Patent Description:
Rechargeable electrochemical storage systems are becoming increasingly significant in 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).

Typically, lithium batteries do not contain any metallic lithium for safety reasons but instead use a graphitic material as the anode. However, the use of graphite, which can be charged up to the limit composition LiC<NUM>, results in a much lower capacity, in comparison with the use of silicon-blended graphite. Currently, the industry is moving away from graphitic-based anodes to silicon-blended graphite to increase energy cell density. However, silicon blended graphite anodes suffer from first cycle irreversible capacity loss (IRC). Li-ion battery specific energy and energy density appreciably declines due to active lithium loss during the first cycle charge when approximately five to twenty percent of the lithium from the cathode is consumed by solid electrolyte interphase formation ("SEI") at the anode.

Anode pre-lithiation prior to the first cycle charge is a common strategy for compensating active lithium loss. Furthermore, pre-lithiation provides other performance and reliability advantages to Li-ion battery performance. For example, pre-lithiation can decrease Li-ion battery impedance thereby improving rate capability. In addition, for silicon-based anodes, pre-lithiation can mitigate silicon cracking and pulverization by pre-expanding the silicon to enhance anode mechanical stability.

Various anode pre-lithiation methods exist including chemical pre-lithiation, electrochemical pre-lithiation, pre-lithiation by direct contact to lithium metal, and stabilized lithium metal powder ("SLMP"). However, these various anode pre-lithiation methods have long reaction times and inherent safety risks, which are unsuitable for volume Li-ion battery manufacturing. Document <CIT> describes methods and devices for improved sputtering systems. A magnetron sputtering system with a plurality of sputtering chambers is provided. Chilled rollers are provided in an area outside the sputter chamber to reduce the temperature of the substrate before it enters another sputtering chamber. Document <CIT> describes systems and methods for atomic layer deposition (ALD). Reactive first and second precursor gases are introduced into respective first and second precursor zones, and an inert gas is introduced into an isolation zone. As the substrate transits through the first precursor zone a monolayer of the first precursor gas is adsorbed to the surface of the substrate, and on a subsequent transit of the substrate through the second precursor zone the second precursor gas reacts with the adsorbed first precursor at the surface of the substrate, to thereby deposit a thin film on the substrate. Document <CIT> describes a modular substrate processing system for processing a flexible substrate. A process module includes a substrate guiding means including a first substrate guiding device and a second substrate guiding device. Two deposition sources are arranged at opposing sides of an intermediate space. The deposition sources are oriented vertically and facing the front surface of the substrate.

Thus, there is a need for pre-lithiation apparatus and methods to replenish lithium in various electrode structures lost due to first cycle irreversible capacity loss.

Implementations described herein generally relate to continuous web processing systems and more specifically to continuous web processing systems for pre-lithiating Li-ion battery substrates. In one implementation, a modular processing system is provided. The system comprises a common transfer chamber body defining a transfer volume. The system further comprises a first vertical chamber body defining a 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 a 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.

In another implementation, a modular processing system is provided. The processing system comprises a reel-to-reel system operable to transport a continuous flexible substrate having an electrode structure formed thereon. The reel-to-reel system comprises 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 comprises a winding reel operable to receive the continuous flexible substrate following processing, and operable to wind the continuous flexible substrate thereon. The reel-to-reel system further comprises a plurality of auxiliary tension reels, located on a path between the unwinding reel and the winding reel operable to guide the continuous flexible substrate. The processing system further comprises a common transfer chamber body defining a transfer volume. The processing system further comprises a first vertical chamber body defining a first processing volume and positioned on the common transfer chamber body. The transfer volume is in fluid communication with the first processing volume. The processing system further comprises a second vertical chamber body defining a second processing volume and positioned on the common transfer 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, returning to the transfer volume, through the second processing volume, and returning to the transfer volume.

In yet another implementation, a method of forming a pre-lithiated electrode on a flexible substrate is provided. The method comprises transporting a continuous flexible substrate into a first processing region of a first vertical processing module. The continuous flexible substrate comprises an electrode structure. The method further comprises exposing the continuous flexible substrate to a free-span pre-lithiation process while transporting the continuous flexible substrate through the first processing region. The method further comprises transporting the continuous flexible substrate out of the first processing region through a common transfer volume and into a second processing region of a second vertical processing chamber. The method further comprises exposing the continuous flexible substrate to a free-span passivation process while transporting the continuous flexible substrate through the second processing region.

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 implementations, briefly summarized above, may be had by reference to implementations, some of which are illustrated in the appended drawings.

It is contemplated that elements and features of one implementation may be beneficially incorporated in other implementations without further recitation.

The following disclosure describes pre-lithiated electrodes, high performance electrochemical cells and batteries including the aforementioned pre-lithiated electrodes, apparatus and methods for fabricating the same. Certain details are set forth in the following description and in <FIG> to provide a thorough understanding of various implementations of the 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 implementations.

Many of the details, dimensions, angles and other features shown in the Figures are merely illustrative of particular implementations.

Implementations described herein will be described below in reference to a roll-to-roll coating system. The apparatus description described herein is illustrative and should not be construed or interpreted as limiting the scope of the implementations described herein. It should also be understood that although described as a roll-to-roll process, the implementations described herein may be performed on discrete substrates.

Implementations described herein refer to a free-span coating system adapted for pre-lithiation of a flexible substrate such as a web for lithium-ion battery devices. In particular, the free-span coating system is adapted for continuous processing of a flexible substrate such as a web unwound from an unwinding module. The free-span coating system is configured in a modular design, for example, an appropriate number of process modules may be arranged adjacent to each other in a processing line, and the flexible substrate is inserted into the first process module and may be ejected from the last process module of the line. Furthermore, the entire free-span coating system may be re-configured if a change of individual processing operations is desired.

It is noted that while the particular substrate on which some implementations described herein may 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 substrate may also be in the form of a foil, a film, or a thin plate.

It is also noted here that a flexible substrate or web as used within the implementations described herein can typically be characterized in that it is bendable. The term "web" may be synonymously used to the term "strip" or the term "flexible substrate. " For example, the web as described in implementations herein may be a foil.

It is further noted that in some implementations where the substrate is a vertically oriented substrate, the vertically oriented substrate may be angled relative to a vertical plane. For example, in some implementations, the substrate may be angled from between about <NUM> degree to about <NUM> degrees from the vertical plane. In some implementations where the substrate is a horizontally oriented substrate, the horizontally oriented substrate may be angled relative to a horizontal plane. For example, in some implementations, the substrate may be angled from between about <NUM> degree to about <NUM> degrees from the horizontal plane. As used herein, the term "vertical" is defined as a major surface or deposition surface of the flexible conductive substrate being perpendicular relative to the horizon. As used herein, the term "horizontal" is defined as a major surface or deposition surface of the flexible conductive substrate being parallel relative to the horizon.

It is also noted that free-span coating refers to a web-coating machine or process in which the web is not in contact with a surface during the actual film deposition part of the web coating process.

The web of substrate material may be continuously advanced through the line of interconnected process modules. In each process module, a portion of the pre-lithiation process may be performed. For example, if the lithium-ion device includes an anode structure, one or more processing modules may be adapted for pre-lithiating the anode structure and one or more succeeding process modules may be adapted for forming a protective coating or "passivation coating" over the pre-lithiated anode structure.

Li-ion batteries specific energy and energy density appreciably declines due to active lithium loss during the first cycle charge. Anode pre-lithiation prior to the first cycle charge is a common strategy for compensating for active lithium loss. Furthermore, pre-lithiation provides other performance and reliability advantages to Li-ion battery performance. For example, pre-lithiation can decrease Li-ion battery impedance thereby improving rate capability. In addition, for silicon (Si)-based anodes, pre-lithiation can mitigate silicon cracking and pulverization by pre-expanding the silicon to enhance anode mechanical stability.

Various anode pre-lithiation methods exist including chemical pre-lithiation, electrochemical pre-lithiation, pre-lithiation by direct contact to lithium metal, and stabilized lithium metal powder ("SLMP"). These existing pre-lithiation methods share common volume Li-ion battery manufacturing disadvantages, such as, long reaction times and inherent safety risks, which are unsuitable for volume lithium-ion battery manufacture.

SLMP, with up to <NUM>% of the Li<NUM>CO<NUM> powder shells remaining uncracked, incorporates inactive material into the cell mass, which reduces energy density of the Li-ion battery. Loose powder particles dislodged within the electrolyte while spreading SLMP, present inherent safety and reliability risks. Electrochemical pre-lithiation produces reactive material in ambient air, which can increase cell impedance due to nitrogen and oxygen contamination. Direct contact to lithium metal is a non-uniform and low yield process hindered by thin lithium metal foils sixty centimeters wide and discontinuous at twenty meters long or shorter. In addition, except for electrochemical pre-lithiation, Li-ion batteries manufactured using the aforementioned pre-lithiation methods may not perform as well as Li-ion batteries pre-lithiated with methods involving reactive lithium ions. Reactive lithium ions are more effective than lithium metal because the ions can penetrate and intercalate electrode pores to form lithium alloys throughout the graphite composite.

One pre-lithiation approach involving reactive lithium ions is vacuum thermal evaporation. Thermal evaporation involves heating lithium to produce a vapor composed of clusters of lithium atoms. The lithium cluster vapor mass flux and residual heat is controlled by the lithium-heating mode. Pools of molten lithium can be heated and controlled using electron beam, plasma, or resistive heating sources. As with electrochemical pre-lithiation, thermal evaporation delivers reactive lithium ions that can form alloys within the anode. Unlike electrochemical pre-lithiation, thermal evaporation is a vacuum process where reactive materials are isolated from oxygen and other species that could contaminate the anode. Further, regarding contamination minimization, vacuum processing at 10E-<NUM> Torr or lower pressures has the ancillary benefit of dewatering residual moisture from the anode more effectively than oven heat treatments usually performed at higher pressures.

Thermal evaporation is believed to facilitate high quality and controllable pre-lithiation. However, strategies using thermal evaporation historically were cost prohibitive due to capital, energy, and maintenance costs. Commercial demand for advanced electrode active materials has since matured to the extent that vacuum thermal evaporation now has merit. Cost-competitive thermal evaporation requires an electrode application-specific web coating system design and operating method. The optimal pre-lithiation process for compensating active lithium loss involves reactive lithium ions alloying with the graphite, silicon, and/or other anode constituents to compensate for lithium consumed during SEI formation. The optimal production worthy manufacturing method involves web processing anode substrates over one meter wide and thousands of meters long at web speeds around forty meters per minute or faster.

Conventional web handling systems are not capable of double-sided coating let alone safe lithium thermal evaporation. The need therefore exists for a vacuum thermal evaporation pre-lithiation system and method that can meet volume lithium-ion battery manufacturing objectives for device performance, yield, throughput, and cost.

In some implementations of the present disclosure, a free-span coating system with cooling rollers to facilitate multiple pass lithium-ion battery pre-lithiation is provided. In some implementations, the free-span coating system has modular elements including at least one of deposition chambers, cooling turn-around chambers, and one or more load lock chambers. Therefore, each of the modular elements, can be arranged, rearranged, replaced, or maintained independently without affecting each other.

The free-span coating system is designed for producing either single-sided or double-sided coatings depending on the specific application. In some implementations, the free-span coating system is designed to facilitate deposition of multiple reactive materials at different temperatures. In some implementations, temperature measurement is accomplished using non-contact pyrometers and thermocouples to monitor the hot zone. In some implementations, quartz crystal monitors and residual gas analyzers are used to verify deposition rates.

In some implementations, the free-span coating system is used in spatial or temporal converting modes so that films of uniform thickness are produced by modulating the processing time or the processing length depending on the specific application. In some implementations, additional modular processing chambers are installed with similar process kits to process the web at faster speeds as an alternative to increasing temperature, which could damage the web. In some implementations, gas separation is accomplished by a common transfer chamber positioned beneath the deposition chambers. In some implementations, the web is cooled before exiting the deposition chamber and entering the common transfer chamber, which minimizes wrinkling of the web on the rollers of the transfer chamber.

In some implementations, cooling is accomplished by passing the web between two fluid cooled plates coupled via an appropriate coupling gas such as argon or helium. In some implementations, cooling is accomplished by the use of cooling plates, cooling drums, and/or cooling rollers.

In some implementations, the free-span coating system has features for efficient serviceability and maintenance. For example, the entire modular deposition chamber is removable from the transfer chamber for service, which facilitates safe lithium handling.

In some implementations, the free-span coating system is operable to simultaneously pre-lithiate both sides of a battery electrode. Alternative systems, which utilize single-pass double-sided coating around two cooling drums, are capital intensive, prone to web wrinkles and/or surface defects, low throughput, and harder to control pre-lithiation. Furthermore, some cooling drum designs suffer from parasitic deposition, which causes the heat transfer coefficient to drift. In some implementations, the free-span coating system operates without cooling drums and thus minimizes parasitic surface area.

In some implementations, pre-lithiation of coated electrodes using the systems described herein allows for (<NUM>) an increase in the lithium-ion battery energy density (kWh), and (<NUM>) reduction of the cathodic coating loading for the anode/cathode balancing, specifically the costly elements of cobalt and nickel. Thus, in some implementations, the free-span coating system described herein has a direct impact on the main figure of merit, cost/kWh, used in lithium-ion battery manufacturing. The free-span coating systems described herein are suitable for pre-lithiating any coated electrodes, either negative or positive. The free-span systems described herein provide battery manufacturers with great flexibility in cell balancing, for example, the ability to independently match reversible anode/cathode capacities and irreversible anode/cathode capacities.

In some implementations, a close couple gas diffuser is used to perform vertical free-span coating.

<FIG> illustrates a cross-sectional view of one implementation of an energy storage device <NUM> including a pre-lithiated electrode structure formed according to implementations described herein. The energy storage device <NUM> may be a lithium-ion energy storage device that uses solid electrolytes (e.g., a solid-state battery) as well as a lithium-ion energy storage device, which uses a liquid or polymer electrolyte. The energy storage device <NUM> has a positive current collector <NUM>, a positive electrode structure <NUM>, a separator <NUM>, a negative electrode structure <NUM>, and a negative current collector <NUM>. At least one of the positive electrode structure <NUM> and the negative electrode structure <NUM> are pre-lithiated according to the implementations described herein. Note in <FIG> that the current collectors are shown to extend beyond the stack, although it is not necessary for the current collectors to extend beyond the stack, the portions extending beyond the stack may be used as tabs.

The current collectors <NUM>, <NUM>, on positive electrode structure <NUM> and negative electrode structure <NUM>, respectively, can be identical or different electronic conductors. Examples of metals that the current collectors <NUM>, <NUM> may be comprised of 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 implementations, the current collectors <NUM>, <NUM> are comprised of metal deposited on a polymer substrate.

The negative electrode structure <NUM> or anode may be any material compatible with the positive electrode structure <NUM>. In some implementations, the negative electrode structure <NUM> is pre-lithiated according to implementations described herein. In some implementations, the negative electrode structure <NUM> has an energy capacity greater than or equal to <NUM> mAh/g, preferably ≥ <NUM> mAh/g, and most preferably ≥ <NUM> mAh/g. In some implementations, the negative electrode structure <NUM> is constructed from a carbonaceous material (e.g., natural graphite or artificial graphite), silicon-containing graphite, silicon, nickel, copper, tin, indium, aluminum, silicon, oxides thereof, combinations thereof, or a mixture of a lithium metal and/or lithium alloy and 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 artificial graphite, partially graphitized or amorphous carbon, petroleum, coke, needle coke, and various mesophases. In some implementations, the negative electrode structure <NUM> comprises intercalation compounds containing lithium or insertion compounds containing lithium. In some implementations, the negative electrode structure <NUM> is a silicon graphite anode.

In some implementations, the material that forms the negative electrode structure <NUM> is in a disperse form such as powders, fibers, or flakes. In some implementations, the negative electrode structure <NUM> is manufactured by any method known in the art such as by preparing slurry from a carbonaceous powder and a binder agent, applying the slurry onto/into a current-collector, and drying. If employed, the binder agent can be chosen from such compounds including, but not limited, to, polyvinylidene fluoride (PVDF), ethylene-propylene diene monomer (EPDM), ethylene vinyl acetate copolymer (EVA), and combinations thereof.

The positive electrode structure <NUM> 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 implementations, the positive electrode structure <NUM> is pre-lithiated according to implementations described herein. Suitable intercalation materials include, for example, lithium-containing metal oxides, MoS<NUM>, FeS<NUM>, MnO<NUM>, TiS<NUM>, NbSe<NUM>, LiCoO<NUM>, LiNiO<NUM>, LiMnO<NUM>, LiMn<NUM>O<NUM>, V<NUM>O<NUM> and V<NUM>O<NUM>. Suitable lithium-containing oxides may be layered, such as lithium cobalt oxide (LiCoO<NUM>), or mixed metal oxides, such as LiNixCo<NUM>-2xMnO<NUM>, LiNiMnCoO<NUM> ("NMC"), LiNi<NUM>Mn<NUM>O<NUM>, Li(Ni<NUM>Co<NUM>Al<NUM>)O<NUM>, LiMn<NUM>O<NUM>, and doped lithium rich layered-layered materials, wherein x is zero or a non-zero number. Suitable phosphates may be iron olivine (LiFePO<NUM>) and it is variants (such as LiFe(<NUM>-x)MgxPO<NUM>), LiMoPO<NUM>, LiCoPO<NUM>, LiNiPO<NUM>, Li<NUM>V<NUM>(PO<NUM>)<NUM>, LiVOPO<NUM>, LiMP<NUM>O<NUM>, or LiFe<NUM>P<NUM>O<NUM>, wherein x is zero or a non-zero number. Exemplary fluorophosphates may be LiVPO<NUM>F, LiAlPO<NUM>F, Li<NUM>V(PO<NUM>)<NUM>F<NUM>, Li<NUM>Cr(PO<NUM>)<NUM>F<NUM>, Li<NUM>CoPO<NUM>F, or Li<NUM>NiPO<NUM>F. Exemplary silicates may be Li<NUM>FeSiO<NUM>, Li<NUM>MnSiO<NUM>, or Li<NUM>VOSiO<NUM>. An exemplary non-lithium compound is Na<NUM>V<NUM>(PO<NUM>)<NUM>F<NUM>.

In some implementations of a lithium-ion cell according to the present disclosure, lithium is contained in atomic layers of crystal structures of carbon graphite (LiC<NUM>) at the negative electrode and lithium manganese oxide (LiMnO<NUM>) or lithium cobalt oxide (LiCoO<NUM>) at the positive electrode. Although in some implementations, the negative electrode may also include lithium-absorbing materials such as silicon, and/or tin. The cell, even though shown as a planar structure, may also be formed into a cylinder by reeling the stack of layers; furthermore, other cell configurations (e.g., prismatic cells, button cells) may be formed.

In one implementation, the separator <NUM> is a porous polymeric ion-conducting polymeric substrate. In one implementation, the porous polymeric substrate is a multi-layer polymeric substrate. In some implementations, the separator <NUM> includes any commercially available polymeric microporous membranes (e.g., single or multi-ply), for example, those products produced by Polypore (Celgard® LLC. , of Charlotte, North Carolina), Toray Tonen (Battery separator film (BSF)), SK Energy (lithium ion battery separator (LiBS), Evonik industries (SEPARION® ceramic separator membrane), Asahi Kasei (Hipore™ polyolefin flat film membrane), and DuPont (Energain®).

In some implementations, the electrolyte infused in cell components <NUM>, <NUM>, and <NUM> is comprised of a liquid/gel or a solid polymer and may be different in each. In some implementations, the electrolyte primarily includes a salt and a medium (e.g., in a liquid electrolyte, the medium may be referred to as a solvent; 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, LiPF<NUM>, LiAsF<NUM>, LiCF<NUM>SO<NUM>, LiN(CF<NUM>SO<NUM>)<NUM>, LiBF<NUM>, and LiClO<NUM>, BETTE electrolyte (commercially available from <NUM> Corp. of Minneapolis, MN) and combinations thereof.

<FIG> illustrates a cross-sectional view of a dual-sided electrode structure <NUM> that is pre-lithiated according to implementations described herein. Although the dual-sided electrode structure <NUM> is depicted as a dual-sided electrode structure, it should be understood that the implementations described herein also apply to single-sided electrode structures. The dual-sided electrode structure <NUM> comprises the negative current collector <NUM> with a negative electrode structure 140a, 140b (collectively <NUM>) formed on opposing sides of the negative current collector <NUM>. The negative electrode structures 140a, 140b each have a passivation film 160a, 160b (collectively <NUM>) formed respectively thereon for protecting the negative electrode structure <NUM> from contaminants, such as ambient oxidants. In some implementations, the passivation film <NUM> is permeable to at least one of lithium ions and lithium atoms. The passivation film <NUM> provides surface protection of the negative electrode structure <NUM>, which allows for handling of the negative electrode structure <NUM> in a dry room and can contribute to stable SEI formation. Examples of materials that may be used to form the passivation film <NUM> include, but are not limited to, a lithium fluoride (LiF) film, a lithium carbonate (Li<NUM>CO<NUM>) film, a lithium oxide film, a lithium nitride (Li<NUM>N) film, a lithium phosphate (Li<NUM>PO<NUM>) film, a lithium chloride (LiCl) film, lithium alkyl silanolate based film, alkyl siloxanes based film, a polyethylene (PE) film, a polypropylene (PP) film, a polystyrene (PS) film, or other polymer film that does not react with lithium, a poly(acrylic acid), ethylene vinyl acetate, or other polymer film that reacts with lithium, or combinations thereof. In some implementations, the passivation film <NUM> can be formed on the negative electrode structure <NUM> by vapor deposition methods, for example, chemical vapor deposition (CVD), atomic layer deposition (ALD), physical vapor deposition (PVD), such as thermal evaporation or sputtering. In some implementations, the passivation film <NUM> is deposited on the negative electrode structure <NUM> above the melting point of lithium to facilitate chemical bonding. In some implementations, the passivation film <NUM> can be deposited below the melting point of lithium and then the negative electrode structure <NUM> heat-treated up to or above the melting point of lithium.

In some implementations, the passivation film <NUM> may be a conformal coating or a discrete film, either having a thickness in the range of <NUM> nanometer to <NUM>,<NUM> nanometers (e.g., in the range of <NUM> nanometers to <NUM> nanometers; in the range of <NUM> nanometers to <NUM> nanometers; in the range of <NUM> nanometers to <NUM> nanometers; in the range of <NUM> nanometers to <NUM> nanometers). In some implementations, the passivation film <NUM> is a discrete film having a thickness in the range of <NUM> micron to <NUM> microns (e.g., in the range of <NUM> micron to <NUM> microns). Coating process parameters control the passivation film <NUM> protective surface properties including, for example, mechanical durability, hydrophobicity, and stickiness. Passivation film <NUM> properties can be optimized to minimize reaction with air for extending coated web usable shelf life, to facilitate battery substrate and device manufacturability including web handling, and to contribute to stable SEI formation during battery assembly and charging.

<FIG> depicts a schematic side view of a modular free-span coating system <NUM> according to one or more implementations 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 implementations, the modular free-span coating system <NUM> is operable for pre-lithiating anode structures or cathode structures formed on flexible substrates. The modular free-span coating system <NUM> is constituted as a roll-to-roll system including an upstream unwinding module <NUM>, a common transfer chamber <NUM>, a plurality of vertical processing modules 210a, 210b. 210n (collectively <NUM>), and a downstream winding module <NUM>. In some implementations, the vertical processing modules 210a, 210b. 210n are arranged in sequence, each configured to perform one processing operation to a continuous flexible substrate <NUM>. Each vertical processing module <NUM> is operable to perform a free-span coating process on a continuous flexible substrate <NUM>, which is vertically oriented within the vertical processing modules <NUM> during the free-span coating process.

As shown in <FIG>, the vertical processing modules 210a, 210b. 210n are positioned on the common transfer chamber <NUM>. The continuous flexible substrate <NUM> is shown to be inserted into the first vertical processing module 210a, and to be ejected, after appropriate processing operations or processing steps, from the last vertical processing module 210n. Thus, each vertical processing module 210a-210n has upstream components on the side where the substrate is inserted in the process module, and downstream components on the side where the substrate is ejected from that process module, such as the upstream unwinding module <NUM> and the downstream winding module <NUM>. In some implementations, the upstream unwinding module <NUM> and the downstream winding module <NUM> are installed in separate chambers (e.g., a winding chamber and an unwinding chamber).

In some implementations, the continuous flexible substrate <NUM> is provided as a web, which is wound up on a roll and has a width in a range from <NUM> to <NUM>, and typically has a width of approximately <NUM>. In some implementations, the continuous flexible substrate <NUM> has a thickness in a range from <NUM> to <NUM>, for example, a thickness of approximately <NUM>. The continuous flexible substrate <NUM> has a front surface <NUM> and a back surface <NUM>. In some implementations, the continuous flexible substrate <NUM> 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 the negative current collector <NUM> having the negative electrode structure <NUM> formed thereon as shown in <FIG>. In some implementations, only the front surface <NUM> of the flexible substrate has an electrode structure formed thereon. In some implementations, both the front surface <NUM> and the back surface <NUM> have electrode structures formed thereon.

The common transfer chamber <NUM> includes a common transfer chamber body <NUM> that defines a transfer volume <NUM>. In some implementations, the common transfer chamber body <NUM> is fabricated from standard materials, such as aluminum, quartz, ceramic, or stainless steel. The common transfer chamber body <NUM> includes a plurality of through-holes 226a-<NUM> (collectively <NUM>) for accommodating the continuous flexible substrate <NUM>. The plurality of through-holes <NUM> are typically aligned with corresponding through-holes in a vertical chamber body <NUM> of each corresponding vertical processing chamber <NUM>. Each through-hole <NUM> in the common transfer chamber body <NUM> is sized to accommodate the continuous flexible substrate <NUM> while enabling differential pumping between a processing volume 244a, 244b. 244n (collectively <NUM>) of each vertical processing module <NUM> and the transfer volume <NUM>. The processing volume <NUM> is in fluid communication with the transfer volume <NUM>. In some implementations, the processing volume <NUM> is a vacuum processing volume. In some implementations, an inert gas environment is maintained in the transfer volume <NUM>. This inert gas environment of the transfer volume <NUM> isolates (e.g., provides gas separation) the processing volume <NUM>, which may be a vacuum processing volume, of each vertical processing module <NUM> from the processing volume <NUM> of other vertical processing modules <NUM> positioned on the common transfer chamber <NUM>. This isolation enables use of incompatible chemistries in different vertical processing modules <NUM>. The inert gas flows between adjacent vertical processing modules and prevents the diffusion of precursor gaseous mixtures between the adjacent vertical processing modules. In some implementations, the common transfer chamber <NUM> is coupled to a pressure control system (not shown) which pumps down and vents the common transfer chamber <NUM> as needed to facilitate passing the continuous flexible substrate <NUM> between the vacuum environment of one vertical processing chamber and the substantially ambient (e.g., atmospheric) environment outside of the modular free-span coating system <NUM>.

In some implementations, the vertical processing modules 210a-210n are stand-alone modular processing chambers wherein each modular processing chamber is structurally separated from the other modular processing chambers and the common transfer chamber <NUM>. Therefore, each of the stand-alone vertical processing modules 210a-210n, can be arranged, rearranged, replaced, or maintained independently without affecting 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 free-span coating system <NUM>. For example, in some implementations, <NUM>, <NUM>, <NUM>, <NUM>, or more vertical processing modules <NUM> are included in the modular free-span coating system <NUM>.

A lateral dimension of the modular free-span coating system <NUM>, e.g., a dimension extending in a substrate transport direction <NUM> is reduced by arranging the processing chambers of individual vertical processing modules 210a-210n in a vertical orientation. Furthermore, according to implementations described herein, a horizontal movement of the continuous flexible substrate <NUM> from one module to the next module and, thereby, a horizontal web control can be realized. In addition, a vertical movement of the continuous flexible substrate <NUM> can be provided during pre-lithiation of the electrode structure on the continuous flexible substrate <NUM> by the arrangement of the modular system. Thereby, free graphite and parasitic particles from the deposition process that might be generated in the deposition regions are less likely to fall on the front face of the continuous flexible substrate <NUM>, such that, for example damage to the deposited layers may occur due to flaking down of particles.

In some implementations of the present disclosure only two vertical processing modules 210a, 210b are presented, but additional vertical processing modules 210n may be included depending upon the targeted pre-lithiation process. For example, in some implementations where only two vertical processing modules <NUM> are present, the first vertical processing module 210a is operable to perform a thermal evaporation pre-lithiation process and the second vertical processing module 210b is operable to form a passivation film over the pre-lithiated electrode. In some implementations where more than two vertical processing modules <NUM> are present, multiple vertical processing modules <NUM> may be dedicated to the pre-lithiation process and/or the passivation process. In some implementations, additional vertical processing modules <NUM> are added and are operable to perform additional surface treatment processes, such as a corona surface treatment process, a pre-clean process, or a post clean process.

In some implementations, the vertical processing module <NUM> includes a vertical chamber body 240a, 240b. 240n (collectively <NUM>). In some implementations, the vertical chamber body <NUM> is fabricated from standard materials, such as aluminum, quartz, ceramic, or stainless steel. A partition plate 242a, 242b,. 242n (collectively <NUM>) extends across an interior volume defined by the vertical chamber body <NUM>. The partition plate <NUM> separates the interior volume into the processing volume <NUM> for processing the continuous flexible substrate <NUM> and a turnaround volume 246a, 246b. 246n (collectively <NUM>) for reversing the direction of the continuous flexible substrate <NUM>. The partition plate <NUM> includes a plurality of through holes 243a-243f (collectively <NUM>) for accommodating the continuous flexible substrate <NUM>. Each through-hole <NUM> in the partition plate <NUM> is sized to accommodate the continuous flexible substrate <NUM> while enabling differential pumping between the processing volume <NUM> and the turnaround volume <NUM>.

It should be understood that although the processing volume <NUM> and the turnaround volume <NUM> are shown as sharing a common chamber body, in some implementations, the processing volume <NUM> and the turnaround volume <NUM> are defined by separate chamber bodies with the chamber body defining the turnaround volume <NUM> stacked upon the chamber body defining the processing volume <NUM>. For example, in some implementations, the vertical processing module <NUM> includes a deposition chamber, which defines the processing volume <NUM> and a separate turnaround chamber, which defines the turnaround volume <NUM>. The deposition chamber and the turnaround chamber are separate modular and stackable elements with the turnaround chamber stacked upon the deposition chamber.

The vertical processing modules 210a-210n may include any suitable structure, configuration, arrangement, and/or components that enable the modular free-span coating system <NUM> to pre-lithiate and/or passivate an electrode structure formed on the continuous flexible substrate <NUM> according to implementations of the present disclosure. For example, in some implementations the vertical processing modules 210a-210n include, but are not limited to, suitable deposition systems including thermal evaporation sources, vapor diffusers, power sources, individual pressure controls, deposition control systems, and temperature control components. In some implementations, the vertical processing modules 210a-210n are each provided with individual gas supplies. The vertical processing modules 210a-210n are typically separated from each other for providing a good gas separation. In some implementations, the vertical processing modules 210a-210n are separated from each other by the common transfer chamber <NUM>. The modular free-span coating system <NUM> is not limited in the number of vertical processing modules 210a-210n. For example, in some implementations, the modular free-span coating system <NUM> may include two, three, four, five, or more vertical processing modules.

In some implementations, the vertical processing modules 210a-210n include one or more deposition units 252a-252f (collectively <NUM>) operable to perform a surface modification treatment on one or more surfaces of the continuous flexible substrate <NUM>. The one or more deposition units <NUM> are typically positioned in the processing volume <NUM> to perform free-span processing of the continuous flexible substrate <NUM>. For example, with reference to <FIG>, deposition unit 252a is positioned to process the continuous flexible substrate <NUM> while the continuous flexible substrate <NUM> is traveling between auxiliary tension reels 266b and auxiliary tension reel 266c. In some implementations, two deposition units 252a, 252b are arranged at opposing sides of the processing volume <NUM> with respect to the continuous flexible substrate <NUM>, the deposition units 252a, 252b being oriented vertically and facing the front surface <NUM> of the continuous flexible substrate <NUM>. In some implementations, the one or more deposition units <NUM> are positioned in the processing volume <NUM> parallel to the substrate transport direction <NUM> of the continuous flexible substrate <NUM>. In some implementations, the one or more deposition units <NUM> are positioned such that a material to be deposited on the continuous flexible substrate <NUM> is delivered in a substantially perpendicular orientation relative to the substrate transport direction <NUM> of the continuous flexible substrate <NUM>.

In some implementations, the one or more deposition units 252a-252f are vapor deposition sources. In some implementations, at least one of the one or more deposition units is a vertical diffuser operable for delivering evaporated lithium to the surface of the continuous flexible substrate <NUM>. In some implementations, the one or more deposition units are each individually selected from the group of a CVD source, a PECVD source, and a PVD source such as a sputtering or thermal evaporation source. In some implementations, the one or more deposition units 252a-252f can independently include an evaporation source, a sputter source, such as, a magnetron sputter source, a DC sputter source, an AC sputter source, a pulsed sputter source, a radio frequency (RF) sputter source, or a middle frequency (MF) sputter source. The one or more deposition units can include an evaporation source. In some implementations, the evaporation source includes either a thermal evaporation source or an electron beam evaporation source. In some implementations, the evaporation source includes a lithium (Li) source. In some implementations, 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 implementations, the lithium is evaporated by thermal evaporation techniques or by electron beam evaporation techniques.

In some implementations, the vertical processing modules 210a-210n include one or more cooling sources 254a, 254b,. 254n (collectively <NUM>). In some implementations, the cooling source <NUM> is a fluid cooled plate. In some implementations, the cooling source <NUM> is positioned in the processing volume <NUM> of the vertical processing module <NUM>. In some implementations, as shown in <FIG>, the cooling source <NUM> is positioned in between the dual deposition units <NUM>. For example, in the first vertical processing module 210a, the cooling source 254a is positioned in between the deposition units 252a, 252b. Positioning the cooling source 254a in between the deposition units 252a, 252b allows the cooling source 254a to cool the continuous flexible substrate <NUM> both as the continuous flexible substrate <NUM> approaches the turnaround volume <NUM> and returns from the turnaround volume <NUM> approaching the transfer volume <NUM>.

In some implementations, one or more of the vertical processing modules 210a-210n 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 implementations, one or more of the vertical processing modules are operable to perform a plasma treatment process, such as a plasma oxidation, or a plasma nitridation process.

In some implementations, the turnaround volume <NUM> includes an intermediate turnaround roller 248a, 248b,. 248n (collectively <NUM>). The intermediate turnaround roller <NUM> diverts the direction of the continuous flexible substrate <NUM> from a vertical upward movement to a vertical downward movement. In some implementations, where the intermediate turnaround roller <NUM> faces the back surface <NUM> of the continuous flexible substrate <NUM>, the intermediate turnaround roller may directly contact the back surface <NUM> of the continuous flexible substrate <NUM> and need not be designed as a gas cushion roller. In some implementations, the intermediate turnaround roller <NUM> is designed a gas cushion roller. In some implementations, the intermediate turnaround roller <NUM> is temperature-controlled. In some implementations, the intermediate turnaround roller <NUM> is heated. Heating of the intermediate turnaround roller <NUM> is believed to reduce wrinkles that may form in the continuous flexible substrate <NUM>. In some implementations, the intermediate turnaround roller <NUM> is cooled. Cooling the intermediate turnaround roller <NUM> helps reduce the temperature of the continuous flexible substrate <NUM> after processing in the processing volume <NUM>. Cooling the continuous flexible substrate <NUM> after processing is believed to reduce thermal damage to the continuous flexible substrate <NUM>.

In some implementations, the modular free-span coating system <NUM> comprises a common transport architecture <NUM>. The common transport architecture <NUM> may comprise any transfer mechanism capable of moving the continuous flexible substrate <NUM> through the processing volume <NUM> of each of the vertical processing modules 210a-210n. In some implementations, the common transport architecture <NUM> is a reel-to-reel system with a common winding reel <NUM> positioned in the downstream winding module <NUM>, the intermediate turnaround roller <NUM> positioned in the turnaround volume <NUM>, and an unwinding reel <NUM> positioned in the upstream unwinding module <NUM>. In some implementations, the downstream winding module <NUM>, the intermediate turnaround roller <NUM>, and the unwinding reel <NUM> are individually heated or cooled depending upon the targeted process conditions. In some implementations, the downstream winding module <NUM>, the intermediate turnaround roller <NUM>, and the unwinding reel <NUM> are individually heated either using an internal heat source positioned within each reel or an external heat source. In some implementations, the downstream winding module <NUM>, the intermediate turnaround roller <NUM>, and the unwinding reel <NUM> are individually cooled using either an internal cooling source positioned within each reel or an external cooling source.

In some implementations, the common transport architecture <NUM> further includes one or more auxiliary tension reels 266a-266n (collectively <NUM>) positioned between the unwinding reel <NUM>, the intermediate turnaround roller <NUM>, and the common winding reel <NUM>. The auxiliary tension reels <NUM> are disposed on the path where the continuous flexible substrate <NUM> is conveyed between each vertical processing module 210a-210n, the unwinding reel <NUM>, and the common winding reel <NUM>, to allow a tensile force to the continuous flexible substrate <NUM>. This tensile force prevents the continuous flexible substrate <NUM> from sagging down as well as to change the movement direction of the continuous flexible substrate <NUM>. Accordingly, even though the continuous flexible substrate <NUM> is moved along a continuously long path, a certain movement rate is constantly maintained. In some implementations, any of the auxiliary tension reels <NUM> may be replace with gas cushion rollers. For implementations having discrete processing regions, modules, or chambers, the common transport architecture may be a reel-to-reel system where each vertical processing module or processing volume has an individual take-up-reel and feed reel and one or more optional intermediate transfer reels positioned between the take-up reel and the feed reel.

The transport speed of the continuous flexible substrate <NUM> through the modular free-span coating system <NUM>, and through the individual vertical processing modules 210a-210n, is based on the number of vertical processing modules 210a-210n. In some implementations, a transport speed, which is used to move the continuous flexible substrate <NUM> through the vertical processing modules 210a-210n, is in a range from <NUM>/min to <NUM>/min, and typically amounts to <NUM>/min.

In operation, the continuous flexible substrate <NUM> is conveyed from the upstream unwinding module <NUM> and passes through the through-hole 226a, advancing into the common transfer chamber <NUM>. The continuous flexible substrate <NUM> is then moved vertically upward through the through-hole 226b so that the continuous flexible substrate <NUM> advances into the processing volume 244a of the first vertical processing module 210a. In the processing volume 244a, the continuous flexible substrate <NUM> travels in between the deposition unit 252a and the cooling source 254a where the continuous flexible substrate <NUM> is exposed to a free-span surface modification process such as a free-span pre-lithiation process. The continuous flexible substrate <NUM> is moved vertically upward through through-hole 243a, advancing into the turnaround volume <NUM> of the first vertical processing module 210a around the intermediate turnaround roller <NUM> where the continuous flexible substrate <NUM> is diverted to move vertically downward. The continuous flexible substrate <NUM> is moved vertically downward through the through-hole 243b returning to the processing volume 244a. In the processing volume 244a, the continuous flexible substrate <NUM> travels in between the deposition unit 252b and the cooling source 254a where the continuous flexible substrate <NUM> is exposed to an additional free-span surface modification process such as an additional free-span pre-lithiation process or a free-span passivation process. The continuous flexible substrate <NUM> is moved vertically downward through the through-hole 226c into the common transfer chamber <NUM>. The continuous flexible substrate <NUM> then travels in a horizontal direction through the common transfer chamber <NUM> until the continuous flexible substrate <NUM> is diverted vertically upward through the through-hole 226d so that the continuous flexible substrate <NUM> advances into the processing volume 244b of the second vertical processing module 210b. In the processing volume 244b, the continuous flexible substrate <NUM> is exposed to a free-span surface modification process such as a free-span passivation process. The continuous flexible substrate <NUM> is moved vertically upward through through-hole 243c, advancing into the turnaround volume 246b of the second vertical processing module 210b around the intermediate turnaround roller 248b where the continuous flexible substrate <NUM> is diverted to move vertically downward. The continuous flexible substrate <NUM> is moved vertically downward through the through-hole 243d returning to the processing volume 244b where the continuous flexible substrate <NUM> is exposed to an additional free-span surface modification process such as a free-span passivation process. The continuous flexible substrate <NUM> is moved vertically downward through through-hole 226e returning to the common transfer chamber <NUM>. In some implementations, the flexible substrate is subject to additional processing in additional vertical processing modules, for example, vertical processing module 210n.

Generally, the modular free-span coating system <NUM> includes a system controller <NUM> configured to control the automated aspects of the modular free-span coating system <NUM>. The system controller <NUM> facilitates the control and automation of the overall modular free-span coating system <NUM> and may include a central processing unit (CPU) (not shown), memory (not shown), and support circuits (or I/O) (not shown). Software instructions and data can be coded and stored within the memory for instructing the CPU. A program (or computer instructions) readable by the system controller <NUM> determines which tasks are performable on a substrate. Preferably, the program is software readable by the system controller <NUM>, which includes code to generate and store at least substrate positional information, the sequence of movement of the various controlled components, and any combination thereof.

<FIG> depicts a schematic side view of a vertical processing module <NUM> that may be use in the modular free-span coating system <NUM> of <FIG>. The vertical processing module <NUM> is operable to perform a double-sided surface modification process such as a double-sided free-span pre-lithiation process and/or a double-sided free-span passivation process. During the double-sided free-span pre-lithiation process opposing sides (e.g., the front surface <NUM> and the back surface <NUM>) of the continuous flexible substrate <NUM> are simultaneously exposed to a free-span pre-lithiation process or a free-span passivation process. The vertical processing module <NUM> is similar to the vertical processing module <NUM> except that the vertical processing module <NUM> has three deposition units 352a-352c (collectively <NUM>). The one or more deposition units <NUM> are typically positioned in the processing volume <NUM> to perform free-span processing of the continuous flexible substrate <NUM>. For example, with reference to <FIG>, deposition unit 352a is positioned to process the continuous flexible substrate <NUM> while the continuous flexible substrate <NUM> is traveling between auxiliary tension reels 366b and auxiliary tension reel 366c. Deposition unit 352b is positioned to process the continuous flexible substrate <NUM> while the continuous flexible substrate <NUM> is traveling between auxiliary tension reels 366d and auxiliary tension reel 366e. Deposition units 352a and 352b are positioned to process the front surface <NUM> of the continuous flexible substrate <NUM>. Deposition unit 352c is positioned in between deposition units 352a and 352b and operable to process the back surface <NUM> of the continuous flexible substrate <NUM>. In some implementations, the deposition units 352a-352c are configured similarly to the deposition unit <NUM>.

<FIG> illustrates a process flow chart summarizing one implementation of a processing sequence <NUM> of pre-lithiation and passivation of an electrode structure according to one or more implementations of the present disclosure. The processing sequence <NUM> may be used to pre-lithiate a single-sided electrode structure, for example, the electrode structure depicted in <FIG>, or a dual-sided electrode structure, for example, the electrode structure depicted in <FIG>. The processing sequence <NUM> may be performed using, for example, the modular free-span coating system <NUM> depicted in <FIG>.

The processing sequence <NUM> begins at operation <NUM> by providing a flexible substrate comprising an electrode structure. In some implementations, the flexible substrate is continuous flexible substrate <NUM>, which includes a negative electrode (anode electrode), for example, the negative electrode structure <NUM> formed on the negative current collector <NUM>, or a positive electrode (cathode electrode), for example, the positive electrode structure <NUM> formed on the positive current collector <NUM> as depicted in <FIG>. In some implementations, the continuous flexible substrate <NUM> includes a dual-sided electrode structure, such as the dual-sided electrode structure <NUM>, which comprises the negative current collector <NUM> with a negative electrode structure 140a, 140b (collectively <NUM>) formed on opposing sides of the negative current collector <NUM> as shown in <FIG>.

At operation <NUM>, the flexible substrate is moved into a first vertical processing module. Referring to <FIG>, in some implementations, the continuous flexible substrate <NUM> is conveyed from the upstream unwinding module <NUM> and passes through the through-hole 226a, advancing into the common transfer chamber <NUM>. The continuous flexible substrate <NUM> is then moved vertically upward through the through-hole 226b so that the continuous flexible substrate <NUM> advances into the processing volume 244a of the first vertical processing module 210a.

At operation <NUM>, the flexible substrate is processed in the first vertical processing module. In some implementations, the process is a free-span pre-lithiation process that involves reactive lithium ions condensing on the continuous flexible substrate <NUM> and intercalating along grain boundaries in the negative electrode structure <NUM>. Referring to <FIG>, in some implementations, in the processing volume 244a, the continuous flexible substrate <NUM> travels in between the deposition unit 252a and the cooling source 254a where the continuous flexible substrate <NUM> is exposed to a free-span surface modification process such as a free-span pre-lithiation process. In some implementations, the deposition unit 252a is a vapor diffuser. The free-span pre-lithiation process includes delivering vaporized lithium via the deposition unit 252a toward the continuous flexible substrate <NUM>. The vaporized lithium pre-lithiates the electrode structure by condensing on the electrode structure of the continuous flexible substrate <NUM>. In some implementations, the degree of pre-lithiation is controlled by adjusting the temperature and concentration of reactive lithium ions emitted by the deposition unit <NUM>. The degree of pre-lithiation is also controlled by the heat transfer from the continuous flexible substrate <NUM> to cooling sources <NUM> and transport speed. It is noted that lithium can continue to intercalate along grain boundaries in the negative electrode after the coating process is complete. Therefore, in some implementations, the free-span pre-lithiation process is utilized with subsequent material aging and other treatments to produce material having a controlled degree of pre-lithiation.

After the first pre-lithiation process, the continuous flexible substrate <NUM> is moved vertically upward through through-hole 243a, advancing into the turnaround volume <NUM> of the first vertical processing module 210a around the intermediate turnaround roller 248a where the continuous flexible substrate <NUM> is diverted to move vertically downward. In some implementations where the intermediate turnaround roller 248a is temperature-controlled, the continuous flexible substrate <NUM> is cooled or heated by the intermediate turnaround roller 248a. The continuous flexible substrate <NUM> is moved vertically downward through the through-hole 243b returning to the processing volume 244a. In the processing volume 244a, the continuous flexible substrate <NUM> travels in between the deposition unit 252b and the cooling source 254a where the continuous flexible substrate <NUM> is exposed to an additional free-span pre-lithiation process to provide additional lithium to the electrode structure of the continuous flexible substrate <NUM>.

At operation <NUM>, the continuous flexible substrate <NUM> is moved out of the first vertical processing module 210a. The continuous flexible substrate <NUM> is moved vertically downward through the through-hole 226c into the common transfer chamber <NUM>. The continuous flexible substrate <NUM> then travels in a horizontal direction through the common transfer chamber <NUM> until the continuous flexible substrate <NUM> is diverted vertically upward through the through-hole 226d so that the continuous flexible substrate <NUM> advances into the processing volume 244b of the second vertical processing module 210b at operation <NUM>.

At operation <NUM>, the continuous flexible substrate <NUM> 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 <NUM> is exposed to a free-span surface modification process such as a free-span passivation process. In some implementations, the free-span passivation process forms a passivation film, such as the passivation film <NUM>, on the pre-lithiated electrode structure. In some implementations, the passivation film can be formed on the electrode structure by vapor deposition methods, for example, 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.

At operation <NUM>, the continuous flexible substrate <NUM> is moved out of the second vertical processing module 210b. The continuous flexible substrate <NUM> is moved vertically downward through the through-hole 226e into the common transfer chamber <NUM>. In one implementation, where the continuous flexible substrate <NUM> is subjected to additional processing, the continuous flexible substrate <NUM> then travels in a horizontal direction through the common transfer chamber <NUM> until the continuous flexible substrate <NUM> is diverted vertically upward through the through-hole 226f so that the continuous flexible substrate <NUM> advances into the processing volume 244n of the vertical processing module 210n. In another implementation, where processing of the continuous flexible substrate <NUM> is complete, the continuous flexible substrate <NUM> exits the common transfer chamber <NUM> via through-hole <NUM>. After exiting the common transfer chamber <NUM>, the continuous flexible substrate <NUM> may be wound onto the winding reel <NUM>.

In some implementations, the passivation film <NUM> can be formed using gaseous or liquid precursors that are either inert or reactive with lithium above or below the lithium melting point. For example, the passivation film <NUM> can be formed by introducing anhydrous carbon dioxide in between the deposition unit <NUM> in the processing volume 244b of the second vertical processing module 210b to form a protective layer of lithium carbonate (Li<NUM>CO<NUM>) on pre-lithiated surfaces formed in the processing volume 244a of the first vertical processing module 210a. The operating temperature of the deposition unit <NUM> and latent heat of the continuous flexible substrate <NUM> affect the lithium carbonate pinhole-free quality and total thickness. In some implementations, phosphoric acid is used instead of carbon dioxide to form a protective layer of lithium phosphate (Li<NUM>PO<NUM>) which is more moisture resistant than lithium carbonate and therefore more effective at reducing coated web air reactivity for a longer period. In some implementations, where it is desirable to avoid heating the pre-lithiated negative electrode structure <NUM> during passivation processing, chlorosilane vapors are used to produce a thin layer of lithium chloride (LiCl) and either lithium alkyl silanolate derivatives or alkyl siloxanes to produce a passivation film, for example, passivation film <NUM> that is more heat stable than lithium carbonate or lithium phosphate. In some implementations, the passivation film <NUM> is comprised of two or more laminar films such as a lithium carbonate film that minimizes air reactivity and an organic layer such as wax, for example, a polyethylene wax such as Luwax® that improves web durability and facilitates battery assembly. In some implementations, the passivation film <NUM> is comprised of one or more layers of polyethylene oxide, ethylene vinyl acetate, or other polymer that has low solubility in N-methyl-<NUM>-pyrrolidone (NMP) to improve stability and storage life. The common transfer chamber <NUM> provides spatial isolation between the processing volume 244a and the processing volume 244b prevents reactive gas or vapor precursors used in the passivation process from migrating upstream and contaminating the pre-lithiation process.

The continuous flexible substrate <NUM> is moved vertically upward through through-hole 243c, advancing into the turnaround volume 246b of the second vertical processing module 210b around the intermediate turnaround roller 248b where the continuous flexible substrate <NUM> is diverted to move vertically downward. The continuous flexible substrate <NUM> is moved vertically downward through the through-hole 243d returning to the processing volume 244b where the continuous flexible substrate <NUM> is exposed to an additional free-span surface modification process such as a free-span passivation process. The continuous flexible substrate <NUM> is moved vertically downward through through-hole 226e returning to the common transfer chamber <NUM>.

In some implementations, the continuous flexible substrate <NUM> is subject to additional processing in additional vertical processing modules, for example, vertical processing module 210n. In some implementations, additional processing may provide for deposition of a separator, an electrolyte soluble binder, or in some implementations, additional chambers may provide for formation of a positive electrode structure. In some implementations, additional chambers provide for cutting of the negative electrode. The passivation film may be removed after cutting of the negative electrode.

In summary, some of the benefits of the present disclosure include the efficient integration of pre-lithiation and passivation into a modular free-span processing system. Currently, lithium metal deposition is performed in a dry room or an argon gas atmosphere. Due to the volatility of lithium metal, subsequent processing steps must also be performed in an argon gas atmosphere. Performance of subsequent processing steps in an argon gas atmosphere would require retrofitting of current manufacturing tools. It has been found by the inventors that coating the lithium metal with a protective film prior to subsequent processing, allows subsequent processing to be performed either under vacuum or at atmosphere. The protective film eliminates the need to perform additional processing operations in an inert gas atmosphere reducing the complexity of tools. The protective film also allows for the transportation, storage, or both of the negative electrode with the lithium metal film formed thereon. Additionally, vertically oriented pre-lithiation and passivation of an electrode structure allows for modulation of either processing time or processing length while reducing the footprint of the system.

In addition, free-span coating eliminates contact between the web and cooling drum near the vapor source high thermal load. Removing web handling requirements from the deposition in volume prevents winding defects such as wrinkles. Free-span coating also facilitates high web speed (e.g., greater than <NUM> meter per minute, up to <NUM> meters per minute) at low level cost of equipment. The free-span coating system is designed to minimize wrinkles. In some implementations, the coating system has multiple chambers operating at different temperatures to maximize coating thickness and uniformity without damaging the heat sensitive substrate. In some implementations, the coating system can control the coating rate by optimizing temperatures, processing length, and web speed. In some implementations, the coating system has a high lithium utilization rate due to the minimization of parasitic surfaces.

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.

Claim 1:
A modular processing system, comprising:
a common transfer chamber body (<NUM>) defining a transfer volume (<NUM>);
a first vertical chamber body (<NUM>) defining a first processing volume (<NUM>) and positioned on the common transfer chamber body (<NUM>), wherein the transfer volume (<NUM>) is in fluid communication with the first processing volume (<NUM>);
a second vertical chamber body (<NUM>) defining a second processing volume (<NUM>) and positioned on the common transfer chamber body (<NUM>), wherein the transfer volume (<NUM>) is in fluid communication with the second processing volume (<NUM>); and
a reel-to-reel system operable to transport a continuous flexible substrate (<NUM>) having an electrode structure (<NUM>, <NUM>) formed thereon, wherein the continuous flexible substrate (<NUM>) extends from the transfer volume (<NUM>), through the first processing volume (<NUM>), returning to the transfer volume (<NUM>), through the second processing volume (<NUM>), and returning to the transfer volume (<NUM>);
the modular processing system further comprising
a first deposition unit (<NUM>) installed in the first processing volume (<NUM>) and positioned vertically to be parallel to a movement direction of the continuous flexible substrate (<NUM>);
a second deposition unit (<NUM>) installed in the first processing volume (<NUM>) opposite the first deposition unit (<NUM>) and disposed vertically to be parallel to a movement direction of the continuous flexible substrate (<NUM>); and
a cooling plate (<NUM>) positioned in between the first deposition unit (<NUM>) and the second deposition unit (<NUM>); or
a third deposition unit (<NUM>) positioned in between the first deposition unit (<NUM>) and the second deposition unit (<NUM>).