Method for manufacturing electrode-electrolyte laminate

Abstract

The present invention relates to a method for manufacturing an electrode-electrolyte laminate for a lithium metal battery cell. The method includes depositing a ceramic electrolyte layer onto a first surface of a sacrificial polymer substrate, and depositing a lithium metal layer onto an exposed surface of the ceramic electrolyte layer. The sacrificial polymer substrate is then removed to form an electrode-electrolyte laminate. The electrode-electrolyte laminate prepared by the method can be used to manufacture an electrochemical cell.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an electrode - electrolyte laminate for a lithium metal battery cell, and an electrode - electrolyte laminate manufactured by such a method. Background Art

[0002] Lithium - ion secondary batteries are currently the leading battery technology used in applications ranging from small personal devices to electric vehicles. Lithium - ion batteries are favored for their advantages such as high energy density and long cycle life. They contain multiple lithium - ion secondary battery cells, which are an example of alkali metal ion secondary battery cells.

[0003] Compared to more conventional anodes such as graphite, lithium metal anodes have received significant attention due to their high energy density. However, Li anodes are prone to failure, mainly in two modes: First, Li dendrites may grow through the cell during operation, potentially leading to short - circuits and catastrophic cell failure. Second, the continuous consumption of electrolyte components during SEI formation affects the cycle life and cell performance.

[0004] It is known to use a protective coating on the anode surface to address one or more of these drawbacks. For example, US7 939 205 describes a "hard electrolyte" layer covering the negative and / or positive electrodes. A lithium phosphorus oxynitride (LiPON) layer has been proposed as a coating on the anode to prevent dendrites from growing on the cell.

[0005] However, the inventors have found that coating LiPON onto a lithium metal anode by PVD causes some of the lithium in the anode to be converted to Li3N, thereby reducing the energy density of the anode. In addition, erosive species in the plasma used for deposition produce a Li2O film on the surface of the Li metal anode, further degrading anode performance.

[0006] Conventional lithium - ion battery components (such as electrodes) are made by a solvent casting process that uses a sacrificial solvent. This is an energy - expensive step, and thus a process that avoids using a sacrificial solvent is needed.

[0007] Another major drawback of lithium - ion technology and other alkali metal ion secondary battery cell technologies is that a liquid electrolyte is often used within the lithium - ion battery cells of the battery to provide lithium - ion conductivity within the cell between the solid, solvent - cast anode and cathode. This leads to safety concerns because liquid electrolytes are typically highly flammable. This is a particular problem for electric vehicles, where a collision with another vehicle may be relatively large, and the resulting impact may cause battery damage and electrolyte ignition. This is also a problem for household devices because a lithium - ion battery fire can cause property damage or serious injury.

[0008] One way to avoid using sacrificial solvents and the need for a liquid electrolyte within the battery cell is to prepare gel electrodes. These electrodes can be formed from a composition prepared by mixing the necessary components such as an electrochemically active material, a polymer, and a liquid electrolyte, and then subjecting the composition to a heat treatment. Such gel electrodes are described in WO 2017 / 017023 A1, which attempts to fabricate an electrochemical device without a liquid electrolyte.

[0009] The gel electrodes are assembled with other gel or solid-state components to form a battery cell, thereby reducing the fire risk due to the removal of free liquid from the battery cell. The manufacturing cost of the battery cell is also reduced because the gel components can be produced by simpler processing steps without the need for the slow drying of solvents required for solvent-cast electrodes.

[0010] There is a need for a process to fabricate Li metal battery cells that provides protection against dendrite growth for the battery cell and limits the consumption of electrolyte components without adversely affecting the performance of the Li metal anode. For such a process, it is also desirable to allow the Li metal battery cell to also contain gel components. Currently, due to the reactivity of the Li metal anode, it is necessary to use only all-solid-state (ceramic) cathodes and exclude other solvent-cast or gel cathodes. All-solid-state cathodes are complex and expensive to manufacture. Opening the possibility of using solvent-cast or gel cathodes with a Li metal anode would provide greater flexibility in manufacturing and component selection.

[0011] With this in mind, the present invention has been developed, which provides a manufacturing method that can protect the Li metal anode from dendrite growth while avoiding the harmful generation of large amounts of Li3N and Li2O and allowing the anode to be assembled with gel battery cell components. Summary of the Invention

[0012] The present invention generally relates to a method for manufacturing an electrode-electrolyte laminate, and particularly to the sequential deposition of layers on a sacrificial polymer substrate before removing the sacrificial polymer substrate.

[0013] A first aspect of the present invention is a method for manufacturing an electrode-electrolyte laminate for a lithium metal battery cell, comprising:

[0014] Depositing a ceramic electrolyte layer on a first surface of a sacrificial polymer substrate;

[0015] Depositing a lithium metal layer on the exposed surface of the ceramic electrolyte layer to form a laminate precursor; and

[0016] Removing the sacrificial polymer substrate from the laminate precursor to form an electrode-electrolyte laminate.

[0017] Sequential deposition of a ceramic electrolyte layer on a sacrificial polymer substrate, followed by deposition of lithium metal, offers several advantages. First, since the ceramic electrolyte layer is deposited directly onto the sacrificial polymer substrate rather than onto a lithium metal anode layer, the formation of problematic substances such as Li3N and Li2O is avoided. The inventors have found that when the ceramic electrolyte layer is deposited directly onto a Li metal anode, large amounts of Li3N and Li2O are formed, which in some cases consume the entire Li metal anode and render the cell unit unusable. Instead, by depositing the ceramic electrolyte layer directly onto the sacrificial polymer substrate and then depositing lithium metal onto the ceramic electrolyte layer, a thin layer of Li3N and Li2O (solid electrolyte interface) spontaneously forms between the lithium metal layer and the ceramic electrolyte layer (typically 50 - 100 nm thick), which does not impair cell unit functionality and is actually beneficial, providing a SEI layer that protects the Li metal anode from being consumed or degraded during cell unit cycling. The SEI formed in this way is stable, providing protection for multiple cell unit cycles.

[0018] Second, the electrode - electrolyte laminate structure obtained by this method is easily assembled with a cathode layer, which can be a conventional solvent - cast cathode or a gel cathode, thus providing versatility. Therefore, the electrode - electrolyte laminate can be used to fabricate a cell unit that includes a gel cathode as well as a lithium metal anode, providing all the benefits associated with the gel component within a Li metal cell unit.

[0019] Third, the method is simple and effective because the same equipment and procedures can be used to deposit the initial ceramic electrolyte layer and the subsequent lithium metal layer, reducing the manufacturing cost, complexity, and environmental impact.

[0020] In addition, the method provides an electrode - electrolyte laminate structure that is simply a lithium metal layer coated within a ceramic electrolyte layer. This can be combined with a cathode structure to form a cell unit without the need for any separator layer between the cathode and the ceramic electrolyte layer. As a result, the cell unit has few layers, reducing the number of interfaces within the cell unit, thereby reducing impedance, and also increasing the weight and volume energy density of the device due to the reduced number of layers.

[0021] A second aspect of the present invention provides an electrode - electrolyte laminate for a lithium metal cell unit, prepared by the method according to the first aspect, comprising:

[0022] A ceramic electrolyte layer; and

[0023] A lithium metal layer on a first surface of the ceramic electrolyte layer.

[0024] A third aspect of the present invention provides an electrochemical cell unit comprising the electrode - electrolyte laminate structure according to the second aspect.

[0025] A fourth aspect of the present invention provides an electrochemical energy storage device comprising an electrochemical cell unit according to the third aspect.

[0026] Preferred and / or optional features of the present invention will now be described. Unless the context requires otherwise, any aspect of the present invention may be combined with any other aspect of the present invention. Any preferred and / or optional feature of any aspect may be combined with any aspect of the present invention, either alone or in combination, unless the context requires otherwise.

[0027] Ceramic electrolyte layer

[0028] In some embodiments, the ceramic electrolyte layer comprises a thin film of ceramic electrolyte material (before removal of the sacrificial polymer substrate) in contact with or adhered to the first surface of the sacrificial polymer substrate. There may be direct contact between the ceramic electrolyte layer and the first surface of the sacrificial polymer substrate, i.e., there is no other material layer between the ceramic electrolyte layer and the first surface of the sacrificial polymer substrate.

[0029] In some embodiments, the ceramic electrolyte layer comprises one or more of the following: lithium phosphorus oxynitride (LiPON), lithium borosilicate (LBSO), lithium phosphate (Li3PO4), boron-doped lithium phosphorus oxynitride (LiBPON), lithium silicate, lithium borate, LAGP, LATP, LiSICON, lithium garnet ceramics (such as LLTO, LLZO, and LLZTO), and perovskite.

[0030] The ceramic electrolyte layer may comprise or consist of a solid inorganic material that conducts lithium ions. The ceramic electrolyte layer may comprise or consist of a solid ceramic material that conducts lithium ions.

[0031] In some embodiments, the ceramic electrolyte layer comprises a ceramic electrolyte material having a modulus of at least 5 GPa, such as at least 6 GPa, at least 8 GPa, or at least 10 GPa. Providing a material with such a modulus ensures that dendrite growth is slowed down.

[0032] In some embodiments, the ceramic electrolyte layer comprises or consists of LiPON. LiPON is a solid Li ion conductor with the general formula Li x PO y N z . LiPON can be deposited onto the sacrificial polymer substrate with a very small thickness, such as as low as about 100 nm, such that the size of the cell unit is limited. Even at such a thickness, due to its amorphous and pore-free structure, LiPON still retains its ability to prevent or reduce dendrite growth through the cell unit, meaning there are no grain boundaries or pores for dendrites to grow.

[0033] In some embodiments, the ceramic electrolyte layer has an amorphous structure. The amorphous ceramic electrolyte layer lacks any grain boundaries present in the crystalline layer. Since grain boundaries can theoretically provide a path for dendrite growth, the amorphous ceramic electrolyte layer is not prone to dendrite growth that can lead to cell failure.

[0034] In some embodiments, the ceramic electrolyte layer has no or substantially no pores extending through the plane of the layer. Such pores are commonly referred to as "pinholes" and can provide another way for dendrites to grow through the electrolyte layer. By ensuring that there are no or substantially no pinholes, dendrite growth through the layer is further restricted. For example, by ensuring little or no contamination of the sacrificial polymer substrate before depositing the ceramic electrolyte (such as ensuring no dust formation on the sacrificial polymer substrate), and by providing ceramic electrolyte deposition conditions that ensure maximum diffusion of adsorbed atoms on the surface of the sacrificial polymer substrate, such that the deposited ceramic electrolyte fills the maximum number of voids in the film growing on the substrate, the risk of pinhole formation can be reduced.

[0035] In some embodiments, the ceramic electrolyte layer is deposited onto a first surface of a sacrificial polymer substrate by a deposition process that includes gradually depositing atoms or molecules of the ceramic electrolyte onto the first surface of the sacrificial polymer substrate. In this way, a continuous thin layer of complete contact between the sacrificial polymer substrate and the ceramic electrolyte layer can be formed, which cannot be achieved by mechanically placing a pre-formed ceramic electrolyte layer onto the sacrificial polymer substrate. This ensures a minimum internal resistance of the cell.

[0036] In some embodiments, the ceramic electrolyte layer is deposited onto a first surface of a sacrificial polymer substrate by a vacuum deposition process, preferably by PVD. By performing the deposition under vacuum, this ensures a controllable thickness of the film and reduced film contamination.

[0037] The ceramic electrolyte layer can be deposited onto a first surface of a sacrificial polymer substrate by a PVD process selected from (a) reactive sputtering or (b) plasma-assisted reactive evaporation.

[0038] Reactive sputtering includes RF sputtering of a suitable target using a nitrogen plasma. The target can include a material that forms the ceramic material of the ceramic electrolyte layer when sputtered and then deposited onto the sacrificial polymer substrate. In embodiments where the ceramic electrolyte layer comprises or consists of LiPON, the target can comprise or consist of lithium phosphate.

[0039] Plasma-assisted reactive evaporation involves evaporating a source material in the presence of a nitrogen plasma. The evaporation can be achieved thermally or using an electron gun. The source material can include materials that form a ceramic electrolyte layer when sputtered and then deposited onto a sacrificial polymer substrate. In embodiments where the ceramic electrolyte layer comprises or consists of LiPON, the source material can include or consist of lithium phosphate.

[0040] Alternatively, deposition of the ceramic electrolyte layer can be achieved by atomic layer deposition (ALD) or chemical vapor deposition (CVD).

[0041] In some embodiments, after deposition, the thickness of the ceramic electrolyte layer is from about 0.1 μm to about 4 μm, such as from about 0.1 μm to about 3.5 μm, from about 0.1 μm to about 3 μm, from about 0.1 μm to about 2.5 μm, or from about 0.1 μm to about 2 μm.

[0042] In some embodiments, after deposition, the thickness of the ceramic electrolyte layer is from about 0.1 μm to about 1 μm, such as from about 0.1 μm to less than 1 μm.

[0043] The thickness of the ceramic electrolyte layer can be controlled by controlling the length of time of deposition during the vacuum deposition process.

[0044] In some embodiments, the ceramic electrolyte layer comprises or consists of LiPON and is deposited onto a first surface of a sacrificial polymer substrate by a PVD method, the method comprising:

[0045] Preparing a vacuum chamber having a lithium phosphate target and a sputtering source;

[0046] Providing a sacrificial polymer substrate within the vacuum chamber;

[0047] Providing a vacuum within the vacuum chamber having a pressure less than 0.1 Pa; and

[0048] Depositing LiPON onto the first surface of the sacrificial polymer substrate by sputtering the lithium phosphate target.

[0049] The sputtering source can include an RF magnetron.

[0050] The sacrificial polymer substrate can be tensioned on a frame within the vacuum chamber to ensure a smooth tensioned surface for uniform deposition.

[0051] Ensuring a vacuum less than 0.1 Pa minimizes the presence of chamber contaminants, thereby improving the purity of the deposited LiPON layer. In a preferred embodiment, a vacuum less than 1×10 -4 Pa is provided to further reduce chamber contaminants and improve the purity of the deposited layer.

[0052] In some embodiments, the step of depositing LiPON onto the surface of a sacrificial polymer substrate by sputtering a lithium phosphate target comprises the following steps:

[0053] Supply continuously nitrogen gas into the vacuum chamber;

[0054] Apply an RF power source to RF-bias the lithium phosphate target;

[0055] Form a nitrogen plasma with an RF field;

[0056] Sputter the lithium phosphate target by bombarding with the nitrogen plasma to eject material from the lithium phosphate target into the vacuum chamber; and

[0057] Condense the material onto the surface of the sacrificial polymer substrate to form a LiPON layer.

[0058] In some embodiments, the continuous supply of nitrogen gas causes the pressure in the vacuum chamber to rise to a pressure within the range of 0.1 to 1.0 Pa.

[0059] Lithium metal layer

[0060] The method of the first aspect includes depositing a lithium metal layer onto the exposed surface of a ceramic electrolyte layer to form a laminate precursor.

[0061] Deposit a lithium metal layer onto the exposed surface of the ceramic electrolyte layer. In other words, after depositing the ceramic electrolyte layer and the lithium metal layer, the laminate precursor sequentially includes a sacrificial polymer substrate, a ceramic electrolyte layer, and a lithium metal layer. The ceramic electrolyte layer is thus sandwiched between the sacrificial polymer substrate and the lithium metal layer.

[0062] The term "laminate precursor" refers to a laminate structure that includes a sacrificial polymer substrate, a ceramic electrolyte layer, and a lithium metal layer before removing the sacrificial polymer substrate. This structure is the precursor of the final electrode-electrolyte laminate, which is produced by removing the sacrificial polymer substrate layer from the precursor.

[0063] In some embodiments, after depositing the lithium metal layer, there is no material layer between the ceramic electrolyte layer and the lithium metal layer.

[0064] The lithium metal layer comprises or consists of metallic lithium.

[0065] In some embodiments, the ceramic electrolyte layer and the lithium metal layer are deposited by a deposition technique that includes gradually depositing atoms or molecules of a material onto the surface of a substrate under vacuum conditions. This simplifies the process, allows similar methods and equipment to be used for both deposition steps, reduces the total manufacturing cost, and eliminates the need to remove a sacrificial polymer substrate from the vacuum chamber between deposition steps. In some embodiments, the ceramic electrolyte layer and the lithium metal layer are each deposited by a PVD-type technique. For example, the ceramic electrolyte layer can be deposited by sputtering, and the lithium metal layer can be deposited by thermal evaporation, both of which are examples of PVD methods.

[0066] In some embodiments, after depositing the ceramic electrolyte layer, the sacrificial polymer substrate can be moved (e.g., rotated or translated) within the vacuum chamber to facilitate subsequent deposition of the lithium metal layer.

[0067] In some embodiments, a pre-formed lithium metal thin film is deposited onto the ceramic electrolyte layer. However, this method is less preferred because the resulting contact between the ceramic electrolyte layer and the lithium metal layer is not complete, leading to variations in current density across the battery cell and ultimately to battery cell failure. This method may also pose a higher risk of introducing contaminants due to the need for manual manipulation of the lithium metal layer. This may also damage the ceramic electrolyte and the lithium metal layer.

[0068] In some embodiments, the lithium metal layer is deposited onto the exposed surface of the ceramic electrolyte layer by a deposition process that includes gradually depositing lithium atoms onto the ceramic electrolyte layer. In this way, a continuous thin layer of complete contact between the ceramic electrolyte layer and the lithium metal layer can be formed, which cannot be achieved by mechanically placing a pre-formed lithium metal layer onto the ceramic electrolyte layer. This ensures a minimum internal resistance of the battery cell.

[0069] In some embodiments, the lithium metal layer is deposited onto the exposed surface of the ceramic electrolyte layer by a vacuum deposition process, preferably by PVD. By performing the deposition under vacuum, this ensures a controllable thickness of the film and reduced film contamination.

[0070] In some embodiments, the ceramic electrolyte layer and the lithium metal layer are sequentially deposited by PVD. In some embodiments, the ceramic electrolyte layer and the lithium metal layer are sequentially deposited by PVD without removing the sacrificial polymer substrate from the vacuum chamber and without venting the vacuum chamber between deposition steps.

[0071] In some embodiments, after deposition, the thickness of the lithium metal layer is from about 0.01 μm to about 15 μm, such as from about 0.1 μm to about 15 μm, from about 0.1 μm to about 10 μm, from about 0.1 μm to about 5 μm, or from about 0.1 μm to about 2 μm.

[0072] In some embodiments, the lithium metal layer is very thin, e.g., about 0.01 μm to about 1 μm thick or about 0.01 μm to about 0.1 μm thick. Such thicknesses are possible because the lithium metal does not need to provide structural support for the laminate (which is provided by the ceramic electrolyte layer). This thin lithium metal layer serves as a useful seed layer for subsequent lithium electroplating during battery cell charging while maintaining high volumetric and gravimetric energy densities.

[0073] The thickness of the lithium metal layer can be controlled by controlling the length of the deposition duration during the vacuum deposition process.

[0074] In some embodiments, vacuum conditions are maintained between the deposition of the ceramic electrolyte layer and the deposition of the lithium metal. This provides a simple and effective process that eliminates the need to evacuate the vacuum chamber or re - establish the vacuum for Li metal deposition.

[0075] In some embodiments, the lithium metal layer is deposited by thermal evaporation.

[0076] In some embodiments, the method includes providing a thermal evaporation source containing lithium metal. The thermal evaporation source can include a resistively - heated crucible containing lithium metal, which is heated to evaporate the lithium.

[0077] In some embodiments, the method includes heating the lithium metal to a temperature above 250 °C, e.g., above 300 °C, above 350 °C, or above 400 °C, under vacuum to form Li vapor, and depositing Li from the vapor onto the exposed surface of the ceramic electrolyte layer by condensation. Higher temperatures above 300 °C are preferred because below this temperature, the vapor pressure of lithium may be too low for effective evaporation and deposition.

[0078] At temperatures greater than 250 °C, e.g., greater than 300 °C, greater than 350 °C, or greater than 400 °C, when under a vacuum of about 1×10 -6 mbar, the molten lithium begins to evaporate, and then the resulting Li vapor will condense onto the surface of the ceramic electrolyte layer that has been previously deposited onto a sacrificial polymer substrate, thereby forming a Li metal layer on the ceramic electrolyte layer.

[0079] In some embodiments, resistive heating is used to heat the Li metal. The heating can be carried out in a suitable crucible.

[0080] In some embodiments, the lithium metal layer is deposited onto the exposed surface of the ceramic electrolyte layer by a PVD method, which includes:

[0081] Preparing a vacuum chamber having a thermal evaporation source containing lithium metal;

[0082] Providing a substrate in the vacuum chamber that includes a ceramic electrolyte layer deposited onto a sacrificial polymer substrate;

[0083] Provide a vacuum with a pressure less than 1×10 -6 mbar in a vacuum chamber; and

[0084] Deposit lithium metal onto the surface of a ceramic electrolyte layer by evaporating lithium from a thermal evaporation source and condensing the lithium onto the ceramic electrolyte layer.

[0085] Ensure that a vacuum of less than 1×10 -6 mbar minimizes the presence of contaminants in the chamber, thereby improving the purity of the deposited Li layer.

[0086] In some embodiments, a method of fabricating an electrode-electrolyte laminate includes:

[0087] Deposit a LiPON layer onto a first surface of a sacrificial polymer substrate; and

[0088] Deposit a lithium metal layer onto the exposed surface of the LiPON layer.

[0089] In some embodiments, a method of fabricating an electrode-electrolyte laminate includes:

[0090] Deposit a LiPON layer onto a first surface of a sacrificial polymer substrate comprising or consisting of polystyrene (PS); and

[0091] Deposit a lithium metal layer onto the exposed surface of the LiPON layer;

[0092] wherein the deposition of the LiPON layer and the deposition of the lithium metal layer are both achieved by PVD.

[0093] In some embodiments, a method of fabricating an electrode-electrolyte laminate includes:

[0094] Prepare a vacuum chamber containing a lithium phosphate target, a sputtering source, and a thermal evaporation source containing lithium;

[0095] Provide a sacrificial polymer substrate in the vacuum chamber;

[0096] Provide a vacuum with a pressure less than 1×10 -6 mbar in the vacuum chamber;

[0097] Deposit LiPON onto the surface of the sacrificial polymer substrate by sputtering the lithium phosphate target to form a LiPON layer on the surface of the sacrificial polymer substrate;

[0098] After the desired thickness of the LiPON layer has been achieved, stop the deposition of LiPON;

[0099] Maintain the vacuum conditions in the vacuum chamber;

[0100] Deposit lithium metal onto the surface of the LiPON layer by evaporating lithium from the thermal evaporation source and condensing the lithium onto the LiPON layer; and

[0101] After achieving the desired lithium metal layer thickness, the deposition of lithium metal is stopped.

[0102] sacrificial polymer substrate

[0103] The method of the first aspect includes removing the sacrificial polymer substrate from the laminate precursor to form an electrode-electrolyte laminate.

[0104] In some embodiments, the sacrificial polymer substrate includes one or more sacrificial polymers. The term "sacrificial polymer" as used herein refers to a polymer that can be removed from the laminate precursor by dissolving in a solvent without any degradation of the ceramic electrolyte or lithium metal layer of the laminate precursor.

[0105] The sacrificial polymer substrate may include one or more sacrificial polymers independently selected from: poly(ethylene glycol dimethacrylate), poly(ethylene glycol diacrylate), poly(propylene glycol dimethacrylate), poly(propylene glycol diacrylate), poly(methyl methacrylate) (PMMA), poly(acrylonitrile) (PAN), polyurethane (PU), poly(vinylidene fluoride) (PVdF), poly(vinylidene fluoride-co-hexafluoropropylene) (PvDF-HFP), poly(ethylene oxide) (PEO), poly-L-lactic acid (PLA), polystyrene (PS), poly(ethylene glycol dimethyl ether), poly(ethylene glycol diethyl ether), poly[bis(methoxyethoxyethoxy)-phosphazene], poly(dimethylsiloxane) (PDMS), polyacene, polydisulfide, polystyrene, polystyrene sulfonate, polypyrrole, polyaniline, polythiophene, polythione, polyvinyl pyridine (PVP), polyvinyl chloride (PVC), polyaniline, poly(3,4-ethylenedioxythiophene) (PEDOT), poly(phenylene), poly(perylene), polyazene, polyfluorene, polynaphthalene, polyanthracene, polyfuran, polycarbazole, tetrathiafulvalene-substituted polystyrene, ferrocene-substituted polyethylene, carbazole-substituted polyethylene, polyoxazine, poly(heteroacene), poly[(4-styrenesulfonyl)(trifluoromethanesulfonyl)imide-co-methoxy-polyethylene glycol acrylate] (Li[PSTFSI-co-MPEGA]), sulfonated polyphenylene oxide (PPO), N,N-dimethylacrylamide (DMAAm), lithium 2-acrylamido-2-methyl-1-propanesulfonate (LiAMPS), poly(lithium 2-acrylamido-2-methylpropane sulfonate-co-vinyltriethoxysilane), poly(ethylene oxide) (PEO) / poly(lithium sorbate), PEO / poly(lithium mucate), PEO / [poly(lithium sorbate)+BF3], PEO copolymers, PEO terpolymers, and NIPPON polymer.

[0106] The sacrificial polymer substrate may include one or more sacrificial polymers independently selected from the following: polyvinylidene fluoride (PVdF), polymethyl methacrylate (PMMA), polyethylene oxide (PEO), poly-L-lactic acid (PLA), and polystyrene (PS). In some embodiments, the sacrificial polymer substrate comprises or consists of a single sacrificial polymer selected from polyvinylidene fluoride (PVdF), polymethyl methacrylate (PMMA), polyethylene oxide (PEO), poly-L-lactic acid (PLA), and polystyrene (PS). In some embodiments, the sacrificial polymer substrate comprises or consists of poly(vinylidene fluoride) (PVdF), poly-L-lactic acid (PLA), and polystyrene (PS). In some embodiments, the sacrificial polymer substrate comprises or consists of polystyrene (PS).

[0107] The sacrificial polymer substrate comprising or consisting of PS provides a robust structure that is easy to handle. A mechanically stable PS film can have a very small thickness, such as a thickness below 10 μm, which makes it easier to remove the thin sacrificial polymer substrate from the laminate precursor by dissolving it in a solvent to form the electrode-electrolyte laminate. PVdF, PLA, or PS can also be dissolved in a solvent that does not cause any degradation of the ceramic electrolyte or lithium metal layer of the laminate precursor, such as a linear or cyclic carbonate solvent.

[0108] In some embodiments, the sacrificial polymer substrate has no or substantially no holes extending through the plane of the sacrificial polymer substrate. Such holes are commonly referred to as "pinholes". If such pinholes are present in the sacrificial polymer substrate, then corresponding pinholes may also be present in the deposited ceramic electrolyte layer. For example, the risk of forming pinholes can be reduced by ensuring that a dense polymer material is formed during the preparation of the sacrificial polymer substrate, such as by extruding the polymer into a film or by casting a slurry of polymer powder to form the sacrificial polymer substrate. The choice of polymer also helps to reduce the risk of pinhole formation. The inventors have found that PS or PvDF-HFP are particularly suitable polymers for forming defect-free sacrificial polymer substrates with little or no pinhole formation.

[0109] In some embodiments, the porosity of the sacrificial polymer substrate is less than 2%, such as less than 1%, less than 0.5%, less than 0.1%, or less than 0.01%. In some embodiments, the sacrificial polymer substrate is 100% dense, i.e., 0% porous. The presence of pores is undesirable because it causes difficulties in forming a conformal film of the ceramic electrolyte on the sacrificial polymer substrate.

[0110] In some embodiments, the sacrificial polymer substrate has the ability to support its own weight, i.e., the sacrificial polymer substrate is freestanding. This allows it to be tensioned in a vacuum chamber to deposit the ceramic electrolyte layer.

[0111] In some embodiments, the polymer used for the sacrificial polymer substrate has a melting point such that it does not melt under the heat of the deposition of the ceramic electrolyte layer. A person skilled in the art can select a suitable polymer and adjust the deposition conditions to ensure this.

[0112] The thickness of the sacrificial polymer substrate also affects the ease of its dissolution and removal. A thinner substrate may be easier to dissolve and remove, and subsequently there is a lower chance of residual polymer deposition on the ceramic electrolyte layer. However, the substrate should also be thick enough to have a robust structure and facilitate the coating of the ceramic electrolyte layer. In some embodiments, the thickness of the sacrificial polymer substrate is from about 2 μm to about 100 μm, such as from about 2 μm to about 50 μm, such as from about 5 μm to about 100 μm, such as from about 5 μm to about 40 μm, such as from about 2 μm to about 10 μm.

[0113] In some embodiments, the sacrificial polymer substrate is removed by dissolving it in a solvent.

[0114] In some embodiments, the solvent comprises or consists of one or more linear or cyclic carbonate compounds. The solvent may comprise or consist of one or more of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and acetone. In some embodiments, the solvent comprises DMC or consists of it.

[0115] In some embodiments, the sacrificial polymer substrate is immersed in the solvent, followed by a rinsing step to remove any residual sacrificial polymer substrate. The immersion in the solvent can be carried out for at least 30 minutes, such as at least 45 minutes or at least 1 hour. A longer immersion time may help to ensure more complete dissolution and removal of the polymer.

[0116] The immersion in the solvent can be carried out with or without stirring.

[0117] During the immersion, in some embodiments, the solvent is maintained at a temperature of 10 °C to 30 °C, such as 15 °C to 25 °C, or at room temperature.

[0118] In some embodiments, a higher temperature solvent may be preferred in order to reduce the time required to remove the sacrificial polymer substrate and / or ensure more complete dissolution and removal of the residual polymer. During the immersion, in some embodiments, the solvent is maintained at a temperature of 25 °C to 60 °C, such as 30 °C to 60 °C.

[0119] Passivation interface layer

[0120] In some embodiments, the method further comprises forming a passivation interface layer between the ceramic electrolyte layer and the lithium metal layer.

[0121] According to the method of depositing lithium metal on a ceramic electrolyte layer, such a layer can form spontaneously.

[0122] In some embodiments, the passivation interface layer between the ceramic electrolyte layer and the lithium metal layer comprises or consists of Li3PO4, Li3N, and LiO2.

[0123] The passivation layer provides a stable SEI that protects the lithium metal anode layer. Its function is to limit the consumption or degradation of lithium in the lithium anode during battery cell cycling.

[0124] The amount of Li3N in the passivation layer is much lower than that produced by depositing LiPON onto a lithium metal anode by PVD. This is because PVD of LiPON onto a lithium metal anode requires supplying nitrogen gas to the system during deposition, resulting in a high level of Li3N forming on the surface of the lithium anode. In contrast, in the present method, before depositing lithium metal using thermal evaporation which does not require nitrogen, a ceramic electrolyte layer (such as LiPON) is first formed on a sacrificial polymer substrate. The passivation layer is formed entirely by the reaction between the LiPON layer and the lithium metal layer after deposition. Thus, the amount of Li3N at the layer interface is minimized and the performance of the battery cell is not adversely affected.

[0125] Encapsulation layer

[0126] In some embodiments, the method of the present invention further includes the step of providing a protective encapsulation layer on the exposed surface of the lithium metal layer. The encapsulation layer can be deposited before the step of removing the sacrificial polymer substrate from the laminate precursor. Thus, the formed laminate precursor includes the following layers in sequence: sacrificial polymer substrate, ceramic electrolyte, lithium metal, encapsulation.

[0127] The protective encapsulation layer can protect the lithium metal layer from reacting with air. This helps to maintain the purity of the lithium metal layer between manufacturing the electrode - electrolyte laminate and incorporating it into a battery cell, thereby improving the performance of the battery cell.

[0128] In some embodiments, the encapsulation layer is deposited onto the exposed surface of the lithium metal layer by a deposition process that includes gradually depositing atoms or molecules onto the lithium metal layer.

[0129] In some embodiments, the encapsulation layer is deposited on the exposed surface of the lithium metal layer by a vacuum deposition process, preferably by PVD. By performing the deposition under vacuum, this ensures a controllable thickness of the film and reduced film contamination.

[0130] Alternatively, the deposition of the encapsulation layer can be achieved by atomic layer deposition (ALD) or chemical vapor deposition (CVD).

[0131] In some embodiments, the ceramic electrolyte layer, the lithium metal layer, and the encapsulation layer are sequentially deposited by PVD. In some embodiments, the lithium metal layer and the encapsulation layer are sequentially deposited by PVD without removing the substrate from the vacuum chamber and without venting the vacuum chamber between deposition steps. In some embodiments, the ceramic electrolyte layer, the lithium metal layer, and the encapsulation layer are sequentially deposited by PVD without removing the substrate from the vacuum chamber and without venting the vacuum chamber between deposition steps. This ensures little or no contamination of the laminate during construction of the layers and provides a more efficient and lower cost process since minimal equipment is used and re - establishing the vacuum during manufacturing is not required.

[0132] Alternatively, the encapsulation layer can be deposited after the step of removing the sacrificial polymer substrate from the laminate precursor, thereby providing an electrode - electrolyte laminate that sequentially includes the following layers: ceramic electrolyte, lithium metal, encapsulation.

[0133] In some embodiments, the encapsulation layer completely covers all exposed surfaces of the lithium metal layer. In other words, the encapsulation layer can cover the exposed upper (planar) surface of the lithium metal layer as well as all edges of the lithium metal layer such that the encapsulation layer contacts the ceramic electrolyte layer surrounding the periphery of the lithium metal layer. In this way, no lithium metal is exposed to the external atmosphere and contamination of the lithium metal is minimized.

[0134] Those skilled in the art know materials suitable for deposition onto the lithium metal layer as the encapsulation layer. The encapsulation layer will have chemical and electrochemical stability relative to the lithium metal, will be impermeable or substantially impermeable to air (to protect the lithium from reacting with air), and in some embodiments is thin enough so as not to compromise the volumetric and gravimetric energy density of the battery cell.

[0135] In some embodiments, the encapsulation layer is a metal encapsulation layer. In some embodiments, the encapsulation layer is a conductive metal encapsulation layer. In this way, the lithium metal layer is encapsulated while maintaining the ability to make electrical connection to the lithium via the conductive metal encapsulation layer. In some embodiments, the encapsulation layer is a metal encapsulation layer that comprises or consists of one or more metal elements selected from Cu, W, Mo, and any other metal element that is chemically and electrochemically stable relative to the lithium metal. In some embodiments, the encapsulation layer is a metal encapsulation layer that comprises or consists of one or more metal elements selected from Cu, W, and Mo.

[0136] In some embodiments, the encapsulation layer is a polymer encapsulation layer or a ceramic encapsulation layer. However, this is less preferred for metal encapsulation layers since the conductivity of polymers or ceramics is typically lower than that of metal layers, making it more difficult to ensure electrical connection to the lithium anode. In some embodiments, the encapsulation layer is a conductive polymer encapsulation layer or a conductive ceramic encapsulation layer.

[0137] In some embodiments, the encapsulation layer is not removed from the lithium metal layer prior to assembling the battery cell, such that the finished battery cell includes the encapsulation layer between the lithium metal layer and the anode current collector layer.

[0138] Optional polymer separator layer

[0139] In some embodiments, the method includes contacting a surface of the ceramic electrolyte layer, exposed by removing the sacrificial polymer substrate, with a polymer separator layer prior to introducing any cathode layer. As a result, the electrode - electrolyte laminate sequentially includes the following layers: polymer separator, ceramic electrolyte, lithium metal, optional encapsulation. The method may then further include contacting a surface of the polymer separator layer that is not in contact with the ceramic electrolyte layer with the cathode layer. As a result, the electrode - electrolyte laminate sequentially includes the following layers: cathode, polymer separator, ceramic electrolyte, lithium metal, optional encapsulation.

[0140] The polymer separator layer between the cathode and the ceramic electrolyte is optional. Its presence reduces the weight and volumetric energy density of the battery cell, but may still be required in certain cases. For example, the surface of a solvent - cast cathode may not conform well to the surface of the ceramic electrolyte layer; in contrast, the surface of a solvent - cast cathode is expected to be relatively "rough", while the surface of the ceramic electrolyte layer is "smooth". As a result, a relatively high resistance may occur at the interface between the solvent - cast cathode and the ceramic electrolyte layer. Introducing an intermediate polymer separator can reduce the total interface resistance and impedance of the battery cell.

[0141] The polymer separator can be made of a polymer that swells upon exposure to an appropriate amount of liquid electrolyte to form a gel matrix comprising the gel polymer and the absorbed liquid electrolyte.

[0142] The polymer separator can be "dry", i.e., non - gelled when added to the laminate, and then undergo a gelation process after the laminate has been fabricated. This can be achieved by immersing the finished laminate structure in a liquid electrolyte.

[0143] Thus, in some embodiments, the method includes adding a liquid electrolyte to the polymer separator to gel the polymer separator after laminate assembly.

[0144] The liquid electrolyte can be added to the polymer separator before, during, or after battery cell or battery assembly.

[0145] To add the liquid electrolyte prior to assembling the battery cell, the laminate can first be immersed in the liquid electrolyte to gel the polymer separator and then multiple battery cells can be stacked or wound together to form a battery, prior to laminating with the cathode layer to form the battery cell.

[0146] To add a liquid electrolyte during cell assembly, the liquid electrolyte can be injected between the polymer separator and the cathode layer when the two layers are brought together during assembly. Thus, when the cell is formed, the polymer separator gels, and then multiple cells can be stacked or wound together to form a battery.

[0147] To add a liquid electrolyte after assembling the cell, the laminate can be laminated with the cathode layer to form a cell before adding the liquid electrolyte to the polymer separator and allowing the liquid electrolyte to laterally diffuse through the polymer separator to gel the polymer separator; then multiple cells are stacked or wound together to form a battery.

[0148] The polymer separator can be manufactured by methods known to those skilled in the art. In some embodiments, the polymer separator is made by taking a powder form of a desired polymer that is commercially available, forming a slurry of the powder in a suitable solvent, and casting the slurry to form the separator. Alternatively, the polymer can be extruded to form the polymer separator.

[0149] In some embodiments, the second surface of the polymer separator has no ceramic electrolyte layer coated between the polymer separator and the cathode layer.

[0150] In some embodiments, the cathode layer includes a liquid electrolyte that combines with the polymer separator to form a gel when the cathode layer contacts the polymer separator. In other words, the polymer separator is "dry", and gelation occurs due to the contact between the "dry" polymer separator layer of the laminate and the "wet" cathode layer. This allows gelation to occur simultaneously with the assembly of the cell without the need for any separate steps of adding or injecting a liquid electrolyte.

[0151] Cathode layer

[0152] In some embodiments, the method further includes contacting the surface of the ceramic electrolyte layer exposed by removing the sacrificial polymer substrate with the cathode layer. In other words, one surface of the ceramic electrolyte layer contacts the lithium metal layer, and the remaining surfaces contact the cathode layer. After assembly with the cathode layer, the ceramic electrolyte layer is thus sandwiched between the cathode layer and the lithium metal layer.

[0153] In some embodiments, when an optional polymer separator layer is present, the method further includes contacting the surface of the polymer separator layer that does not contact the ceramic electrolyte layer with the cathode layer. In other words, one surface of the polymer separator contacts the ceramic electrolyte layer, and the remaining surfaces contact the cathode layer. After assembly with the cathode layer, the polymer separator layer is thus sandwiched between the cathode layer and the ceramic electrolyte layer.

[0154] In some embodiments, the cathode layer includes a gel cathode or a solvent-cast cathode.

[0155] A ceramic electrolyte (such as LiPON) layer acts as a barrier between a “dry” lithium metal anode and the “wet” components of the battery cell, namely the cathode layer (and an optional polymer separator layer). This provides a battery cell with the advantages associated with a lithium metal anode (such as high energy density) and a gel component (such as increased operational safety and high ionic conductivity).

[0156] The cathode layer can be a “conventional” solvent-cast cathode. Such a cathode includes a positive electrode active material and can also include one or more of a binder, a liquid electrolyte, and a conductive additive. Such a cathode is made by preparing a slurry of the above components in a solvent and solvent-casting it onto a current collector before drying and optionally calendaring to increase the electrode density.

[0157] Alternatively, the cathode can be a gel cathode. The gel cathode can include a polymer-electrolyte gel matrix phase and a dispersed phase containing a positive electrode active material. The dispersed phase can further include a conductive additive. The polymer-electrolyte gel matrix phase includes a gel containing a polymer and an absorbed liquid electrolyte. The polymer can be selected from one or more of the polymers listed above as options for the sacrificial polymer substrate. In some embodiments, the liquid electrolyte includes or consists of a solvent containing one or more cyclic or linear carbonate compounds. In some embodiments, the solvent contains one or more cyclic carbonate compounds. In some embodiments, the solvent contains one or more of the following: ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl-methyl carbonate, butylene carbonate, vinylene carbonate, fluorinated ethylene carbonate, fluorinated propylene carbonate, and γ-butyrolactone. In some embodiments, the liquid electrolyte further includes a lithium salt. Examples of suitable lithium salts include LiPF6, LiBF4, and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

[0158] Electrode-electrolyte laminate

[0159] A second aspect of the present invention is an electrode-electrolyte laminate for a lithium metal battery cell, prepared by the method according to the first aspect, comprising:

[0160] A ceramic electrolyte layer; and

[0161] A lithium metal layer on a first surface of the ceramic electrolyte layer.

[0162] In some embodiments, the electrode-electrolyte laminate includes an encapsulation layer on the surface of the lithium metal layer. In other words, the electrode-electrolyte laminate can sequentially include the following layers: ceramic electrolyte, lithium metal, encapsulation layer.

[0163] In some embodiments, the electrode - electrolyte laminate does not include a current collector in contact with the lithium metal layer. Other methods of fabricating the laminate that rely on the deposition of lithium metal on a current collector will inevitably produce a laminate in which the lithium metal contacts a current collector such as a copper foil. Since the method of the present invention constructs the laminate from a sacrificial polymer substrate that is subsequently removed, the initial laminate does not contain a current collector and can be brought into contact with a current collector during later battery cell assembly.

[0164] In some embodiments, the electrode - electrolyte laminate includes a cathode layer in contact with a second surface of the ceramic electrolyte layer.

[0165] In some embodiments, the electrode - electrolyte laminate includes a polymer separator between the cathode layer and the ceramic electrolyte layer.

[0166] In some embodiments, the cathode layer includes a gel cathode or a solvent - cast cathode.

[0167] In some embodiments, the electrode - electrolyte laminate includes a polymer separator between the solvent - cast cathode layer and the ceramic electrolyte layer.

[0168] In some embodiments, when present, one surface of the polymer separator is not coated with any ceramic electrolyte layer between the polymer separator and the cathode layer.

[0169] In some embodiments, the ceramic electrolyte layer comprises or consists of LiPON.

[0170] In some embodiments, the ceramic electrolyte layer has an amorphous structure.

[0171] In some embodiments, when present, the polymer separator includes one or more gelling polymers independently selected from: polyvinylidene fluoride (PVdF), polymethyl methacrylate (PMMA), poly(ethylene oxide) (PEO), poly(L - lactic acid) (PLA), and polystyrene (PS).

[0172] A third aspect of the present invention is an electrochemical cell unit comprising the electrode - electrolyte laminate structure according to the second aspect.

[0173] A fourth aspect of the present invention is an electrochemical energy storage device comprising the electrochemical cell unit according to the third aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0174] Figure 1 Schematically shows a method of fabricating an electrode - electrolyte laminate article.

[0175] Figure 2 Schematically shows a method of constructing a battery cell from an electrode - electrolyte laminate article.

[0176] Figure 3 schematically shows an electrode - electrolyte laminate constructed from an anode current collector according to the prior art method.

[0177] Figure 4 Schematically shows an electrode - electrolyte laminate constructed from a sacrificial polymer substrate according to the method of the present invention. Detailed Description

[0178] Examples

[0179] Figure 1 Is a schematic diagram of the method for manufacturing the electrode - electrolyte laminate 1 according to the present invention and further downstream processing steps.

[0180] The sequential deposition of LiPON, lithium metal (anode layer), and tungsten metal (encapsulation layer) is carried out in the same small - scale modular deposition system, which has a vacuum chamber attached to argon and nitrogen gas cylinders.

[0181] First, a vacuum chamber (not shown) is prepared, including two independent deposition sources: an RF magnetron sputtering source with a lithium phosphate target (diameter 5.08 cm); and a thermal evaporation source consisting of a resistively heated crucible containing Li metal.

[0182] A polystyrene (PS) sacrificial polymer substrate 11 is tensioned on a frame and loaded into the vacuum chamber, directly above the deposition sources. The vacuum chamber is pumped down to 1×10 -4 Pa.

[0183] Then the LiPON layer 12 is deposited by the following method. First, a continuous supply of an N2 / argon mixture (Ar flow rate 16 sccm; N2 flow rate 30 sccm) is supplied into the vacuum chamber to bring the chamber pressure to 0.15 Pa. Then an RF power supply (145 W) is used to RF - bias the lithium phosphate target in the RF magnetron sputtering source. The sacrificial polymer substrate is 9.5 cm from the sputtering gun. During LiPON deposition, the sacrificial polymer substrate rotates at 20 RPM. The resulting material sputtered from the target causes the condensation of the LiPON layer 12. A 500 - nm - thick LiPON layer is deposited over a 10 - hour period. Then the RF power supply and gas supply are turned off, but the vacuum in the vacuum chamber is maintained.

[0184] Then the lithium metal layer 13 is deposited by the following method. At a pressure of 1×10 -4 Pa, the crucible containing lithium metal is resistively heated to about 400 °C to first melt and then evaporate lithium. The lithium source is 21 cm from the substrate. During Li deposition, the substrate rotates at 20 RPM. The Li vapor condenses onto the LiPON layer 12 to form the Li layer 13. A 10 - μm - thick lithium layer is deposited over a 2 - hour period.

[0185] Then, a tungsten encapsulation layer 14 is deposited onto the surface of the lithium metal layer 13 to protect the lithium metal from reacting with air, which would occur once the vacuum chamber is vented. In the same vacuum chamber used for LiPON and Li deposition, and without breaking the vacuum between depositions, W is directly deposited onto the lithium metal layer using RF magnetron sputtering (200W RF power). Argon gas with a flow rate of 60 sccm (working pressure of 0.2 Pa) is used, and the lithium metal substrate is located 13.5 cm from the sputtering gun. During W deposition, the substrate rotates at 20 RPM. Sputtering is continued until a 100 nm thick tungsten film is formed on the substrate.

[0186] After depositing the encapsulation layer, the vacuum chamber is vented to atmospheric pressure, and the laminate precursor 1a still including the sacrificial polymer substrate is removed from the chamber.

[0187] Then, the sacrificial polymer substrate is removed from the laminate precursor 1a to form the electrode - electrolyte laminate 1. The sacrificial polymer substrate is removed by soaking the laminate precursor 1a in DMC solvent for 1 hour, followed by a step of rinsing the laminate to remove any residual polymer deposits that were not completely dissolved during the soaking step.

[0188] Then, the resulting laminate 1 can be directly combined with different types of cathode layers. In one embodiment, a cathode layer 15 is solvent - cast onto a current collector layer 17 by preparing a slurry of a cathode active material and optional additives in a solvent, casting the slurry onto the current collector substrate, and evaporating the solvent. After an optional calendering step, the laminate of the cathode layer 15 on the current collector 17 contacts the LiPON layer 12 of the laminate 1, resulting in a battery cell structure.

[0189] Alternatively, a battery cell structure is produced by contacting a gel electrode layer 16 on a current collector layer 17 with the LiPON layer 12 of the laminate 1. The gel electrode layer contains a gellable polymer, which can be gelled by introducing a liquid before, after, or during the process of contacting the gel electrode layer 16 with the LiPON layer 12. An example of a suitable liquid is an electrolyte including dimethyl carbonate (DMC) and one or more lithium salts.

[0190] Figure 2 An alternative method of manufacturing a battery cell from the laminate 1 is shown, which first includes adding a polymer separator layer. After removing the sacrificial polymer substrate 11, the polymer separator layer 18 is laminated onto the LiPON layer 12.

[0191] Then, in one embodiment, a cathode active material and optional additives are prepared as a slurry in a solvent, the slurry is cast onto a current collector substrate and the solvent is evaporated, and the solvent-cast cathode layer 15 is cast onto the current collector layer 17. After an optional calendaring step, the laminate of the cathode layer 15 on the current collector 17 is brought into contact with the polymer separator layer 18, resulting in a battery cell structure. By including the polymer separator layer 18, an interface with lower impedance can be produced.

[0192] Alternatively, a battery cell structure is produced by bringing the gel electrode layer 16 into contact with the polymer separator layer 18, bringing the gel electrode layer 16 on the current collector layer 17 into contact with the polymer separator layer 18. The gel electrode layer contains a gelled polymer, which can be gelled by introducing a liquid before, after, or during the process of bringing the gel electrode layer 16 into contact with the polymer separator layer 18. An example of a suitable liquid is an electrolyte comprising dimethyl carbonate (DMC) and one or more lithium salts. The liquid used to gel the cathode layer 16 will also cause the gelation of the polymer separator layer 18.

[0193] Figure 3 shows a schematic diagram of a laminate formed by a prior art method, where a LiPON layer is deposited onto a lithium metal anode. The anode current collector layer 21 bears the lithium metal anode layer 22. After depositing LiPON on the lithium metal, a LiPON layer 23 is formed, which encapsulates the lithium metal layer. A high level of contaminants, such as Li3N and Li2O, is expected to be present at the interface between the lithium metal and LiPON.

[0194] Figure 4 Figure 10 shows a schematic diagram of a laminate formed by the method of the present invention, where a LiPON layer is deposited onto a sacrificial polymer substrate before removing the sacrificial polymer substrate. The LiPON layer 32 bears a lithium metal layer, which serves as the lithium metal anode layer 33. Finally, a encapsulation layer 34 is formed, which completely encapsulates the lithium metal layer 33, thus protecting it from reacting with air.

[0195] Example 1 - Lithium-ion Shuttling in a Half-Cell

[0196] According to the above method, a PS polymer substrate is first coated with LiPON and then with Li to form a PS / LiPON / Li stack. The PS separator is 29 μm thick, the LiPON layer is 500 nm thick, the Li metal layer is 10 μm thick, and the W encapsulation layer is 100 nm thick.

[0197] Then the PS layer is removed by soaking the stack in DMC solvent for 1 hour without any stirring, followed by rinsing with DMC to remove the residual PS.

[0198] SEM-EDS showed that the bare LiPON surface was exposed through the soaking and washing process, i.e., the polystyrene was dissolved by DMC soaking / rinsing, but the underlying LiPON layer remained intact.

Claims

1. A method of fabricating an electrode - electrolyte laminate for a lithium - metal battery cell, comprising: Depositing a ceramic electrolyte layer onto a first surface of a sacrificial polymer substrate; Depositing a lithium - metal layer onto the exposed surface of the ceramic electrolyte layer to form a laminate precursor; And Removing the sacrificial polymer substrate from the laminate precursor to form the electrode - electrolyte laminate.

2. The method according to claim 1, further comprising depositing a encapsulation layer onto the exposed surface of the lithium - metal layer after depositing the lithium - metal layer and before removing the sacrificial polymer substrate.

3. The method according to claim 1 or 2, wherein The sacrificial polymer substrate is removed by dissolving it in a solvent.

4. The method according to claim 3, wherein, The solvent comprises or consists of one or more linear or cyclic carbonate compounds.

5. The method according to claim 3 or 4, wherein, The sacrificial polymer substrate is immersed in the solvent and then subjected to a rinsing step to remove any residual sacrificial polymer substrate.

6. The method according to any one of the preceding claims, wherein, The ceramic electrolyte layer comprises or consists of one or more of LiPON, LAGP, LATP, LiSICON, perovskite, and garnet ceramics.

7. The method according to any one of the preceding claims, wherein, The ceramic electrolyte layer comprises or consists of LiPON.

8. The method according to any one of the preceding claims, wherein, The ceramic electrolyte layer is deposited onto the first surface of the sacrificial polymer substrate by a deposition process that includes gradually depositing atoms or molecules of the ceramic electrolyte onto the first surface of the sacrificial polymer substrate.

9. The method according to any one of the preceding claims, wherein, The lithium - metal layer is deposited onto the exposed surface of the ceramic electrolyte layer by a deposition process that includes gradually depositing lithium atoms onto the ceramic electrolyte layer.

10. The method according to claim 8 or 9, wherein, Vacuum conditions are maintained between depositing the ceramic electrolyte layer and depositing the lithium metal.

11. The method according to any one of the preceding claims, wherein, The sacrificial polymer substrate comprises one or more sacrificial polymers independently selected from the following: poly(vinylidene fluoride) (PVdF), poly(methyl methacrylate) (PMMA), poly(ethylene oxide) (PEO), poly(L - lactic acid) (PLA), and polystyrene (PS).

12. The method according to any one of the preceding claims, wherein, The sacrificial polymer substrate comprises or consists of polystyrene (PS).

13. The method according to any one of the preceding claims, wherein, The sacrificial polymer substrate has a thickness of about 2 μm to about 100 μm.

14. The method according to any one of the preceding claims, wherein, After deposition, the ceramic electrolyte layer has a thickness of about 0.1 μm to about 4 μm.

15. The method according to any one of the preceding claims, wherein, After deposition, the lithium - metal layer has a thickness of about 0.01 μm to about 15 μm.

16. The method according to any one of the preceding claims, further comprising bringing the surface of the ceramic electrolyte layer exposed by removing the sacrificial polymer substrate into contact with a cathode layer.

17. The method according to claim 16, wherein, The cathode layer comprises a gel cathode or a solvent - cast cathode.

18. An electrode - electrolyte laminate for a lithium - metal battery cell, prepared by the method according to any one of claims 1 to 17, comprising: A ceramic electrolyte layer; And A lithium - metal layer on a first surface of the ceramic electrolyte layer.

19. The electrode - electrolyte laminate structure according to claim 18, comprising a cathode layer in contact with a second surface of the ceramic electrolyte layer.

20. The electrode-electrolyte laminate structure according to claim 19, wherein, The cathode layer comprises a gel cathode or a solvent - cast cathode.

21. The electrode-electrolyte laminate structure according to any one of claims 18 to 20, wherein, The ceramic electrolyte layer comprises or consists of LiPON.

22. The electrode-electrolyte laminate structure according to any one of claims 18 to 21, wherein, The ceramic electrolyte layer has an amorphous structure.

23. An electrochemical cell unit, comprising an electrode-electrolyte laminate structure according to any one of claims 18 to 22.

24. An electrochemical energy storage device, comprising the electrochemical cell unit according to claim 23.

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