma processing gas into the cleaning unit can be from about 10 standard cubic centimeters per minute (seem) to about 1 ,000 seem, such as from about 50 seem to about 500 seem, such as from about 100 seem to about 300 seem, though other values are contemplated. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range.

[0044] Here, and in some embodiments which can be combined with other embodiments, the plasma processing gas can be activated by plasma activation, whereby the plasma processing gas is exposed to a current prior to entering the chamber or while the plasma processing gas is in the chamber to form reactive or activated species (for example, atomic species, ions, radicals, high energy molecules, etc.). Additionally, or alternatively, activated or reactive species can be delivered to the chamber (for example, cleaning unit 400A) by, for example, a remote plasma generator.

[0045] Such exposure converts the plasma processing gas into the reactive or activated species. The materials 208 (for example, release layer materials) are then exposed to the reactive or activated species to form materials (removal species) that are more easily removed than the unmodified materials 208 (for example, unmodified release layer materials).

[0046] The plasma treatment process of operation 205 can be performed for a duration of less than about 10 minutes (min), such as less than about 5 min, such as less than about 2 min, such as less than about 1 min, such as less than about 30 seconds (s), such as less than about 20 s, such as less than about 10 s, or from about 1 s to about 30 s, such as from about 5 s to about 20 s, though other values are contemplated. Any of the foregoing numbers can be used singly to describe an open- ended range or in combination to describe a close-ended range.

[0047] The plasma treatment can include an alternating current (AC) generated linear plasma source. The AC power source can be utilized to bias the film stack 260 such that only certain species of particles with a minimum energy and vertical trajectory to hit the film stack 260 having the materials 208 disposed thereon. The AC power source can be set to a power that is from about 1 W / cm to about 50 W / cm, such as from about 10 W / cm to about 30 W / cm, though other values are contemplated. Any of the foregoing numbers can be used singly to describe an open- ended range or in combination to describe a close-ended range. The AC power sourcecan have a frequency range that is from about 1 kHz to about 13.56 MHz, such as from about 1 MHz to about 5 MHz, though other values are contemplated. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range. The Ac power source can have a power that is from about 1 W / cm to about 50 W / cm, such as from about 10 W / cm to about 30 W / cm, though other values are contemplated. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close- ended range. In some embodiments, an inductively coupled atmospheric plasma can be used.

[0048] The plasma treatment of operation 205 can be a pass-by process where the substrate (for example, at least a portion of the film stack 260) is a thin web. The linear dimension described above can be larger than the width of the substrate to assure uniform coverage. In some embodiments, the overlap can be from about 0 cm to about 20 cm , such as from about 5 cm to about 15 cm on either side of the substrate, though other values are contemplated. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range. The process can be a continuous process where the film stack 260 is in continuous motion.

[0049] The plasma treatment of operation 205 forms removal species (for example, dissociated materials or reaction products) from the materials 208. Such removal species can be removed by a vacuum, a purge gas stream, or converted into materials compatible with other battery components with minimal impact on battery cell performance. Here, a vacuum pump fluidically connected to the cleaning unit 400A can be utilized to draw the removal species from the cleaning unit 400A. Additionally, or alternatively, a purge gas stream can be fluidically connected to cleaning unit 400A. The purge gas stream can be flowed into the cleaning unit to remove the removal species.

[0050] UV treatment of operation 205 can be performed in cleaning unit 400A with the film stack 260 disposed therein. The UV treatment of operation 205 can include utilization of a UV light energy source such as a UV lamp array, UV pulsed lamp array, a light emitting diode (LED) assembly, or combinations thereof.

[0051] The UV light energy source can include lamp(s), bulb(s), light emitting diode(s), and combinations thereof, which emit energy / light in the UV region. Each individual lamp, bulb, or LED can be customized to emit radiation at, e.g., a specificpower and specific wavelength. In some embodiments, the electromagnetic energy delivered from the UV light energy source has a wavelength or wavelength range that is from about 10 nm to about 400 nm, such as from about 50 nm to about 350 nm, such as from about 100 nm to about 300 nm, such as from about 150 nm to about 250 nm, from about 100 nm to about 150 nm, from about 150 nm to about 200 nm, or from about 200 nm to about 250 nm, though other values are contemplated. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range.

[0052] In some embodiments, the UV treatment of operation 205 can include use of a low pressure mercury vapor lamp as the UV light energy source. Such a low pressure mercury vapor lamp can provide broad UV spectrum having spectral lines from about 180 nm to about 380 nm, such as spectral lines at about 185 nm, 254 nm, and about 365 nm, though other values are contemplated. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range.

[0053] A temperature inside the cleaning unit during UV treatment can be about room temperature or from about 20°C to about 100°C, such as from about 20°C to about 60°C, such as from about 30°C to about 50°C, though other values are contemplated. Any of the foregoing numbers can be used singly to describe an open- ended range or in combination to describe a close-ended range. A pressure inside the cleaning unit can be from about 1x10-6Torr to about 1x10-2Torr (about 10 mTorr), such as from about 1x10-5Torr to about 1x10-3Torr (about 1 mTorr), though other values are contemplated. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range. A processing gas can be flowed into the cleaning unit and react with the materials 208 in the presence of the UV light. The processing gas can include H2O, H2, O2, CO2, CO, Ar, He, Ne, Kr, Xe, N2, or combinations thereof. For example, Ar alone can be used. In some examples, Ar with H2O, Ar with H2, Ar with CO2, CO2 alone, CO alone, He alone, Ne alone, can be utilized. A processing gas flow rate into the cleaning unit can be from about 10 seem to about 1 ,000 seem, such as from about 50 seem to about 500 seem, such as from about 100 seem to about 300 seem, though other values are contemplated. Any of the foregoing numbers can be used singly to describe an open- ended range or in combination to describe a close-ended range.

[0054] Here, and in some embodiments which can be combined with other embodiments, the processing gas can be activated by ultraviolet activation, whereby the processing gas is exposed to ultraviolet radiation prior to entering the chamber or while the processing gas is in the chamber to form reactive or activated species (for example, atomic species, ions, radicals, high energy molecules, etc.). Additionally, or alternatively, activated or reactive species can be delivered to the chamber (for example, cleaning unit 400A) by, for example, a remote generator.

[0055] Such exposure converts the processing gas into the reactive or activated species. The materials 208 (for example, release layer materials) are then exposed to the reactive or activated species to form materials (removal species) that are more easily removed than the unmodified materials 208 (for example, unmodified release layer materials).

[0056] The UV treatment process of operation 205 can be performed for a duration of less than about 10 min, such as less than about 5 min, such as less than about 2 min, such as less than about 1 min, such as less than about 30 s, such as less than about 20 s, such as less than about 10 s, or from about 1 s to about 30 s, such as from about 5 s to about 20 s, though other values are contemplated. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range.

[0057] The UV light energy source can include one or more LEDs. Pulse durations can be from about 1 millisecond (ms) to about 1 s, such as from about 100 ms to about 800 ms, such as from about 200 ms to about 600 ms, though greater or lesser durations are contemplated. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range.

[0058] Any suitable number of pulses may be applied depending on the desired processing result. Additionally, or alternatively, the one or more LEDs can be continuously on during at least a portion of the UV treatment process of operation 205. Gaps between pulses can be from about 100 ms to about 100 s, such as from about 500 ms to about 50 s, such as from about 1 s to about 25 s, though greater or lesser time gaps between pulses are contemplated. Any suitable LEDs can be used including those that emit a power density of about 200 Watts / cm2or more, such as about 500 Watts / cm2or more, such as about 1000 Watts / cm2or more, and / or less than about 1 MW / cm2, though greater or lesser power densities are contemplated. Any of the foregoing numbers can be used singly to describe an open-ended range or incombination to describe a close-ended range. In some examples, the one or more LEDs include those emitting UV light, e.g., about 400 nm or less.

[0059] Pulse durations can be about 1 ms or less, such as about 1 ps or less, depending on, e.g., the UV light energy source.

[0060] In addition to being able to control pulse duration, repetition rate, number of repetitions and intensity, LEDs can enable the optical pulse shape to be varied by simply controlling the voltage applied to the diodes. LEDs can also provide benefits when processing film stacks outside the time region ranging from about 1 millisecond to about 1 second. In some embodiments, LEDs may be used to produce pulses under about 1 milliseconds down to the time required to initiate illumination, which may be less than about 10 microseconds.

[0061] In some examples, energy is delivered to the film stack 260 (or the materials 208 of the film stack) in a continuous and / or a pulsed manner. Different amounts of energy at different wavelengths can also be delivered to the film stack 260 (or the materials 208 of the film stack). For example, a first amount of electromagnetic energy at a first wavelength (or first wavelength range) and a second amount of electromagnetic energy at a second wavelength (or second wavelength range) can be delivered simultaneously, at different times, overlapping times, cyclically, or combinations thereof. Thus a plurality of electromagnetic pulses can be delivered to the film stack 260 (or the materials 208 of the film stack) if desired. Additionally, the electromagnetic energy can be selectively delivered to certain region(s) of the film stack 260 (or the materials 208 of the film stack). For example, a first wavelength or wavelength range of radiation can be delivered to a first region of the film stack 260, and a second wavelength or wavelength range of radiation can be delivered to a second region of the film stack 260. The first region can be the same region or a different region as the second region. The selectivity of the light for different regions or layers of the film stack 260 enables areal selectivity and / or depth selectivity.

[0062] Besides the kinetic energy from the charged particles and electrons, the photons emitted by the excited molecular and atomic species in plasma in the UV range can also induce cleavage of covalent bonds. Such a process can turn polymers into fragments or even smaller moieties that can be removed by vacuum or other suitable means.

[0063] The UV light treatment of operation 205 can enable, for example, reactions to occur so as to form removal species from the materials 208. The removal species(for example, dissociated materials or reaction products) can be removed by a vacuum, a purge gas stream, or converted into materials compatible with other battery components with minimal impact on battery cell performance. Here, a vacuum pump fluidically connected to the cleaning unit 400A can be utilized to draw the removal species from the cleaning unit 400A. Additionally, or alternatively, a purge gas stream can be fluidically connected to cleaning unit 400A. The purge gas stream can be flowed into the cleaning unit to remove the removal species.

[0064] The ozone treatment of operation 205 can be performed in cleaning unit 400A. The ozone treatment of operation 205 includes flowing ozone (O3) gas into the cleaning unit with the film stack 260 disposed therein. The ozone gas reacts with the materials 208 of the film stack 260 to form dissociated materials or reaction products that can be removed from the film stack. For example, ozone can act as an agent to cleave unsaturated bonds of alkenes (present in polyolefins), to form carboxyl products that can be removed.

[0065] A temperature inside the cleaning unit during ozone treatment can be about room temperature or from about 20°C to about 100°C, such as from about 20°C to about 60°C, such as from about 30°C to about 50°C, though other values are contemplated. Any of the foregoing numbers can be used singly to describe an open- ended range or in combination to describe a close-ended range. A pressure inside the cleaning unit during ozone treatment can be from about 1x1 O’6Torr to about 1x1 O’2Torr (about 10 mTorr), such as from about 1x10-5Torr to about 1x10-3Torr (about 1 mTorr), though other values are contemplated. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close- ended range.

[0066] Besides ozone gas, a non-reactive gas such as Ar, He, Ne, Kr, Xe, N2, or combinations thereof can be flowed into the cleaning unit 400A. A gas flow rate of the ozone, the non-reactive gas, or both, into the cleaning unit can be from about 10 seem to about 1 ,000 seem, such as from about 50 seem to about 500 seem, such as from about 100 seem to about 300 seem, though other values are contemplated. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range. The ozone treatment process of operation 205 can be performed for a duration of less than about 10 min, such as less than about 5 min, such as less than about 2 min, such as less than about 1 min, such as less than about 30 s, such as less than about 20 s, such as less than about 10 s,or from about 1 s to about 30 s, such as from about 5 s to about 20 s, though other values are contemplated. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range.

[0067] Exposure of the materials 208 (for example, release layer materials) to ozone (or reactive or activated species present in the ozone) forms materials (removal species) that are more easily removed than the unmodified materials 208 (for example, unmodified release layer materials).

[0068] Such removal species can be removed by suitable techniques including using a vacuum, using a purge gas stream, or converted into materials compatible with other battery components with minimal impact on battery cell performance. Here, a vacuum pump fluidically connected to the cleaning unit 400A can be utilized to draw the removal species from the cleaning unit 400A. Additionally, or alternatively, a purge gas stream can be fluidically connected to cleaning unit 400A. The purge gas stream can be flowed into the cleaning unit to remove the removal species.

[0069] Plasma treatment, UV treatment, ozone treatment, or combinations thereof can be performed on the film stack 260. The plasma treatment, UV treatment, and / or ozone treatment enables removal of the materials 208 to form the film stack 270.

[0070] The method 200 further includes passivating a surface (for example, top surface 104b) of the alkali metal-containing layer 104 at operation 210. Here, surface passivation (indicated by arrows 284) can include treating top surface 104b of the film stack 270 with a gas to form the passivation layer 106, depositing a passivation layer 106 on the top surface 104b, or combinations thereof using a source 282 to form the film stack 100. The passivation process of operation 210 can be performed in passivation unit 400B described below. The passivation unit 400B is interchangeably referred to herein as a chamber. The passivation process of operation 210 can be a continuous process where the film stack 270 is in continuous motion such that film stack 100 is formed continuously.

[0071] In some embodiments which can be combined with other embodiments, passivating the top surface 104b with a passivation processing gas at operation 210 to form the passivation layer 106 can be facilitated by plasma activation and / or UV activation of the passivation processing gas. Plasma activation and / or UV activation of the passivation processing gas converts the passivation processing gas into reactive or activated species that can react with materials present in the alkali metalcontaining layer 104.

[0072] The plasma activation and / or UV activation during operation 210 can be accomplished using the same or similar methods and parameters described above with respect to operation 205.

[0073] The passivation layer 106 formed by operation 210 can include an alkali metal (such as the alkali metal of the alkali metal-containing layer 104), reaction product(s) of an alkali metal with reagent(s), a remainder balance of reagent(s), or combinations thereof. Illustrative, but non-limiting, examples of reagent(s) (the passivation processing gas) utilized for passivation can include carbon dioxide (CO2), carbon monoxide (CO), hydrogen (H2), oxygen (O2), water vapor, halogen-containing reagents (for example, sulfur hexafluoride (SFe), ammonia (NH3), chlorine-containing gases), among others. Besides these gases, a non-reactive gas such as Ar, He, Ne, Kr, Xe, N2, or combinations thereof can be flowed into the passivation unit 400B to facilitate formation of the passivation layer 106.

[0074] As described above, the passivation layer 106 can comprise, consist essentially of, or consist of reaction product(s) of an alkali metal (or other metal) with one or more reagents reaction product(s) of an alkali metal or other metal with one or more reagents, a remainder balance of reagent(s), or combinations thereof. Reaction products can include carbonates, halides, oxides, or nitrides of metals; carbonates, halides, oxides, or nitrides of alkali metals, chalcogenides, or combinations thereof, among others. Illustrative, but non-limiting examples of reaction products that can form at least a part of passivation layer 106 can include Li2CO3, LiF, LixSFe (wherein x is a number from 0 to 1 ), l_i2C2, AIOx, AIOOH, LisN, l_i2O, LiAIC>2, Li-ZrO2, chalcogenides (for example, Bi2Tes), halides (for example, LiX, wherein X = F, Cl, Br), Li4TisOi2, or combinations thereof, among others.

[0075] In some examples, CO2 is provided with one or more of argon (Ar), H2, O2, and water vapor to form a passivation layer 106 comprising U2CO3. In at least one embodiment, SFe is provided with one or more of Ar, H2, O2, and water vapor to form a passivation layer 106 comprising LiF and / or LixSFe. In some examples, CF4 plasma is provided to form a passivation layer 106 comprising LiF and / or Li2C2.

[0076] In the case of plasma treatment, for example, a gas such as CO2 is introduced to the system. Excited species are present in different forms including various radicals, molecular or atomic neutral species, and ions derived from the source gas CO2. These activated species can react with lithium at a much higher rate than neutral CO2 gas. A passivation layer 106 formed can include Li2CO3. Dependingon the residence time, the plasma reactivity can be tuned by including other gases as a minor component, e.g., O2, O3, or air.

[0077] When surface passivation of operation 210 includes deposition of a passivation layer, such deposition can be achieved by direct deposition of thin films on the top surface 104b of the alkali metal-containing layer 104 using physical vapor deposition (PVD), by chemical vapor deposition, (CVD), or electron beam deposition.

[0078] Embodiments of the present disclosure also generally relate to flexible substrate processing systems that include one or more passivation units to treat a newly exposed surface of a film positioned on a flexible substrate. One exemplary use of the processing systems and methods provided in this disclosure include passivating a surface of a lithium film that can be used as part of an electrode in a lithium ionbattery. For example, a lithium film can be transferred from a flexible carrier (for example, a polymer-based carrier) to a flexible substrate (for example, a flexible copper substrate) by having the flexible carrier and the flexible substrate pass through a calendering unit and then peeling away the flexible carrier. Transferring the lithium film to the flexible substrate exposes a new surface of the lithium film to the surrounding environment when the flexible carrier is peeled away from the flexible substrate. This newly exposed surface can then be conveyed through a passivation unit with the flexible substrate to prevent reactions of the newly exposed surface with the ambient environment that can negatively affect the performance of the lithium film in a lithium-ion battery. For example, reactions between lithium and nitrogen can negatively affect the performance of using a lithium film on the anode of a lithium-ion battery.

[0079] The passivation unit can supply one or more gases (for example, CO2) to form a passivation layer on the newly exposed surface of the lithium film, which prevents the negative reactions mentioned above from occurring, such as the reactions with nitrogen. As the passivation layer forms, the available locations for the lithium to react with ambient environment are consumed, and thus after the formation of the passivation layer is completed, the negative reactions between the lithium film and components (for example, nitrogen) of the ambient environment are prevented or substantially reduced. In some embodiments, the passivation layers are also formed in a self-limiting manner, so that while the gases used to form the passivation layer can react with lithium to form the passivation layer, the gases do not continue to react with the passivation layer to increase the thickness of the passivation layer.

[0080] The passivation unit can include ultraviolet lamps or a plasma generator to increase the rate of these passivation reactions between the one or more supplied gases (for example, CO2) and the newly exposed surface of the lithium film. Although the following disclosure mainly describes passivating an exposed surface of a lithium film formed on a flexible substrate, the benefits of this disclosure can be applied for passivating exposed surfaces of other films, such as films of other alkali metals or alloys including an alkali metal, transferred to any type of flexible substrate. More generally, the benefits can particularly apply to situations when new surfaces of films formed of highly reactive materials, such as lithium, are exposed.

[0081] FIG. 3 shows a side cross-sectional view of a flexible substrate processing system 300 according to at least one embodiment of the present disclosure. The processing system 300 includes equipment for transferring lithium films on a first flexible carrier 310 and a second flexible carrier 320 to each side of a flexible substrate 330, so that the flexible substrate 330 with the lithium films can be used as an electrode (for example, anode) in a lithium-ion battery. The processing system 300 includes a calendering unit 340 to transfer the lithium films on the flexible carriers 310, 320 to the flexible substrate 330. The processing system 300 further includes a cleaning unit 400A for cleaning the lithium films and a passivation unit 400B for passivating the newly exposed surfaces of the lithium films transferred onto the flexible substrate 330.

[0082] In some embodiments which can be combined with other embodiments, cleaning unit 400A includes a tunnel with a reactive gas distribution manifold, a UV source, and / or an atmospheric plasma source where the substrate passes thru the passivation / cleaning tunnel and the surface of the substrate reacts with the precursor to modify or remove materials from the surface.

[0083] Additional detail on an illustrative, but non-limiting, passivation unit 400B is described in reference to FIG. 4 below.

[0084] The processing system 300 includes a first flexible carrier supply hub 315. A supply roll 311 of the first flexible carrier 310 is positioned on the first flexible carrier supply hub 315. In some embodiments, the first flexible carrier 310 can be formed of a polymer material, such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), or combinations thereof. A lithium film (not shown in FIG. 3) is positioned on the lower side 310L of the first flexible carrier 310, so that this lithium film faces an upper surface 330LI of the flexible substrate 330 as the firstflexible carrier 310 and the flexible substrate 330 are conveyed through the calendering unit 340. This lithium film is shown as the lithium film 401 in FIG. 4 after being transferred to the flexible substrate 330. The upper surface 330LI of the flexible substrate 330 is on an opposite side relative to a lower surface 330L of the flexible substrate 330. The upper surface 330LI is also referred to as the first surface or the first side of the flexible substrate 330 while the lower surface is also referred to as the second surface or the second side of the flexible substrate 330.

[0085] The processing system 300 includes a second flexible carrier supply hub 325. A supply roll 321 of the second flexible carrier 320 is positioned on the second flexible carrier supply hub 325. In some embodiments, the second flexible carrier 320 can be formed of a same material (for example, PET) as the first flexible carrier 310. A lithium film (not shown in FIG. 3) is positioned on the upper side 320LI of the second flexible carrier 320, so that this lithium film faces the lower surface 330L of the flexible substrate 330 as the second flexible carrier 320 and the flexible substrate 330 are conveyed through the calendering unit 340. This lithium film is shown as the lithium film 402 in FIG. 4 after being transferred to the flexible substrate 330.

[0086] In some embodiments which can be combined with other embodiments, the lithium films on the first flexible carrier 310 and the second flexible carrier 320 can be formed of lithium metal, another alkali metals or an alloy including an alkali metal.

[0087] The processing system 300 includes a flexible substrate supply hub 335. A supply roll 331 of the flexible substrate 330 is positioned on the flexible substrate supply hub 335. In some embodiments, the flexible substrate 330 can be formed of one or more of copper, graphite, silicon, silicon graphite, silicon oxide graphite, silicon, metalized plastic, or other materials.

[0088] The processing system 300 further includes the calendering unit 340. The calendering unit 340 includes a first calender roller 341 and a second calender roller 342. The first flexible carrier 310, the second flexible carrier 320, and the flexible substrate 330 are arranged to be conveyed along a path that extends between the first calender roller 341 and the second calender roller 342. The flexible substrate 330 is positioned between the first flexible carrier 310 and the second flexible carrier 320 when the first flexible carrier 310, the second flexible carrier 320, and the flexible substrate 330 are conveyed between the first calender roller 341 and the second calender roller 342. The calender rollers 341 , 342 exert a high amount of pressure on the flexible carriers 310, 320 and the flexible substrate 330 that causes the lithium filmon each of the flexible carriers 310, 320 to be transferred to the flexible substrate 330. In some embodiments, a release layer is disposed on each of the flexible carriers 310, 320 between the corresponding flexible carrier 310, 320 and the lithium film on that flexible carrier. In some embodiments, the release layer can be formed of siloxane.

[0089] The processing system 300 includes a first flexible carrier pickup hub 316. A pickup roll 312 of the first flexible carrier 310 is positioned on the first flexible carrier pickup hub 316. The lithium film is no longer on the first flexible carrier 310 when the first flexible carrier 310 is wound onto the first flexible carrier pickup hub 316 because the lithium film previously on the first flexible carrier 310 is transferred onto the flexible substrate 330 by the calendering unit 340.

[0090] The processing system 300 includes a second flexible carrier pickup hub 326. A pickup roll 322 of the second flexible carrier 320 is positioned on the second flexible carrier pickup hub 326. The lithium film is no longer on the second flexible carrier 320 when the second flexible carrier 320 is wound onto the second flexible carrier pickup hub 326 because the lithium film previously on the second flexible carrier 320 is transferred onto the flexible substrate 330 by the calendering unit 340.

[0091] The processing system 300 includes a flexible substrate pickup hub 336. A pickup roll 332 of the flexible substrate 330 is positioned on the flexible substrate pickup hub 336. The flexible substrate 330 includes a lithium film on each of the upper surface 330LI and the lower surface 330L of the flexible substrate 330. These lithium films are transferred from the respective flexible carriers 310, 320 onto the flexible substrate 330 by the calendering unit 340.

[0092] The processing system 300 further includes a plurality of rollers 381 -388. In some embodiments, each of the rollers 381 -388 can be passive rollers. The rollers 381-388 can assist in applying proper tension to and assist in changing the direction of the flexible carriers 310, 320 and the flexible substrate 330 during the movement of each of the flexible carriers 310, 320 and the flexible substrate 330 through the different portions of the processing system 300. Some of the rollers 381 -388 can also assist in moving the flexible carriers 310, 320 closer to or further away from the flexible substrate 330. For example, the second and third rollers 382, 383 assist in bringing the flexible carriers 310, 320 into contact with the flexible substrate 330 before the flexible carriers 310, 320 and the flexible substrate 330 are conveyed through the calendering unit 340. Additionally, the fourth and fifth rollers 384, 385 provide a location at which tension can be applied to the flexible carriers 310, 320 to peel theseflexible carriers 310, 320 away from the flexible substrate 330. In some embodiments, one or more of the rollers 381 -388 can instead be a bar, such as metal bar, that can apply tension to the carrier or flexible substrate during the movement of the carrier or flexible substrate.

[0093] In some embodiments which can be combined with other embodiments, the passivation unit 400B is placed within a short distance from the rollers 384, 385 to reduce the duration of the time from when the surfaces of the lithium films are exposed by the peeling away of the flexible carriers 310, 320 to when the newly exposed surfaces of the lithium films are passivated by the corresponding passivation unit 400B. In some examples, the corresponding passivation unit 400B can be positioned within two feet of the rollers 384, 385, such as within one foot, such as within six inches of the rollers 384, 385. Similarly, in some examples, the corresponding passivation unit 400B can be positioned within two feet of the calender rollers 341 , 342, such as within one foot, such as within six inches of the rollers 341 , 342.

[0094] Furthermore, in some embodiments which may be combined with other embodiments, the rollers 384, 385 can be positioned in a controlled atmosphere, such as an atmosphere including no nitrogen, an atmosphere of inert gas without any significant amount of other gases, or an atmosphere including one or more gases provided to the interior volume of the passivation unit 400B, such as carbon dioxide without any gases known to negatively affect the performance of the lithium films, such as nitrogen. In one example, the rollers 384, 385 and the corresponding passivation unit 400B are housed in a same enclosure that has a controlled atmosphere as described above, so that there is no exposure of the newly exposed lithium surfaces to an uncontrolled atmosphere, such as an atmosphere including nitrogen. In some embodiments, each portion of the processing system 300 is in a controlled atmosphere, such as an environment including no nitrogen.

[0095] The processing system 300 can further include actuators (not shown) configured to rotate each of the hubs 315, 316, 325, 326, 335, 336, so that the flexible carriers 310, 320 and the flexible substrate 330 can be conveyed from the corresponding supply hub 315, 325, 335, through the calendering unit 340, and to the corresponding pick hub 316, 326, 336. The processing system 300 can further include one or more actuators (not shown) to rotate the calender rollers 341 , 342 of the calendering unit 340. The rotational speed of the actuators can be adjusted to controlthe speed at which the flexible substrate 330 and flexible carriers 310, 320 are conveyed through the processing system 300.

[0096] In the processing system 300, the flexible substrate 330 is conveyed along a path from the supply roll 331 that is supported by the supply hub 335, past the first roller 381 , between the second and third rollers 382, 383, between the calender rollers 341 , 342, between the fourth and fifth rollers 384, 385, through the passivation unit 400B past the eighth roller 388, and to the pickup roll 332 around the pickup 336. The flexible substrate pickup hub 336 is configured to rotate and assist in conveying the flexible substrate through the interior volume of the corresponding passivation unit 400B after the flexible substrate 330 passes between the first calender roller 341 and the second calender roller 342. Similarly, the pickup hubs 316, 326 are configured to rotate and assist in conveying the flexible carriers along paths between the flexible carrier supply hubs 315, 325 and the pickup hubs 316, 326.

[0100] The processing system 300 can also include a controller 305 for controlling processes performed by the processing system 300. The controller 305 can be any type of controller used in an industrial setting, such as a programmable logic controller (PLC). The controller 305 includes a processor 307, a memory 306, and input / output (I / O) circuits 308. The controller 305 can further include one or more of the following components (not shown), such as one or more power supplies, clocks, communication components (for example, network interface card), and user interfaces typically found in controllers for semiconductor equipment.

[0097] The memory 306 can include non-transitory memory. The non-transitory memory can be used to store the programs and settings described below. The memory 306 can include one or more readily available types of memory, such as read only memory (ROM) (for example, electrically erasable programmable read-only memory (EEPROM), flash memory, floppy disk, hard disk, or random access memory (RAM) (for example, non-volatile random access memory (NVRAM).

[0098] The processor 307 is configured to execute various programs stored in the memory 306 such as a program configured to execute methods described herein. During execution of these programs, the controller 305 can communicate to I / O devices through the I / O circuits 308. For example, during execution of these programs and communication through the I / O circuits 308, the controller 305 can control outputs (for example, the actuators connected to the different hubs and the calendering unit 340). The memory 306 can further include various operational settings used to controlthe processing system 300. For example, the settings can include speed settings for the actuators connected to the hubs as well as settings to control the passivation unit 400B described below.

[0099] FIG. 4 shows a side cross-sectional view of the passivation unit 400B shown in FIG. 3 according to at least one embodiment of the present disclosure. In FIG. 4, an upper lithium film 401 (first lithium film) is positioned on the upper surface 330LI of the flexible substrate 330, and a lower lithium film 402 (second lithium film) is positioned on the lower surface 330L of the flexible substrate 330. The flexible substrate 330 and the lithium films 401 , 402 can be conveyed in a direction D through the passivation unit 400B and towards the flexible substrate pickup hub 336 (see FIG. 3). The upper lithium film 401 includes an outer surface 403. The lower lithium film 402 includes an outer surface 404. The outer surfaces 403, 404 become exposed when the first flexible carrier 310 and the second flexible carrier 320 are peeled away from the flexible substrate 330 after being conveyed through the calendering unit 340 and passing the rollers 384, 385 (see FIG. 3).

[0100] The newly exposed surfaces 403, 404 of the lithium films 401 , 402 can begin to react with the surrounding environment, for example by reacting with nitrogen in the atmosphere if the environment is not a controlled atmosphere as described above. These reactions with nitrogen reduce the benefits of pre-lith iating an electrode (for example, an anode) for a lithium-ion battery. To address this problem, one or more different gases (for example, CO2) are supplied to the passivation unit 400B (FIG. 4) to passivate these newly exposed surfaces 403, 404. These one or more different gases (for example, CO2) undergo passivation reactions with the lithium on the surfaces 403, 404, which passivate these surfaces 403, 404 to prevent or substantially reduce further undesirable reactions of the lithium films 401 , 402 with components (for example, nitrogen) in an uncontrolled atmosphere.

[0101] The passivation layer 106 and properties thereof, described above, can be formed in the passivation unit 400B.

[0102] In some examples, carbon dioxide (CO2) is provided to the corresponding passivation unit 400B 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 (SFe) is provided to the passivation unit 400B 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 sulfur hexafluoride (LixSFe).Other gases that can be used to form passivation layers on a lithium surface include carbon monoxide (CO), carbon tetrafluoride (CF4), ammonia (NH3) as well as other oxide, fluoride, and chloride gases. The thickness of the passivation layers formed on the lithium surfaces can be from about 1 nm to about 1000 nm, such as from about 10 nm to about 500 nm, though other values are contemplated such as those described for passivation layer 106. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range. In some embodiments, the lithium films 401 , 402 can have a thickness from about 1 micron to about 100 micron, such as about 10 micron.

[0103] The passivation unit 400B includes a housing 415 disposed around an interior volume 408. The housing 415 includes an upper housing 415U and a lower housing 415L. The flexible substrate 330 with the lithium films 401 , 402 is conveyed through the interior volume 408 as the flexible substrate 330 is moved towards the flexible substrate pickup hub 336. The interior volume 408 includes an upper interior volume 408U above the flexible substrate 330 and a lower interior volume 408L below the flexible substrate 330.

[0104] The passivation unit 400B further includes a plurality of seals 451 -454. The seals 451 -454 can be formed of a compressible material. The seals 451 -454 can be used to maintain a separate environment in the interior volume 408 relative to the environment surrounding the passivation unit 400B. For example, the interior volume 408 can have different concentrations of gases as well as a different temperature and / or pressure relative to the environment surrounding the passivation unit 400B.

[0105] Optionally, the seals 451 -454 can be omitted and pressure differentials between the interior volume 408 and the surrounding environment can be used. For example, the pressure in the interior volume 408 is higher than a pressure of the surrounding environment, so that nitrogen and other undesirable gases do not enter the interior volume 408 of the passivation unit 400B. In some examples, an air knife, for example using an inert gas or other gas (for example, CO2), can be used at the entrance and exit to the interior volume to prevent mixing of gases in the interior volume 408 with gases in the surrounding environment.

[0106] The first seal 451 is positioned between the upper housing 415U and the flexible substrate 330 at the entrance to the interior volume 408 of the passivation unit 400B. The second seal 452 is positioned between the lower housing 415L and the flexible substrate 330 at the entrance to the interior volume 408 of the passivation unit400B. The third seal 453 is positioned between the upper housing 415U and the flexible substrate 330 at the exit from the interior volume 408 of the passivation unit 400B. The fourth seal 454 is positioned between the lower housing 415L and the flexible substrate 330 at the exit from the interior volume 408 of the passivation unit 400B. In some embodiments, the upper housing 415U or the lower housing 415L can be configured to move, for example in a vertical direction, so that it can be easier to position a new flexible substrate 330 in the interior volume 408 as well as to adjust the pressure of the seals 451 -454 on the flexible substrate 330 or distance between the seals 451-454 and the flexible substrate 330 during processing.

[0107] The upper housing 415U includes a gas inlet port 431 U near the entrance to the upper interior volume 408LI and a gas outlet port 441 U near the exit from the upper interior volume 408LI. The lower housing 415L includes a gas inlet port 431 L near the entrance to the lower interior volume 408L and a gas outlet port 441 L near the exit from the lower interior volume 408L. The gas inlet ports 431 U, 431 L can be connected to gas sources 430A, 430B. In some embodiments, the gas sources 430A, 430B can be a single gas source. The gas outlet ports 441 U, 441 L can be connected to exhaust pumps 440A, 440B. Optionally, the exhaust pumps 440A, 440B can be a single exhaust pump.

[0108] The passivation unit 400B further includes a plurality of ultraviolet (UV) lamps 410. Five UV lamps 410 are positioned in the upper housing 415U. Five UV lamps 410 are positioned in the lower housing 415L. Each of the UV lamps 410 can be connected to an electrical power supply (not shown) and electrical power to the UV lamps 410 can be controlled by the controller 305 (FIG. 3). The passivation unit 400B includes an upper window 460U positioned between the UV lamps 410 in the upper housing 415U and the upper interior volume 408U. The passivation unit 400B includes a lower window 460L positioned between the UV lamps 410 in the lower housing 415L and the lower interior volume 408L. The upper window 460U and the lower window 460L can be formed of a UV-transparent material, such as quartz. In some embodiments, the UV lamps 410 can be positioned in the corresponding interior volumes 408U, 408L.

[0109] The UV lamps 410 in the upper housing 415U can direct UV energy into the upper interior volume 408U to increase the rate of the passivation reactions between the upper lithium film 401 and the one or more gases (for example, CO2) supplied to the upper interior volume 408U from the gas source 430A. Similarly, the UV lamps410 in the lower housing 415L can direct UV energy into the lower interior volume 408L to increase the rate of the passivation reactions between the lower lithium film 402 and the one or more gases (for example, CO2) supplied to the lower interior volume 408L from the gas source 430B. The increased rate of passivation reactions on the exposed lithium surfaces 403, 404 provided by the UV energy enables a sufficient portion of the exposed lithium surfaces 403, 404 to be effectively passivated before the flexible substrate 330 exits the passivation unit 400B. In some embodiments, the UV lamps 410 can emit UV radiation having a wavelength from about 100 nm to about 270 nm, such as from about 185 nm to about 254 nm. Wavelengths within these ranges can dissociate gases supplied to the passivation unit 400B. For example, UV radiation within these wavelengths can split carbon dioxide (CO2) into CO and O, which can be more reactive than the originally supplied CO2. Similarly, these wavelengths can split water (H2O) into H and OH, and oxygen (O2) into O and O3, which can also be more reactive than the originally supplied water vapor or oxygen.

[0110] Implementations and all of the functional operations described in this specification can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structural means disclosed in this specification and structural equivalents thereof, or in combinations of them. Implementations described herein can be implemented as one or more non-transitory computer program products, i.e. , one or more computer programs tangibly embodied in a machine readable storage device, for execution by, or to control the operation of, data processing apparatus, e.g., a programmable processor, a computer, or multiple processors or computers.

[0111] The processes and logic flows described in this specification can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).

[0112] Embodiments of the present disclosure generally relate to film stacks for electronic devices and to methods of forming film stacks. Film stacks described herein can have superior device performance relative to conventional technologies. Methods described herein are reproducible and can yield uniform passivation layers. Further,embodiments described herein can enable, for example, streamlined material handling and integration and longer shelf life for the passivated film stacks (passivated film rolls) than conventional technologies.

[0113] As is apparent from the foregoing general description and the specific aspects, while forms of the aspects have been illustrated and described, various modifications can be made without departing from the spirit and scope of the present disclosure. Accordingly, it is not intended that the present disclosure be limited thereby. Likewise, the term “comprising” is considered synonymous with the term “including.” Likewise whenever a composition, process operation, process operations, an element or a group of elements is preceded with the transitional phrase “comprising,” it is understood that we also contemplate the same composition or group of elements with transitional phrases “consisting essentially of,” “consisting of,” “selected from the group of consisting of,” or “Is” preceding the recitation of the composition, process operation, process operations, element, or elements and vice versa, such as the terms “comprising,” “consisting essentially of,” “consisting of” also include the product of the combinations of elements listed after the term.

[0114] For purposes of this present disclosure, and unless otherwise specified, all numerical values within the detailed description and the claims herein are modified by “about” or “approximately” the indicated value, and consider experimental error and variations that would be expected by a person having ordinary skill in the art. For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. For example, the recitation of the numerical range 1 to 5 includes the subranges 1 to 4, 1 .5 to 4.5, 1 to 2, among other subranges. As another example, the recitation of the numerical ranges 1 to 5, such as 2 to 4, includes the subranges 1 to 4 and 2 to 5, among other subranges. Additionally, within a range includes every point or individual value between its end points even though not explicitly recited. For example, the recitation of the numerical range 1 to 5 includes the numbers 1 , 1.5, 2, 2.75, 3, 3.80, 4, 5, among other numbers. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited.

[0115] As used herein, the indefinite article “a” or “an” shall mean “at least one” unless specified to the contrary or the context clearly indicates otherwise. For example, aspects comprising “a layer” includes aspects comprising one, two, or more layers, unless specified to the contrary or the context clearly indicates only one layer is included.

[0116] While the foregoing is directed to aspects of the present disclosure, other and further aspects of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

CLAIMSWhat is claimed is:1 . A film stack for an energy storage device, the film stack comprising: a current collector layer; an alkali metal-containing layer disposed over the current collector layer; and a passivation layer disposed over the alkali metal-containing layer.

2. The film stack of claim 1 , wherein the passivation layer has: a thickness of about 1 nm to about 200 nm; an impedance of less than about 200 Q; or combinations thereof.

3. The film stack of claim 1 , wherein the alkali metal-containing layer comprises lithium or sodium.

4. The film stack of claim 1 , wherein the passivation layer comprises Li2CO3, Li F, LixSFe, Li2C2, LisN, Li2O, LiAIC>2, Li-ZrO2, LiCI, LiBr, Li4TisOi2, or combinations thereof.

5. An energy storage device comprising an anode and the film stack of claim 1 disposed over the anode.

6. A method of forming a film stack for an energy storage device, the method comprising: removing release layer materials from a surface of an alkali metal-containing layer of a first film stack disposed in a chamber; and passivating an exposed surface of the alkali metal-containing layer to form a second film stack, the second film stack comprising: the alkali metal-containing layer; and a passivation layer disposed on the alkali metal-containing layer.

7. The method of claim 6, wherein the first film stack is formed by substrate independent direct transfer.

8. The method of claim 6, wherein the passivation layer has: a thickness of about 1 nm to about 200 nm; an impedance of less than about 200 Q; or combinations thereof.

9. The method of claim 6, wherein the removing release layer materials from the surface of the alkali metal-containing layer comprises: performing a plasma treatment, an ultraviolet light treatment, an ozone treatment, or combinations thereof on the first film stack to form a removal species from the release layer materials; and removing the removal species from the first film stack by a vacuum or a purge gas stream.

10. The method of claim 9, wherein the performing the plasma treatment comprises: flowing a plasma processing gas into the chamber, the plasma processing gas comprising H2O, H2, O2, CO2, CO, CF4, Ar, He, Ne, Kr, Xe, N2, or combinations thereof; exciting the plasma processing gas into reactive or activated species; and exposing the release layer materials to the reactive or activated species to form the removal species.

11. The method of claim 9, wherein the performing the plasma treatment comprises: forming reactive or activated species from a plasma processing gas in a remote plasma generator, the plasma processing gas comprising H2O, H2, O2, CO2, CO, CF4, Ar, He, Ne, Kr, Xe, N2, or combinations thereof; flowing the reactive or activated species into the chamber from the remote plasma generator; and exposing the release layer materials to the reactive or activated species to form the removal species.

12. The method of claim 9, wherein the performing the ultraviolet light treatment comprises:flowing a processing gas into the chamber, the processing gas comprising H2O, H2, O2, CO2, CO, CF4, Ar, He, Ne, Kr, Xe, N2, or combinations thereof; forming reactive or activated species from the processing gas by exposing the processing gas to ultraviolet light activation; and exposing the release layer materials to the reactive or activated species.

13. The method of claim 6, wherein the passivating the exposed surface of the alkali metal-containing layer to form the second film stack comprises: treating the exposed surface of the alkali metal-containing layer with a reactive or activated species formed from a passivation processing gas; depositing the passivation layer by chemical vapor deposition, physical vapor deposition, or electron beam deposition; or combinations thereof.

14. The method of claim 13, wherein the treating the exposed surface of the alkali metal-containing layer with the reactive or activated species comprises: forming the reactive or activated species from the passivation processing gas by plasma activation, ultraviolet activation, or combinations thereof; and exposing the exposed surface of the alkali metal-containing layer with the reactive or activated species to form the passivation layer.

15. The method of claim 14, wherein the passivation processing gas comprises CO2, H2O, H2, O2, CO, CF4, or combinations thereof.

16. The method of claim 15, wherein the passivation processing gas further comprises a non-reactive gas comprising Ar, He, Ne, Kr, Xe, N2, or combinations thereof.

17. The method of claim 6, wherein the passivation layer comprises Li2CO3, LiF, LixSFe, l_i2C2, LisN, l_i2O, UAIO2, Li-ZrO2, LiCI, LiBr, Li4TisOi2, or combinations thereof.

18. A method of forming a film stack for an energy storage device, the method comprising:removing release layer materials from a surface of an alkali metal-containing layer of a first film stack, the first film stack formed by substrate independent direct transfer; and passivating an exposed surface of the alkali metal-containing layer to form a second film stack comprising: the alkali metal-containing layer; and a passivation layer disposed on the alkali metal-containing layer.

19. The method of claim 18, wherein the removing release layer materials from the surface of the alkali metal-containing layer comprises: forming reactive or activated species from a processing gas by exposing the processing gas to plasma activation, UV activation, or combinations thereof; exposing the release layer materials to the reactive or activated species to form a removal species; and removing the removal species from the first film stack by a vacuum or a purge gas stream.

20. The method of claim 18, wherein the passivating the exposed surface of the alkali metal-containing layer to form the second film stack comprises: treating the exposed surface of the alkali metal-containing layer with a reactive or activated species formed from a passivation processing gas; depositing the passivation layer by chemical vapor deposition, physical vapor deposition, or electron beam deposition; or combinations thereof.

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