Free-span coating systems and methods therefor

Abstract

To provide a method and an apparatus for continuous web processing systems for pre-lithiating Li-ion battery substrates.SOLUTION: A modular processing system comprises a common transfer chamber body defining transfer volume. The system further comprises a first vertical chamber body defining first processing volume and positioned on the common transfer chamber body. The transfer volume is in fluid communication with the first processing volume. The system further comprises a second vertical chamber body defining second processing volume and positioned on the common transfer chamber body. The transfer volume is in fluid communication with the second processing volume. The system further comprises a reel-to-reel system operable to transport a continuous flexible substrate having an electrode structure formed thereon. The continuous flexible substrate extends from the transfer volume, through the first processing volume, returning to the transfer volume, through the second processing volume, and returning to the transfer volume.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001]

[0001] FIELD OF THE DISCLOSURE

[0002] The embodiments described herein relate generally to a continuous web processing system, and more particularly, to a continuous web processing system for prelithiating lithium ion battery substrates. [Background technology]

[0002]

[0002] Rechargeable electrochemical energy storage systems are becoming increasingly important in everyday life. Large-capacity electrochemical energy storage devices, such as lithium-ion (Li-ion) batteries, are being used in an increasing number of applications, including portable electronics, healthcare, transportation, large-scale grid-connected energy storage, renewable energy storage and uninterruptible power supplies (UPS).

[0003]

[0003] Lithium batteries generally do not contain metallic lithium for safety reasons, and instead use graphite materials as the anode. However, the use of graphite, which can be charged up to the limit composition LiC6, results in a significant reduction in capacity compared to the use of silicon-blended graphite. Currently, the industry is moving away from graphite-based anodes to silicon-blended graphite to increase the density of energy batteries. However, silicon-blended graphite anodes suffer from first cycle irreversible capacity fade (IRC). The specific energy and energy density of lithium-ion batteries are significantly reduced during the first cycle charge due to active lithium loss when approximately 5-20% of the lithium from the cathode is consumed by solid electrolyte interphase formation ("SEI") in the anode.

[0004]

[0004] Prelithiation of anodes before the first cycle charge is a common strategy to compensate for the activity loss of lithium. Prelithiation also provides other benefits to improve the performance and reliability of lithium-ion batteries. For example, prelithiation can reduce the impedance of lithium-ion batteries, which improves the rate capability. Furthermore, for silicon-based anodes, prelithiation can pre-expand the silicon to improve the mechanical stability of the anode, suppressing silicon cracking and pulverization.

[0005]

[0005] There are various methods for prelithiation of the anode, including chemical prelithiation, electrochemical prelithiation, prelithiation by direct contact with lithium metal, stabilized lithium metal powder (SLMP), etc. However, these various methods for prelithiation of the anode are not suitable for mass production of lithium-ion batteries due to their long reaction times and inherent safety concerns.

[0006]

[0006] Thus, there is a need for a prelithiation apparatus and method to replace lithium in various electrode structures lost due to irreversible first cycle capacity fade.

[0007] [Summary of the Invention]

[0007] SUMMARY OF THE DISCLOSURE The embodiments described herein generally relate to continuous web processing systems, and more particularly, to continuous web processing systems for prelithiating lithium ion battery substrates. In one embodiment, a modular processing system is provided. The system includes a common transfer chamber body defining a transfer volume. The system further includes a first vertical chamber body defining a first processing volume and disposed on the common transfer chamber body. The transfer volume is in fluid communication with the first processing volume. The system further includes a second vertical chamber body defining a second processing volume and disposed on the common transfer chamber body. The transfer volume is in fluid communication with the second processing volume. The system further includes a reel-to-reel system operable to transport a continuous flexible substrate having an electrode structure formed thereon. The continuous flexible substrate is transported from the transfer volume through the first processing volume, back to the transfer volume, through the second processing volume, and back to the transfer volume.

[0008]

[0008] In another embodiment, a modular processing system is provided. The processing system includes a reel-to-reel system operable to transport a continuous flexible substrate having an electrode structure formed thereon. The reel-to-reel system includes an unwinding reel on which the continuous flexible substrate is wound prior to processing and operable to unwind and release the continuous flexible substrate for processing. The reel-to-reel system further includes a take-up reel operable to receive the continuous flexible substrate after processing and operable to wind the continuous flexible substrate thereon. The reel-to-reel system further includes a plurality of auxiliary tension reels disposed on a path between the unwinding reel and the take-up reel and operable to guide the continuous flexible substrate. The processing system further includes a common transfer chamber body defining a transfer volume. The processing system further includes a first vertical chamber body defining a first processing volume and disposed on the common transfer chamber body. The transfer volume is in fluid communication with the first processing volume. The processing system further includes a second vertical chamber body defining a second processing volume and disposed on the common transfer chamber body. The transfer volume is in fluid communication with the second processing volume. The continuous flexible substrate extends from the transfer volume, through the first processing volume, back to the transfer volume, through the second processing volume, and back to the transfer volume.

[0009]

[0009] In yet another embodiment, a method of forming a prelithiated electrode on a flexible substrate is provided. The method includes transferring a continuous flexible substrate to a first processing region of a first vertical processing module. The continuous flexible substrate comprises an electrode structure. The method further includes subjecting the continuous flexible substrate to a free-span prelithiation while transferring the continuous flexible substrate to the first processing region. The method further includes transferring the continuous flexible substrate from the first processing region through a common transfer volume to a second processing region of a second vertical processing chamber. The method further includes exposing the continuous flexible substrate to a free-span passivation treatment while transferring the continuous flexible substrate through the second processing region.

[0010]

[0010] In order that the above-mentioned features of the present disclosure may be understood in detail, a more particular description of the briefly summarized embodiments may be rendered with reference to the embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings only illustrate exemplary embodiments of the present disclosure and are not to be considered as limiting its scope, since the present disclosure includes other equally effective embodiments. [Brief description of the drawings]

[0011] [Figure 1] 1A shows a cross-sectional view of one embodiment of an energy storage device including a prelithiated electrode structure formed according to embodiments described herein, and FIG. 1B shows a cross-sectional view of a double-sided electrode structure prelithiated according to embodiments described herein. [Diagram 2] 1 is a schematic side view of a modular substrate processing system in accordance with one or more embodiments of the present disclosure. [Diagram 3] 3 shows a schematic side view of a vertical processing module usable in the modular processing system of FIG. 2. [Figure 4]1 shows a process flow diagram summarizing one embodiment of a process sequence for prelithiation and passivation of an electrode structure in accordance with one or more embodiments of the present disclosure.

[0012]

[0016] For ease of understanding, the same reference numerals are used, where possible, to designate identical elements common to the figures, and it is contemplated that elements or features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

[0013] [Detailed Description of the Invention]

[0017] The following disclosure describes prelithiated electrodes, high performance electrochemical cells and batteries including said prelithiated electrodes, and apparatus and methods for making the same. Certain details are set forth in the following description and in Figures 1A-4 to provide a thorough understanding of the various embodiments of the present disclosure. Other details describing well-known structures and systems often associated with electrochemical cells and batteries are not set forth in the following disclosure to avoid unnecessarily obscuring the description of the various embodiments.

[0014]

[0018] Many of the details, dimensions, angles, and other features shown in the drawings are merely illustrative of particular embodiments. Thus, other embodiments can have other details, components, dimensions, angles, and features without departing from the spirit or scope of the present disclosure. Furthermore, further embodiments of the present disclosure can be practiced without some of the details described below.

[0015]

[0019] The embodiments described herein are described below with reference to a roll-to-roll coating system. The apparatus description described herein is exemplary and should not be construed or understood as limiting the scope of the embodiments described herein. Also, although described as a roll-to-roll process, it should be understood that the embodiments described herein can be performed on separate substrates.

[0016]

[0020] In the embodiments described herein, a free-span coating system suitable for prelithiation of flexible substrates, such as webs for lithium-ion battery devices, is described. In particular, the free-span coating system is suitable for continuously processing flexible substrates, such as webs unwound from an unwinding module. The free-span coating system is configured in a modular design, e.g., a suitable number of process modules may be arranged adjacent to each other in a processing line, where the flexible substrate is inserted into the first process module and discharged from the last process module in the line. Furthermore, the entire free-span coating system may be reconfigured if modifications of individual processing operations are desired.

[0017]

[0021] It should be noted that the particular substrate on which some of the embodiments described herein may be practiced is not limited, but it is particularly beneficial to practice the embodiments on flexible substrates, including, for example, web-based substrates, panels, separate sheets, and the substrate may be in the form of a foil, film, or thin plate.

[0018]

[0022] It should also be noted here that the flexible substrate or web used in the embodiments described herein is typically characterized as being capable of being bent. The term "web" is sometimes used synonymously with the term "strip" or the term "flexible substrate." For example, the web described in the embodiments herein may be a foil.

[0019]

[0023] Further, it should be noted that in some embodiments where the substrate is a vertically oriented substrate, the vertically oriented substrate may be angled with respect to the vertical plane. For example, in some embodiments, the substrate may be angled between about 1 degree and about 20 degrees from the vertical plane. In some embodiments where the substrate is a horizontally oriented substrate, the horizontally oriented substrate may be angled with respect to the horizontal plane. For example, in some embodiments, the substrate may be angled between about 1 degree and about 20 degrees from the horizontal plane. As used herein, the term "vertical" is defined as the major surface or deposition surface of the flexible conductive substrate being perpendicular to the horizontal plane. As used herein, the term "horizontal" is defined as the major surface or deposition surface of the flexible conductive substrate being parallel to the horizon.

[0020]

[0024] Also, note that free span coating refers to a web coating apparatus or process in which the web is not in contact with the surface during the actual deposition portion of the web coating process.

[0021]

[0025] The web of substrate material may advance continuously through a line of interconnected process modules. In each process module, a portion of the prelithiation process may be performed. For example, if a lithium ion device includes an anode structure, one or more process modules may be suitable for prelithiating the anode structure, and one or more subsequent process modules may be suitable for forming a protective coating or "passivation coating" over the prelithiated anode structure.

[0022]

[0026] The specific energy and energy density of lithium-ion batteries are significantly degraded by active lithium loss during the first cycle charge. Prelithiation of the anode before the first cycle charge is a common strategy to compensate for the active lithium loss. In addition, prelithiation brings other performance and reliability benefits to lithium-ion batteries. For example, prelithiation reduces the impedance of lithium-ion batteries, thereby improving their rate capability. In addition, for silicon (Si)-based anodes, prelithiation can reduce silicon cracking and pulverization by pre-expanding the silicon to increase the mechanical stability of the anode.

[0023]

[0027] There are various methods for prelithiation of the anode, including chemical prelithiation, electrochemical prelithiation, prelithiation by direct contact with lithium metal, stabilized lithium metal powder (SLMP), etc. These existing methods share drawbacks such as long reaction times and inherent safety concerns, making them unsuitable for mass production of lithium-ion batteries.

[0024]

[0028] SLMPs have a maximum of 30% of the Li2CO3 powder shell remaining uncracked, which introduces inert material into the cell material, thereby reducing the energy density of Li-ion batteries. Loose powder particles dislodged into the electrolyte as the SLMP spreads pose inherent safety and reliability hazards. Electrochemical prelithiation generates reactive materials in the surrounding air, which can increase cell impedance due to nitrogen and oxygen contamination. Direct contact with lithium metal is a non-uniform, low-yield process, hindered by a non-continuous thin lithium metal foil, up to 60 centimeters wide and 20 meters long. Also, with the exception of electrochemical prelithiation, lithium-ion batteries produced by the aforementioned prelithiation methods can perform less well than lithium-ion batteries prelithiated by methods involving reactive lithium ions. Reactive lithium ions are more effective than metallic lithium, as they can penetrate and intercalate into the electrode pores and form lithium alloys throughout the graphite composite.

[0025]

[0029] One prelithiation approach involving reactive lithium ions is vacuum thermal evaporation. In thermal evaporation, lithium is heated to produce a vapor composed of clusters of lithium atoms. The flux and residual heat of the lithium cluster vapor material are controlled by the lithium heating mode. The pool of molten lithium can be heated and controlled using an electron beam, plasma, or resistive heating source. As electrochemical prelithiation proceeds, thermal evaporation provides highly reactive lithium ions that can form an alloy in the anode. Unlike electrochemical prelithiation, thermal evaporation is a vacuum process, and the reactive materials are isolated from oxygen and other species that may contaminate the anode. In addition, in terms of minimizing contamination, vacuum processing at pressures below 10E-04 Torr has the added benefit of being able to dehydrate residual moisture in the anode more effectively than furnace heat treatments, which are typically performed at higher pressures.

[0026]

[0030] Thermal evaporation is believed to facilitate high quality and controllable prelithiation. However, traditional thermal evaporation strategies have been prohibitively expensive in terms of capital, energy and maintenance costs. Nowadays, the demand for advanced electrode active materials is growing, which offers advantages to vacuum thermal evaporation. To achieve a cost-competitive thermal evaporation process, the design and operation of web coating systems are required according to the electrode application. The optimal prelithiation process to compensate for active lithium loss is to alloy reactive lithium ions with graphite, silicon and / or other anode components to replace the lithium consumed during SEI formation. The optimal production-worthy manufacturing method is to web process anode substrates more than one meter wide and several thousand meters long at web speeds of about 40 meters per minute or more.

[0027]

[0031] Conventional web handling systems do not allow for safe lithium thermal evaporation, let alone double-sided coating. Thus, there is a need for a vacuum thermal evaporation prelithiation system and method that can meet the mass production goals of lithium-ion batteries in terms of device performance, yield, throughput, and cost.

[0028]

[0032] In some embodiments of the present disclosure, a free-span coating system with a cooling roller that facilitates multi-pass lithium-ion battery prelithiation is provided. In some embodiments, the free-span coating system has modular elements including at least one of a deposition chamber, a cooling turn-back chamber, and one or more load lock chambers. Thus, each modular element can be positioned, repositioned, replaced, or maintained independently without affecting the other.

[0029]

[0033] Freespan coating systems are designed to produce single-sided or double-sided coatings depending on the specific application. In some embodiments, freespan coating systems are designed to facilitate the deposition of multiple reactive materials at different temperatures. In some embodiments, non-contact pyrometers and thermocouples are used to measure temperature and monitor hot zones. In some embodiments, quartz crystal monitors and residual gas analyzers are used to verify deposition rate.

[0030]

[0034] In some embodiments, the free-span coating system is used in spatial or temporal conversion mode to produce films of uniform thickness by adjusting the processing time or processing length depending on the specific application. In some embodiments, additional modular processing chambers with similar process kits are installed to process the web at a higher speed instead of increasing the temperature, which may damage the web. In some embodiments, gas separation is achieved by a common transfer chamber located below the deposition chamber. In some embodiments, the web is cooled before leaving the deposition chamber and entering the common transfer chamber to minimize wrinkling of the web on the rollers of the transfer chamber.

[0031]

[0035] In some embodiments, cooling is accomplished by passing the web between two fluid cooling plates coupled through a suitable coupling gas such as argon or helium, hi some embodiments, cooling is accomplished through the use of cooling plates, cooling drums, and / or cooling rollers.

[0032]

[0036] In some embodiments, the free-span coating system includes features for efficient service and maintenance, such as making the entire modular deposition chamber conveniently removable from the transfer chamber to facilitate safe handling of lithium.

[0033]

[0037] In some embodiments, the free-span coating system is operable to simultaneously prelithiate both sides of a battery electrode. Alternative systems that perform single-pass double-sided coating around two cooling drums are expensive, prone to web wrinkling and surface defects, have low throughput, and are difficult to control prelithiation. In addition, depending on the cooling drum design, parasitic deposition can occur and heat transfer coefficients can drift. In some embodiments, the free-span coating system operates without cooling drums, thereby minimizing parasitic surface area.

[0034]

[0038] In some embodiments, prelithiating coated electrodes using the systems described herein can (1) improve the energy density (kWh) of lithium-ion batteries and (2) reduce the loading of cathode coatings for anode / cathode balancing, particularly the costly elements cobalt and nickel. Thus, in some embodiments, the free-span coating systems described herein directly impact the cost / kWh figure, which is the primary benefit used in the manufacture of lithium-ion batteries. The free-span coating systems described herein are suitable for prelithiating either negative or positive coated electrodes. The free-span systems described herein provide battery manufacturers with greater flexibility in cell balancing, for example, to independently match the capacity of reversible and non-reversible cathodes / anodes.

[0035]

[0039] In some embodiments, a proximity coupled gas diffuser is used to achieve vertical free span coating.

[0036]

[0040] FIG. 1A is a cross-sectional view of one embodiment of an energy storage device 100 including a prelithiated electrode structure formed according to embodiments described herein. The energy storage device 100 may be a lithium ion energy storage device using a solid electrolyte (e.g., a solid-state battery) or a lithium ion energy storage device using a liquid or polymer electrolyte. The power storage device 100 has a positive electrode current collector 110, a positive electrode structure 120, a separator 130, a negative electrode structure 140, and a negative electrode current collector 150. At least one of the positive electrode structure 120 and the negative electrode structure 140 is prelithiated according to embodiments described herein. It should be noted that while the current collector is shown in FIG. 1A as extending beyond the stack, the current collector need not extend beyond the stack and the portion extending beyond the stack may be used as a tab.

[0037]

[0041] The current collectors 110, 150 on the positive and negative electrode structures 120, 140, respectively, may be the same or different electronic conductors. Examples of metals that may comprise the current collectors 110, 150 include aluminum (Al), copper (Cu), zinc (Zn), nickel (Ni), cobalt (Co), tin (Sn), silicon (Si), manganese (Mn), magnesium (Mg), alloys thereof, and combinations thereof. In some embodiments, the current collectors 110, 150 are comprised of metals deposited on a polymer substrate.

[0038]

[0042] The negative electrode structure 140 or anode can be any material compatible with the positive electrode structure 120. In some embodiments, the negative electrode structure 140 is prelithiated according to the embodiments described herein. In some embodiments, the negative electrode structure 140 has an energy capacity of 372 mAh / g or more, preferably 700 mAh / g or more, and most preferably 1000 mAh / g or more. In some embodiments, the negative electrode structure 140 is composed of carbonaceous materials (e.g., natural or synthetic graphite), silicon-containing graphite, silicon, nickel, copper, tin, indium, aluminum, silicon, oxides thereof, combinations thereof, or mixtures of lithium metal and / or lithium alloys with materials such as carbon (e.g., coke, graphite), nickel, copper, tin, indium, aluminum, silicon, oxides thereof, or combinations thereof. Suitable examples of carbonaceous materials include natural and synthetic graphite, partially graphitized or amorphous carbon, petroleum, coke, needle coke, and various intermediate phases. In some embodiments, the negative electrode structure 140 includes a lithium-containing intercalation compound or a lithium-containing insertion compound. In some embodiments, the negative electrode structure 140 is a silicon-graphite anode.

[0039]

[0043] In some embodiments, the materials forming the anode structure 140 are in dispersed form, such as powder, fiber, or flakes. In some embodiments, the anode structure 140 is manufactured by any method known in the art, such as preparing a slurry from a carbonaceous powder and a binder agent, applying the slurry onto / in a current collector, and drying. If used, the binder agent can be selected from compounds including, but not limited to, polyvinylidene fluoride (PVDF), ethylene propylene diene monomer (EPDM), ethylene vinyl acetate copolymer (EVA), and combinations thereof.

[0040]

[0044] The positive electrode structure 120, or cathode, may be any material compatible with the anode and may include an intercalation compound, an insertion compound, or an electrochemically active polymer. In some embodiments, the positive electrode structure 120 is prelithiated according to embodiments described herein. Suitable intercalation materials include, for example, lithium-containing metal oxides, MoS2, FeS2, MnO2, TiS2, NbSe3, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, V6O 13 and V2O5. Suitable lithium-containing oxides may be layered, such as lithium cobalt oxide (LiCoO2), LiNi x Co 1-2x MnO2, LiNiMnCoO2 (“NMC”), LiNi 0.5 Mn 1.5 O4, Li(Ni 0.8 Co 0.15 Al 0.05 )O2, LiMn2O4, and doped lithium-rich layered materials, where x is zero or a non-zero number. Suitable phosphates include iron olivine (LiFePO4) and its variants (LiFe (1-x) Mg x PO4), LiMoPO4, LiCoPO4, LiNiPO4, Li3V2(PO4)3, LiVOPO4, LiMP2O7, or LiFe 1.5 P2O7, where x is zero or a non-zero number. Exemplary fluorophosphates can be LiVPO4F, LiAlPO4F, Li5V(PO4)2F2, Li5Cr(PO4)2F2, Li2CoPO4F, or Li2NiPO4F. Exemplary silicates can be Li2FeSiO4, Li2MnSiO4, or Li2VOSiO4. An exemplary non-lithium compound is Na5V2(PO4)2F3.

[0041]

[0045] In some embodiments of lithium-ion batteries according to the present disclosure, lithium is contained in atomic layers of a crystal structure of carbon graphite (LiC6) in the negative electrode and lithium manganese oxide (LiMnO4) or lithium cobalt oxide (LiCoO2) in the positive electrode. In some embodiments, the negative electrode may also contain lithium storage materials such as silicon and / or tin. Also, the cells are shown as planar structures, may be formed into cylinders by rolling up a stack of layers, and other cell configurations (e.g., prismatic cells, button cells) may be formed.

[0042]

[0046] In some embodiments, separator 130 is a porous, ion-conducting polymer substrate. In some embodiments, the porous polymer substrate is a multi-layer polymer substrate. In some embodiments, separator 130 comprises any commercially available polymeric microporous membrane (e.g., monolayer or multilayer), such as those available from Polypore (Celgard® LLC, Charlotte, North Carolina), Toray Tonen (battery separator membrane (BSF)), SK Energy (lithium ion battery separator (LiBS)), Evonik Industries (SEPARION® ceramic separator membrane), Asahi Kasei (Hipore™ polyolefin flat film membrane), DuPont (Energain®), and others.

[0043]

[0047] In some embodiments, the electrolyte injected into the cell components 120, 130, and 140 may be composed of a liquid / gel or a solid polymer, each of which may be different. In some embodiments, the electrolyte primarily comprises a salt and a medium (e.g., in a liquid electrolyte, the medium may be referred to as a solvent, and in a gel electrolyte, the medium may be a polymer matrix). The salt may be a lithium salt. The lithium salt may include, for example, LiPF6, LiAsF6, LiCF3SO3, LiN(CF3SO3)3, LiBF6, and LiClO4, BETTE electrolyte (commercially available from 3M Corp., Minneapolis, Minnesota), and combinations thereof.

[0044]

[0048] FIG. 1B is a cross-sectional view of a double-sided electrode structure 170 prelithiated according to embodiments described herein. Although the double-sided electrode structure 170 is depicted as a double-sided electrode structure, it should be understood that the embodiments described herein also apply to single-sided electrode structures. The double-sided electrode structure 170 includes a negative electrode current collector 150 having anode structures 140a, 140b (collectively 140) formed on both sides of the negative electrode current collector 150. The anode structures 140a, 140b each have a passivation film 160a, 160b (collectively 160) formed thereon, respectively, to protect the anode structure 140 from contaminants such as oxidizing agents in the environment. In some embodiments, the passivation film 160 is permeable to at least one of lithium ions and lithium atoms. The passivation film 160 provides surface protection for the anode structure 140, allowing the anode structure 140 to be handled in a dry room and contributing to stable SEI formation. Examples of materials that can be used to form the passivation film 160 include, but are not limited to, lithium fluoride (LiF), lithium carbonate (Li2CO3), lithium oxide, lithium nitride (Li3N), lithium phosphate (Li3PO4), lithium chloride (LiCl), lithium alkylsilanolate-based films, lithium alkylsiloxane-based films, polymer films that do not react with lithium, such as polyethylene (PE), polypropylene (PP), and polystyrene (PS), polymer films that react with lithium, such as poly(acrylic acid), and ethylene vinyl acetate, or combinations thereof. In some embodiments, the passivation film 160 can be formed on the anode structure 140 by deposition techniques, such as chemical vapor deposition (CVD), atomic layer deposition (ALD), and physical vapor deposition (PVD), such as thermal evaporation and sputtering. In some embodiments, the passivation film 160 is deposited on the anode structure 140 above the melting point of lithium to promote chemical bonding. In some embodiments, the passivation film 160 can be deposited below the melting point of lithium and then the anode structure 140 can be heat treated to above the melting point of lithium.

[0045]

[0049] In some embodiments, the passivation film 160 may be a conformal coating or a separate film, with a thickness ranging from 1 nanometer to 2000 nanometers (e.g., 10 nanometers to 600 nanometers; 50 nanometers to 100 nanometers; 50 nanometers to 200 nanometers; 100 nanometers to 150 nanometers). In some embodiments, the passivation film 160 is a separate film with a thickness ranging from 1 micron to 50 microns (e.g., 1 micron to 25 microns). Coating process parameters control the protective surface properties of the passivation film 160, including, for example, mechanical durability, hydrophobicity, and adhesion. The properties of the passivation film 160 can be optimized to minimize reactions with air, extend the usable shelf life of the coated web, ease manufacturability of the battery substrate and device, including handling of the web, and contribute to stable SEI formation during battery assembly and charging.

[0046]

[0050] FIG. 2 illustrates a schematic side view of a modular free-span coating system 200 according to one or more embodiments of the present disclosure. The modular free-span coating system may be operable for either single-sided or double-sided processing of a flexible web. In some embodiments, the modular free-span coating system 200 is operable for prelithiating a cathode or anode structure formed on a flexible substrate. The modular free-span coating system 200 is configured as a roll-to-roll system including an upstream unwind module 202, a common transfer chamber 220, a number of vertical processing modules 210a, 210b...210n (collectively 210), and a downstream take-up module 204. In some embodiments, the vertical processing modules 210a, 210b...210n are arranged in series and each configured to perform one processing operation on a continuous flexible substrate 230. Each vertical processing module 210 is operable to perform a free-span coating process on a continuous flexible substrate 230, which is vertically oriented within the vertical processing module 210 during the free-span coating process.

[0047]

[0051] As shown in FIG. 2, vertical processing modules 210a, 210b, . . . 210n are arranged on a common transfer chamber 220. A continuous flexible substrate 230 is shown inserted into the first vertical processing module 210a and, after a suitable processing operation or step, ejected from the last vertical processing module 210n. Thus, each vertical processing module 210a-210n has an upstream component where the substrate is inserted into the process module and a downstream component where the substrate is ejected from the process module, such as an upstream unwind module 202 and a downstream take-up module 204. In some embodiments, the upstream unwind module 202 and the downstream take-up module 204 are located in separate chambers (e.g., a take-up chamber and an unwind chamber).

[0048]

[0052] In some embodiments, the continuous flexible substrate 230 is provided as a web wound into a roll and has a width in the range of 15 cm to 160 cm, typically about 300 cm. In some embodiments, the continuous flexible substrate 230 has a thickness in the range of 8 μm to 200 μm, for example about 50 μm. The continuous flexible substrate 230 has a front surface 234 and a back surface 236. In some embodiments, the continuous flexible substrate 230 includes a flexible material having an electrode structure formed thereon. The electrode structure may be an anode structure or a cathode structure. For example, the flexible substrate may be a negative electrode current collector 150 having a negative electrode structure 140 formed thereon, as shown in FIG. 1B. In some embodiments, only the front surface 234 of the flexible substrate has an electrode structure formed thereon. In some embodiments, both the front surface 234 and the back surface 236 have an electrode structure formed thereon.

[0049]

[0053] The common transfer chamber 220 includes a common transfer chamber body 222 that defines a transfer volume 224. In some embodiments, the common transfer chamber body 222 is fabricated from standard materials such as aluminum, quartz, ceramic, or stainless steel. The common transfer chamber body 222 includes a plurality of through-holes 226a-226h (collectively 226) for accommodating a continuous flexible substrate 230. The plurality of through-holes 226 are typically aligned with corresponding through-holes in the vertical chamber body 240 of each corresponding vertical processing chamber 210. Each through-hole 226 in the common transfer chamber body 222 is sized to accommodate the continuous flexible substrate 230 while allowing differential pumping between the processing volumes 244a, 244b, . . . 244n (collectively 244) of each vertical processing module 210 and the transfer volume 224. The processing volume 244 is in fluid communication with the transfer volume 224. In some embodiments, the processing volume 244 is a vacuum processing volume. In some embodiments, an inert gas environment is maintained in the transfer volume 224. This inert gas environment in the transfer volume 224 isolates (e.g., provides gas isolation) the process volume 244 (which may be a vacuum process volume) of each vertical processing module 210 from the process volumes 244 of other vertical processing modules 210 disposed on the common transfer chamber 220. This isolation allows the use of incompatible chemicals in the different vertical processing modules 210. The inert gas flows between adjacent vertical processing modules to prevent diffusion of precursor gas mixtures between adjacent vertical processing modules. In some embodiments, the common transfer chamber 220 is coupled to a pressure control system (not shown) that pumps down and vents the common transfer chamber 220 as needed to facilitate the passage of the continuous flexible substrate 230 between the vacuum environment of one vertical processing chamber and a substantially ambient (e.g., atmospheric) environment outside the modular freespan coating system 200.

[0050]

[0054] In some embodiments, the vertical processing modules 210a-210n are stand-alone modular processing chambers, with each modular processing chamber being structurally isolated from the other modular processing chambers and the common transfer chamber 220. Thus, each of the stand-alone vertical processing modules 210a-210n can be independently positioned, rearranged, replaced, or maintained without affecting the other vertical processing modules. Although three vertical processing modules 210a, 210b, and 210n are shown, it should be understood that any number of vertical processing modules may be included in the modular freespan coating system 200. For example, in some embodiments, two, three, four, five, or more vertical processing modules 210 are included in the modular freespan coating system 200.

[0051]

[0055] The lateral dimensions of the modular free-span coating system 200, e.g., the dimensions extending in the substrate transport direction 232, are reduced by vertically arranging the processing chambers of the individual vertical processing modules 210a-210n. Moreover, the embodiments described herein provide horizontal movement of the continuous flexible substrate 230 from one module to the next, and thus horizontal web control. Furthermore, the arrangement of the modular system provides vertical movement of the continuous flexible substrate 230 during prelithiation of electrode structures on the continuous flexible substrate 230. This reduces the likelihood of loose graphite and parasitic particles from the deposition process that may occur in the deposition region (which may cause damage to the deposition layer, e.g., by particle flaking) falling onto the front surface of the continuous flexible substrate 230.

[0052]

[0056] In some embodiments of the present disclosure, only two vertical processing modules 210a, 210b are presented, but additional vertical processing modules 210n may be included depending on the prelithiation process of interest. For example, in some embodiments where only two vertical processing modules 210 are present, the first vertical processing module 210a is operable to perform a thermal evaporation prelithiation process, and the second vertical processing module 210b is operable to form a passivation film on the prelithiated electrodes. In some embodiments where more than two vertical processing modules 210 are present, multiple vertical processing modules 210 may be dedicated for the prelithiation process and / or the passivation process. In some embodiments, additional vertical processing modules 210 are added, and the additional vertical processing modules 210 are operable to perform additional surface treatment processes, such as a corona surface treatment process, a pre-cleaning process, or a post-cleaning process.

[0053]

[0057] In some embodiments, the vertical processing module 210 includes a vertical chamber body 240a, 240b, . . . 240n (collectively 240). In some embodiments, the vertical chamber body 240 is fabricated from standard materials such as aluminum, quartz, ceramic, or stainless steel. Partition plates 242a, 242b, . . . 242n (collectively 242 hereafter) extend across an interior volume defined by the vertical chamber body 240. The partition plate 242 separates the interior volume into a processing volume 244 for processing the continuous flexible substrate 230 and a turn-back volume 246a, 246b, . . . 246n (collectively 246) for reversing the direction of the continuous flexible substrate 230. The partition plate 242 includes a plurality of through holes 243a-243f (collectively 243) for accommodating the continuous flexible substrate 230. Each through-hole 243 in the divider plate 242 is sized to accommodate a continuous flexible substrate 230 while allowing differential pumping between the process volume 244 and the foldback volume 246 .

[0054]

[0058] Although the processing volume 244 and the turn-down volume 246 are shown as sharing a common chamber body, it should be understood that in some embodiments, the processing volume 244 and the turn-down volume 246 are defined by separate chamber bodies, with the chamber body defining the turn-down volume 246 stacked on the chamber body defining the processing volume 244. For example, in some embodiments, the vertical processing module 210 includes a deposition chamber that defines the processing volume 244 and a separate turn-down chamber that defines the turn-down volume 246. The deposition chamber and the turn-down chamber are separate modular, stackable elements, with the turn-down chamber stacked on top of the deposition chamber.

[0055]

[0059] The vertical processing modules 210a-210n may include any suitable structure, configuration, arrangement, and / or components that enable the modular free-span coating system 200 to prelithiate and / or passivate electrode structures formed on the continuous flexible substrate 230 in accordance with embodiments of the present disclosure. For example, in some embodiments, the vertical processing modules 210a-210n include a suitable deposition system including, but not limited to, a thermal evaporation source, a vapor diffuser, a power supply, individual pressure control, a deposition control system, and temperature control components. In some embodiments, the vertical processing modules 210a-210n each include an individual gas supply. The vertical processing modules 210a-210n are typically separated from one another to provide good gas isolation. In some embodiments, the vertical processing modules 210a-210n are separated from one another by a common transfer chamber 220. The modular free-span coating system 200 is not limited to the number of vertical processing modules 210a-210n. For example, in some embodiments, the modular freespan coating system 200 may include two, three, four, five, or more vertical processing modules.

[0056]

[0060] In some embodiments, the vertical processing modules 210a-210n include one or more deposition units 252a-252f (collectively 252) operable to perform a surface modification treatment on one or more surfaces of the continuous flexible substrate 230. The one or more deposition units 252 are typically disposed within the processing volume 244 to perform free-span processing of the continuous flexible substrate 230. For example, referring to FIG. 2, the deposition unit 252a is positioned to process the continuous flexible substrate 230 while the continuous flexible substrate 230 is moving between the auxiliary tension reel 266b and the auxiliary tension reel 266c. In some embodiments, the two deposition units 252a, 252b are disposed on opposite sides of the processing volume 244 relative to the continuous flexible substrate 230, and the deposition units 252a, 252b are vertically oriented and face the front surface 234 of the continuous flexible substrate 230. In some embodiments, the one or more deposition units 252 are positioned within the processing volume 244 parallel to the substrate transport direction 232 of the continuous flexible substrate 230. In some embodiments, the one or more deposition units 252 are positioned such that material to be deposited on the continuous flexible substrate 230 is delivered in a direction substantially perpendicular to the substrate transport direction 232 of the continuous flexible substrate 230.

[0057]

[0061] In some embodiments, one or more of the deposition units 252a-252f are evaporation sources. In some embodiments, at least one of the one or more deposition units is a vertical diffuser operable to deliver evaporated lithium to the surface of the continuous flexible substrate 230. In some embodiments, the one or more deposition units are each individually selected from the group of CVD sources, PECVD sources, and PVD sources, such as sputtering or thermal evaporation sources. In some embodiments, the one or more deposition units 252a-252f can independently include and provide an evaporation source, a sputter source, for example, a magnetron sputter source, a DC sputter source, an AC sputter source, a pulsed sputter source, radio frequency (RF) sputtering, or a medium frequency (MF) sputtering. The one or more deposition units can include an evaporation source. In some embodiments, the evaporation source includes either a thermal evaporation source or an electron beam evaporation source. In some embodiments, the evaporation source includes a lithium (Li) source. In some embodiments, the evaporation source includes an alloy of two or more metals. The material to be deposited (e.g., lithium) can be provided in a crucible. In some embodiments, the lithium is evaporated by thermal evaporation or electron beam evaporation techniques.

[0058]

[0062] In some embodiments, the vertical processing modules 210a-210n include one or more cooling sources 254a, 254b, . . . 254n (collectively 254). In some embodiments, the cooling source 254 is a fluid-cooled plate. In some embodiments, the cooling source 254 is disposed in the processing volume 244 of the vertical processing module 210. In some embodiments, the cooling source 254 is disposed between the dual deposition units 252, as shown in FIG. 2. For example, in the first vertical processing module 210a, the cooling source 254a is disposed between the deposition units 252a, 252b. Positioning the cooling source 254a between the deposition units 252a, 252b allows the cooling source 254a to cool the continuous flexible substrate 230 both as it approaches the turn volume 246 and as it approaches and returns from the turn volume 246 to the transfer volume 224.

[0059]

[0063] In some embodiments, one or more of the vertical processing modules 210a-210n are operable to perform deposition by other methods, such as, but not limited to, chemical vapor deposition, atomic laser deposition, or pulsed laser deposition. In some embodiments, one or more of the vertical processing modules are operable to perform a plasma treatment process, such as a plasma oxidation or plasma nitridation process.

[0060]

[0064] In some embodiments, the folding volume 246 includes intermediate folding rollers 248a, 248b, . . . 248n (collectively 248). The intermediate folding rollers 248 change the direction of the continuous flexible substrate 230 from a vertical upward motion to a vertical downward motion. In some embodiments, if the intermediate folding rollers 248 face the back surface 236 of the continuous flexible substrate 230, the intermediate folding rollers may directly contact the back surface 236 of the continuous flexible substrate 230 and do not need to be designed as gas cushion rollers. In some embodiments, the intermediate folding rollers 248 are designed as gas cushion rollers. In some embodiments, the intermediate folding rollers 248 are temperature controlled. In some embodiments, the intermediate folding rollers 248 are heated. It is believed that the heating of the intermediate folding rollers 248 reduces wrinkles that may form in the continuous flexible substrate 230. In some embodiments, the intermediate folding rollers 248 are cooled. Cooling the intermediate folding rollers 248 helps to reduce the temperature of the continuous flexible substrate 230 after processing in the processing volume 244. Cooling the continuous flexible substrate 230 after processing is believed to reduce heat damage to the continuous flexible substrate 230.

[0061]

[0065] In some embodiments, the modular freespan coating system 200 includes a common transport architecture 260. The common transport architecture 260 can include any transport mechanism capable of moving the continuous flexible substrate 230 through the processing volume 244 of each of the vertical processing modules 210a-210n. In some embodiments, the common transport architecture 260 is a reel-to-reel system having a common take-up reel 264 disposed in the downstream take-up module 204, an intermediate take-up roller 248 disposed in the turn-up volume 246, and an unwind reel 262 disposed in the upstream unwind module 202. In some embodiments, the downstream take-up module 204, the intermediate turn-up roller 248, and the unwind reel 262 are individually heated or cooled depending on the target process conditions. In some embodiments, the downstream take-up module 204, the intermediate turn-up roller 248, and the unwind reel 262 are individually heated using either an internal or external heat source disposed within each reel. In some embodiments, the downstream winding module 204, the intermediate turn-up roller 248, and the unwind reel 262 are individually cooled using either an internal or external cooling source located within each reel.

[0062]

[0066] In some embodiments, the common transport architecture 260 further includes one or more auxiliary tension reels 266a-266n (collectively 266) disposed between the unwind reel 262, the intermediate turn-down roller 248, and the common take-up reel 264. The auxiliary tension reels 266 are disposed on a path along which the continuous flexible substrate 230 is conveyed between each of the vertical processing modules 210a-210n, the unwind reel 262, and the common take-up reel 264, and can provide a tension force to the continuous flexible substrate 230. This tension force prevents the continuous flexible substrate 230 from sagging and changes the direction of movement of the continuous flexible substrate 230. Thus, a constant moving speed is always maintained even when the continuous flexible substrate 230 is moved along a continuously long path. In some embodiments, any of the auxiliary tension reels 266 may be replaced with a gas cushion roller. For embodiments having separate processing regions, modules, or chambers, the common transport architecture may be a reel-to-reel system in which each vertical processing module or processing volume has a separate take-up reel and supply reel, and one or more optional intermediate transport reels positioned between the take-up reel and supply reel.

[0063]

[0067] The transport speed of the continuous flexible substrate 230 through the modular free span coating system 200 and through the individual vertical processing modules 210a-210n is based on the number of vertical processing modules 210a-210n. In some embodiments, the transport speed used to move the continuous flexible substrate 230 through the vertical processing modules 210a-210n ranges from 0.1 m / min to 2.5 m / min, and is typically 0.6 m / min.

[0064]

[0068] In operation, the continuous flexible substrate 230 is transported from the upstream unwinding module 202 and passes through the through hole 226a to the common transfer chamber 220. The continuous flexible substrate 230 is then moved vertically upward through the through hole 226b to proceed to the processing volume 244a of the first vertical processing module 210a. In the processing volume 244a, the continuous flexible substrate 230 moves between the deposition unit 252a and the cooling source 254a, where the continuous flexible substrate 230 is exposed to a free-span surface modification process, such as a free-span prelithiation process. The continuous flexible substrate 230 moves vertically upward through the through hole 243a and proceeds to the turn-up volume 246 of the first vertical processing module 210a around the intermediate turn-up rollers 248 where the continuous flexible substrate 230 is redirected to move vertically downward. The continuous flexible substrate 230 moves vertically downward through the through hole 243b back to the processing volume 244a. In the processing volume 244a, the continuous flexible substrate 230 travels between the deposition unit 252b and the cooling source 254a, where the continuous flexible substrate 230 is exposed to an additional free-span surface modification process, such as an additional free-span prelithiation process or a free-span passivation process. The continuous flexible substrate 230 is moved vertically downwards through the through-hole 226c into the common transfer chamber 220. The continuous flexible substrate 230 then travels horizontally within the common transfer chamber 220 until the continuous flexible substrate 230 is redirected vertically upwards through the through-hole 226d to proceed to the processing volume 244b of the second vertical processing module 210b. In the processing volume 244b, the continuous flexible substrate 230 is exposed to a free-span surface modification process, such as a free-span passivation process. The continuous flexible substrate 230 moves vertically upwards through the through holes 243c and proceeds to a turn volume 246b of the second vertical processing module 210b around intermediate turn rollers 248b where the continuous flexible substrate 230 is redirected to move vertically downwards.The continuous flexible substrate 230 moves vertically downward through through-hole 243d and back to processing volume 244b where the continuous flexible substrate 230 is exposed to an additional free-span surface modification process, such as a free-span passivation process. The continuous flexible substrate 230 is moved vertically downward through through-hole 226e back to the common transfer chamber 220. In some embodiments, the flexible substrate undergoes additional processing in an additional vertical processing module, such as, for example, vertical processing module 210n.

[0065]

[0069] Generally, the modular freespan coating system 200 includes a system controller 290 configured to control the automated aspects of the modular freespan coating system 200. The system controller 290 facilitates the control and automation of the entire modular freespan coating system 200 and may include a central processing unit (CPU) (not shown), memory (not shown), and support circuitry (or I / O) (not shown). Software instructions and data may be coded and stored in the memory to instruct the CPU. A program (or computer instructions) readable by the system controller 290 determines which tasks are executable on the substrate. Preferably, the program is software readable by the system controller 290 and includes code for generating and storing at least positional information of the substrate, sequences of movement of the various controlled components, and any combination thereof.

[0066]

[0070] FIG. 3 shows a schematic side view of a vertical processing module 300 that can be used in the modular free-span coating system 200 of FIG. 2. The vertical processing module 300 is operable to perform a double-sided surface modification process, such as a double-sided free-span prelithiation process and / or a double-sided free-span passivation process. During a double-sided free-span prelithiation process, both sides (e.g., front side 234 and back side 236) of the continuous flexible substrate 230 are simultaneously exposed to a free-span prelithiation process or a free-span passivation process. The vertical processing module 300 is similar to the vertical processing module 210, except that the vertical processing module 300 has three deposition units 352a-352c (collectively 352). The one or more deposition units 352 are typically disposed in a processing volume 344 to perform free-span processing of the continuous flexible substrate 230. For example, referring to FIG. 3, deposition unit 352a is positioned to process continuous flexible substrate 230 while continuous flexible substrate 230 moves between auxiliary tension reels 366b and 366c. Deposition unit 352b is positioned to process continuous flexible substrate 230 while continuous flexible substrate 230 moves between auxiliary tension reels 366d and 366e. Deposition units 352a and 352b are positioned to process front side 234 of continuous flexible substrate 230. Deposition unit 352c is disposed between deposition units 352a and 352b and is operable to process back side 236 of continuous flexible substrate 230. In some embodiments, deposition units 352a-352c are configured similarly to deposition unit 252.

[0067]

[0071] 4 shows a process flow diagram summarizing one embodiment of a processing sequence 400 for prelithiation and passivation of an electrode structure according to one or more embodiments of the present disclosure. Processing sequence 400 can be used to prelithiate a single-sided electrode structure, such as the electrode structure depicted in FIG. 1A, or a double-sided electrode structure, such as the electrode structure depicted in FIG. 1B. Processing sequence 400 can be performed using, for example, the modular free-span coating system 200 depicted in FIG. 2.

[0068]

[0072] The processing sequence 400 begins at operation 410 by providing a flexible substrate including an electrode structure. In some embodiments, the flexible substrate is a continuous flexible substrate 230 that includes a negative electrode (anode electrode), such as, for example, a negative electrode structure 140 formed on a negative electrode current collector 150, or a positive electrode (cathode electrode), such as, for example, a positive electrode structure 120 formed on a positive electrode current collector 110, as depicted in FIG. 1A. In some embodiments, the continuous flexible substrate 230 includes a double-sided electrode structure, such as a double-sided electrode structure 170 that includes a negative electrode current collector 150 with negative electrode structures 140a, 140b (collectively 140) formed on either side of the negative electrode current collector 150, as shown in FIG. 1B.

[0069]

[0073] In operation 420, the flexible substrate moves to a first vertical processing module. Referring to FIG. 2, in some embodiments, the continuous flexible substrate 230 is conveyed from the upstream unwind module 202 and passes through hole 226a into the common transfer chamber 220. The continuous flexible substrate 230 then moves vertically upward through hole 226b to proceed to the processing volume 244a of the first vertical processing module 210a.

[0070]

[0074] In operation 430, the flexible substrate is processed in a first vertical processing module. In some embodiments, the process is a free-span prelithiation process in which reactive lithium ions condense on the continuous flexible substrate 230 and intercalate along the grain boundaries of the anode structure 140. Referring to FIG. 2, in some embodiments, in the processing volume 244a, the continuous flexible substrate 230 moves between a deposition unit 252a and a cooling source 254a, during which the continuous flexible substrate 230 is exposed to a free-span surface modification process, such as a free-span prelithiation process. In some embodiments, the deposition unit 252a is a vapor diffuser. The free-span prelithiation process includes directing vaporized lithium toward the continuous flexible substrate 230 through the deposition unit 252a. The vaporized lithium condenses on the electrode structure of the continuous flexible substrate 230, thereby prelithiating the electrode structure. In some embodiments, the degree of prelithiation is controlled by adjusting the temperature and concentration of the reactive lithium ions released by the deposition unit 252. The degree of prelithiation is also controlled by the rate of heat transfer and transport from the continuous flexible substrate 230 to the cooling source 254. It is noted that lithium may continue to intercalate along the grain boundaries of the anode even after the coating process is complete. Thus, in some embodiments, a free-span prelithiation process is utilized along with subsequent aging and other treatment of the material to produce a material with a controlled degree of prelithiation.

[0071]

[0075] After the first prelithiation process, the continuous flexible substrate 230 moves vertically upward through the through hole 243a and proceeds to the turn-around volume 246 of the first vertical processing module 210a around the intermediate turn-around roller 248a where the continuous flexible substrate 230 turns to move vertically downward. In some embodiments where the intermediate turn-around roller 248a is temperature controlled, the continuous flexible substrate 230 is cooled or heated by the intermediate turn-around roller 248a. The continuous flexible substrate 230 moves vertically downward through the through hole 243b back to the processing volume 244a. In the processing volume 244a, the continuous flexible substrate 230 moves between the deposition unit 252b and the cooling source 254a where the continuous flexible substrate 230 is subjected to an additional free-span prelithiation process to provide additional lithium to the electrode structure of the continuous flexible substrate 230.

[0072]

[0076] In operation 440, the continuous flexible substrate 230 is moved from the first vertical processing module 210a. The continuous flexible substrate 230 is moved vertically through the through-hole 226c into the common transfer chamber 220. The continuous flexible substrate 230 then moves horizontally through the common transfer chamber 220 until, in operation 450, the continuous flexible substrate 230 is redirected vertically upward through the through-hole 226d to proceed into the processing volume 244b of the second vertical processing module 210b.

[0073]

[0077] In operation 460, the continuous flexible substrate 230 is processed in the processing volume 244b of the second vertical processing module 210b. In the processing volume 244b of the second vertical processing module 210b, the continuous flexible substrate 230 is exposed to a free-span surface modification process, such as a free-span passivation process. In some embodiments, the free-span passivation process forms a passivation film, such as the passivation film 160, on the prelithiated electrode structure. In some embodiments, the passivation film can be formed on the electrode structure by a deposition method, such as chemical vapor deposition (CVD), aerosol-assisted chemical vapor deposition (AACVD), atomic layer deposition (ALD), electrospray deposition (ESD), or physical vapor deposition (PVD), such as evaporation or sputtering.

[0074]

[0078] In operation 470, the continuous flexible substrate 230 is moved from the second vertical processing module 210b. The continuous flexible substrate 230 moves vertically downward through the through hole 226e and enters the common transfer chamber 220. In one embodiment in which the continuous flexible substrate 230 undergoes additional processing, the continuous flexible substrate 230 then moves horizontally through the common transfer chamber 220 until the continuous flexible substrate 230 is redirected vertically upward through the through hole 226f so that the continuous flexible substrate 230 proceeds to the processing volume 244n of the vertical processing module 210n. In another embodiment, once the processing of the continuous flexible substrate 230 is completed, the continuous flexible substrate 230 exits the common transfer chamber 220 through the through hole 226h. After exiting the common transfer chamber 220, the continuous flexible substrate 230 may be wound onto the take-up reel 264.

[0075]

[0079] In some embodiments, the passivation film 160 can be formed using gas or liquid precursors that are inert or reactive with lithium above or below the melting point of lithium. For example, the passivation film 160 can be formed by introducing anhydrous carbon dioxide during the deposition unit 252 in the processing volume 244b of the second vertical processing module 210b to form a protective layer of lithium carbonate (Li2CO3) on the prelithiated surface formed in the processing volume 244a of the first vertical processing module 210a. The operating temperature of the deposition unit 252 and the latent heat of the continuous flexible substrate 230 affect the pinhole-free quality and total thickness of the lithium carbonate. In some embodiments, phosphoric acid is used instead of carbon dioxide to form a protective layer of lithium phosphate (Li3PO4). Lithium phosphate is more moisture resistant than lithium carbonate and is therefore more effective in reducing air reactivity of the coated web over a longer period of time. In some embodiments where it is desirable to avoid heating the prelithiated anode structure 140 during the passivation process, chlorosilane vapor is used to produce a thin layer of either lithium chloride (LiCl) and lithium alkylsilanolate derivatives or alkylsiloxanes to produce a passivation film with greater thermal stability than lithium carbonate or lithium phosphate, e.g., passivation film 160. In some embodiments, passivation film 160 is comprised of two or more layered films, a lithium carbonate film to minimize air reactivity and an organic layer such as a wax, e.g., a polyethylene wax such as Luwax®, to improve web durability and facilitate battery assembly. In some embodiments, passivation film 160 is comprised of one or more layers of polyethylene oxide, ethylene vinyl acetate, or other polymers with low solubility in N-methyl-2-pyrrolidone (NMP) to improve stability and shelf life. The common transfer chamber 220 provides spatial isolation between the processing volumes 244a and 244b to prevent reactive gas or vapor precursors used in the passivation process from migrating upstream and contaminating the prelithiation process.

[0076]

[0080] The continuous flexible substrate 230 moves vertically upward through through hole 243c and proceeds to a turn volume 246b of the second vertical processing module 210b around intermediate turn rollers 248b where the continuous flexible substrate 230 is redirected to move vertically downward. The continuous flexible substrate 230 moves vertically downward through through hole 243d and returns to processing volume 244b where the continuous flexible substrate 230 is exposed to an additional free-span surface modification process, such as a free-span passivation process. The continuous flexible substrate 230 is moved vertically downward through through hole 226e back to the common transfer chamber 220.

[0077]

[0081] In some embodiments, the continuous flexible substrate 230 undergoes additional processing in additional vertical processing modules, such as vertical processing module 210n. In some embodiments, the additional processing may provide for the deposition of a separator, an electrolyte soluble binder, or in some embodiments, the additional chamber may provide for the formation of a positive electrode structure. In some embodiments, the additional chamber provides for the cutting of the negative electrode. The passivation film may be removed after the cutting of the negative electrode.

[0078]

[0082] In summary, some of the advantages of the present disclosure include the efficient integration of prelithiation and passivation into a modular free-span processing system. Currently, lithium metal deposition is performed in a dry room or argon gas atmosphere. Because lithium metal is volatile, subsequent processing steps must also be performed in argon gas atmosphere. Current manufacturing tools must be modified to perform subsequent processing steps in argon gas atmosphere. The inventors have discovered that by coating the lithium metal with a protective film prior to subsequent processing, subsequent processing can be performed under vacuum or atmospheric pressure. The protective film eliminates the need for additional processing in an inert gas atmosphere, which increases the complexity of the manufacturing equipment. The protective film also allows the negative electrode with the lithium metal film to be transported and / or stored. Additionally, the prelithiation and passivation can be performed vertically to the electrode structure, reducing the system footprint while allowing for tunable processing time and length.

[0079]

[0083] Free-span coating also eliminates contact of the web with the cooling drum near the heat-intensive vapor source. Eliminating the need to handle the web from deposition in the volume prevents winding defects such as wrinkles. Free-span coating also allows for high web speeds (e.g., greater than 1 meter per minute, up to 40 meters per minute) at low capital costs. Free-span coating systems are designed to minimize wrinkles. In some embodiments, the coating system includes multiple chambers that operate at different temperatures to maximize coating thickness and uniformity without damaging heat-sensitive substrates. In some embodiments, the coating system can control the coating speed by optimizing temperature, process length, and web speed. In some embodiments, the coating system achieves high lithium utilization by minimizing parasitic surfaces.

[0080]

[0084] When introducing elements of the present disclosure or exemplary aspects or embodiments thereof, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of the elements.

[0081]

[0085] The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0082]

[0086] While the forgoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, which scope is determined by the following claims.

Claims

1. 1. A modular processing system comprising: a common transfer chamber body defining a transfer volume; a first vertical chamber body defining a first processing volume and disposed on the common transfer chamber body, the transfer volume being in fluid communication with the first processing volume; a second vertical chamber body defining a second processing volume and disposed on the common transfer chamber body, the transfer volume being in fluid communication with the second processing volume; and a reel-to-reel system operable to transport a continuous flexible substrate having electrode structures formed thereon, said continuous flexible substrate moving from said transfer volume through said first processing volume, back to said transfer volume, through said second processing volume and back to said transfer volume; A modular processing system comprising:

2. The modular processing system of claim 1 , further comprising an unwind reel that delivers the continuous flexible substrate wound thereon to the transfer volume.

3. The modular processing system of claim 2 , further comprising a take-up reel operable to receive and take-up the continuous surface treated flexible substrate from the transfer volume.

4. 4. The modular processing system of claim 3, wherein the continuous flexible substrate passes from the unwind reel, through the transfer volume, through the first processing volume, back to the transfer volume, through the second processing volume, back to the transfer volume, and back to the take-up reel.

5. The modular processing system of claim 1 , further comprising a first tension reel disposed within the transfer volume and operable to change the orientation of the continuous flexible substrate from a horizontal to a vertical orientation.

6. 10. The modular processing system of claim 1, further comprising a first vapor diffuser disposed within said first processing volume and vertically oriented parallel to a direction of movement of said continuous flexible substrate.

7. 7. The modular processing system of claim 6, further comprising a second vapor diffuser disposed opposite the second vapor diffuser within the first processing volume and vertically oriented parallel to a direction of movement of the continuous flexible substrate.

8. The modular processing system of claim 7 , further comprising a cold plate disposed between said first vapor diffuser and said second vapor diffuser.

9. The modular treatment system of claim 7 , further comprising a third vapor diffuser disposed between said first vapor diffuser and said second vapor diffuser.

10. 2. The modular processing system of claim 1, further comprising a first partition extending across said first vertical chamber body, said first partition dividing said first vertical transfer chamber body into said first processing volume and a first folded volume.

11. 11. The modular processing system of claim 10, further comprising a first turn roller disposed within the first turn volume and operable to change the direction of the continuous flexible substrate from a vertically upward motion to a vertically downward motion.

12. The modular processing system of claim 11 , wherein the first folding roller is temperature controlled.

13. 1. A method for forming a prelithiated electrode on a flexible substrate, comprising: transferring a continuous flexible substrate carrying an electrode structure to a first processing region of a first vertical processing module; exposing the continuous flexible substrate to a free-span prelithiation process while transporting the continuous flexible substrate through the first processing region; transferring the continuous flexible substrate from the first processing region through a common transfer volume to a second processing region of a second vertical processing chamber; and exposing the continuous flexible substrate to a free span passivation treatment while transporting the continuous flexible substrate through the second treatment region; A method comprising:

14. The method of claim 13 , further comprising transferring the continuous flexible substrate from the second processing region through the common transfer volume.

15. The method of claim 14 , wherein the common transfer volume comprises an inert gas atmosphere.

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