Manufacturing tool architecture for lithium transfer by lift off process

Abstract

A flexible substrate processing system is provided. The flexible substrate processing system includes a first supply hub for supplying a flexible carrier film having an alkali-metal film formed thereover, a second supply hub for supplying a flexible substrate film stack, a first pickup hub for collecting the flexible carrier film after the alkali-metal film is transferred to the flexible substrate film stack, a second pickup hub for collecting the flexible substrate film stack having the alkali-metal film formed thereon, and a laser lift-off unit positioned downstream from the first supply hub and the second supply hub and upstream from the first pickup hub and the second pickup hub. The laser lift-off unit includes a laser source configured to generate laser energy directed toward a first surface of the flexible carrier film and an optical scanner configured to direct the laser energy toward the first surface of the flexible carrier film.

Description

MANUFACTURING TOOL ARCHITECTURE FOR LITHIUM TRANSFER BY LIFT OFF PROCESSTECHNICAL FIELD

[0001] The disclosure generally relates to alkali-metal containing energy storage devices and methods for manufacturing alkali-metal containing energy storage devices. More particularly, the disclosure relates to device stacks including patterned alkali-metal containing electrodes and methods for manufacturing the same.BACKGROUND

[0002] Rechargeable electrochemical storage systems are currently becoming increasingly essential for many fields of everyday life. High-capacity electrochemical energy storage devices, such as lithium-ion (Li-ion) batteries, are used in a growing number of applications, including portable electronics, medical, transportation, grid- connected large energy storage, renewable energy storage, and uninterruptible power supply (UPS). Traditional lead / sulfuric acid batteries often lack the capacitance and are often inadequately cyclable for these growing applications. Lithium-ion batteries, however, are thought to provide the best solution.

[0003] Therefore, there is a need for methods and systems for the deposition and processing of alkali-metals used in energy storage devices.SUMMARY

[0004] The disclosure generally relates to an alkali-metal containing devices and methods for manufacturing alkali-metal containing devices. More particularly, the disclosure relates to device stacks including lithium metal anodes and pre-lithiated anodes for energy storage devices and a methods for manufacturing the same.

[0005] In one aspect, a flexible substrate processing system is provided. The flexible substrate processing system includes a first supply hub for supplying a flexible carrier film having an alkali-metal film formed thereover, a second supply hub for supplying a flexible substrate film stack, a first pickup hub for collecting the flexible carrier film after the alkali-metal film is transferred to the flexible substrate film stack,a second pickup hub for collecting the flexible substrate film stack having the alkali- metal film formed thereon, and a laser lift-off unit positioned downstream from the first supply hub and the second supply hub and upstream from the first pickup hub and the second pickup hub. The laser lift-off unit includes a laser source configured to generate laser energy, the laser energy directed toward a first surface of the flexible carrier film and an optical scanner configured to direct the laser energy toward the first surface of the flexible carrier film.

[0006] Implementations may include one or more of the following. The flexible substrate processing system further includes a pair of rollers positioned downstream of the first supply hub and the second supply hub and upstream of the laser source, the pair of rollers configured to contact the alkali-metal film to the flexible substrate film stack. The pair of rollers include at least one nip roller. The pair of rollers include at least one calender roller. The laser source is selected from an infrared (IR) fiber laser, an ultraviolet (UV) laser, or a Green Laser. The optical scanner is a single- or multiaxis large angle galvanometer optical scanner. The optical scanner is a polygon scanner, an electro-optic scanner, an acousto-optic, or a combination thereof. The flexible substrate processing system further includes a passivation unit positioned downstream from the laser lift-off unit and upstream from the second pickup hub, the passivation unit positioned to passivate the alkali-metal film formed on the flexible substrate film stack. The flexible substrate processing system further includes an inline slitting assembly including a blade for cutting the flexible carrier film, the inline slitting assembly positioned downstream from the laser lift-off unit and upstream from the first pickup hub.

[0007] In another aspect, a flexible substrate processing system for forming an energy storage device is provided. The flexible substrate processing system includes a laser lift-off unit. The laser lift-off unit includes a laser source configured to generate laser energy, the laser energy directed toward a first surface of a flexible carrier film and an optical scanner configured to direct the laser energy toward the first surface of the flexible carrier film. The flexible substrate processing system further includes a system controller. The system controller is configured to cause the laser lift-off unit to perform a process, including conveying a flexible carrier film stack including the flexible carrier film having an alkali-metal film formed thereover from a supply hub toward apickup hub; contacting the flexible carrier film stack with a flexible substrate film stack, wherein the alkali-metal film contacts the flexible substrate film stack; exposing the first surface of the flexible carrier film stack to the laser energy to separate the flexible carrier film from the alkali-metal film; and removing the flexible carrier film from the flexible substrate film stack.

[0008] Implementations may include one or more of the following. The laser source is selected from an infrared (IR) fiber laser, an ultraviolet (UV) laser, or a Green Laser. The optical scanner is a single- or multi-axis large angle galvanometer optical scanner. The flexible substrate processing system further includes a pair of rollers positioned upstream of the laser source, the pair of rollers contacting the flexible carrier film stack with the flexible substrate film stack. The pair of rollers include at least one nip roller. The pair of rollers include at least one calender roller.

[0009] In yet another aspect, a method of forming a film stack for an energy storage device is provided. The method includes conveying a flexible carrier film stack including a flexible carrier film having an alkali-metal film formed thereover from a supply hub toward a pickup hub, contacting the flexible carrier film stack with a flexible substrate film stack, wherein the alkali-metal film contacts the flexible substrate film stack, exposing a first surface of the flexible carrier film stack to laser energy to separate the flexible carrier film from the alkali-metal film, and removing the flexible carrier film from the flexible substrate film stack.

[0010] Implementations may include one or more of the following. Exposing the first surface of the flexible carrier film stack to laser energy to separate the flexible carrier film from the alkali-metal film includes patterning the alkali-metal film by exposing portions of the alkali-metal film to the laser energy. The laser energy is directed through a backside of the flexible carrier film. Exposing the first surface of the flexible carrier film stack to laser energy creates a void volume between the alkali- metal film and the flexible carrier film stack. The flexible carrier film stack further includes a release layer disposed between the flexible carrier film and the alkali-metal film, the release layer is capable of photoinduced depolymerization.

[0011] In another aspect, a non-transitory computer readable medium has stored thereon instructions, which, when executed by a processor, causes the process to perform operations of the above apparatus and / or method.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] 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 aspects, briefly summarized above, may be had by reference to implementations, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical implementations of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective implementations.

[0013] FIG. 1 illustrates a schematic side view of one example of a flexible substrate transfer system incorporating a laser lift-off unit, in accordance with one or more implementations of the present disclosure.

[0014] FIG. 2 illustrates a schematic side view of one example of a laser lift-off unit in accordance with one or more implementations of the present disclosure.

[0015] FIG. 3 illustrates a schematic side view of another example of a flexible substrate transfer system incorporating a laser lift-off unit, in accordance with one or more implementations of the present disclosure.

[0016] FIG. 4 illustrates a schematic side view of yet another example of a flexible substrate transfer system incorporating a laser lift-off unit, in accordance with one or more implementations of the present disclosure.

[0017] FIG. 5 illustrates a schematic side view of yet another example of a flexible substrate transfer system incorporating a laser lift-off unit, in accordance with one or more implementations of the present disclosure.

[0018] FIG. 6 illustrates a flowchart showing selected operations of a method of forming an energy storage device via a laser lift-off process in accordance with one or more implementations of the present disclosure.

[0019] FIGS. 7A-7D illustrate views of various stages of manufacturing an energy storage device according to the method of FIG. 6 in accordance with one or more implementations of the present disclosure.

[0020] FIG. 8 illustrates a flowchart showing selected operations of another method of forming an energy storage device via a laser lift-off process in accordance with one or more implementations of the present disclosure.

[0021] FIG. 9 illustrates a flowchart showing selected operations of yet another method of forming an energy storage device via a laser lift-off process in accordance with one or more implementations of the present disclosure.

[0022] FIG. 10 illustrates a schematic view of a flash lamp assembly in accordance with one or more implementations of the present disclosure.

[0023] 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 implementation may be beneficially incorporated in other implementations without further recitation.DETAILED DESCRIPTION

[0024] The disclosure generally relates to alkali-metal containing energy storage devices and methods for manufacturing alkali-metal containing energy storage devices. More particularly, the disclosure relates to device stacks including patterned alkali-metal containing electrodes and methods for manufacturing the same.

[0025] Substrate independent direct transfer (SIDT) is a method for forming electrode device stacks by transferring one or more layers including an alkali-metal layer, for example, a lithium metal layer, to a substrate stack, for example, a current collector in implementations where lithium metal functions as an anode or for pre- lithiating an anode material which is already formed on the current collector. The alkali-metal or alloy includes an alkali-metal, for example, lithium metal, sodium, potassium, rubidium, cesium, francium, an alloy including the alkali-metal, or a combination thereof. The already formed anode material can include or be, but is not limited to, graphite, silicon, silicon graphite, silicon oxide graphite, silicon, tin, hardcarbon, metal oxide, or combinations thereof. The current collector can include or be metalized plastic, copper, or combinations thereof. In SIDT processes, alkali-metal is formed over a flexible support layer stack composed of one or more materials such as a polymer substrate, for example, polyethylene terephthalate (PET), paper, or combinations thereof. The materials formed on the flexible support layer stack are directly transferred to a substrate stack. The substrate stack can include or be a current collector, a current collector having anode material formed thereover, a metallized plastic substrate, a separator, or a metallized plastic substrate having alkali- metal formed thereover. A release layer, if present, formed between the alkali-metal layer and the flexible support layer stack enables transferring alkali-metal and other materials off of the support layer stack and onto the current collector or anode material if already present. The release layer can be selected from one or more of fluorocarbons, silicone, latex, AIOx, LiF, AIOOH, Ag, AgF, Bi, Zn, Mg, Sn, or metal halides.

[0026] However, transfer of the alkali-metal layer from the flexible support layer stack onto a current collector or anode material can present several challenges. For example, following SIDT, materials such as trace amounts of release layer remain on a surface of the alkali-metal of the formed film stack. Such release layer materials are typically 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, an energy storage device). 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 because such industries require high-quality alkali-metal films that can be used for device integration.

[0027] In one or more implementations, which can be combined with other implementations, systems and methods for patterned alkali-metal transfer onto a substrate stack utilizing a laser-lift off (LLO) process are provided. The substrate stack can be or include a current collector substrate, for example, a copper substrate or a metalized plastic substrate and optionally an anode material, for example, one of more of silicon graphite, SiOx-Gr, or graphite. The LLO process is performed using anenergy source generally adapted to deliver electromagnetic energy to a targeted region of a substrate stack. The energy source for delivering electromagnetic energy can include and optical radiation source, for example, a laser source or a flash lamp. Suitable laser sources include but are not limited to an IR fiber laser, a UV laser, or a Green Laser. Suitable flash lamp sources include, for example, xenon or krypton flash lamps, which may be used in place of or in conjunction with the laser sources. Not to be bound by theory but it is believed that the energy source activate the interface of the alkali-metal film and a flexible carrier file, for example, the PET-Li interface, from the flexible carrier film side and transfers patterned alkali-metal onto the substrate stack. Alkali-metal at the activated flexible carrier film-alkali-metal interface may be subsequently released from the flexible carrier film during removal of the flexible carrier film.

[0028] In one or more implementations, which can be combined with other implementations, the laser-lift off process described can be incorporated into a roll-to- roll tool and used in a roll-to-roll process. The laser-lift off process enables transfer of patterned alkali-metal from a plastic carrier substrate onto a roll-to-roll battery anode substrate by exposing an interface between the alkali-metal metal layer and the plastic carrier substrate, for example, the Li-PET interface, to a laser which induces alkali- metal transfer at the interface. This interface between the alkali-metal metal layer and the flexible carrier film may also include a release layer as described.

[0029] In one or more implementations, which can be combined with other implementations, the laser lift-off process enables the patterning of alkali-metal. The alkali-metal film can be patterned to match the pattern of an already deposited material, for example, an anode material, in a lane coating process or a skip coating process. In some implementations, the patterned alkali-metal can be transferred directly onto a current collector substrate. Any suitable pattern may be achieved, for example, a square, a triangle, or a circle.

[0030] In one or more implementations, which can be combined with other implementations, the laser lift-off process uses a laser source to create an interface reaction with either a release layer, an interface layer, or both the release layer and the interface layer between the alkali-metal layer and the flexible carrier film, forexample, a PET film, to enable subsequent removal of the flexible carrier film from the alkali-metal layer at the activated interface.

[0031] In one or more implementations, which can be combined with other implementations, a flexible carrier film stack is provided. The flexible carrier film stack can include a plastic containing substrate, for example, a polyethylene terephthalate (PET) substrate. The flexible carrier film stack can further include a release layer, for example, silicone or other deposited release layers, formed on the flexible carrier film stack. An alkali-metal layer, for example, a lithium metal layer is formed over the flexible carrier film stack. In some implementations where the release layer is not present, the alkali-metal layer can be formed directly on the plastic containing substrate. In implementations where the release layer is present, the alkali-metal layer can be formed directly on the release layer. The flexible carrier film stack having the alkali-metal layer formed thereon is exposed to a laser lift-off process. In one or more implementations, during the laser lift-off process, a laser is directed through the flexible carrier film stack to activate the interface of the alkali-metal layer and the flexible carrier film stack, for example, the Li-PET interface. The laser can be directed through the backside of the flexible carrier film stack, for example, from the plastic containing substrate or PET side. Exposure to the laser can induce an alkali-metal transfer process creating a void volume between the alkali-metal layer and the flexible carrier film stack. This void volume can make separation of the alkali-metal layer from the flexible carrier film stack easier during transfer of the alkali-metal layer from the flexible carrier film stack to the current collector substrate. In addition, precise laser beam position control enables the selective transfer of alkali-metal into desired shapes from the flexible carrier film stack to the substrate stack to form electrode device stacks with various shapes. Further, exposure to the laser can be used to pattern the alkali-metal layer such that a precise pattern of alkali-metal is transferred from the flexible carrier film stack to the substrate stack to form an anode device stack. A cathode structure and / or separator can be integrated with the formed anode device stack to form the energy storage device.

[0032] In one or more implementations, which can be combined with other implementations, an IR fiber laser is used for the laser-lift of process. The laser-lift of process can include laser activation and lift-off from a PET substrate with an alkali-metal layer, for example, a 20 urn lithium layer, and a silicone release layer. In one example, the IR fiber laser is a 1060-nm laser with a pulse width of 5 to 500 nanoseconds, for example, a 30 nanosecond pulse width, a Gaussian profile, ~150 urn spot size, 2 m / sec raster speed, and a line distance of 70 urn.

[0033] Laser parameters selection, such as pulse width, can be fundamental to developing a successful laser lift-off process that minimizes damage to the underlying substrate during the laser lift-off process while achieving a clean pattern. A high frequency nanosecond-pulsed IR laser or picosecond-pulsed IR laser can be used based on laser-material interaction specific to lithium material stacks. Lithium is unique in that its melting temperature is only 453.65 K (180.50 °C) while the boiling temperature is 1603 K (1330 °C), which is still very high. In comparison, PET has a melting temperature of 523 K (250 °C), and a boiling temperature 623 K (350 °C). For a conductive substrate such as copper, it has a much lower absorption to IR laser than to green (~520 — 540 ns) or UV laser (< 360 nanometer). For example, at ambient temperature, a 1064-nanometer laser has less than 5% optical absorption in copper, while a 532-nanometer Green laser has about 40% optical absorption in copper. The 1064-nanometer laser in a melted copper liquid still has about 5% optical absorption. From the aspect of avoiding copper damage, the 1 -pm IR laser wavelength is more advantageous than a Green or UV laser wavelength. In addition, at the same average power level and with the same type of laser, an IR laser is more reliable and cost- effective.

[0034] An IR nanosecond laser with a pulse duration of less than 30 nanoseconds and a near-infrared wavelength of 1064-nanometer is suitable for the LLO process. However, ultrashort pulsed lasers may be used for some purposes like quality improvement. The laser with a longer pulse duration generates a higher density plasma resulting in a greater gas pressure to release the interface between the PET carrier film and the lithium film. However, pulse duration longer than 50 nanoseconds involves much higher pulse energy (or laser power) due to a low peak power. On the contrary, a shorter pulse duration can process precisely so that it can achieve a cleaner lithium edge.

[0035] Laser parameters can be selected with benefits and advantages such as providing sufficiently high laser intensity to achieve patterning of lithium and to minimize damage to the underlying substrate. Also, parameters can be selected to provide meaningful process throughput for industrial applications with precisely controlled ablation width (e.g., kerf width) and depth. As described, an ultrashort pulse (USP) laser (e.g., a laser with a pulse duration of, at most, in a femtosecond range) such as a femtosecond or picosecond pulse laser is suitable for providing such advantages. Such pulse width ranges for UPS may be 5 femtosecond to 999 femtoseconds, preferably 10 femtoseconds to 999 femtoseconds for a femtosecond pulse laser and 1 picosecond to 10 picoseconds for a picosecond pulse laser. Regarding USPs, a shorter pulse width results in higher peak power and fewer thermal effects, which increases control over the removal rate. For example, a 10 femtosecond pulse has 1000 times higher peak power than a 10 picosecond pulse of the same pulse energy. Therefore, the wavelength range is of less importance as patterning may be ceased at a precise depth without thermally damaging the underlying substrate.

[0036] However, nanosecond-pulse laser lift-off is also suitable, as pulses longer than a few tens of picoseconds will start having more pronounced thermal effects. Nanosecond pulse lasers are also more cost-effective, although certain wavelengths may provide better performance than others. For a PET substrate, a wavelength range of about 450 nm to about 1600 nm, or from about 450 nm to about 1550 nm, will facilitate laser lift-off of lithium with nanosecond pulses such that the PET film is highly transparent to light. A wavelength of less than 450 nm, or less than 355 nm, may result in scribing or cutting of the PET substrate. For a polyimide (PI) substrate, a wavelength in a range from about 700 nm to about 1700 nm, or in a range from about 750 nm to about 1600 nm, will provide laser lift-off of lithium using nanosecond pulses. Similarly, a wavelength of less than 450 nm may scribe or cut the PI substrate.

[0037] The nanosecond pulses may range in a range from about 1 ns to about 200 ns, or in a range from about 1 nanosecond to about 50 nanoseconds, or in a range from about 1 nanosecond to about 10 nanoseconds. For example, in one implementation, a nanosecond-pulse laser process having a wavelength closer to or in the IR range provides a cleaner patterning process than a nanosecond-pulse laserprocess having a wavelength closer to or in the UV range. In one or more implementations, a femtosecond-pulse laser process suitable for LLO processes is based on a laser having a wavelength of approximately greater than or equal to one micrometer. In a particular implementation, pulses of approximately less than or equal to 15 nanoseconds of the laser having the wavelength of approximately greater than or equal to one micrometer are used. However, in an alternative implementation, dual laser wavelengths (e.g., a combination of an IR laser and a UV laser) can be used.

[0038] It is noted that while the particular substrate on which some implementations described herein can be practiced is not limited, it is particularly beneficial to practice the implementations on flexible substrates, including for example, web-based substrates, panels and discrete sheets. The flexible substrate can also be in the form of a foil, a polymer film, or a thin plate.

[0039] It is also noted here that a flexible substrate, film, or web as used within the implementations described herein can typically be characterized in that it is bendable. The term “web” can be synonymously used to the term “strip,” the term “flexible film,” the term “flexible substrate,” or the term “flexible conductive substrate.” For example, the web as described in implementations herein can be a polymer material.

[0040] It is further noted that the methods and systems described may be used in forming single-sided electrode structures and double-sided electrode structures.

[0041] FIG. 1 illustrates a schematic view of a flexible substrate transfer system 100 incorporating a laser lift-off unit 200 in accordance with one or more implementations of the present disclosure. The transfer system 100 includes equipment for transferring alkali-metal films on a first flexible carrier film 110 and a second flexible carrier film 120 to each side of a flexible substrate stack 130, so that the flexible substrate stack 130 with the alkali-metal films can be used as an electrode, for example, an anode, in an energy storage device, for example, a lithium-ion battery. The transfer system 100 includes a laser lift-off unit 200 for transferring the alkali-metal films from the flexible carrier films 110, 120 to the flexible substrate stack 130. The transfer system 100 may further include a passivation unit 190 for passivating the newly exposed surfaces of the alkali-metal films transferred onto the flexible substratestack 130. The components of the transfer system 100 may be positioned in an enclosure 102 or chamber body.

[0042] The transfer system 100 includes a first flexible carrier supply hub 115. A supply roll 111 of the first flexible carrier film 110 is positioned on the first flexible carrier supply hub 115. In some implementations, the first flexible carrier film 110 can be formed of a polymer material. Suitable polymer materials include polymer materials that are transparent to laser light and have low to no photon absorption to prevent overheating and fire incidents. Example of suitable polymer materials include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), poly(methyl methacrylate) (PMMA), cellulose tri-acetate (TAC), polypropylene (PP), polyethylene (PE), polycarbonates (PC), bio degradable polymer such as Polyethylene 2,5-furandicarboxylate (PEF), multilayers thereof, or a combination thereof. An alkali-metal film is positioned on the lower surface 110L of the first flexible carrier film 110, so that this alkali-metal film faces an upper surface 130U of the flexible substrate stack 130 as the first flexible carrier film 110 and the flexible substrate stack 130 are conveyed through the laser lift-off unit 200. The alkali-metal film is shown as the alkali-metal film 241 in FIG. 2 after contacting the flexible substrate stack 130 during the laser lift-off process. The upper surface 130U of the flexible substrate stack 130 is on an opposite side relative to a lower surface 130L of the flexible substrate stack 130. The upper surface 13011 is also referred to as the first surface or the first side of the flexible substrate stack 130 while the lower surface is also referred to as the second surface or the second side of the flexible substrate stack 130.

[0043] The transfer system 100 includes a second flexible carrier supply hub 125. A supply roll 121 of the second flexible carrier film 120 is positioned on the second flexible carrier supply hub 125. In some implementations, the second flexible carrier film 120 can be formed of the same polymer material (e.g., PET) as the first flexible carrier film 110. An alkali-metal film is positioned on the upper side 120U of the second flexible carrier film 120, so that this alkali-metal film faces the lower surface 130L of the flexible substrate stack 130 as the second flexible carrier film 120 and the flexible substrate stack 130 are conveyed through the laser lift-off unit 200. The alkali-metal film is shown as the alkali-metal film 242 in FIG. 2 after contacting the flexible substrate stack 130 during the laser lift-off process.

[0044] In some implementations, the alkali-metal films on the first flexible carrier film 110 and the second flexible carrier film 120 can be formed of lithium metal, another alkali-metal, for example, sodium, or an alloy including an alkali-metal.

[0045] The transfer system 100 includes a flexible substrate stack supply hub 135. A supply roll 131 of the flexible substrate stack 130 is positioned on the flexible substrate stack supply hub 135. The flexible substrate stack 130 can include one or more layers. In some implementations, for example, for a lithium metal anode device, the flexible substrate stack 130 can include a current collector. In some implementations, for example, for a pre-lithiation process, the flexible substrate stack 130 can include anode material. In other implementations, for a pre-lithiation process, the flexible substrate stack 130 can include both a current collector and anode material. In yet other implementations, the flexible substrate stack 130 can be or include a separator, for example, a polymer separator. The flexible substrate stack 130 can be or include a current collector or a current collector having anode material formed thereover. In one or more implementations, which can be combined with other implementations, the flexible substrate stack 130 includes a web-based substrate, for example, the current collector can be a web-based substrate. Any suitable current collector may be used. The current collector can include or be, but is not limited to, aluminum (Al), copper (Cu), zinc (Zn), nickel (Ni), cobalt (Co), manganese (Mn), chromium (Cr), stainless steel, clad materials, metallized plastic, paper, stainless steel, metal mesh, or a combination thereof. Any suitable anode material may be used. During the laser lift-off process, the alkali-metal films 241 , 242 are contacted to the flexible substrate stack 130. For example, an exposed surface of the alkali-metal films 241 , 242 is contacted to a surface of the flexible substrate stack 130. In some implementations, where the flexible substrate stack 130 only includes a current collector substrate, the exposed surface of the alkali-metal film 241 , 242 is contacted to a surface of the current collector substrate. In some implementations, where the flexible substrate stack 130 includes the anode material, the exposed surface of the alkali-metal film 241 , 242 is contacted to a surface of the anode material to pre-l ithiate the anode material.

[0046] The transfer system 100 further includes the laser lift-off unit 200. The laser lift-off unit 200 includes a first laser source assembly 201 a and a second laser sourceassembly 201 b. The first flexible carrier film 110, the second flexible carrier film 120, and the flexible substrate stack 130 are arranged to be conveyed along a path that extends between the first laser source assembly 201a and the second laser source assembly 201 b. The flexible substrate stack 130 is positioned between the first flexible carrier film 110 and the second flexible carrier film 120 when the first flexible carrier film 110, the second flexible carrier film 120, and the flexible substrate stack 130 are conveyed between the first laser source assembly 201 a and the second laser source assembly 201 b. Energy from the laser source assemblies 201 a, 201 b separates each alkali-metal film 241 , 242 from its respective flexible carrier film 110, 120 causing each alkali-metal film 241 , 242 to be transferred to the flexible substrate stack 130. In some implementations, a release layer is disposed on each of the flexible carrier films 110, 120 between the corresponding flexible carrier film 110, 120 and the alkali-metal film 241 , 242 on each respective flexible carrier film.

[0047] The transfer system 100 includes a first flexible carrier pickup hub 116. A pickup roll 112 of the first flexible carrier film 110 is positioned on the first flexible carrier pickup hub 116. The alkali-metal film is no longer on the first flexible carrier film 110 when the first flexible carrier film 110 is wound onto the first flexible carrier pickup hub 116 because the alkali-metal film previously on the first flexible carrier film 110 is transferred onto the flexible substrate stack 130 by the laser lift-off unit 200.

[0048] The transfer system 100 includes a second flexible carrier pickup hub 126. A pickup roll 122 of the second flexible carrier film 120 is positioned on the second flexible carrier pickup hub 126. The alkali-metal film is no longer on the second flexible carrier film 120 when the second flexible carrier film 120 is wound onto the second flexible carrier pickup hub 126 because the alkali-metal film previously on the second flexible carrier film 120 is transferred onto the flexible substrate stack 130 by the laser lift-off unit 200.

[0049] The transfer system 100 includes a flexible substrate stack pickup hub 136. A pickup roll 132 of the flexible substrate stack 130 is positioned on the flexible substrate stack pickup hub 136. The flexible substrate stack 130 includes an alkali- metal film on each of the upper surface 130U and the lower surface 130L of the flexiblesubstrate stack 130. These lithium films are transferred from the respective flexible carrier films 110, 120 onto the flexible substrate stack 130 by the laser lift-off unit 200.

[0050] The transfer system 100 further includes a plurality of rollers 181 -188. In some implementations, each of the rollers 181 -188 can be passive rollers. The rollers 181-188 can assist in applying proper tension to and assist in changing the direction of the flexible carrier films 110, 120 and the flexible substrate stack 130 during the movement of each of the flexible carrier films 110, 120 and the flexible substrate stack 130 through the different portions of the transfer system 100. Some of the rollers 181 - 188 can also assist in moving the flexible carrier films 110, 120 closer to or further away from the flexible substrate stack 130. For example, the second and third rollers 182, 183 may function as nip rollers and assist in bringing the flexible carrier films 110, 120 into contact with the flexible substrate stack 130 before the flexible carrier films 110, 120 and the flexible substrate stack 130 are conveyed through the laser lift-off unit 200. Additionally, the fourth and fifth rollers 184, 185 provide a location at which tension can be applied to the flexible carrier films 110, 120 to peel the flexible carrier films 110, 120 away from the flexible substrate stack 130. The sixth roller 186 and seventh roller 187 provide locations at which additional tension can be applied to the first flexible carrier film 110 and the second flexible carrier film 120 to peel the first flexible carrier film 110 and the second flexible carrier film 120 away from the flexible substrate stack 130. In some implementations, one or more of the rollers 181 -188 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.

[0051] Furthermore, in some implementations the rollers 184, 185 can be positioned in a controlled atmosphere, such as an atmosphere including no nitrogen, no oxygen, an atmosphere of inert gas without any significant amount of other gases, a vacuum environment, or an atmosphere including one or more gases provided to an interior volume of the passivation unit 190, such as carbon dioxide without any gases known to negatively affect the performance of the alkali-metal films, such as nitrogen. In other implementations, the controlled atmosphere includes an inert gas, for example, argon gas, CO2, NO, N2, O2, or combinations thereof. In one implementation, the rollers 184, 185 and the corresponding passivation unit 190 are housed in the same enclosure that has a controlled atmosphere as described above,so that there is no exposure of the newly exposed alkali-metal surfaces to an uncontrolled atmosphere, such as an atmosphere including nitrogen. In some implementations, each portion of the transfer system 100 is in a controlled atmosphere, such as an environment including no nitrogen and no oxygen.

[0052] The transfer system 100 can further include actuators (not shown) configured to rotate each of the hubs 115, 116, 125, 126, 135, 136, so that the flexible carrier films 110, 120 and the flexible substrate stack 130 can be conveyed from the corresponding supply hub 115, 125, 135, through the laser lift-off unit 200, and to the corresponding pickup hub 116, 126, 136. The transfer system 100 can further include one or more actuators (not shown) to rotate the various hubs and rollers of the transfer system 100. The rotational speed of the actuators can be adjusted to control the speed at which the flexible substrate stack 130 and flexible carrier films 110, 120 are conveyed through the transfer system 100.

[0053] In the transfer system 100, the flexible substrate stack 130 is conveyed along a path from the supply roll 131 that is supported by the supply hub 135, past the first roller 181 , between the second and third rollers 182, 183, between the laser source assemblies 201 a, 201 b, between the fourth and fifth rollers 184, 185, through the passivation unit 190, past the eighth roller 188, and to the pickup roll 132 around the pickup hub 136. The pickup hub 136 is configured to rotate and assist in conveying the flexible substrate through the interior volume of the passivation unit 190 after the flexible substrate stack 130 passes between the first laser source assembly 201 a and the second laser source assembly 201 b. Similarly, the pickup hubs 116, 126 are configured to rotate and assist in conveying the flexible carriers along paths between the supply hubs 115, 125 and the pickup hubs 116, 126. The transfer system 100 can also include a controller 105 for controlling processes performed by the transfer system 100. The controller 105 can be any type of controller used in an industrial setting, such as a programmable logic controller (PLC). The controller 105 includes a processor 107, a memory 106, and input / output (I / O) circuits 108. The controller 105 can further include one or more of the following components (not shown), such as one or more power supplies, clocks, communication components (e.g., network interface card), and user interfaces typically found in controllers for semiconductor equipment.

[0054] The memory 106 can include non-transitory memory. The non-transitory memory can be used to store the programs and settings described below. The memory 106 can include one or more readily available types of memory, such as read only memory (ROM) (e.g., electrically erasable programmable read-only memory (EEPROM), flash memory, floppy disk, hard disk, or random access memory (RAM) (e.g., non-volatile random access memory (NVRAM).

[0055] The processor 107 is configured to execute various programs stored in the memory 106, such as a program configured to execute any of the methods 600, 800, 900 described herein. During execution of these programs, the controller 105 can communicate to I / O devices through the I / O circuits 108. For example, during execution of these programs and communication through the I / O circuits 108, the controller 105 can control outputs (e.g., the actuators connected to the different hubs and the laser lift-off unit 200). The memory 106 can further include various operational settings used to control the transfer system 100. For example, the settings can include speed settings for the actuators connected to the hubs as well as settings to control the passivation unit 190 described below.

[0056] FIG. 2 illustrates a schematic side view of one example of the laser lift-off unit 200 that may be used with the transfer systems described, in accordance with one or more implementations of the present disclosure. The laser lift-off unit 200 may be part of the transfer systems as shown herein or may be a stand-alone unit. The laser lift-off unit 200 is configured to provide electromagnetic energy to the alkali-metal films 241 , 242 to create an interface reaction with either a release layer, an interface layer, or both the release layer and the interface layer between the alkali-metal films 241 , 242 and the flexible carrier films 110, 120, for example, PET, to enable subsequent removal of the flexible carrier films 110, 120 from the alkali-metal films 241 , 242 at the activated interface. The laser lift-off unit 200 includes a first laser source assembly 201a positioned to deliver electromagnetic energy toward the first flexible carrier film 110 and a second laser source assembly 201 b positioned to deliver electromagnetic energy toward the second flexible carrier film 120. The first flexible carrier film 110, the second flexible carrier film 120, having alkali-metal films 241 , 242 formed thereonrespectively and the flexible substrate stack 130 are arranged to be conveyed along a path that extends between the first laser source assembly 201 a and the second laser source assembly 201 b. The flexible substrate stack 130 is positioned between the first flexible carrier film 110 and the second flexible carrier film 120 when the first flexible carrier film 110, the second flexible carrier film 120, and the flexible substrate stack 130 are conveyed between the first laser source assembly 201 a and the second laser source assembly 201 b.

[0057] The first laser source assembly 201 a and the second laser source assembly 201 b include at least one of a laser source 202a-b and an optical source assembly 206a-b. The laser source 202a-b is configured to generate a laser beam 230a-b and the optical source assembly 206a-b is configured to direct the laser beam 230a-b toward a back surface, for example, the upper surface 110U of the first flexible carrier film 110 and the lower surface 110L of the second flexible carrier film 120. In one or more implementations, the first laser source assembly 201a and the second laser source assembly 201 b are positioned such that the laser beams 230a-b are offset relative to each other as is shown in FIG. 2. For example, referring to FIG. 2, the second laser source assembly 201 b is positioned downstream from the first laser source assembly 201 a. In addition, although FIG. 2 shows the LLO process performed in a free-span orientation, a roller or another surface may be positioned opposite each of the first laser source assembly 201 a and the second laser source assembly 201 b as is shown in FIGS. 3-5.

[0058] In one or more implementations, which can be combined with other implementations, the laser source 202a-b may be a solid-state laser, such as a diode- pumped solid-state laser having a fiber, a rod, or slab gain medium, configured to generate the laser beam 230a-b. The laser beam 230a-b may be a continuous or pulsed laser beam. The laser fiber, rod, or slab may be formed of any suitable laser crystal materials, including neodymium-doped yttrium aluminum garnet (Nd:YAG; Nd:Y3AI5O12), ytterbium-doped YAG (Yb:YAG), neodymium-doped yttrium orthovanadate (Nd:YVO; Nd:YVO4), and alexandrite. In particular implementations, the laser rod or slab has a face pumping geometry. In particular implementations, the laser slab has an edge pumping geometry. Other types of lasers can be used such as a fiber laser or a gas laser. Suitable laser sources include but are not limited to anIR fiber laser, a UV laser, or a Green Laser. In other implementations, the laser source 202a-b can be replaced with a flash lamp as described.

[0059] In particular implementations, the laser source 202a-b is an infrared laser source configured to operate at infrared (IR) wavelengths for removing sections of alkali-metal on alkali-metal coated substrates. The laser source 202a-b may generate a pulsed laser beam 230a-b. In some implementations described herein, frequency, pulse width, and pulse energy of the laser beam 230a-b generated by the laser source 202a-b are tunable (e.g., adjustable) depending on the material being removed, targeted lateral dimensions of the sections being removed, as well as a depth of the removal. Additionally, the movement speed of the laser beam 230a-b, number of pulses, and beam profile and focused spot size may be tuned.

[0060] In any form, the laser beam 230a-b produced by the laser source 202a-b is projected (e.g., transmitted) towards the flexible stack 240 via the optical source assembly 206a-b. The optical source assembly 206a-b is optically coupled with the laser source 202a-b and includes any suitable image projection devices for directing the laser beam 230a-b towards the flexible stack 240 for the laser lift-off process. In particular implementations, the optical source assembly 206a-b includes a scanner 232a-b, such as a single- or multi-axis large angle galvanometer optical scanner (i.e., galvanometer scanner). The term “galvanometer scanner” refers to any device that responds to an electronic signal from the controller 105 to change a projection or reflection angle of the laser beam 230a-b to sweep the laser beam 230a-b across the flexible stack 240. Scanner 232a-b may also be a polygon scanner, an electro-optic scanner, an acousto-optic, or a combination thereof. Utilization of the scanner 232a- b enables activation of multiple sections of alkali-metal on the flexible stack 240 via the laser lift-off process, in addition to scanning of the laser beam 230a-b across a surface of the flexible stack 240 without mechanical translation of the flexible stack 240 itself. The scanner 232a-b may further include any suitable features to facilitate activation of the materials and structures described herein, such as digital servo feedback, low drift, fast dynamic response, and precise calibration capability.

[0061] In one or more implementations, which can be combined with other implementations, the optical source assembly 206a-b further includes one or morescan lenses 234a-b having a large field of view that encompasses the entirety of the flexible stack 240. In one or more implementations, which can be combined with other implementations, two or more scan lenses 234a-b may be utilized for laser removal of different types of materials, each scan lens of the scan lenses 234a-b specific to a wavelength range of the laser source 202a-b. The scan lenses 234a-b may be telecentric lenses, F-theta lenses, or a combination thereof. During operation, the laser beam 230a-b projected by the optical source assembly 206a-b is directed towards the flexible stack 240.

[0062] The laser lift-off unit 200 includes a housing 215 disposed around an interior volume 208. The housing 215 includes an upper housing 215U and a lower housing 215L. The flexible stack 240 is conveyed through the interior volume 208 as the flexible stack 240 is moved towards the pickup hub 136. The interior volume 208 includes an upper volume 208LI above the flexible stack 240 and a lower volume 208L below the flexible stack 240.

[0063] In some implementations, the laser lift-off unit 200 further includes a plurality of seals 251 -254. The seals 251-254 can be formed of a compressible material. The seals 251 -254 can be used to maintain a separate environment in the interior volume 208 relative to the environment surrounding the laser lift-off unit 200. For example, the interior volume 208 can have different concentrations of gases as well as a different temperature and / or pressure relative to the environment surrounding the laser lift-off unit 200.

[0064] The laser lift-off unit 200 may further include an atmosphere control system 297 is coupled to the housing 215. The atmosphere control system 297 includes throttle valves and pumps for controlling chamber pressure. The atmosphere control system 297 may additionally include gas sources for providing process or other gases to the interior volume 208 of the laser lift-off unit 200. The atmosphere control system 297 may be controlled by the controller 105. In one or more implementations, the atmosphere control system 297 may assist controlling the pressure at a targeted range during the laser lift-off process. In one example, the pressure during the laser lift-off process may be controlled at atmospheric pressure, such as at ambient pressure.

[0065] FIG. 3 illustrates a schematic side view of another flexible substrate transfer system 300 incorporating a laser lift-off unit, in accordance with one or more implementations of the present disclosure. The flexible substrate transfer system 300 is configured to process the lower surface 130L and the upper surface 130U of the flexible substrate stack 130 sequentially rather than simultaneously. Although no enclosure is shown in FIG. 3, the components of the flexible substrate transfer system 300 can be positioned in an enclosure similar to the enclosure 100 of the flexible substrate transfer system 100.

[0066] The flexible substrate transfer system 300 includes a plurality of rollers 381 - 388. In some implementations, 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 carrier films 110, 120 and the flexible substrate stack 130 during the movement of each of the flexible carrier films 110, 120 and the flexible substrate stack 130 through the different portions of the transfer system 300. For example, the first roller 381 and the fifth roller 385 provide locations at which additional tension can be applied to the first flexible carrier film 110 and the second flexible carrier film 120. Some of the rollers 381 -388 can also assist in moving the flexible carrier films 110, 120 closer to or further away from the flexible substrate stack 130. For example, in one or more implementations, the second and third rollers 382, 383 function as nip rollers and assist in bringing the second flexible carrier film 120 into contact with the flexible substrate stack 130 before the second flexible carrier film 120 and the flexible substrate stack 130 are conveyed past the second laser source assembly 201 b. In one or more other implementations, the second and third rollers 382, 383 function as calender rollers. The calender rollers not only assist in bringing the second flexible carrier film 120 into contact with the flexible substrate stack 130 before the second flexible carrier film 120 and the flexible substrate stack 130 are conveyed past the second laser source assembly 201 b, but also apply sufficient pressure to laminate the second flexible carrier film 120 with the flexible substrate stack 130. Additionally, the fourth roller 384 provides a location at which tension can be applied to the second flexible carrier film 120 to peel the second flexible carrier film 120 away from the flexible substrate stack 130. The sixth and seventh rollers 386, 387 may function as nip rollers or calender rollers and assist in bringing the first flexible carrier film 110 intocontact with the flexible substrate stack 130 before the first flexible carrier film 110 and the flexible substrate stack 130 are conveyed past the first laser source assembly 201a. The eighth roller 388 provides a location at which tension can be applied to the first flexible carrier film 110 to peel the first flexible carrier film 110 away from the flexible substrate stack 130. In some implementations, 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.

[0067] In one or more implementations, which can be combined with other implementations, the flexible substrate transfer system 300 further includes an interleaf supply hub 315. A supply roll 311 of the interleaf film 310 is positioned on the interleaf supply hub 315. The interleaf supply hub 315 is positioned downstream from the first laser source assembly 201a and / or the inline passivation unit 190 (if present) and upstream from the pickup hub 136. The interleaf film 310 can function as a protective film, which protects the alkali-metal film from exposure to atmosphere and / or from damage when the flexible substrate stack 130 is collected on the pickup hub 136 as the pickup roll 132. The interleaf film 310 may comprises any suitable material for protecting the underlying film. In some implementations, the interleaf film 310 is formed of a polymer material, a metallic material, or a combination of a polymer material and a metallic material, for example, metallized plastic. Examples of suitable interleaf materials include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), poly(methyl methacrylate) (PMMA), cellulose tri-acetate (TAC), polypropylene (PP), polyethylene (PE), polycarbonates (PC), stainless steel, multilayers thereof, or a combination thereof.

[0068] Referring to FIG. 3, in operation, the flexible substrate stack 130 and the second flexible carrier film 120 are conveyed toward the second laser source assembly 201 b. As the flexible substrate stack 130 and the second flexible carrier film 120 travel between the second roller 382 and the third roller 383, the rollers 382, 383 supply sufficient pressure to the flexible substrate stack 130 and the second flexible carrier film 120 such that the flexible substrate stack 130 and the second flexible carrier film 120 contact each and / or are laminated to each other prior to or while traveling past the second laser source assembly 201 b. The second laser source assembly 201 b provides laser energy to the second alkali-metal film 242, which is sandwichedbetween the lower surface 130L of the flexible substrate stack 130 and the second flexible carrier film 120, to create an interface reaction with either a release layer, an interface layer, or both the release layer and the interface layer between the second alkali-metal film 242 and the second flexible carrier film 120 to enable subsequent removal of the second flexible carrier film 120 from the second alkali-metal films 242 at the activated interface. The fourth roller 384 applies tension to the second flexible carrier film 120 to peel the second flexible carrier film 120 away from the flexible substrate stack 130. The second flexible carrier film 120 is collected on the second flexible carrier pickup hub 126. The flexible substrate stack 130 having the second alkali-metal film on the lower surface 130L is transferred to the sixth roller 386 and the seventh roller 387, which supply sufficient pressure to the flexible substrate stack 130 and the first flexible carrier film 110 such that the upper surface 13011 of the flexible substrate stack 130 and the lower surface 110L of the first flexible carrier film 110 contact each other and / or are laminated to prior to or while traveling past the first laser source assembly 201a. The first laser source assembly 201 a provides laser energy to the first alkali-metal film 241 , which is sandwiched between the upper surface 13011 of the flexible substrate stack 130 and the lower surface 110L of the first flexible carrier film 110, to create an interface reaction with either a release layer, an interface layer, or both the release layer and the interface layer between the first alkali-metal film 241 and the first flexible carrier film 110 to enable subsequent removal of the first flexible carrier film 110 from the first alkali-metal film 241 at the activated interface. The eighth roller 388 applies tension to the first flexible carrier film 110 to peel the first flexible carrier film 110 away from the flexible substrate stack 130. The first flexible carrier film 110 is collected on the first flexible carrier pickup hub 116. The flexible substrate stack 130 having the second alkali-metal film 242 attached to the lower surface 130L and the first alkali-metal film 241 attached to the upper surface 13011 travel through the inline passivation unit 190 (if present) where passivation films are formed on the first alkali-metal film 241 and the second alkali-metal film 242 formed on the second alkali-metal film 242. The flexible substrate stack 130 having the second alkali-metal film 242 attached to the lower surface 130L and the first alkali-metal film 241 attached to the upper surface 13011 may be combined with an interleaf film supplied from the interleaf supply hub 315 prior to or during final rewind on the flexible substrate stack pickup hub 136.

[0069] FIG. 4 illustrates a schematic side view of another flexible substrate transfer system 400 incorporating a laser lift-off unit, in accordance with one or more implementations of the present disclosure. The flexible substrate transfer system 400 is configured to process the lower surface 130L and the upper surface 130U of the flexible substrate stack 130 sequentially similar to the flexible substrate transfer system 300 shown in FIG. 3. The flexible substrate transfer system 400 includes a single nip / calender followed by successive processing of the lower surface 130L and the upper surface 13011. Although no enclosure is shown in FIG. 4, the components of the flexible substrate transfer system 400 can be positioned in an enclosure similar to the enclosure 100 of the flexible substrate transfer system 100.

[0070] The flexible substrate transfer system 400 includes a plurality of rollers 481 - 486. In some implementations, one or more of the rollers 481 -486 can be passive rollers. The rollers 481-486 can assist in applying proper tension to and assist in changing the direction of the flexible carrier films 110, 120 and the flexible substrate stack 130 during the movement of each of the flexible carrier films 110, 120 and the flexible substrate stack 130 through the different portions of the transfer system 400. For example, the first roller 481 provides a location at which additional tension can be applied to the second flexible carrier film 120. Some of the rollers 481-486 can also assist in moving the flexible carrier films 110, 120 closer to or further away from the flexible substrate stack 130. For example, the second and third rollers 482, 483 may function as nip rollers or calender rollers and assist in bringing the first flexible carrier film 110 and the second flexible carrier film 120 into contact with opposing sides of the flexible substrate stack 130 before or while the first flexible carrier film 110, the second flexible carrier film 120, and the flexible substrate stack 130 are conveyed past the second laser source assembly 201 b. Additionally, the fourth roller 484 provides a location at which tension can be applied to the second flexible carrier film 120 to peel the second flexible carrier film 120 away from the flexible substrate stack 130. The fourth roller 484 may be positioned to peel away the second flexible carrier film 120 after exposure of the substrate stack to the second laser source assembly 201 b but prior to exposure of the substrate stack to the first laser source assembly 201a. The fifth roller 485 provides a processing surface over which the first flexible carrier film 110 and the flexible substrate stack 130 travel during exposure to laser energy fromthe first laser source assembly 201 a. The sixth roller 486 provides a location at which tension can be applied to the first flexible carrier film 110 to peel the first flexible carrier film 110 away from the flexible substrate stack 130. In some implementations, one or more of the rollers 481 -486 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.

[0071] In one or more implementations, which can be combined with other implementations, the flexible substrate transfer system 400 further includes the interleaf supply hub 315. The supply roll 311 of the interleaf film 310 is positioned on the interleaf supply hub 315. The interleaf supply hub 315 is positioned downstream from the first laser source assembly 201 a and / or the inline passivation unit 190 (if present) and upstream from the pickup hub 136.

[0072] Referring to FIG. 4, in operation, the first flexible carrier film 110, the second flexible carrier film 120, and the flexible substrate stack 130 are conveyed toward the second laser source assembly 201 b. As the flexible substrate stack 130 and the second flexible carrier film 120 travel in between the second roller 482 and the third roller 483, the rollers 482, 483 supply sufficient pressure the first flexible carrier film 110, the second flexible carrier film 120, and the flexible substrate stack 130 such that the first flexible carrier film 110, the second flexible carrier film 120, and the flexible substrate stack 130 contact each other prior to or while traveling past the second laser source assembly 201 b. In one or more implementations, at least one of the second roller 482 and the third roller 483 is a calender roller and the first flexible carrier film 110, the second flexible carrier film 120, and the flexible substrate stack 130 are laminated together by the pressure applied by the calendering rollers. In one or more implementations, the second roller 482 and the third roller 483 are nip rollers. The second laser source assembly 201 b provides laser energy to the second alkali-metal film 242, which is sandwiched between the lower surface 130L of the flexible substrate stack 130 and the second flexible carrier film 120, to create an interface reaction with either a release layer, an interface layer, or both the release layer and the interface layer between the second alkali-metal film 242 and the second flexible carrier film 120 to enable subsequent removal of the second flexible carrier film 120 from the second alkali-metal films 242 at the activated interface. The fourth roller 484 applies tensionto the second flexible carrier film 120 to peel the second flexible carrier film 120 away from the flexible substrate stack 130. The second flexible carrier film 120 is collected on the second flexible carrier pickup hub 126. The flexible substrate stack 130 having the second alkali-metal film on the lower surface 130L and the lower surface 110L of the first flexible carrier film 110 contacting the upper surface 13011 of the flexible substrate stack 130 travel over the fifth roller 485 prior to or while traveling past the first laser source assembly 201 a. The first laser source assembly 201 a provides laser energy to the first alkali-metal film 241 , which is sandwiched between the upper surface 130U of the flexible substrate stack 130 and the lower surface 110L of the first flexible carrier film 110, to create an interface reaction with either a release layer, an interface layer, or both the release layer and the interface layer between the first alkali- metal film 241 and the first flexible carrier film 110 to enable subsequent removal of the first flexible carrier film 110 from the first alkali-metal film 241 at the activated interface. The sixth roller 486 applies tension to the first flexible carrier film 110 to peel the first flexible carrier film 110 away from the flexible substrate stack 130. The first flexible carrier film 110 is collected on the first flexible carrier pickup hub 116. The flexible substrate stack 130 having the second alkali-metal film 242 attached to the lower surface 130L and the first alkali-metal film 241 attached to the upper surface 130U travels through the inline passivation unit 190 (if present) where passivation films are formed on the first alkali-metal film 241 and the second alkali-metal film 242. The flexible substrate stack 130 having the second alkali-metal film 242 attached to the lower surface 130L and the first alkali-metal film 241 attached to the upper surface 130U may be combined with an interleaf film supplied from the interleaf supply hub 315 prior to final rewind on the flexible substrate stack pickup hub 136.

[0073] FIG. 5 illustrates a schematic side view of yet another example of a flexible substrate transfer system 500 incorporating a laser lift-off unit, in accordance with one or more implementations of the present disclosure. The flexible substrate transfer system 400 is configured to process the lower surface 130L and the upper surface 130U of the flexible substrate stack 130 sequentially similar to the flexible substrate transfer system 300 shown in FIG. 3 and the flexible substrate transfer system 400 shown in FIG. 4. Although no enclosure is shown in FIG. 5, the components of the flexible substrate transfer system 500 can be positioned in an enclosure similar to theenclosure 100 of the flexible substrate transfer system 100. The flexible substrate transfer system 500 further includes a first inline slitting assembly 530a positioned to slit the first flexible carrier film 110 and a second inline slitting assembly 530b positioned to slit the second flexible carrier film 120 after the flexible carriers are peeled away from the processed flexible substrate stack 130. In some implementations where it is desirable to transfer only a portion of the alkali-metal film formed on the flexible carrier, for example, transferring alkali-metal from half the width of the flexible carrier to the flexible substrate stack 130, the remaining unprocessed portion of the flexible carrier, which still has the alkali-metal film formed thereon, is separated from the processed portion of the flexible carrier by the inline slitting assemblies 530a-b and collected on a separate pickup hub for reuse. The inline slitting assemblies 530a-b include a blade, for example, rotary blade for cutting the flexible carrier films.

[0074] The flexible substrate transfer system 500 includes a plurality of rollers 581 - 589. In some implementations, one or more of the rollers 581 -589 can be passive rollers. The rollers 581-589 can assist in applying proper tension to and assist in changing the direction of the flexible carrier films 110, 120 and the flexible substrate stack 130 during the movement of each of the flexible carrier films 110, 120 and the flexible substrate stack 130 through the different portions of the transfer system 500. For example, the first roller 581 provides a location at which additional tension can be applied to the second flexible carrier film 120. Some of the rollers 581-589 can also assist in moving the flexible carrier films 110, 120 closer to or further away from the flexible substrate stack 130. For example, the second and third rollers 582, 583 can function as nip rollers and / or calender rollers and assist in bringing the first flexible carrier film 110 and the second flexible carrier film 120 into contact with opposing sides of the flexible substrate stack 130 before or while the first flexible carrier film 110, the second flexible carrier film 120, and the flexible substrate stack 130 are conveyed past the second laser source assembly 201 b. Additionally, the fourth roller 584 provides a location at which tension can be applied to the second flexible carrier film 120 to peel the second flexible carrier film 120 away from the flexible substrate stack 130. The fourth roller 584 may be positioned to peel away the second flexible carrier film 120 after exposure of the substrate stack to the second laser source assembly 201 b but prior to exposure of the substrate stack to the first laser source assembly 201a. Thefifth roller 585 may positioned downstream from the fourth roller 584 and upstream from the pickup hub 126 for collecting the processed portion of the second flexible carrier film 120 and a pickup roll 522 for collecting the unprocessed portion of the second flexible carrier film 120. The second inline slitting assembly 530b is positioned downstream from the fourth roller 584 and upstream from the fifth roller 585, the pickup hub 126 and the pickup hub 526. The second inline slitting assembly 530b is positioned to slit the second flexible carrier film 120 after the second flexible carrier film 120 is peeled away from the processed flexible substrate stack 130. The second inline slitting assembly 530b cuts the flexible carrier film 120 into a processed portion, which is collected as the pickup roll 122 on the pickup hub 126, and an unprocessed portion, which is collected as the pickup roll 522 on the pickup hub 526.

[0075] The sixth roller 586 provides a processing surface over which the first flexible carrier film 110 and the flexible substrate stack 130 travel during exposure to laser energy from the first laser source assembly 201 a. The sixth roller 586 provides a location at which tension can be applied to the first flexible carrier film 110 to peel the first flexible carrier film 110 away from the flexible substrate stack 130. The seventh roller 587 may be positioned to peel away the first flexible carrier film 110 after exposure of the substrate stack to the first laser source assembly 201 a. The eighth roller 588 may be positioned downstream from the seventh roller 587 and upstream from the pickup hub 116 for collecting the processed portion of the first flexible carrier film 110 and a pickup hub 516 for collecting the unprocessed portion of the first flexible carrier film 110. The first inline slitting assembly 530a is positioned downstream from the seventh roller 587 and upstream from the eighth roller 588, the pickup hub 116 and the pickup hub 516. The first inline slitting assembly 530a is positioned to slit the first flexible carrier film 110 after the first flexible carrier film 110 is peeled away from the processed flexible substrate stack 130. The first inline slitting assembly 530a cuts the flexible carrier film 110 into a processed portion, which is collected as the pickup roll 112 on the pickup hub 116, and an unprocessed portion 512, which is collected on the pickup hub 516. The flexible substrate stack 130 having the second alkali-metal film 242 attached to the lower surface 130L and the first alkali-metal film 241 attached to the upper surface 13011 then travels through the inline passivation unit 190 (if present) where passivation films are formed on the first alkali-metal film 241 and thesecond alkali-metal film 242. The flexible substrate stack 130 having the second alkali- metal film 242 attached to the lower surface 130L and the first alkali-metal film 241 attached to the upper surface 13011 is then redirected by the ninth roller 589 may be combined with an interleaf film supplied from the interleaf supply hub 315 prior to or during final rewind on the flexible substrate stack pickup hub 136.

[0076] In some implementations, one or more of the rollers 581 -589 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.

[0077] FIG. 6 illustrates a flowchart showing selected operations of a method 600 of forming an energy storage device via a laser lift-off process in accordance with one or more implementations of the present disclosure. FIGS. 7A-7D illustrate views of various stages of manufacturing an energy storage device in accordance with one or more implementations of the present disclosure. Although FIGS. 7A-7D are described in relation to the method 600, it will be appreciated that the structures disclosed in FIGS. 7A-7D are not limited to the method 600, but instead may stand alone as structures independent of the method 600. Similarly, although the method 600 is described in relation to FIGS. 7A-7D, it will be appreciated that the method 600 is not limited to the structures disclosed in FIGS. 7A-7D but instead may stand alone independent of the structures disclosed in FIGS. 7A-7D. It should be understood that FIGS. 7A-7D illustrate only partial schematic views of the energy storage device structure 700, and the energy storage device structure 700 may contain any number of additional layers and / or additional materials common to energy storage devices, which are not shown for the sake of brevity. It should also be noted that although the method 600 illustrated in FIG. 6 is described sequentially, other process sequences that include one or more operations that have been omitted and / or added, and / or have been rearranged in another desirable order, fall within the scope of the implementations of the disclosure provided herein. The method 600 may be performed using any of the aforementioned flexible substrate transfer systems 100, 300, 400, and 500.

[0078] Referring to FIG. 7A, at operation 610, a flexible substrate stack 130, a first flexible carrier film 110, and a second flexible carrier film 120 are conveyed toward alaser lift-off unit, for example, the laser lift-off unit 200. The first flexible carrier film 110 and the second flexible carrier film 120 each include a polymer substrate 702a-b as described. The first flexible carrier film 110 and the second flexible carrier film 120 may further include a release film 710a-b respectively. The release film 710a-b assists in removal of the alkali-metal films 241 , 242 from the underlying polymer substrate 702a-b.

[0079] In one or more implementations, the release film 710a-b can be or include a polymer material that is capable of photoinduced depolymerization. In one or more implementations, the polymer material can be or include a poly(olefin sulfone) material capable of photoinduced depolymerization. The poly(olefin sulfone) may be combined with photobase generators (PBGs). The poly(olefin sulfone) can be doped with a photosensitizer, for example, pyridine N-oxide. The depolymerization process can be induced by, for example, X-rays, electron-beam irradiation, or low-energy irradiation. Suitable poly(olefin sulfone) materials include poly(1 -butene sulfone) (PBS), poly(1 - pentane sulfone) (PPS), poly(1 -hexane sulfone) (PHS), poly(1 -octene sulfone) (POS), poly(cyclopentene sulfone), poly(2-methyl-1 -butene sulfone) (PMBS), poly(2-methyl- 1 -pentene sulfone) (PMPS), poly(2-methyl 1 -hexene sulfone) (PMHS), poly(2-methyl- 1 -nonene sulfone) (PMNS), poly(cyclohexene sulfone), or a combination thereof. In other implementations, the release film 710a-b can be or include one or more of fluorocarbons, silicone, latex, AIOx, LiF, AIOOH, Ag, AgF, Bi, or Sn. The release layer can also be an engineered polymer tailored for high laser absorption. Optionally, the laser absorbing material can also be pattern coated on top of the plastic substrate with or without a release layer for areas of alkali metal or alloy to be transferred vs nontransferred to create desired pattern transfer.

[0080] The flexible substrate stack 130 can include one or more layers. In some implementations, for example, for a lithium metal anode device, the flexible substrate stack 130 can include a current collector substrate 720. In some implementations, for example, for a pre-lithiation process, the flexible substrate stack 130 can further include an anode film 730a-b. In other implementations, for a pre-lithiation process, the flexible substrate stack 130 can include both a current collector substrate 720 and an anode film 730a-b. The flexible substrate stack 130 can be or include a current collector substrate 720 or a current collector substrate 720 having anode film 730a-bformed thereover. In one or more implementations, which can be combined with other implementations, the flexible substrate stack 130 includes a web-based substrate, for example, the current collector substrate 720 can be a web-based substrate. Any suitable current collector may be used. The current collector can include or be, but is not limited to, aluminum (Al), copper (Cu), zinc (Zn), nickel (Ni), cobalt (Co), manganese (Mn), chromium (Cr), stainless steel, clad materials, metallized plastic, paper, stainless steel, metal mesh, or a combination thereof. Any suitable anode material may be used. The anode film 730a-b can include or be, but is not limited to, graphite, silicon, silicon graphite, silicon oxide graphite, silicon, or combinations thereof.

[0081] The flexible substrate stack 130 can be exposed to a surface activation process prior to the alkali-metal transfer process. The surface activation process enhances bonding between the alkali-metal film and the flexible substrate stack 130, for example, either the current collector substrate 720 or the anode film 730a-b. The surface activation process can include exposure to ultraviolet (UV) energy or a plasma. The surface activation process can include a corona surface treatment process, an atmospheric plasma treatment process, or a combination thereof.

[0082] In one or more implementations, the surface activation process is a plasma treatment process, for example, a corona discharge treatment process or an atmospheric plasma treatment process. The surface activation process performed includes supplying a treatment gas mixture into a processing region. A plasma is then formed from the treatment gas mixture to plasma treat the surface of the flexible substrate stack 130 to activate at least a portion of the flexible substrate stack 130 into an excited state, forming a treated flexible substrate stack having a treated upper surface which may then enhance bonding between the alkali-metal film and the flexible substrate stack 130.

[0083] In one or more implementations, the treatment gas mixture includes at least one of oxygen-containing gas, an inert gas (e.g., argon, helium), or combinations thereof. In one or more implementations, the oxygen-containing gas supplied into the processing region includes at least one of oxygen (O2), ozone (O3), oxygen radicals (O*), ionized oxygen atoms, carbon dioxide (CO2), nitric oxide (NOx), water vapor, orcombinations thereof. Other oxygen-containing gases may be used. The one or more oxygen-containing gas can be introduced with one or more inert gases, such as nitrogen, helium or argon.

[0084] In one or more implementations involving oxidation, a gas source supplies oxygen gas (O2) through a mass flow controller to an ozonator, which converts a large fraction of the oxygen to ozone gas (O3). The resultant oxygen-based mixture of O2 and O3 and perhaps some oxygen radicals 0* and ionized oxygen atoms or molecules is delivered into the processing region. The oxygen-based gas reacts within the processing region with the surface of the flexible substrate stack 130, which has been heated to a predetermined, preferably low temperature. Ozone is a metastable molecule which spontaneously quickly dissociates in the reaction O3 — O2+O*, where 0* is a radical, which very quickly reacts with whatever available material can be oxidized. The ozonator may be implemented in a number of forms including capacitively or inductively coupled plasma or a UV lamp source.

[0085] The corona treatment can be performed using a low temperature corona discharge plasma to impart changes to the surface energy of the electrode structure. The corona treatment discharge process can include generating an ionized corona discharge plasma. The generated corona discharge plasma can include a positive or negatively charged plasma. In one or more implementations, the corona is positive. In other implementations, the corona is negative. In some implementations, the corona treatment is carried out in part under atmospheric or partial pressure, under vacuum, or a combination thereof.

[0086] In one or more implementations, the atmospheric plasma treatment process includes generating plasma at a pressure greater than or equal to 500 Torr, 600 Terr, 700 Torr, 750 Torr or 755 Torr and less than or equal to 1000 Torr, 900 Torr, 800 Torr or 765 Torr, or in the range of 500 Torr to 1000 Torr, or in the range of 600 Torr to 900 Torr, or in the range of 700 Torr to 800 Torr, or in the range of 725 Torr to 775 Torr, or in the range of 750 Torr to 770 Torr. In one or more implementations, the atmospheric plasma treatment process includes generating plasma in an ambient or uncontrolled pressure environment. The atmospheric plasma can be comprised of a chemically non-reactive species, for example, argon or helium, and / or a chemically reactivespecies, for example, oxygen containing gases, nitrogen containing gases, or hydrogen.

[0087] Referring to FIG. 7B, at operation 620, during the laser lift-off process of operation 620, the first alkali-metal film 241 and the second alkali-metal film 242 are contacted to opposite sides of the flexible substrate stack 130. For example, a surface of the alkali-metal film 241 is contacted to a first surface of the flexible substrate stack 130 and a surface of the alkali-metal film 242 is contacted to a second surface of the flexible substrate stack 130. In some implementations, where the flexible substrate stack 130 only includes the current collector substrate 720, the surface of the alkali- metal film 241 and the surface of the alkali-metal film 242 contact opposite sides of the current collector substrate 720. In some implementations, where the flexible substrate stack 130 includes the anode films 730a-b, the surface of the alkali-metal film 241 contacts the anode film 730a and the surface of the alkali-metal film 242 contacts the anode film 730b to pre-lithiate the anode material.

[0088] The laser lift-off process of operation 620 includes exposing the flexible stack 240 having the alkali-metal films 241 , 242 formed thereon to laser energy, for example, the laser energy supplied by the first laser source assembly 201a and the second laser source assembly 201 b. In one or more implementations, during the laser lift-off process of operation 620, a laser beam 230a-b provided by the laser source assembly 201 a-b is directed through a backside of the polymer substrates 702a-b respectively to activate the interface of the alkali-metal films 241 , 242 the first flexible carrier film 110 and the second flexible carrier film 120, for example, the Li-PET interface. As is shown in FIG. 2, the laser beam 230a-b can be directed through the backside of the first flexible carrier film 110 and the second flexible carrier film 120, for example, from the plastic containing substrate or PET side of the flexible carrier film 110, 120. Exposure to the laser energy can activate not only the alkali-metal film 241 , 242 but also a portion of the first flexible carrier film 110 and the second flexible carrier film 120. For example, exposure to the laser energy can activate a portion of the flexible carrier film 110, 120, for example, the release film 710a-b, a portion of the polymer substrate 702a-b if the release film 710a-b is not present, or both a portion of the flexible carrier film 110, 120, and the release film 710a-b. In one or more implementations, the activated portion can correspond to a void volume. Exposure tothe laser energy can induce an alkali-metal transfer process creating a void volume between the alkali-metal film 241 , 242 and each respective flexible carrier film 110, 120. This void volume can make separation of the alkali-metal film 241 , 242 and each respective flexible carrier film 110, 120 easier during transfer of the alkali-metal film 241 , 242 from the flexible carrier film 110, 120 to the flexible substrate stack 130. The void volume can be formed in a pattern such that portions of the alkali-metal film 241 , 242 that are above the patterned void volume can be more easily removed thus forming a pattern when transferred onto the flexible substrate stack 130. In addition, exposure to the laser beam 230a-b can be used to pattern the alkali-metal film 241 , 242 such that a precise pattern of the alkali-metal film 241 , 242 can be transferred from the flexible carrier film 110, 120 to the flexible substrate stack 130.

[0089] In some implementations, which can be combined with other implementations, the release film 710a-b can be or include a polymer material that is capable of photoinduced depolymerization. Selective exposure of the release film 710a-b and / or the polymer substrate 702a-b during the laser lift-off process can also be utilized for local interface debonding by selective heating of the portions of the release film 710a-b, which can also be used for pattern transfer.

[0090] In some implementations, which can be combined with other implementations, the mechanism of void formation during the laser lift-off process is believed to be a combination of plasma generation by photoionization with recombination of sublimation and lithium.

[0091] Referring to FIG. 7C, at operation 630, the flexible carrier films 110, 120 are peeled away from the flexible substrate stack 130, for example, as the flexible carrier films 110, 120 are conveyed past the rollers 184, 185 as shown in FIG. 1. In some implementations where the release film 710a-b is present, the release film 710a-b is removed with the flexible carrier films 110, 120. Each of the flexible carrier films 110, 120 is then conveyed to the respective pickup hub, for example, the pickup hubs 116, 126.

[0092] Referring to FIG. 7D, optionally at operation 640, a passivation film 750a-b is formed on the newly transferred alkali-metal films 241 , 242. For example, theflexible substrate stack 130 including the newly transferred alkali-metal films 241 , 242 is conveyed into the passivation unit 190, and the newly exposed surfaces of the alkali- metal films 241 , 242 are passivated in the corresponding passivation unit 190.

[0093] In some implementations, carbon dioxide (CO2) is provided to the passivation unit 190 along with one or more of argon (Ar), oxygen (O2), and water vapor to form a passivation film of lithium carbonate (Li2CO3). In other implementations, sulfur hexafluoride (SFe) is provided to the passivation unit 190 along with one or more of argon (Ar), hydrogen (H2), oxygen (O2), and water vapor to form a passivation film of lithium fluoride (LiF), AIOx, AIOOH, or lithium sulfur hexafluoride (LixSFe). Other gases that can be used to form passivation films on an alkali-metal surface include carbon monoxide (CO), carbon tetrafluoride (CF4), ammonia (NH3) as well as other hydrocarbons containing oxide, fluoride, and chloride functional groups and individual element gases.

[0094] In one or more implementations, which can be combined with other implementations, the gases are exposed to UV radiation to form the passivation film 750a-b. The UV radiation can have 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 190. 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. In addition, these wavelengths can split SF6. The thickness of the passivation layers formed on the alkali-metal films 241 , 242 can be from about 1 nm to about 1000 nm, such as from about 10 nm to about 500 nm. 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 implementations, the alkali-metal films 241 , 242 can have a thickness in a range from about 1 micron to about 100 microns, such as about 10 micron.

[0095] In one or more implementations of operation 640 using the passivation unit 190, one or more gases (e.g., CO2) are supplied into the passivation unit 190 and UV energy is directed into interior volumes of the passivation unit 190 to increase the rateof the passivation reactions between the alkali-metal films 241 , 242 and the gases activated by the UV energy. The activated gas energized by the UV energy effectively passivate the alkali-metal films 241 , 242 on the flexible substrate stack 130 by the time the alkali-metal films 241 , 242 and the flexible substrate stack 130 exit the passivation unit 190.

[0096] In one or more implementations, which can be combined with other implementations, the gases are exposed to plasma to form the passivation film 750a- b. In one example, the passivation film 750a-b is formed by exposing the alkali-metal film 241 , 242 to one of CO2 and SFe and argon plasma or other plasma formed from Ar and H2, O2, H2O, CxFy, or a combination thereof. Examples of suitable perfluorocarbon gases include carbon tetrafluoride (CF4), hexafluoroethane (C2F6), hexafluoropropylene (C3F6), perfluorocyclobutane (C4F8), perfluorocyclopentene (C5F8), or a combination thereof.

[0097] In one or more implementations of operation 640 using the passivation unit 190, one or more gases (e.g., CO2) are supplied into the interior volume of the passivation unit 190. RF power is supplied from the corresponding RF power source to electrodes of plasma-generating units positioned in the passivation unit 190 to generate the plasma P in the interior volume in each of the plasma-generating units. The plasma including plasma species (e.g., CO2 ions and radicals) then flows towards the corresponding alkali-metal films 241 , 242 and reacts with the alkali-metal films 241 , 242 to form the passivation films 750a-b on the respective surfaces of the alkali- metal films 241 , 242. The plasma effectively passivates the alkali-metal films 241 , 242 on the flexible substrate stack 130 by the time the alkali-metal films 241 , 242 and the flexible substrate stack 130 exit the passivation unit 190.

[0098] At operation 650, the passivated alkali-metal films 241 , 242 on the flexible substrate stack 130 are conveyed to the pickup hub 136. Because the surfaces of the alkali-metal films 241 , 242 on the flexible substrate stack 130 have been passivated, the alkali-metal films 241 , 242 can remain exposed to an ambient environment, for example including nitrogen, for substantially longer durations without significantly effecting the performance of the alkali-metal films 241 , 242 for eventual use as part of an electrode (e.g., anode) in a lithium-ion battery compared to otherwise similar thealkali-metal films not having passivated surfaces. Furthermore, the passivation of the alkali-metal films 241 , 242 improves the performance of the alkali-metal films 241 , 242 when the alkali-metal films 241 , 242 are used as part of an electrode (e.g., anode) of a lithium-ion battery.

[0099] FIG. 8 illustrates a flowchart showing selected operations of a method 800 of forming an energy storage device via a laser lift-off process in accordance with one or more implementations of the present disclosure. It should also be noted that although the method 800 illustrated in FIG. 8 is described sequentially, other process sequences that include one or more operations that have been omitted and / or added, and / or have been rearranged in another desirable order, fall within the scope of the implementations of the disclosure provided herein. The method 800 may be performed using any of the aforementioned flexible substrate transfer systems 100, 300, 400, and 500. The method 800 is similar to the method 600 except that the lower surface 130L and the upper surface 13011 of the flexible substrate stack 130 are processed sequentially rather than simultaneously.

[0100] At operation 810, a flexible substrate stack 130 and a second flexible carrier film 120 are conveyed toward a laser lift-off unit, for example, the laser lift-off unit 200. The flexible substrate stack 130 can be exposed to a surface activation process prior to the alkali-metal transfer process as described. At operation 820, the second alkali- metal film 242 is contacted to a surface of the flexible substrate stack 130. For example, a surface of the alkali-metal film 242 is contacted to the lower surface 130L of the flexible substrate stack 130. The laser lift-off process of operation 820 includes exposing the second flexible carrier film 120 having the alkali-metal film 242 formed thereon to laser energy, for example, the laser energy supplied by the second laser source assembly 201 b. At operation 830, the second flexible carrier film 120 can be peeled away from the flexible substrate stack 130, for example, as the second flexible carrier film 120 is conveyed past the rollers 382, 383 as shown in FIG. 3. The second flexible carrier film 120 is then conveyed to the respective pickup hub, for example, the pickup hub 126. At operation 840, the flexible substrate stack 130 having the alkali-metal film 242 on the lower surface 130L and the first flexible carrier film 110 are conveyed toward the laser lift-off unit, for example, the laser lift-off unit 200. At operation 820, the first alkali-metal film 241 is contacted to a surface of the flexiblesubstrate stack 130. For example, a surface of the alkali-metal film 241 is contacted to the upper surface 130U of the flexible substrate stack 130. The laser lift-off process of operation 840 includes exposing the first flexible carrier film 110 having the alkali- metal film 241 formed thereon to laser energy, for example, the laser energy supplied by the first laser source assembly 201a. At operation 850, the first flexible carrier film 110 can be peeled away from the flexible substrate stack 130, for example, as the first flexible carrier film 110 is conveyed past the rollers 386, 387 as shown in FIG. 3. At operation 860 the exposed alkali-metal films 241 , 242 may optionally be exposed to a passivation process to form passivation films 750a-b as previously described. At operation 870, the alkali-metal films 241 , 242 on the flexible substrate stack 130 are conveyed to the pickup hub 136. The alkali-metal films 241 , 242 on the flexible substrate stack 130 may be combined with an interleaf film to further protect the alkali- metal films prior to or during rolling on the pickup hub 136.

[0101] FIG. 9 illustrates a flowchart showing selected operations of yet another method 900 of forming an energy storage device via a laser lift-off process in accordance with one or more implementations of the present disclosure. It should also be noted that although the method 900 illustrated in FIG. 9 is described sequentially, other process sequences that include one or more operations that have been omitted and / or added, and / or have been rearranged in another desirable order, fall within the scope of the implementations of the disclosure provided herein. The method 900 may be performed using any of the aforementioned flexible substrate transfer systems 100, 300, 400, and 500. In the method 900 the lower surface 130L and the upper surface 130U of the flexible substrate stack 130 are processed sequentially rather than simultaneously.

[0102] At operation 910, a flexible substrate stack 130, a first flexible carrier film 110, and a second flexible carrier film 120 are conveyed toward a laser lift-off unit, for example, the laser lift-off unit 200. The flexible substrate stack 130 can be exposed to a surface activation process prior to the alkali-metal transfer process as described. At operation 920, first alkali-metal film 241 and the second alkali-metal film 242 are each contacted to opposing surfaces of the flexible substrate stack 130. For example, a surface of the alkali-metal film 242 is contacted to the lower surface 130L of the flexible substrate stack 130 and a surface of the alkali-metal film 241 is contacted toan upper surface 130U of the flexible substrate stack 130. The laser lift-off process of operation 920 includes exposing the second flexible carrier film 120 having the alkali- metal film 242 formed thereon to laser energy, for example, the laser energy supplied by the second laser source assembly 201 b. At operation 930, the second flexible carrier film 120 can be peeled away from the flexible substrate stack 130, for example, as the second flexible carrier film 120 is conveyed past the rollers 482, 483 as shown in FIG. 4. The second flexible carrier film 120 is then conveyed to the respective pickup hub, for example, the pickup hub 126. At operation 940, the flexible substrate stack 130 having the alkali-metal film 242 on the lower surface 130L and the first flexible carrier film 110 and alkali-metal film 241 on the upper surface 13011 of the flexible substrate stack 130 are conveyed toward the laser lift-off unit, for example, the laser lift-off unit 200. The laser lift-off process of operation 940 includes exposing the first flexible carrier film 110 having the alkali-metal film 241 formed thereon to laser energy, for example, the laser energy supplied by the first laser source assembly 201 a. At operation 950, the first flexible carrier film 110 can be peeled away from the flexible substrate stack 130, for example, as the first flexible carrier film 110 is conveyed past the roller 485 as shown in FIG. 4. The first flexible carrier film 110 is then conveyed to the respective pickup hub, for example, the pickup hub 116. At operation 960 the exposed alkali-metal films 241 , 242 may optionally be exposed to a passivation process to form passivation films 750a-b as previously described. At operation 970, the alkali-metal films 241 , 242 on the flexible substrate stack 130 are conveyed to the pickup hub 136. The alkali-metal films 241 , 242 on the flexible substrate stack 130 may be combined with an interleaf film to further protect the alkali-metal films prior to or during rolling on the pickup hub 136.

[0103] FIG. 10 illustrates a schematic view of a flash lamp assembly 1000 in accordance with one or more implementations of the present disclosure. The flash lamp assembly 1000 may be used in place of at least one of the first laser source assembly 201 a and the second laser source assembly 201 b. The flash lamp assembly 1000 may include a flash lamp array featuring a plurality of radiation-emitting lamps, for example, xenon, argon, or krypton discharge lamps. The flash lamp assembly 1000 includes an energy source 1010 for emitting high energy pulses, an ellipticalreflector 1020 that encompasses the energy source 1010 and focuses energy into a narrow line, and an optical assembly 1030.

[0104] The energy source 1010, which may be a light source, is configured to deliver electromagnetic energy during the lift-off process. The energy source 1010 can include radiation-emitting lamps, for example, xenon, argon, or krypton discharge lamps. The energy source 1010 is configured to deliver energy pulses in a range from about 1 microsecond to about 100 milliseconds. The energy pulses create near instantaneous heating of the film surface but low total wattage reduces substrate heating.

[0105] The energy source 1010 is configured to produce energy 1012 and direct it into the optical assembly 1030, which shapes the energy as desired for delivery to the substrate, for example, the first flexible carrier film 110. The optical assembly 1030 generally includes lenses, filters, mirrors, and the like configured to focus, polarize, de-polarize, filter, or adjust coherency of the energy produced by the energy source 1010 with the goal of delivering a uniform column of energy to the substrate. In one or more implementations, which can be combined with other implementations, the optical assembly 1030 includes a broad band filter or grating that is configured to, for example, reflect radiation having a wavelength less than 750 nanometers and pass radiation having a wavelength greater than 750 nanometers.

[0106] The previously described implementations of the present disclosure have many advantages. However, the present disclosure does not require that all the advantageous features and all the advantages need to be incorporated into every implementation of the present disclosure. The transfer process and systems described enable roll-to-roll laser lift-off processing with one or more of the following advantages: patterned lithium transfer, low-pressure calendering lithium transfer, room temperature lithium transfer, lithium surface modification under a controlled environment, faster transfer rate, reuse of the plastic flexible support substrate, no need to slit the web for pattern transfer, simplifies transfer tool architecture and small tool footprint. This transfer process is safe and industrially scalable for high-volume manufacturing. In addition, the ability to transfer lithium in a controlled environmentand the potential to reuse the plastic substrate rolls provides a low-risk commercialization path.

[0107] In the Summary and in the Detailed Description the claims below, and in the accompanying drawings, reference is made to particular features (including method steps) of the present disclosure. It is to be understood that the disclosure in this specification includes all possible combinations of such particular features. For example, where a particular feature is disclosed in the context of a particular aspect or implementation of the present disclosure, or a particular claim, that feature can also be used, to the extent possible in combination with and / or in the context of other particular aspects and implementations of the present disclosure, and in the present disclosure generally.

[0108] The term “comprising,” “including” and “having” and grammatical equivalents thereof are used herein to mean that other components, ingredients, operations, etc. are optionally present. For example, an article “comprising” (or “which comprises”) components A, B, and C can consist of (i.e., contain only) components A, B, and C, or can contain not only components A, B, and C but also one or more other components. In addition, whenever a composition, an element or a group of elements is preceded with the transitional phrase “comprising” or grammatical equivalents thereof, it is understood that it is contemplated that the same composition or group of elements may be preceded with transitional phrases “consisting essentially of,” “consisting of,” “selected from the group of consisting of,” or “is” preceding the recitation of the composition, element, or elements and vice versa.

[0109] Where reference is made herein to a method comprising two or more defined operations, the defined operations can be carried out in any order or simultaneously (except where the context excludes that possibility), and the method can include one or more other operations which are carried out before any of the defined operations, between two of the defined operations, or after all of the defined operations (except where the context excludes that possibility).

[0110] When, in this specification, a range is given as “(a first number) to (a second number)” or “(a first number)-(a second number),” this means a range whose lowerlimit is the first number and whose upper limit is the second number. For example, 25 to 100 mm means a range whose lower limit is 25 mm, and whose upper limit is 100 mm.

[0111] 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.

[0112] 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).

[0113] The term “data processing apparatus” encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers. The apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them. Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer.

[0114] Computer readable media suitable for storing computer program instructions and data include all forms of nonvolatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM,EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and CD ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

[0115] When introducing elements of the present disclosure or exemplary aspects or implementation(s) thereof, the articles “a,” “an,” “the” and “said” are intended to mean that there are one or more of the elements.

[0116] While the foregoing is directed to implementations of the present disclosure, other and further implementations 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

Claims:1 . A flexible substrate processing system, comprising: a first supply hub for supplying a flexible carrier film having an alkali-metal film formed thereover; a second supply hub for supplying a flexible substrate film stack; a first pickup hub for collecting the flexible carrier film after the alkali-metal film is transferred to the flexible substrate film stack; a second pickup hub for collecting the flexible substrate film stack having the alkali-metal film formed thereon; and a laser lift-off unit positioned downstream from the first supply hub and the second supply hub and upstream from the first pickup hub and the second pickup hub, the laser lift-off unit, comprising: a laser source configured to generate laser energy, the laser energy directed toward a first surface of the flexible carrier film; and an optical scanner configured to direct the laser energy toward the first surface of the flexible carrier film.

2. The flexible substrate processing system of claim 1 , further comprising: a pair of rollers positioned downstream of the first supply hub and the second supply hub and upstream of the laser source, the pair of rollers configured to contact the alkali-metal film to the flexible substrate film stack.

3. The flexible substrate processing system of claim 2, wherein the pair of rollers comprise at least one nip roller.

4. The flexible substrate processing system of claim 2 wherein the pair of rollers comprise at least one calender roller.

5. The flexible substrate processing system of claim 1 , wherein the laser source is selected from an infrared (IR) fiber laser, an ultraviolet (UV) laser, or a Green Laser.

6. The flexible substrate processing system of claim 1 , wherein the optical scanner is a single- or multi-axis large angle galvanometer optical scanner.

7. The flexible substrate processing system of claim 1 , wherein the optical scanner is a polygon scanner, an electro-optic scanner, an acousto-optic, or a combination thereof.

8. The flexible substrate processing system of claim 1 , further comprising: a passivation unit positioned downstream from the laser lift-off unit and upstream from the second pickup hub, the passivation unit positioned to passivate the alkali-metal film formed on the flexible substrate film stack.

9. The flexible substrate processing system of claim 1 , further comprising: an inline slitting assembly comprising a blade for cutting the flexible carrier film, the inline slitting assembly positioned downstream from the laser lift-off unit and upstream from the first pickup hub.

10. A flexible substrate processing system for forming an energy storage device, comprising: a laser lift-off unit, comprising: a laser source configured to generate laser energy, the laser energy directed toward a first surface of a flexible carrier film; and an optical scanner configured to direct the laser energy toward the first surface of the flexible carrier film; and a system controller configured to cause the laser lift-off unit to perform a process, comprising: conveying a flexible carrier film stack comprising the flexible carrier film having an alkali-metal film formed thereover from a supply hub toward a pickup hub; contacting the flexible carrier film stack with a flexible substrate film stack, wherein the alkali-metal film contacts the flexible substrate film stack; exposing the first surface of the flexible carrier film stack to the laser energy to separate the flexible carrier film from the alkali-metal film; and removing the flexible carrier film from the flexible substrate film stack.11 . The flexible substrate processing system of claim 10, wherein the laser source is selected from an infrared (IR) fiber laser, an ultraviolet (UV) laser, or a Green Laser.

12. The flexible substrate processing system of claim 10, wherein the optical scanner is a single- or multi-axis large angle galvanometer optical scanner.

13. The flexible substrate processing system of claim 10, further comprising: a pair of rollers positioned upstream of the laser source, the pair of rollers contacting the flexible carrier film stack with the flexible substrate film stack.

14. The flexible substrate processing system of claim 13, wherein the pair of rollers comprise at least one nip roller.

15. The flexible substrate processing apparatus of claim 13, wherein the pair of rollers comprise at least one calender roller.

16. A method of forming a film stack for an energy storage device, comprising: conveying a flexible carrier film stack comprising a flexible carrier film having an alkali-metal film formed thereover from a supply hub toward a pickup hub; contacting the flexible carrier film stack with a flexible substrate film stack, wherein the alkali-metal film contacts the flexible substrate film stack; exposing a first surface of the flexible carrier film stack to laser energy to separate the flexible carrier film from the alkali-metal film; and removing the flexible carrier film from the flexible substrate film stack.

17. The method of claim 16, exposing the first surface of the flexible carrier film stack to laser energy to separate the flexible carrier film from the alkali-metal film comprises patterning the alkali-metal film by exposing portions of the alkali-metal film to the laser energy.

18. The method of claim 17, wherein the laser energy is directed through a backside of the flexible carrier film.

19. The method of claim 17, wherein exposing the first surface of the flexible carrier film stack to laser energy creates a void volume between the alkali-metal film and the flexible carrier film stack.

20. The method of claim 17, wherein the flexible carrier film stack further comprises a release layer disposed between the flexible carrier film and the alkali-metal film, the release layer is capable of photoinduced depolymerization.

Images