Anode for a lithium-based energy storage device, method for manufacturing the same, and method for manufacturing a lithium ion battery

Abstract

A method for fabricating an anode for use in an energy storage device includes providing a current collector having a conductive layer and a metal oxide layer covering the conductive layer. A continuous porous lithium storage layer is deposited on the metal oxide layer by a CVD process. The anode is heat-treated after deposition of the continuous porous lithium storage layer is complete and before assembly into a battery. The heat treatment involves heating the anode to a temperature ranging from 100°C to 600°C for a time ranging from 0.1 minutes to 120 minutes. The anode may be incorporated into a lithium-ion battery with a cathode. The cathode may include sulfur or selenium. Anodes having at least two auxiliary layers are also described. A method for fabricating a prelithiated anode for use in a lithium-ion battery is also discussed.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of U.S. Provisional Application No. 62 / 886,177, filed Aug. 13, 2019, which is hereby incorporated by reference in its entirety for all purposes.

[0002] The present disclosure relates to lithium - ion batteries and related energy storage devices.

Background Art

[0003] Silicon has been proposed as a potential material for lithium - ion batteries to replace conventional carbon - based anodes, which have a limited storage capacity of about 370 mAh / g. Silicon readily alloys with lithium and has a much higher theoretical storage capacity (about 3600 to 4200 mAh / g at room temperature) than carbon - based anodes. However, the insertion and extraction of lithium into and from the silicon matrix cause significant volume expansion (>300%) and shrinkage. This can lead to rapid pulverization of silicon into small particles and electrical disconnection from the current collector.

[0004] The industry has recently focused on nanostructured or microstructured silicon, i.e., silicon in the form of separated nanowires or micro - wires, tubes, pillars, particles, etc., to reduce the problem of pulverization. The theory is that by structuring it into nanosizes to avoid crack propagation and separating them, more space for volume expansion is allowed, thereby enabling silicon to absorb lithium in a state with reduced stress and improved stability compared to, for example, macroscopic layers of bulk silicon.

[0005] Despite research on structured silicon techniques, such batteries based solely on silicon have not yet had a major impact on the market due to unresolved problems. An important issue is the complexity and investment in manufacturing required to form these anodes. For example, U.S. Patent Application Publication No. 20150325852 describes silicon produced by first growing a silicon-based non-conformal porous layer on a nanowire template by plasma-enhanced chemical vapor deposition (PECVD), followed by depositing a denser conformal silicon layer using thermal chemical vapor deposition (CVD). The formation of silicon nanowires can be very sensitive to small perturbations in the deposition conditions, which pose challenges for quality control and reproducibility. Other methods for forming nanostructured or microstructured silicon use etching of silicon wafers, which is time-consuming and wasteful. Additionally, the connection between the silicon wire and the current collector is inherently fragile, and the structure tends to break or wear when subjected to the stresses during handling required to manufacture the battery.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

[0007] There is still a need for anodes for lithium-based energy storage devices, such as Li-ion batteries, that are easy to manufacture, robust in handling, have a large charge capacity, and are suitable for rapid charging, for example, at least 1C. These and other needs are addressed by the embodiments described herein.

[0008] According to one embodiment of the present disclosure, a method of fabricating an anode for use in an energy storage device includes providing a current collector having a conductive layer and a metal oxide layer covering the conductive layer. The metal oxide layer has an average thickness of at least 0.01 μm. A continuous porous lithium storage layer is deposited on the metal oxide layer by a CVD process. The anode is heat-treated after the deposition of the continuous porous lithium storage layer is completed and before the battery is assembled. The heat treatment includes heating the anode to a temperature in the range of 100°C to 600°C for a time in the range of 0.1 minute to 120 minutes. The anode may be incorporated into a lithium-ion battery together with a cathode. The cathode may include sulfur or selenium, and the anode may be prelithiated.

[0009] According to one embodiment of the present disclosure, an anode for an energy storage device including a current collector having a metal oxide layer is provided. A continuous porous lithium storage layer covers the metal oxide layer, and a first auxiliary layer covers the continuous porous lithium storage layer. The first auxiliary layer includes silicon nitride, silicon dioxide, or silicon oxynitride.

[0010] According to another embodiment of the present disclosure, an anode for an energy storage device is provided that includes a current collector having a metal oxide layer, a continuous porous lithium storage layer covering the metal oxide layer, a first auxiliary layer covering the continuous porous lithium storage layer, and a second auxiliary layer covering the first auxiliary layer. The first auxiliary layer includes silicon nitride, silicon dioxide, or silicon oxynitride, or a first metal compound. The second auxiliary layer is characterized by a composition different from that of the first auxiliary layer and includes silicon dioxide, silicon nitride, silicon oxynitride, or a second metal compound. One of the first auxiliary layer or the second auxiliary layer includes titanium dioxide and has a thickness in the range of about 2 nm to about 50 nm.

[0011] According to another embodiment of the present disclosure, a method of fabricating a prelithiated anode for use in a lithium-ion battery includes providing a current collector having a conductive layer and a metal oxide layer covering the conductive layer. The metal oxide layer has an average thickness of at least 0.01 μm. A continuous porous lithium storage layer is deposited on the metal oxide layer by a CVD process. Lithium is incorporated into the continuous porous lithium storage layer to form a lithiated storage layer prior to the first electrochemical cycle when the anode is assembled into the battery. The anode may be incorporated into a lithium-ion battery together with a cathode. The cathode may include sulfur or selenium, and the anode may be prelithiated.

[0012] The present disclosure provides an anode for an energy storage device that can have one or more of at least the following advantages compared to a conventional anode, namely, improved stability at rapid charging rates of ≧1C, higher overall charge capacity, higher charge capacity per gram of silicon, improved physical durability, a simplified manufacturing process, and a more reproducible manufacturing process.

Brief Description of the Drawings

[0013]

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DETAILED DESCRIPTION OF THE INVENTION

[0014] It should be understood that the drawings are for illustrative purposes of the concepts of the present disclosure and may not be to scale.

[0015] Overview of the Anode FIG. 1 is a cross-sectional view according to some embodiments of the present disclosure. Anode 100 includes a conductive current collector 101 and a continuous porous lithium storage layer 107. In this embodiment, the conductive current collector 101 includes a metal oxide layer 105 provided on a conductive layer 103, such as a conductive metal layer. The continuous porous lithium storage layer 107 is provided on the metal oxide layer 105. In some embodiments, the upper portion of the continuous porous lithium storage layer 107 corresponds to the upper surface 108 of the anode 100. In some embodiments, the continuous porous lithium storage layer 107 is in physical contact with the metal oxide layer. In some embodiments, the active material of the continuous porous lithium storage layer may partially extend into the metal oxide layer. In some embodiments, the continuous porous lithium storage layer includes a material capable of forming an electrochemically reversible alloy with lithium. In some embodiments, the continuous porous lithium storage layer includes silicon, germanium, tin, or an alloy thereof. In some embodiments, the continuous porous lithium storage layer includes at least 40 atomic % of silicon, germanium, or a combination thereof. In some embodiments, the continuous porous lithium storage layer is provided by a chemical vapor deposition (CVD) process including, but not limited to, thermal CVD or plasma enhanced chemical vapor deposition (PECVD). In some embodiments, the CVD storage layer deposition process can reduce a portion of the metal oxide layer to metal.

[0016] In the present disclosure, the continuous porous lithium storage layer substantially does not include nanostructures in the form of, for example, spaced wires, pillars, tubes, etc., or in the form of regular linear vertical channels extending through the lithium storage layer. FIG. 2 shows a cross-sectional view of a prior art anode 170 including some non-limiting examples of nanostructures such as nanowires 190, nanopillars 192, nanotubes 194, and nanochannels 196 provided on a current collector 180. As used herein, the term "nanostructure" generally refers to an active material structure (e.g., a structure of silicon, germanium, or an alloy thereof) having at least one cross-sectional dimension of less than about 2,000 nm, excluding dimensions generally perpendicular to the underlying substrate (such as layer thickness) and excluding dimensions caused by random pores and channels. Similarly, the terms "nanowire", "nanopillar", and "nanotube" each refer to a wire, pillar, and tube having at least a portion thereof with a diameter of less than 2,000 nm. A "high aspect ratio" nanostructure has an aspect ratio greater than 4:1, and the aspect ratio is generally the height or length of a feature (which can be measured along a feature axis aligned at an angle of 45 to 90 degrees with respect to the underlying current collector surface) divided by the width of the feature (which can be measured substantially perpendicular to the feature axis). In some embodiments, the continuous porous lithium storage layer is considered to "substantially not include" nanostructures when the anode has an average of less than 10 nanostructures per 1600 square microns (the number of nanostructures being the total number of nanowires, nanopillars, and nanotubes in the same unit area, such as nanostructures having an aspect ratio of 4:1 or greater). Alternatively, there are less than an average of 1 such nanostructure per 1600 square micrometers. As will be described later, the current collector can have a high surface roughness, or the surface layer can include nanostructures, but these features are separate from the continuous porous lithium storage layer.

[0017] In some embodiments, the deposition conditions are selected in combination with the metal oxide such that the continuous porous lithium storage layer is relatively smooth and provides an anode having a diffuse reflectance or total reflectance of at least 10% or at least 20% (measured on the side of the continuous porous lithium storage layer) at 550 nm. In some embodiments, the anode can have a lower reflectance than that cited above, for example, by providing a current collector having a rough surface or by changing the deposition conditions of the lithium storage layer.

[0018] The anode may be a continuous foil or sheet, but alternatively may be a mesh or may have some other three-dimensional structure. In some embodiments, the anode is flexible.

[0019] In some embodiments shown in FIG. 3, the current collector 301 includes a conductive layer 303 and metal oxide layers (305a, 305b) deposited on both sides of the conductive layer 303, and continuous porous lithium storage layers (307a, 307b) are disposed on both sides to form the anode 300. The metal oxide layers 305a and 305b may be the same or different with respect to composition, thickness, porosity or some other property. Similarly, the continuous porous lithium storage layers 307a and 307b may be the same or different with respect to composition, thickness, porosity or some other property.

[0020] In some embodiments, the current collector has a mesh structure, and a representative cross-section is shown in FIG. 4. The current collector 401 includes an inner conductive core 403, for example, a metal oxide layer 405 substantially surrounding a wire forming part of the mesh, and the core acts as a conductive layer. A continuous porous lithium storage layer 407 is provided on the metal oxide layer to form the anode 400. The mesh can be formed from woven wires or ribbons of metal or conductive carbon and can be formed by patterning holes in a substrate, such as a metal or metal-coated sheet, or any suitable method known in the art.

[0021] Current collector The current collectors (101, 301, 401) include at least one metal oxide layer (105, 305, 405) and may further include a separate conductive layer (103, 303, 403). The metal oxide can be stoichiometric or non-stoichiometric. The metal oxide layer can include a mixture of metal oxides having a homogeneous or heterogeneous distributed oxide stoichiometry, a mixture of metals, or both. When the metal oxide layer (105, 305, 405) has sufficient conductivity to function as a current collector, the separate conductive layer (103, 303, 403) is optional. In embodiments using a conductive layer, the metal oxide layer should have sufficient conductivity (e.g., at least semiconductive or non-insulating) to enable charge transfer between the conductive layer and the continuous porous lithium storage layer. The metal oxide layer may include a dopant or region of unoxidized metal that promotes conductivity. In some embodiments, the conductive layer is at least 10 3 S / m, or at least 10 6 S / m, or at least 10 7 S / m and can include an inorganic or organic conductive material or a combination thereof.

[0022] In some embodiments, the conductive layer includes a metal material, such as titanium (and its alloys), nickel (and its alloys), copper (and its alloys), or stainless steel. In some embodiments, the conductive layer includes conductive carbon such as carbon black, carbon nanotubes, graphene, graphene oxide, reduced graphene oxide, and graphite. In some embodiments, the conductive layer can be in the form of a foil or sheet of a conductive material or a layer deposited on an insulating substrate (e.g., a polymer sheet optionally coated on both sides with a conductive material such as nickel or copper).

[0023] In some embodiments, the metal oxide layer comprises a transition metal oxide, such as an oxide of nickel, titanium, or copper. In some embodiments, the metal oxide layer comprises an oxide of aluminum. In some embodiments, the metal oxide layer is a conductive doped oxide comprising, but not limited to, indium-doped tin oxide (ITO) or aluminum-doped zinc oxide (AZO). In some embodiments, the metal oxide layer comprises an alkali metal oxide or an alkaline earth metal oxide. In some embodiments, the metal oxide layer comprises an oxide of lithium. As described above, the metal oxide layer may contain a mixture of metals. For example, "nickel oxide" may optionally contain other metals in addition to nickel. In some embodiments, the metal oxide layer comprises an oxide of an alkali metal or an alkaline earth metal (such as lithium or sodium) together with an oxide of a transition metal (such as nickel or copper). In some embodiments, the metal oxide layer may contain a small amount of hydroxide such that the ratio of oxygen atoms in the form of hydroxide to the oxide is less than 0.25 each.

[0024] In some embodiments, the metal oxide layer has an average thickness of at least 0.005 μm, or at least 0.01 μm, or at least 0.02 μm, or at least 0.05 μm, or 0.1 μm, or at least 0.2 μm, or at least 0.5 μm. In some embodiments, the metal oxide layer has an average thickness in the range of about 0.005 μm to about 0.01 μm, or about 0.01 μm to about 0.02 μm, or about 0.02 μm to about 0.05 μm, or about 0.05 μm to about 0.1 μm, or about 0.1 μm to about 0.2 μm, or about 0.2 μm to about 0.5 μm, or about 0.5 μm to about 1 μm, or about 1 μm to about 2 μm, or about 2 μm to about 5 μm, or about 5 μm to about 1 μm, or any combination of their continuous ranges.

[0025] The metal oxide layer may include stoichiometric oxides, non-stoichiometric oxides, or both. In some embodiments, the metal within the metal oxide layer may exist in multiple oxidation states. In some embodiments, the metal oxide layer may have an oxygen content gradient where the atomic % of oxygen adjacent to the conductive layer is lower than the atomic % adjacent to the lithium storage layer.

[0026] In some embodiments, the metal oxide layer is formed directly by atomic layer deposition (ALD), CVD, evaporation, or sputtering. In some embodiments, the conductive layer is metal layer 103 and the metal oxide layer is formed by oxidizing a portion of the conductive (metal) layer. For example, the metal can be thermally oxidized, electrochemically oxidized, or chemically oxidized in an oxidizing liquid or gaseous medium in the presence of oxygen to form the metal oxide layer.

[0027] In some embodiments, a metal oxide layer precursor composition can be coated or printed onto the conductive layer 103 and then processed to form the metal oxide layer 105. Some non-limiting examples of metal oxide precursor compositions include sol-gel (metal alkoxides), metal carbonates, metal acetates (including organic acetates), metal hydroxides, and metal oxide dispersions. The metal oxide precursor composition may be heat-treated to form the metal oxide layer. In some embodiments, room temperature may be a sufficient temperature to heat-treat the precursor. In some embodiments, the metal oxide precursor composition is heat-treated by exposure to a temperature of at least 50 °C, or in the range of 50 °C to 150 °C, or in the range of 150 °C to 250 °C, or in the range of 250 °C to 350 °C, or in the range of 350 °C to 450 °C, or any combination of these ranges. The heat treatment time for forming the metal oxide layer from the precursor depends on many factors but can be in the range of about 0.1 minute to about 1 minute, or about 1 minute to about 5 minutes, or about 5 minutes to about 10 minutes, or about 10 minutes to about 30 minutes, or about 30 minutes to about 60 minutes, or about 60 minutes to about 90 minutes, or about 90 minutes to about 120 minutes, or any combination of these successive ranges. In some embodiments, the heat treatment may be performed using an oven, an infrared heating element, contact with a heated surface (e.g., a hot plate), or exposure to a flash lamp. In some embodiments, the metal oxide precursor composition is processed by exposure to reduced pressure to form the metal oxide, for example, to drive off a solvent or volatile reaction product. The reduced pressure may be less than 100 Torr, or in the range of 0.1 to 100 Torr. The exposure time to reduced pressure can be in the range of about 0.1 minute to about 1 minute, or about 1 minute to about 5 minutes, or about 5 minutes to about 10 minutes, or about 10 minutes to about 30 minutes, or about 30 minutes to about 60 minutes, or about 60 minutes to about 90 minutes, or in the range of about 90 minutes to about 120 minutes, or any combination of these successive ranges. In some embodiments, both reduced pressure and heat treatment can be used.

[0028] In some embodiments, the metal oxide layer precursor composition includes a metal, such as metal-containing particles, that is treated with an oxidizing agent (e.g., as described above) under conditions where the oxide layer precursor is readily oxidized while the underlying conductive layer is not oxidized as much. The metal oxide precursor composition may include the same or a different metal as the metal of the conductive layer. In some embodiments, multiple metal precursor compositions can be used to form a pattern of different metal oxides or a multilayer structure of different metal oxides.

[0029] In some embodiments, the conductive layer includes a mesh or sheet of conductive carbon formed from, but not limited to, bundled carbon nanotubes or nanofibers. In some embodiments, such a carbon-based conductive layer can include a surface layer of a conductive metal, such as nickel, copper, zinc, titanium, etc. In some embodiments, the conductive metal surface layer may be applied by electrolytic or electroless plating methods. The metal surface layer may be partially or fully oxidized to form the corresponding metal oxide layer. In some embodiments, the porous metal oxide may have a density lower than that of the non-porous metal oxide. In some embodiments, the density of the porous metal oxide is in the range of 50% to 60%, or 60% to 70%, or 70% to 80%, or 80% to 90%, or 90% to 95%, or 95% to 99% of the density of the non-porous metal oxide, or any combination of those continuous ranges.

[0030] In some embodiments, the metal oxide is formed in or along the same chamber as the tool used to deposit the continuous porous lithium storage layer. The doped metal oxide layer can be formed by adding a dopant or dopant precursor during the metal oxide formation step, or alternatively, by adding a dopant or dopant precursor to the surface of the conductive layer prior to the metal oxide layer formation step, or alternatively, by treating the metal oxide layer with a dopant or dopant precursor after the initial formation of the metal oxide layer. In some embodiments, the metal oxide layer itself may have some reversible or irreversible lithium storage capacity. In some embodiments, the reversible capacity of the metal oxide layer is lower than that of the continuous porous lithium storage layer. In some embodiments, the metal oxide layer may be porous.

[0031] In some embodiments, the metal oxide may be provided in a pattern on the conductive layer, as disclosed in U.S. Patent Application No. 16 / 909,008, the entire content of which is incorporated herein for all purposes.

[0032] In some embodiments, the metal oxide is formed by oxidizing a surface region of a metal substrate, for example, by oxidizing a metal foil such as nickel foil. The unoxidized portion of the metal foil acts as a conductive layer, and the oxidized portion corresponds to the metal oxide layer. This method is suitable for the mass and low-cost production of current collectors. The oxidation conditions depend on the metal / metal surface, the target oxide thickness, and the desired oxide porosity. Unless otherwise specified, any reference to a particular metal includes alloys of that metal. For example, nickel foil can include pure nickel or any nickel alloy having nickel as a main component. In some embodiments, the alloy metal is also oxidized, and the nickel oxide formed from the alloy can include the corresponding oxidized metal. In some embodiments, the current collector is formed by oxidizing a nickel substrate, such as nickel foil, in a furnace with air at a temperature of at least 300 °C, or at least 400 °C, for example, in the range of about 600 °C to about 900 °C, or at a higher temperature. The holding time depends on the selected temperature and the desired thickness / porosity of the metal oxide layer. Typically, the oxidation holding time ranges from about 1 minute to about 2 hours, although shorter or longer times are conceivable. Surface pretreatment steps can be applied to promote or control oxidation. Other metals such as copper and titanium may have other operating holding times, temperatures, and pretreatments depending on their tendency to be oxidized.

[0033] The current collector may have a conductive layer including two or more sub-layers with different chemical compositions. For example, the current collector may include a metallic copper foil as the first conductive sub-layer, a second conductive sub-layer of metallic nickel provided on the copper, and a layer of nickel oxide on the metallic nickel. As described above, the metallic copper and nickel may be in the form of an alloy. Similarly, the metal oxide layer may include two or more sub-layers with different chemical compositions. For example, the current collector may include a metallic copper foil, a layer of copper oxide on the copper foil, and a layer of titanium dioxide on the copper oxide. FIG. 5 is a cross-sectional view showing these embodiments. The anode 500 in FIG. 5 includes a conductive current collector 501 having a metal oxide layer 505 provided on the conductive layer 503. The conductive layer 503 is divided into first and second conductive sub-layers 503a and 503b, respectively, and the metal oxide layer 505 is divided into first and second metal oxide sub-layers 505a and 505b, respectively. A continuous porous lithium storage layer 507 is formed on the second metal oxide sub-layer 505b. Such sub-layers may be discontinuous or may take the form of a chemical composition gradient. In some embodiments, there may be a gradient or transition region between the conductive layer and the metal oxide layer.

[0034] In some embodiments (not shown), the conductive current collector precursor may initially have a conductive layer with metal sub-layers such that the second metal sub-layer on the surface is more easily oxidized than the underlying first metal sub-layer. Under the oxidation conditions for forming the current collector, only the second sub-layer oxidizes (either in whole or in part only). Thereby, the thickness of the metal oxide layer can be better controlled.

[0035] Continuous porous lithium storage layer The continuous porous lithium storage layer contains a porous material capable of reversibly incorporating lithium. In some embodiments, the continuous porous lithium storage layer contains silicon, germanium, or a mixture of both. In some embodiments, the continuous porous lithium storage layer contains antimony or tin. In some embodiments, the continuous porous lithium storage layer is substantially amorphous. In some embodiments, the continuous porous lithium storage layer contains substantially amorphous silicon. Such a substantially amorphous storage layer can contain a small amount (e.g., less than 20 atomic %) of crystalline material dispersed therein. The continuous porous lithium storage layer may contain dopants such as hydrogen, boron, phosphorus, sulfur, fluorine, aluminum, gallium, indium, arsenic, antimony, bismuth, nitrogen, or metallic elements. In some embodiments, the continuous porous lithium storage layer may contain, for example, porous substantially amorphous hydrogenated silicon (a-Si:H) having a hydrogen content of from 0.1 to 20 atomic % or more. In some embodiments, the continuous porous lithium storage layer may contain methylated amorphous silicon. It should be noted that unless otherwise specifically mentioned with respect to the hydrogen content, the atomic % metric used herein for the lithium storage material or layer refers to all atoms other than hydrogen.

[0036] In some embodiments, the continuous porous lithium storage layer contains at least 40 atomic % of silicon, germanium, or a combination thereof, or at least 50 atomic %, or at least 60 atomic %, or at least 70 atomic %, or at least 80 atomic %, or at least 90 atomic %. In some embodiments, the continuous porous lithium storage layer contains at least 40 atomic % of silicon, or at least 50 atomic %, or at least 60 atomic %, or at least 70 atomic %, or at least 80 atomic %, or at least 90 atomic %, or at least 95 atomic %, or at least 97 atomic %.

[0037] In some embodiments, the continuous porous lithium storage layer contains less than 10 atomic percent, or less than 5 atomic percent, or less than 2 atomic percent, or less than 1 atomic percent, or less than 0.5 atomic percent of carbon. In some embodiments, the continuous porous lithium storage layer contains less than 5 wt%, or less than 1 wt% of a carbon-based binder, carbon nanotubes, graphite-like carbon, graphene, graphene oxide, reduced graphene oxide, carbon black, and conductive carbon.

[0038] The continuous porous lithium storage layer contains voids or gaps (pores) that can be random or non-uniform with respect to size, shape, and distribution. Such porosity does not result in, or is not caused by, the formation of any recognizable nanostructures such as nanowires, nanopillars, nanotubes, nanochannels, etc. In some embodiments, the pores are polydisperse. In some embodiments, when analyzed by SEM cross-section, 90% of the pores larger than 100 nm in any dimension are less than about 5 μm, or less than about 3 μm, or less than about 2 μm in any dimension. In some embodiments, the continuous porous lithium storage layer can contain some pores with any dimension less than 100 nm, or any dimension less than 50 nm, or any dimension less than 20 nm. In some embodiments, the continuous porous lithium storage layer has a density of 1.0 - 1.1 g / cm 3 , or 1.1 - 1.2 g / cm 3 , or 1.2 - 1.3 g / cm 3 , or 1.3 - 1.4 g / cm 3 , or 1.4 - 1.5 g / cm 3 , or 1.5 - 1.6 g / cm 3 , or 1.6 - 1.7 g / cm 3 , or 1.7 - 1.8 g / cm 3 , or 1.8 - 1.9 g / cm 3 , or 1.9 - 2.0 g / cm 3 , or 2.0 - 2.1 g / cm 3 , or 2.1 - 2.2 g / cm 3 , or 2.2 - 2.25 g / cm 3or having an average density in any combination of ranges of those or their continuous ranges, and containing at least 40 atomic % of silicon, or at least 50 atomic % of silicon, or at least 60 atomic % of silicon, or at least 70 atomic % of silicon, or 80 atomic % of silicon, or at least 90 atomic % of silicon, or at least 95 atomic % of silicon.

[0039] In some embodiments, most of the active material (e.g., silicon, germanium or their alloys) of the continuous porous lithium storage layer has substantial lateral connectivity across a portion of the current collector, and such connectivity extends around random pores and gaps (as will be described later). Referring again to FIG. 1, in some embodiments, "substantial lateral connectivity" means that the active material at one point X of the continuous porous lithium storage layer 107 can be connected to the active material at a second point X' of the layer at a linear lateral distance LD that is at least as large as the thickness T of the continuous porous lithium storage layer, or at least twice the thickness in lateral distance, or at least three times the thickness in lateral distance. Although not shown, the total distance of the connection path of the material including the surrounding pores may be longer than LD. In some embodiments, the continuous porous lithium storage layer can be described as a matrix of interconnected silicon, germanium or their alloys embedded with random pores and gaps. In some embodiments, the continuous porous lithium storage layer has a sponge-like form. In some embodiments, at least prior to electrochemical formation, more than about 75% of the surface of the metal oxide layer is continuous with the continuous porous lithium storage layer. It should be noted that the continuous porous lithium storage layer does not necessarily extend across the entire anode without any lateral breaks and may include random discontinuities or cracks and is still considered continuous.

[0040] In some embodiments, the continuous porous lithium storage layer is silicon (SiO x ), germanium (GeO x ) or tin (SnO xIt contains a sub-stoichiometric oxide, and the ratio of oxygen atoms to silicon, germanium, or tin atoms is less than 2:1, i.e., x < 2, or less than 1:1, i.e., x < 1. In some embodiments, x ranges from 0.02 to 0.95, or from 0.02 to 0.10, or from 0.10 to 0.50, or from 0.50 to 0.95, or from 0.95 to 1.25, or from 1.25 to 1.50, or any combination of their continuous ranges.

[0041] In some embodiments, the continuous porous lithium storage layer contains a sub-stoichiometric nitride of silicon (SiN y ), germanium (GeN y ), or tin (SnN y ), and the ratio of nitrogen atoms to silicon, germanium, or tin atoms is less than 1.25:1, i.e., y < 1.25. In some embodiments, y ranges from 0.02 to 0.95, or from 0.02 to 0.10, or from 0.10 to 0.50, or from 0.50 to 0.95, or from 0.95 to 1.20, or any combination of their continuous ranges.

[0042] In some embodiments, the continuous porous lithium storage layer contains a sub-stoichiometric oxynitride of silicon (SiO x N y ), germanium (GeO x N y ), or tin (SnO x N y ) in which the ratio of all oxygen and nitrogen atoms to silicon, germanium, or tin atoms is less than 1:1, i.e., (x + y) < 1. In some embodiments, (x + y) ranges from 0.02 to 0.95, or from 0.02 to 0.10, or from 0.10 to 0.50, or from 0.50 to 0.95, or any combination of their continuous ranges.

[0043] In some embodiments, the above-described near-stoichiometric oxides, nitrides, or oxynitrides are provided by a CVD process including, but not limited to, a PECVD process. Oxygen and nitrogen may be uniformly supplied into the continuous porous lithium storage layer, or the oxygen or nitrogen content may vary as a function of the thickness of the storage layer.

[0044] Referring to FIG. 6, anode 600 includes a continuous porous lithium storage layer 607 provided on a current collector 601 including a metal oxide layer 605 and a conductive layer 603. In some embodiments, the continuous porous lithium storage layer 607 has different physical properties or chemical compositions and includes a plurality of continuous porous lithium storage sub-layers (607a and 607b) independently selected from any of the above embodiments. For example, the lithium storage sub-layer 607a can include amorphous silicon with a low oxygen content, and the lithium storage sub-layer 607b can include a sub-oxide SiO x of silicon, where x ranges from 0.02 to 0.95. Alternatively, the compositions of 607a and 607b can be reversed. In another example, the lithium storage sub-layer 607a may include amorphous silicon having a low germanium content, and the lithium storage sub-layer 607b may include a higher atomic % germanium than 607a. In some embodiments, the lithium storage sub-layers may have different amounts or types of dopants. In some other embodiments, the lithium storage sub-layers 607a and 607b have the same chemical composition, but the density of 607a is higher than that of 607b. These are just a few examples of non-limiting examples. Many other combinations are possible. Although two lithium storage sub-layers are shown in FIG. 6, three or more sub-layers may be used instead.

[0045] In some embodiments, the continuous porous lithium storage layer includes a gradient of components, density, or porosity, or a combination thereof, as a function of layer thickness. For example, the continuous porous lithium storage layer 107 may include amorphous silicon having a higher density near the metal oxide layer 105 than near the upper surface 108, or vice versa.

[0046] Additional Lithium Storage Layer The substantially flat nature of some embodiments of this anode further enables a simple coating of an additional lithium storage layer that is not the continuous porous lithium storage layer described herein. For example, a conventional lithium ion battery slurry based on carbon, which may optionally further contain silicon particles, can be coated on the continuous porous lithium storage layer of the present disclosure to further amplify the charge capacity. Coating methods can include curtain coating, slot coating, spin coating, inkjet coating, spray coating, or any other suitable method.

[0047] CVD CVD generally involves flowing a precursor gas, a gasified liquid for direct liquid injection CVD, or a gas and a liquid into a chamber containing one or more objects to be typically heated and coated. Chemical reactions occur at and near the hot surface, and a thin film is deposited on the surface. This is accompanied by the production of chemical by-products that are exhausted from the chamber along with the unreacted precursor gas. There are many variations of CVD that can be used to form a lithium storage layer, a metal oxide layer, a secondary layer (see below), or other layers, as expected for a wide variety of deposited materials and applications. This can be done, in some embodiments, in a hot-wall reactor or a cold-wall reactor, with and without a carrier gas, at total pressures below torr to above atmospheric pressure, typically at temperatures in the range of 100 - 1600 °C. There are also various improved CVD processes that include the use of plasma, ions, photons, lasers, hot filaments, or combustion reactions to increase the deposition rate and / or decrease the deposition temperature. Deposition can be controlled using various process conditions including, but not limited to, temperature, precursor material, amount of gas flow, pressure, substrate voltage bias (if applicable), and plasma energy (if applicable).

[0048] As described above, a continuous porous lithium storage layer, such as a layer of silicon or germanium or both, can be provided by plasma enhanced chemical vapor deposition (PECVD). Compared to conventional CVD, deposition by PECVD is often carried out at lower temperatures and higher rates, which can be advantageous for higher manufacturing throughput. In some embodiments, PECVD is used to deposit a substantially amorphous silicon layer (optionally doped) on a metal oxide layer. In some embodiments, PECVD is used to deposit a substantially amorphous continuous porous silicon layer on a metal oxide layer.

[0049] PECVD In the PECVD process, according to various embodiments, the plasma can be generated within the chamber in which the substrate is disposed or upstream of the chamber and supplied to the chamber. Various types of plasmas can be used, including but not limited to capacitively coupled plasma, inductively coupled plasma, and conductively coupled plasma. Any suitable plasma source can be used, including DC, AC, RF, VHF, combinatorial PECVD, and microwave sources. Some non-limiting examples of useful PECVD tools include hollow cathode tube PECVD, magnetron confinement PECVD, inductively coupled plasma chemical vapor deposition (sometimes called HDPECVD, ICP-CVD, or HDCVD, ICP-PECVD), and expanded thermal plasma chemical vapor deposition (ETP-PECVD).

[0050] The PECVD process conditions (temperature, pressure, precursor gas, carrier gas, dopant gas, flow rate, energy, etc.) can vary according to the particular process and tool used, as is well known in the art.

[0051] In some embodiments, the PECVD process is an Expanded Thermal Plasma Chemical Vapor Deposition (ETP-PECVD) process. In such a process, the plasma generating gas optionally passes through a DC arc plasma generator with a web or other substrate containing a current collector in an adjacent vacuum chamber to form a plasma. In the plasma, a silicon source gas is injected and radicals are generated. The plasma is expanded through a diverging nozzle and injected into the vacuum chamber towards the substrate. An example of the gas for plasma generation is argon (Ar). In some embodiments, the ionized argon species in the plasma collide with the silicon source molecules to form radical species of the silicon source and deposit on the current collector. Exemplary ranges of the voltage and current of the DC plasma source are 60 - 80 volts and 40 - 70 amperes, respectively.

[0052] Silicon can be deposited using any suitable silicon source including silane (SiH4), dichlorosilane (H2SiCl2), monochlorosilane (H3SiCl), trichlorosilane (HSiCl3), silicon tetrachloride (SiCl4), and diethylsilane. Depending on the gas used, the silicon layer can be formed by decomposition or reaction with another compound such as hydrogen reduction. In some embodiments, the gas can include a silicon source such as silane, a noble gas such as helium, argon, neon, or xenon, optionally one or more dopant gases, and may not substantially contain hydrogen. In some embodiments, the gas can include argon, silane, and hydrogen, and optionally some dopant gases. In some embodiments, the ratio of the gas flow of argon to the gas flow of the combined gas of silane and hydrogen is at least 3.0, or at least 4.0. In some embodiments, the ratio of the gas flow of argon to the gas flow of the combined gas of silane and hydrogen is in the range of 3 - 5, or 5 - 10, or 10 - 15, or 15 - 20, or any combination of their continuous ranges. In some embodiments, the ratio of the gas flow amount of hydrogen gas to silane gas is in the range of 0 - 0.1, or 0.1 - 0.2, or 0.2 - 0.5, or 0.5 - 1, or 1 - 2, or 2 - 5, or any combination of their continuous ranges. In some embodiments, as the ratio of the gas flow of silane to the combined gas flow of silane and hydrogen increases, silicon with higher porosity can be formed and / or the silicon deposition rate can increase. In some embodiments, the dopant gas is borane or phosphine which can optionally be mixed with a carrier gas.In some embodiments, the ratio of the amount of the gas flow of the dopant gas (e.g., borane or phosphine) to the silicon source gas (e.g., silane) is in the range of 0.0001 to 0.0002, alternatively 0.0002 to 0.0005, alternatively 0.0005 to 0.001, alternatively 0.001 to 0.002, alternatively 0.002 to 0.005, alternatively 0.005 to 0.01, alternatively 0.01 to 0.02, alternatively 0.02 to 0.05, alternatively 0.05 to 0.10, or any combination of their continuous ranges. Such a ratio of the amount of the gas flow as described above can refer to, for example, the relative amount of the gas flow in standard cubic centimeters per minute (SCCM). In some embodiments, the PECVD deposition conditions and the gas can be changed during the deposition process.

[0053] In some embodiments, the temperature of the current collector during at least a part of the PECVD deposition time is in the range of 100°C to 200°C, or 200°C to 300°C, or 300°C to 400°C, or 400°C to 500°C, or 500°C to 600°C, or any combination of their continuous ranges. In some embodiments, the temperature can change during the PECVD deposition time. For example, the temperature at the initial time of PECVD may be higher than that at a later time. Alternatively, the temperature during a later time of PECVD may be higher than that at a previous time.

[0054] The thickness or mass per unit area of the continuous porous lithium storage layer depends on the storage material, the desired charge capacity, and other operational and lifespan considerations. Increasing the thickness generally results in more capacity being obtained. If the continuous porous lithium storage layer becomes too thick, the electrical resistance may increase and the stability may decrease. In some embodiments, the anode is at least 0.5 mg / cm 2 or at least 1.0 mg / cm 2 or at least 1.5 mg / cm 2 or at least 3 mg / cm 2 or at least 5 mg / cm 2It can be characterized as having an active silicon surface density. In some embodiments, the lithium storage structure has an active silicon surface density in the range of 0.5 to 1.5 mg / cm 2 or in the range of 1.5 to 2 mg / cm 2 or in the range of 2 to 3 mg / cm 2 or in the range of 3 to 5 mg / cm 2 or in the range of 5 to 10 mg / cm 2 or in the range of 10 to 15 mg / cm 2 or in the range of 15 to 20 mg / cm 2 or any combination of continuous ranges thereof. "Active silicon surface density" refers to silicon that is electrically connected to a current collector available for reversible lithium storage at the start of a cell cycle, for example, after the "electrochemical formation" of the anode described below. The "surface" in this term refers to the surface area of the conductive layer on which the active silicon is provided. In some embodiments, not all of the silicon content is active silicon, i.e., some may be bound in the form of inactive silicides or may be electrically insulated from the current collector.

[0055] In some embodiments, the continuous porous lithium storage part has an average thickness of at least 0.5 μm, or at least 1 μm, or at least 3 μm, or at least 7 μm. In some embodiments, the continuous porous lithium storage layer has an average thickness in the range of about 0.5 μm to about 50 μm. In some embodiments, the continuous porous lithium storage layer contains at least 85 atomic% amorphous silicon and has a thickness in the range of 0.5 to 1 μm, or 1 to 2 μm, or 2 to 4 μm, or 4 to 7 μm, or 7 to 10 μm, or 10 to 15 μm, or 15 to 20 μm, or 20 to 25 μm, or 25 to 30 μm, or 30 to 40 μm, or 40 to 50 μm, or any combination of continuous ranges thereof.

[0056] In some embodiments, the continuous porous lithium storage layer contains silicon but does not contain a substantial amount of crystalline silicide, i.e., the presence of silicide is not readily detectable by X-ray diffraction (XRD). Metal silicides, such as nickel silicide, are generally formed when silicon is deposited directly on a metal, such as nickel foil, at a higher temperature. Metal silicides, such as nickel silicide, often have a much lower lithium storage capacity than silicon itself. In some embodiments, the average atomic % of the silicide-forming metal element in the continuous porous lithium storage layer is less than 35%, or less than 20%, or less than 10%, or less than 5% on average. In some embodiments, the average atomic % of the silicide-forming metal element in the continuous porous lithium storage layer ranges from about 0.01% to about 10%, or from about 0.05 to about 5%. In some embodiments, the atomic % of the silicide formed by the metal element in the continuous porous lithium storage layer is higher closer to the current collector than farther away from the current collector.

[0057] Other anode features In some embodiments, the anode may further include one or more auxiliary layers. As shown in FIG. 7A, an auxiliary layer 750 is provided on the surface of a continuous porous lithium storage layer 707 that covers a current collector 701 including a metal oxide layer 705 and a conductive layer 703. In some embodiments, the auxiliary layer is a protective layer for enhancing lifespan or physical durability. The auxiliary layer may be an oxide or nitride formed from the lithium storage material itself, for example, in the case of silicon, silicon dioxide, silicon nitride, or silicon oxynitride. The auxiliary layer may be deposited, for example, by ALD, CVD, PECVD, evaporation, sputtering, solution coating, inkjet, or any method compatible with the anode. In some embodiments, the auxiliary layer is deposited in the same CVD or PECVD apparatus as the continuous lithium storage layer. For example, a stoichiometric silicon dioxide or silicon nitride auxiliary layer is formed by introducing an oxygen or nitrogen-containing gas (or both) together with the silicon precursor gas used to form the continuous porous lithium storage layer. In some embodiments, the auxiliary layer may include boron nitride or silicon carbide. In some embodiments, the auxiliary layer 750 can include a metal compound as described below.

[0058] As shown in FIG. 7B, in some embodiments, the anode includes a first auxiliary layer 750-1 and a second auxiliary layer 750-2 that cover the first auxiliary layer and have a different chemical composition from the first auxiliary layer. In some embodiments, the first auxiliary layer 750-1 can include silicon nitride, silicon dioxide, silicon oxynitride, or a first metal compound. The second auxiliary layer 750-2 has a composition different from that of the first auxiliary layer and can include silicon nitride, silicon dioxide, silicon oxynitride, or a second metal compound. In some embodiments, the second auxiliary layer may be in contact with the first auxiliary layer. In some embodiments, one or more additional auxiliary layers can be provided on the second auxiliary layer. In some embodiments having two or more auxiliary layers, each auxiliary layer is in contact with at least one other auxiliary layer.

[0059] In some embodiments, the first auxiliary layer 750-1 and any second or additional auxiliary layers can help stabilize the continuous porous lithium storage layer by providing a barrier against direct electrochemical reactions with solvents or electrolytes that can degrade the interface. The auxiliary layer should be reasonably conductive to lithium ions and allow lithium ions to enter and exit the continuous porous lithium storage layer during charge and discharge. In some embodiments, the lithium ion conductivity of the auxiliary layer is at least 10 -9 S / cm, or at least 10 -8 S / cm, or at least 10 -7 S / cm, or at least 10 -6 S / cm. In some embodiments, the auxiliary layer acts as a solid electrolyte. In some embodiments, since the auxiliary layer has lower conductivity than the lithium storage structure, little or no electrochemical reduction of lithium ions to lithium metal occurs at the auxiliary layer / electrolyte interface. In addition to providing protection from electrochemical reactions, embodiments with multiple auxiliary layer structures can provide excellent structural support. In some embodiments, when the continuous porous lithium storage layer expands during lithiation, the auxiliary layer may bend and form cracks, but the crack propagation can be dispersed between the layers to reduce the direct exposure of the lithium storage structure to the bulk electrolyte. For example, the cracks in the second auxiliary layer may not be aligned with the cracks in the first auxiliary layer. Such advantages cannot occur when only one thick auxiliary layer is used. In one embodiment, the second auxiliary layer may be formed of a material having higher flexibility than the first auxiliary layer.

[0060] In some embodiments, the auxiliary layer (the first auxiliary layer, the second auxiliary layer, or any additional auxiliary layer) can include silicon nitride, e.g., substantially stoichiometric silicon nitride with a nitrogen-to-silicon ratio in the range of 1.33 to 1.25. The auxiliary layer containing silicon nitride can have an average thickness in the range of about 0.5 nm to 1 nm, or 1 nm to 2 nm, or 2 nm to 10 nm, or 10 nm to 20 nm, or 20 nm to 30 nm, or 30 nm to 40 nm, or 40 nm to 50 nm, or any combination of their continuous ranges. Silicon nitride can be deposited by an atomic layer deposition (ALD) process or a CVD process. In some embodiments, the continuous porous lithium storage layer includes silicon deposited by some kind of CVD process as described above, and finally, a nitrogen gas source is added to the CVD deposition chamber together with the silicon source.

[0061] In some embodiments, the auxiliary layer (the first auxiliary layer, the second auxiliary layer, or any additional auxiliary layer) can include silicon dioxide, e.g., substantially stoichiometric silicon dioxide with an oxygen-to-silicon ratio in the range of 2.0 to 1.9. The auxiliary layer containing silicon dioxide can have an average thickness in the range of about 2 nm to 10 nm, or 10 nm to 30 nm, or 30 nm to 50 nm, or 50 nm to 70 nm, or 70 nm to 100 nm, or 100 nm to 150 nm, or 150 nm to 200 nm, or any combination of their continuous ranges. Silicon dioxide can be deposited by an atomic layer deposition (ALD) process or a CVD process. In some embodiments, the continuous porous lithium storage layer includes silicon deposited by some kind of CVD process as described above, and finally, an oxygen-containing gas source is added to the CVD deposition chamber together with the silicon source.

[0062] In some embodiments, the auxiliary layer (the first auxiliary layer, the second auxiliary layer, or any additional auxiliary layer) is silicon oxynitride, e.g., substantially stoichiometric silicon oxynitride (SiO x N y) can be included, and the sum of 0.5x and 0.75y is in the range from 1.00 to 0.95. The auxiliary layer containing silicon nitride can have an average thickness in the range of about 0.5 nm to 1 nm, or 1 nm to 2 nm, or 2 nm to 10 nm, or 10 nm to 20 nm, or 20 nm to 30 nm, or 30 nm to 40 nm, or 40 nm to 50 nm, or 50 nm to 70 nm, or 70 nm to 100 nm, or 100 nm to 150 nm, or any combination of their continuous ranges. In some embodiments, silicon oxynitride may be provided by a CVD process including but not limited to a PECVD process. Oxygen and nitrogen may be uniformly supplied into the continuous porous lithium storage layer, or the oxygen or nitrogen content may vary as a function of the position (e.g., height) within the storage layer.

[0063] In some embodiments, silicon nitride, silicon dioxide, or silicon oxynitride may be deposited by an atomic layer deposition (ALD) process or a CVD process. In some embodiments, the continuous porous lithium storage layer contains silicon deposited by some kind of CVD process as described above, and finally, a nitrogen and / or oxygen-containing gas source is added to the CVD deposition chamber together with the silicon source.

[0064] In some embodiments, the auxiliary layer (the first auxiliary layer, the second auxiliary layer, or any additional auxiliary layer) can include a metal oxide, a metal nitride, or a metal oxynitride, such as aluminum, titanium, vanadium, zirconium, or tin, or a mixture thereof. In some embodiments, the auxiliary layer including a metal oxide, a metal nitride, or a metal oxynitride can have an average thickness in the range of less than about 100 nm, such as about 0.5 nm to about 1 nm, or about 1 nm to about 2 nm, or 2 nm to 10 nm, or 10 nm to 20 nm, or 20 nm to 30 nm, or 30 nm to 40 nm, or 40 nm to 50 nm, or any combination of their continuous ranges. The metal oxide, metal nitride or metal oxynitride may include other components or dopants such as transition metals, phosphorus or silicon.

[0065] In some embodiments, the metal compound can include a lithium-containing material such as lithium phosphonitride (LIPON), lithium phosphate, lithium aluminum oxide, or lithium lanthanum titanate. In some embodiments, the thickness of the auxiliary layer including the lithium-containing material can be in the range of 0.5 nm to 200 nm, or 1 nm to 10 nm, or 10 nm to 20 nm, or 20 nm to 30 nm, or 30 nm to 40 nm, or 40 nm to 50 nm, or 50 nm to 100 nm, or 100 nm to 200 nm, or any combination of their continuous ranges.

[0066] In some embodiments, the metal compound may be deposited by a process including ALD, thermal evaporation, sputtering, or electron beam evaporation. ALD is a thin film deposition technique typically based on the sequential use of gas phase chemical processes. Most ALD reactions typically use at least two chemical substances, typically called precursors. These precursors react sequentially and self - limitingly with the surface of the material. By repeatedly exposing to the separate precursors, thin films are often deposited conformally. In addition to conventional ALD systems, for example, so - called spatial ALD (SALD) methods and materials can be used as described in U.S. Patent No. 7,413,982, the entire content of which is incorporated herein by reference for all purposes. In certain embodiments, SALD can be performed under ambient conditions and pressures and can have a higher throughput than conventional ALD systems.

[0067] In some embodiments, the process for depositing the metal compound may include electroless deposition, contact with a solution, contact with a reactive gas, or an electrochemical method. In some embodiments, a metal layer (including, but not limited to, thermal evaporation, CVD, sputtering, electron beam evaporation, electrochemical deposition, or electroless deposition) is deposited, followed by a process of converting the metal to a metal compound (including, but not limited to, contact with a reactive solution, contact with an oxidizing agent, contact with a reactive gas, or heat treatment) to form the metal compound.

[0068] The auxiliary layer can include an inorganic-organic hybrid structure having alternating layers of a metal oxide and a crosslinked organic material. These inorganic-organic hybrid structures are sometimes referred to as "metalcones." Such structures can be fabricated using a combination of atomic layer deposition for applying a metal compound and molecular layer deposition (MLD) for applying an organic compound. The organic crosslinker is typically a molecule having multiple functional groups. One group can react with the layer containing the metal compound, and the other group is available to react in a subsequent ALD step to bond a new metal. A wide range of reactive organic functional groups can be used, including but not limited to hydroxy, carboxylic acid, amine, acid chloride, and anhydride. Almost any metal compound suitable for ALD deposition can be used. Some non-limiting examples include ALD compounds for aluminum (e.g., trimethylaluminum), titanium (e.g., titanium tetrachloride), zinc (e.g., diethylzinc), and zirconium (tris(dimethylamino)cyclopentadienylzirconium). For the purposes of the present disclosure, this alternating sublayer structure of metal oxide / crosslinked organic is considered a single auxiliary layer of metalcone. When the metal compound includes aluminum, such a structure is sometimes referred to as an alcone. Similarly, when the metal compound includes zirconium, such a structure is sometimes referred to as a zirconcone. Further examples of inorganic-organic hybrid structures that may be suitable as the auxiliary layer can be found in U.S. Patent No. 9,376,455, as well as U.S. Patent Application Publication Nos. 2019 / 0044151 and 2015 / 0072119, the entire contents of which are incorporated herein by reference.

[0069] In some embodiments, the auxiliary layer having a metalcone can have a thickness in the range of 0.5 nm to 200 nm, or 1 nm to 10 nm, or 10 nm to 20 nm, or 20 nm to 30 nm, or 30 nm to 40 nm, or 40 nm to 50 nm, or 50 nm to 100 nm, or 100 nm to 200 nm, or any combination of those continuous ranges.

[0070] In some embodiments, the auxiliary layer (first, second, or additional auxiliary layer) can include boron nitride or silicon carbide and can have an average thickness in the range of less than about 100 nm, such as from about 0.5 nm to about 1 nm, or from about 1 nm to about 2 nm, or from 2 nm to 10 nm, or from 10 nm to 20 nm, or from 20 nm to 30 nm, or from 30 nm to 40 nm, or from 40 nm to 50 nm, or any combination of these continuous ranges.

[0071] In some embodiments, the anode is at least partially prelithiated, i.e., the continuous porous lithium storage layer and / or the metal oxide layer contains some lithium prior to battery assembly, i.e., before combining the anode with the cathode in the battery cell.

[0072] In some embodiments, lithium metal (or other lithiated material) is deposited on the metal oxide layer before depositing the continuous porous lithium storage layer. Lithium may be deposited, for example, by evaporation, electron beam, or sputtering. A portion of the lithium may form lithium oxide. In embodiments where the metal oxide layer contains an oxide of a transition metal, such as copper or nickel, a mixed metal oxide may be formed. In some embodiments, depositing a lithium layer on the metal oxide can reduce the first cycle loss of lithium during the electrochemical formation of the anode (described below).

[0073] In some embodiments, the deposition ratio of lithium metal atoms to oxygen atoms in the metal oxide layer is at least 0.02, or in the range of 0.05 to 1.0. In some cases, the amount of lithium metal deposited corresponds to at least 1%, or from 2% to 10%, or from 10% to 30%, or from 30% to 50% of the maximum lithium areal capacity of the continuous porous lithium storage layer, or any combination of these ranges.

[0074] In some embodiments, the continuous porous lithium storage layer may be at least partially prelithiated before the first electrochemical cycle after battery assembly or, alternatively, before battery assembly. That is, even before the first battery cycle, some lithium may be incorporated into the continuous porous lithium storage layer to form a lithiated storage layer. In some embodiments, the lithiated storage layer can be electrochemically active and break down into smaller structures, including but not limited to platelets, that continue to store lithium reversibly. Note that the "lithiated storage layer" simply means that at least a portion of the potential storage capacity of the lithium storage layer is filled, and it is not necessary for all of it to be filled. In some embodiments, the lithiated storage layer may contain 1% - 10%, or 10% - 20%, or 20% - 30%, or 30% - 40%, or 40% - 50%, or 50% - 60%, or 60% - 70%, or 70% - 80%, or 80% - 90%, or 90% - 100% of the lithium in the range of the theoretical lithium storage capacity of the continuous porous lithium storage layer, or any combination of those continuous ranges. In some embodiments, the metal oxide layer may capture some of the lithium, and it may be necessary to consider such capture to achieve the desired lithium range within the lithiated storage layer.

[0075] In some embodiments, prelithiation may include depositing lithium metal, for example, by evaporation, electron beam or sputtering, on top of the continuous porous lithium storage layer, or between one or more lithium storage sub-layers, or both. Alternatively, prelithiation may include contacting the anode with a reducing lithium organic compound, such as lithium naphthalene, n-butyllithium, etc. In some embodiments, prelithiation may include the step of incorporating lithium by electrochemical reduction of lithium ions in a prelithiation solution.

[0076] In some embodiments, one or more auxiliary layers (described above) may be formed on the continuous porous lithium storage layer prior to prelithiation. The auxiliary layer can be used to control the lithium uptake rate. Non-limiting examples of auxiliary layer materials include silicon nitride, metal oxides, metal nitrides, or metal oxynitrides.

[0077] In some embodiments, prelithiation includes physical contact between the continuous porous lithium storage layer and the lithiating material. The lithiating material may include a reducing lithium compound, lithium metal, or stabilized lithium metal powder, any of which may be provided as a coating on the lithium transport substrate. The lithium transport substrate can include a metal (e.g., as a foil), a polymer, a ceramic, or optionally some combination of such materials in a multilayer format. In some embodiments, such a lithiating material may be provided on at least one surface of the current separator facing the anode, i.e., the current separator also acts as the lithium transport substrate. Stabilized lithium metal powder ("SLMP") typically has a phosphate, carbonate, or other coating on the lithium metal particles, as described, for example, in U.S. Patent Nos. 8,377,236, 6,911,280, 5,567,474, 5,776,369, and 5,976,403, the entire contents of each of which are incorporated herein by reference. In some embodiments, the SLMP may require physical pressure to break the coating and allow lithium uptake into the continuous porous lithium storage layer. In some embodiments, pressure and / or heat can be applied to other lithiating materials to facilitate lithium transfer into the continuous lithium storage layer, optionally through one or more auxiliary layers. In some embodiments, the pressure applied between the anode and the lithiating material can be at least 200 kPa, or at least 1000 kPa, or at least 5000 kPa. The pressure may be applied, for example, by calendaring, by a pressure plate, or in the case of a lithiating material coating on the current separator, by assembly into a battery having a confinement or other pressure mechanism.

[0078] In some embodiments, prelithiation includes heat treating the continuous porous lithium storage layer during, after, or both during and after lithium uptake. The heat treatment can assist in the uptake of lithium into the continuous porous lithium storage layer, for example, by promoting lithium diffusion. In some embodiments, heat treating comprises exposing the anode to a temperature in the range of 50°C to 100°C, or 100°C to 150°C, or 150°C to 200°C, or 200°C to 250°C, or 250°C to 300°C, or 300°C to 350°C. In some embodiments, the heat treatment can be carried out under a controlled atmosphere, such as a vacuum or an argon atmosphere, to avoid unwanted reactions with oxygen, nitrogen, water, or other reactive gases.

[0079] In some embodiments, prelithiation can soften the continuous porous lithium storage layer, for example, due to the formation of a lithium-silicon alloy. This softening can cause problems in some processes, such as a roll-to-roll process where the softened lithium storage layer begins to adhere to rollers or itself during winding. In some embodiments where one or more auxiliary layers are provided before or after prelithiation, the structural integrity and processability of the anode can be substantially improved. In some embodiments, the auxiliary layer can act as a harder interface with other surfaces to prevent or reduce contact between such surfaces and the softened lithium storage material.

[0080] In some embodiments, lithium metal can be deposited on the continuous porous lithium storage layer, followed by deposition of a lithium ion conducting layer. The anode may be heat treated before deposition of the lithium ion conducting layer, after deposition of the lithium ion conducting layer, or both. In some embodiments, the lithium metal is deposited directly on the continuous porous lithium storage layer. In some embodiments, an auxiliary layer, such as silicon nitride, is deposited on the continuous porous lithium storage layer prior to deposition of the lithium metal. In some embodiments, the lithium ion conducting layer can include a lithium-containing material, a metal oxide, or a metal cone. Some non-limiting examples of lithium ion conducting layer materials include lithium nitride phosphate (LIPON), lithium phosphate, lithium aluminum oxide, lithium lanthanum titanate, and alcon. The lithium ion conducting layer may include a plurality of sub-layers of different materials, for example selected from the above list.

[0081] In some embodiments, the anode may be treated with a reducing agent prior to final battery assembly. The reducing agent can have an electrochemical potential sufficient to reduce at least a portion of the metal oxide layer. Examples of reducing agents can include inorganic hydrides, substituted or unsubstituted borohydrides, amine-boranes, or anionic organic aromatic compounds. In some embodiments, the reducing agent can be provided in a non-aqueous solvent that is itself not reduced by the reducing agent and is applied under controlled conditions having low oxygen and moisture.

[0082] The heat treatment has been described above with respect to prelithiation and the metal oxide precursor. In some embodiments, the anode may be heat treated before battery assembly (after deposition of the continuous porous lithium storage layer is complete but before the anode is combined with the cathode in the battery cell), regardless of the presence or absence of a prelithiation step. In some embodiments, heat treating the anode can improve the adhesion or conductivity of the various layers, for example, by inducing the movement of metals from the current collector (i.e., the metal oxide layer or the conductive metal layer thereunder) or atoms from any auxiliary layer into the continuous porous lithium storage layer. In some embodiments, heat treating the anode can be performed under a controlled environment, such as vacuum, argon, or nitrogen with low oxygen and low water content (e.g., less than 100 ppm, or a partial pressure less than 10 Torr, or less than 1 Torr, or less than 0.1 Torr to prevent degradation). As used herein, "under vacuum" generally refers to a reduced pressure state where the total pressure of all gases (e.g., within a vacuum oven) is less than 10 Torr. Due to equipment limitations, the vacuum pressure usually exceeds about 10 -8 Torr. In some embodiments, the anode heat treatment can be performed using an oven, a tube furnace, an infrared heating element, contact with a hot surface (e.g., a hot plate), or exposure to a flash lamp. The temperature and time of the anode heat treatment depend on the material of the anode. In some embodiments, the anode heat treatment includes heating the anode to a temperature in the range of at least 50°C, optionally 50°C to 600°C, or 100°C to 250°C, or 250°C to 350°C, or 350°C to 450°C, or 450°C to 600°C, or 600°C to 700°C, or 700°C to 800°C, or any combination of their continuous ranges. In some embodiments, the anode heat treatment time can be in the range of about 0.1 minute to about 1 minute, or about 1 minute to about 5 minutes, or about 5 minutes to about 10 minutes, or about 10 minutes to about 30 minutes, or about 30 minutes to about 60 minutes, or about 60 minutes to about 90 minutes, or about 90 minutes to about 120 minutes, or any combination of their continuous ranges.

[0083] As shown in FIG. 8, there are a number of process flow options for manufacturing a battery incorporating the anode of the present disclosure. All steps in FIG. 8 have been described in more detail above, and FIG. 8 is not an exhaustive listing of all possibilities. In some embodiments, at least steps 801, 805, and 817 are followed. In step 801, a metal oxide layer is formed on a conductive layer, such as a conductive metal layer like a metal foil or a metal mesh. In step 805, one or more continuous porous lithium storage layers are deposited on the metal oxide layer. In an alternative embodiment, prior to step 805, lithium metal (or other lithiated material) can be deposited on the metal oxide layer as shown in step 803. In some cases, the anode formed in step 805 is ready to be assembled into a battery in step 817.

[0084] In some embodiments, after step 805, a prelithiation step, such as step 807 where lithium metal can be deposited on the continuous porous lithium storage layer, may be included. In some cases, the anode from step 807 may be ready to be assembled into a battery in step 817. In another embodiment shown in step 811, one or more lithium ion conducting layers may be deposited on the product of step 807 prior to the battery assembly step 817.

[0085] In some embodiments, after step 805, as shown in step 809, one or more auxiliary layers can be deposited on the continuous porous lithium storage layer. In some cases, the anode from step 809 is ready to be assembled into a battery in step 817. In other embodiments, for example, as shown in step 813, a prelithiation step may be included and lithium metal may be deposited on the auxiliary layer. In some cases, the anode from step 813 is ready to be assembled into a battery in step 817. In other embodiments, one or more lithium ion conducting layers may be deposited on the product of step 813 prior to the battery assembly step 817.

[0086] In addition to the explicit steps shown in FIG. 8, heat treatment or other processing can be performed between any of the steps. Further, as described above, after step 805, an additional lithium storage layer that is not a continuous porous lithium storage layer can be coated. In some embodiments, one or more steps may be performed using a roll-to-roll coating method, and the conductive layer is in the form of a roll of a rolled film, such as a metal foil.

[0087] In some cases, as shown schematically in FIG. 9A, the roll-to-roll process may be performed within a particular step, and an apparatus 901 for such a step includes, for example, a loading tool 905 for holding a roll of the film 906 to be processed, and a take-up tool 907 for rolling up the processed film 908 after the step is completed, along with the processing hardware 903 necessary for depositing, forming, or processing the layer. To perform the next step, the processed roll may be transferred to a processing apparatus 911 having its own processing hardware 913, loading tool 915, and take-up tool 917. During transfer, the roll may be maintained in a controlled environment, such as low oxygen or low moisture, depending on the step.

[0088] In some cases, the roll-to-roll process can include directly transferring the film processed in one step to the next step or apparatus, as schematically shown in FIG. 9B. Processing apparatus 921 is similar to apparatus 901 but does not include a take-up tool. Apparatus 921 includes a loading tool 925 for holding a roll of film 926 to be processed and appropriate processing hardware 923 for depositing, forming, or processing layers, for example. The processed film 928 from the first step moves to processing apparatus 931 to receive another processing step. Apparatus 931 includes appropriate processing hardware 933 for depositing, forming, or processing layers, for example, and a take-up tool 937 for rolling up the processed film 938 after the next step is completed. Although not shown, the processed film 938 may instead move to yet another processing apparatus without being rolled up. Also, although depicted as separate units, in some embodiments, apparatus 921 and apparatus 931 may share a common chamber. In some embodiments, a transfer chamber or zone may be provided between apparatus 921 and 931 that is designed to avoid one process contaminating another or to function as a film transport speed buffer if one process requires less time than another process.

[0089] Depending on the compatibility of one apparatus interfacing with others, various combinations of the above-described embodiments can be used together. The shaping apparatus may further include a slit station.

[0090] Battery characteristics The foregoing description relates primarily to the anode (negative electrode) of a lithium-ion battery (LIB). An LIB typically includes a cathode (positive electrode), an electrolyte, and a separator (when a solid electrolyte is not used). As is well known, a battery can be formed as a multilayer stack of an anode and a cathode using an intervening separator. Alternatively, a single anode / cathode stack can be formed into a so-called jelly roll. Such a structure is provided within a suitable housing having the desired electrical contacts.

[0091] In some embodiments, the battery may be configured with a containment mechanism to limit battery swelling, as described, for example, in U.S. Patent Application Publication Nos. 2018 / 0145367 and 2018 / 0166735, the entire contents of which are incorporated herein by reference for all purposes. In some embodiments, physical pressure is applied between the anode and the cathode, using, for example, a tensioned spring or clip, a compressible film, and the like. Containment, pressure, or both containment and pressure can help ensure that the anode remains in active contact with the current collector during formation and cycling, which can cause expansion and contraction of the continuous porous lithium storage layer. In some embodiments, a jelly roll battery design using a metal or other rigid cylindrical housing can provide effective containment, pressure, or both containment and pressure.

[0092] Figure 10 is a schematic cross-sectional view of a battery according to some embodiments of the present disclosure. Battery 790 includes a top plate 760, a bottom plate 762, an anode side plate 764, and a cathode side plate 766, which form part of a housing for a stack of anode 700, cathode 740, and intervening separator 730. The anode is attached to an anode bus 720 connected to an anode lead 722 extending through the anode side plate 764. The cathode is attached to a cathode bus 750 connected to a cathode lead 752 extending through the cathode side plate 766. Battery 790 further includes an electrolyte 780 that fills the space and saturates the separator 730. Upper compression member 770 and lower compression member 772 apply physical pressure (arrows) between the anode and the cathode. The compression member may be, for example, a compressible film made of a porous polymer or silicone. Alternatively, the compression member may include an array of compressible mechanisms made of, for example, a porous polymer or silicone. Alternatively, the compression member may include a spring or an array of springs. Alternatively, the compression member may correspond to two sides of a compression clip or clamp. In some embodiments, the separator can act as a compressible film. In some embodiments, the upper plate and the bottom plate may be made of and / or structured with materials that resist deformation and thereby confine the expansion of the battery.

[0093] Cathode Cathode (negative electrode) materials include lithium metal oxides or compounds (e.g., LiCoO2, LiFePO4, LiMnO2, LiNiO2, LiMn2O4, LiCoPO4, LiNi x Co y Mn z O2, LiNi X Co Y Al ZO2, LiFe2(SO4)3 or Li2FeSiO4), carbon fluoride, metal fluorides such as iron fluoride (FeF3), metal oxides, sulfur, selenium, sulfur-selenium and combinations thereof are included, but not limited thereto. The cathode active material is typically provided on or in electrical communication with a conductive cathode current collector.

[0094] In some embodiments, the prelithiated anodes of the present disclosure are used with cathodes that include sulfur, selenium, or both sulfur and selenium (collectively referred to herein as "chalcogen cathodes"). In some embodiments, the prelithiated anodes of the present disclosure can be paired with a chalcogen cathode having an active material layer, the active material layer comprising a carbon material and a selected compound selected from the group consisting of Se, Se y S x Te y S x Te z Se y S x S, and combinations thereof, where x, y, and z are any values from 0 to 1, the sum of y and x is 1, z, the sum of y and x is 1, and the compound is impregnated in the carbon material, as described, for example, in U.S. Patent Application Publication No. 2019 / 0097275, which is incorporated herein by reference for all purposes. The compound may be present in an amount of 9 to 90% by weight based on the total weight of the active material layer. In some embodiments, the chalcogen cathode active material layer further includes conductive carbon nanotubes to improve overall conductivity and physical durability and may allow for faster charging and discharging. The presence of carbon nanotubes may further allow for a thicker coating having greater flexibility, thereby allowing for a higher capacity.

[0095] Chalcogen cathodes are generally paired with lithium metal anodes. However, lithium metal anodes are difficult to handle, prone to degradation, and can further enable the formation of dangerous dendritic lithium that can lead to catastrophic short circuits. In some embodiments, the prelithiated anodes of the present disclosure can achieve an energy storage capacity equivalent to that of pure lithium anodes, but are much easier to handle and less likely to form dendritic lithium, making them more compatible with chalcogen cathodes.

[0096] Current separator The current separator allows ions to flow between the anode and the cathode while preventing direct electrical contact. Such a separator is typically a porous sheet. Non-aqueous lithium ion separators are typically single or multilayer polymer sheets made of polyolefins, especially for small batteries. Most commonly, these are based on polyethylene or polypropylene, but polyethylene terephthalate (PET) and polyvinylidene fluoride (PVDF) can also be used. For example, the separator can have a porosity greater than 30%, a low ionic resistivity, a thickness of about 10 to 50 μm, and a high bulk puncture strength. Alternatively, the separator may include, for example, a glass material, a ceramic material, a ceramic material embedded in a polymer, a polymer coated with a ceramic, or some other composite or multilayer structure to provide higher mechanical and thermal stability. As described above, the separator can include a lithiated material such as lithium metal, a reducing lithium compound, or an SLMP material coated on at least the side facing the anode.

[0097] Electrolyte The electrolyte in a lithium-ion battery can be liquid, solid, or gel. A typical liquid electrolyte contains one or more solvents and one or more salts, at least one of which contains lithium. During the first few charge cycles (sometimes called formation cycles), the organic solvent and / or electrolyte can partially decompose on the surface of the negative electrode to form a SEI (solid-electrolyte-interface) layer. The SEI is generally electrically insulating but ionically conductive, thereby allowing lithium ions to pass through. The SEI can reduce the decomposition of the electrolyte in subsequent charge cycles.

[0098] Some non-limiting examples of non-aqueous solvents suitable for some lithium-ion batteries include the following cyclic carbonates (e.g., ethylene carbonate (EC), fluoroethylene carbonate (FEC), propylene carbonate (PC), butylene carbonate (BC), and vinylene carbonate (VEC)), vinylene carbonate (VC), lactones (e.g., γ-butyrolactone (GBL), γ-valerolactone (GVL) and α-angelica lactone (AGL)), linear carbonates (e.g., dimethyl carbonate (DMC), methyl ethyl carbonate (MEC, generally abbreviated as EMC), diethyl carbonate (DEC), methyl propyl carbonate (MPC), dipropyl carbonate (DPC), methyl butyl carbonate (NBC) and dibutyl carbonate (DBC)), ethers (e.g., tetrahydrofuran (THF), 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane (DME), 1,2-diethoxyethane, and 1,2-dibutoxyethane), nitriles (e.g., acetonitrile and adiponitrile) linear esters (e.g., methyl propionate, methyl pivalate, butyl pivalate and octyl pivalate), amides (e.g., dimethylformamide), organic phosphates (e.g., trimethyl phosphate and trioctyl phosphate), organic compounds containing an S=O group (e.g., dimethyl sulfone and divinyl sulfone), and combinations thereof.

[0099] Non-aqueous liquid solvents can be used in combination. These combinations include cyclic carbonate - linear carbonate, cyclic carbonate - lactone, cyclic carbonate - lactone - linear carbonate, cyclic carbonate - linear carbonate - lactone, cyclic carbonate - linear carbonate - ether, and cyclic carbonate - linear carbonate - linear ester combinations. In some embodiments, a cyclic carbonate may be combined with a linear ester. Also, a cyclic carbonate may be combined with a lactone and a linear ester. In some embodiments, the weight ratio or volume ratio of the cyclic carbonate to the linear ester is in the range of 1:9 to 10:1, or 2:8 to 7:3.

[0100] Salts for the liquid electrolyte can include one or more of the following non-limiting examples: LiPF6, LiBF4, LiClO4, LiAsF6, LiN(CF3SO2)2, LiN(C2F5SO2)2, LiCF3SO3, LiC(CF3SO2)3, LiPF4(CF3)2, LiPF3(C2F5)3, LiPF3(CF3)3, LiPF3(iso-C3F7)3, LiPF5(iso-C3F7), lithium salts having a cyclic alkyl group (e.g., (CF2)2(SO2) 2x Li and (CF2)3(SO2) 2x Li), and combinations thereof. Common combinations include LiPF6 and LiBF4; LiPF6 and LiN(CF3SO2)2; LiBF4 and LiN(CF3SO2)2.

[0101] In some embodiments, the total concentration of the salt in the liquid non-aqueous solvent (or solvent combination) is at least 0.3 M, or at least 0.7 M. The upper concentration limit can be determined by the solubility limit and the operating temperature range. In some embodiments, the concentration of the salt is about 2.5 M or less, or about 1.5 M or less.

[0102] In some embodiments, the battery electrolyte includes a non-aqueous ionic liquid and a lithium salt.

[0103] Since the solid electrolyte functions as the separator itself, it may be used without using a separator. It is electrically insulating, ion-conductive, and electrochemically stable. In a solid electrolyte configuration, a lithium-containing salt that may be the same as in the liquid electrolyte battery described above is used, but instead of being dissolved in an organic solvent, it is retained in a solid polymer composite. Examples of solid polymer electrolytes are ion-conductive polymers prepared from monomers containing atoms with lone pairs of electrons that are available for lithium ions of electrolyte salts that adhere and move during conduction, such as copolymers of polyvinylidene fluoride (PVDF) or chloride or their derivatives, poly(chlorotrifluoroethylene), poly(ethylene-chlorotrifluoroethylene), or poly(fluorinated ethylene propylene), polyethylene oxide (PEO) and oxyethylene-bonded PEO, PEO-PPO-PEO crosslinked with trifunctional urethane, poly(bis(methoxy-ethoxy-ethoxide))-phosphazene (MEEP), triol-type PEO crosslinked with bifunctional urethane, poly((oligo)oxyethylene) methacrylate-co-alkali metal methacrylate, polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polymethylacrylonitrile (PMAN), polysiloxane and their copolymers and derivatives, acrylate-based polymers, other similar solvent-free polymers, combinations of the aforementioned polymers condensed or crosslinked to form different polymers, and physical mixtures of any of the aforementioned polymers may be used. Other low-conductive polymers that may be used in combination with the above polymers to improve the strength of thin laminates include polyester (PET), polypropylene (PP), polyethylene naphthalate (PEN), polyvinylidene fluoride (PVDF), polycarbonate (PC), polyphenylene sulfide (PPS), and polytetrafluoroethylene (PTFE). Such solid polymer electrolytes may further contain a small amount of the organic solvents listed above. The polymer electrolyte may be an ionic liquid polymer.Such polymer-based electrolytes can be coated using any number of conventional methods such as curtain coating, slot coating, spin coating, inkjet coating, spray coating or other suitable methods.

[0104] Additives may be included in the electrolyte to serve various functions. For example, additives such as polymerizable compounds having unsaturated double bonds may be added to stabilize or modify the SEI. Certain amines or borate compounds can act as cathode protectants. Lewis acids can be added to stabilize fluorine-containing anions such as PF6 - Examples of safety protectants include those for protecting against overcharging, such as anisole, or flame retardants, such as alkyl phosphates.

[0105] In some embodiments, the solid electrolyte may be by vapor deposition, solution coating, melt coating, or combinations thereof. Whether deposited or coated from a solution or a melt, embodiments of the present disclosure are advantageous over nanostructured devices. In the case of vapor-deposited solid electrolytes, the anodes of the present disclosure do not have the problem of physical "shadowing" as nanostructured or microstructured devices do. Shadowing results in non-uniform deposition of the electrolyte. The anodes disclosed herein generally do not have high aspect ratio structures as described above, and as a result, there is no or a reduced shadowing effect. Vapor-phase deposited solid electrolytes can be deposited uniformly and rapidly on the anodes of the present disclosure without relying on low-speed atomic layer or other conformal coating methods. In the case of solution or melt-deposited solid electrolytes, the anodes of the present disclosure can be more robust against the stresses and shear forces caused by the coating operation. High aspect ratio nanostructures or microstructures are susceptible to damage by such forces.

[0106] In some embodiments, the original non-cycled anode can undergo structural or chemical changes during electrochemical charge / discharge, for example, from normal battery use or from a previous "electrochemical formation step". As is known in the art, the electrochemical formation step is generally used to form an initial SEI layer and includes relatively mild conditions of low current and limited voltage. A modified anode prepared in part from such an electrochemical charge / discharge cycle can still have excellent performance characteristics despite such structural and / or chemical changes compared to the original non-cycled anode.

Example

[0107] For Anodes 1 - 10, a current collector having a metal oxide layer (nickel oxide) on a conductive metal layer (nickel) was prepared by placing a nickel foil in a muffle furnace (heated air), holding the foil at 700 °C for 30 minutes, and then cooling to room temperature. The thickness of the metal oxide was about 0.7 to 1.2 microns.

[0108] Anode 1 (without auxiliary layer) The current collector was placed in a high density plasma chemical vapor deposition tool (HDPECVD) using silane gas as a source of silicon and argon carrier gas. Amorphous silicon was deposited on one side of the nickel foil with a total fill of about 0.8 mg / cm 2 to form a continuous porous lithium storage layer having a thickness of about 4 μm.

[0109] Anode 2 (Si3N4 auxiliary layer) Anode 2 was prepared in the same manner as Anode 1, but before removing from the HDPECVD tool, a nitrogen source was added to the silane / Ar gas mixture and 30 nm of substantially stoichiometric silicon nitride was deposited to form an auxiliary layer on the continuous porous lithium storage layer (a-Si).

[0110] Anode 3 (Si3N4 / TiO2 auxiliary layer) The anode 3 was prepared in the same manner as anode 1, but before removing it from the HDPECVD tool, a nitrogen source was added to the silane / Ar gas mixture to deposit 15 nm of substantially stoichiometric silicon nitride to form a first auxiliary layer on the continuous porous lithium storage layer (a-Si). The anode was transferred to an ALD tool and 6 nm of titanium dioxide was deposited on the first auxiliary layer to form a second auxiliary layer.

[0111] Half cell Half cells were constructed using a 1.27 cm diameter punch of each anode. Lithium metal functioned as the counter electrode separated from the test anode using a Celgard™ separator. The electrolyte contained the following: a) 88 wt.% 1.0 M LiPF6 in 3:7 EC:EMC (weight ratio); b) 10 wt.% FEC; and c) 2 wt.% VC. The anodes first underwent an electrochemical formation step. As is known in the art, the electrochemical formation step is used to form the initial SEI layer. Relatively mild conditions of low current and / or limited voltage can be used so that the anode is not unduly stressed. For example, the electrochemical formation can include several cycles at a low C-rate in the range of C / 20 to C / 5. Silicon has a theoretical charge capacity of about 3600 mAh / g when used in a lithium-ion battery, but it has been found that the cycle life is significantly improved when only a portion of the total capacity is used. Unless otherwise specified, the performance cycles were set to use about one-third of the total capacity, i.e., about 1200 mAh / g (“capacity rating”). Unless otherwise noted, the performance cycle protocol generally included 3C charging and C / 3 discharging up to a state of charge of approximately 20%. A 10-minute rest was provided between charge-discharge cycles.

[0112] A plot of discharge capacity as a function of cycle number is shown in Figure 11. All anodes have good cycle life even under these rapid charging conditions (3C). Anode 1 lasted about 300 cycles before showing signs of decay. By adding an auxiliary layer, the cycle life of Anode 2 was extended to about 400 cycles before signs of decay (an increase of about 30%), with only a slight loss in overall capacity at startup (about 10%). Furthermore, when it occurred, the decay rate was substantially lower than that of Anode 1. By adding the first and second auxiliary layers, the cycle life of Anode 3 was extended to almost 500 cycles before signs of decay (an increase of about 60% relative to Anode 1), and the loss of total capacity was even smaller (about 5%). Furthermore, when it occurred, the decay rate was substantially lower than that of Anode 1. The cycle life for cycles up to 80% of the initial charge capacity of Anodes 1 - 3 is shown in Table 1 below along with other anodes.

[0113] Additional anodes were prepared and tested in half - cells in the same manner as above.

[0114] Anode 4 (without auxiliary layer) Anode 4 was substantially the same as Anode 1. The continuous porous lithium storage layer contained amorphous silicon with a thickness of about 4 μm and a density in the range of about 1.8 to 2.0 g / cm 3 ³.

[0115] Anode 5 (Si₃N₄ / Al₂O₃ auxiliary layer) Anode 5 was substantially the same as anode 4, but before removal from the HDPECVD tool, a nitrogen source was added to the silane / Ar gas mixture to deposit substantially stoichiometric silicon nitride of 15 nm to form a first auxiliary layer on the continuous porous lithium storage layer (a-Si). The anode was transferred to an ALD tool and 6 nm of aluminum oxide was deposited on the silicon nitride. In subsequent tests below, this cell could not withstand the electrochemical formation step. Thus, in some embodiments, when using a first auxiliary layer of silicon nitride, it may be preferable not to use aluminum oxide as the second auxiliary layer. Surprisingly, aluminum oxide does not function well, and in this case, titanium dioxide seems to be a better second auxiliary layer.

[0116] Anode 6 (TiO2 / Al2O3 auxiliary layer) Anode 6 was similar to anode 4 except that multiple auxiliary layers were deposited by ALD. The first auxiliary layer contained 10 nm of titanium dioxide and the second auxiliary layer contained 4 nm of aluminum oxide. As shown in Table 1 below, the cycle life was substantially improved compared to anode 4 without auxiliary layers.

[0117] Anode 7 (Al2O3 / TiO2 auxiliary layer) Anode 6 was similar to anode 4 except that multiple auxiliary layers were deposited by ALD. The first auxiliary layer contained 10 nm of aluminum oxide and the second auxiliary layer contained 4 nm of titanium dioxide. As shown in Table 1, the cycle life was acceptable but not as good as anode 4 without auxiliary layers and much lower than anode 5 with the reverse auxiliary layer structure. There may be other reasons for using the structure of anode 7, but in some embodiments, when using multiple metal oxide auxiliary layers, it may be preferable not to use aluminum oxide as the first auxiliary layer. Surprisingly, aluminum oxide does not function well, and in this case, titanium dioxide seems to be a better first auxiliary layer.

[0118] Anode 8 (60 nm SiO2 auxiliary layer) Anode 8 was the same as anode 4, but before removing it from the HDPECVD tool, oxygen gas was added to the silane / Ar gas mixture to deposit substantially stoichiometric silicon dioxide of 60 nm to form an auxiliary layer on the continuous porous lithium storage layer (a-Si). As shown in Table 1, silicon dioxide causes a decrease in the areal charge capacity but can significantly improve the cycle life. By increasing the capacity rating to 1600 mAh / g, the areal charge capacity can be restored to the same level as that of anode 4, and the cycle life is still extended.

[0119] Anode 9 (120-nm SiO2 auxiliary layer) Anode 9 was the same as anode 8 except that substantially stoichiometric silicon dioxide of 120 nm was deposited. As shown in Table 1, silicon dioxide causes a decrease in the areal charge capacity but can significantly improve the cycle life. By increasing the capacity rating to 1600 mAh / g, the areal charge capacity can be restored to the same level as that of anode 4, and the cycle life is still extended.

[0120] Anode 10 (SiOx lithium storage sublayer) Anode 10 was the same as anode 4, but before removing it from the HDPECVD tool, oxygen gas was added to the gas mixture to deposit approximately 250-nm near-stoichiometric silicon oxide to form a lithium storage sublayer on amorphous silicon. The stoichiometry of the SiOx sublayer is not definitely known, but the oxygen gas flow rate was set to only about 12% of the ratio used to produce substantially stoichiometric silicon dioxide. The overall thickness and density of the combined sublayer of a-Si and SiOx were approximately 4.5 μm and 2.1 g / cm 3 respectively, and as shown in Table 1, anode 10 has an improved cycle life compared to anode 4 without the SiOx sublayer. Note that the cycle life in Table 1 is the average value of two times.

[0121]

Table 1

[0122] Anode 11 Different current collectors were prepared for Anode 11. Specifically, a 50-nm TiO2 (metal oxide) layer was deposited on a commercially available conductive copper foil by ALD. Using a tool of Oxford Plasmalabs System 100 PECVD, it was operated at about 300 °C with an RF power of about 225 W for 50 minutes to deposit silicon on the TiO2. The deposition gas was a mixture of silane and argon having a gas flow rate ratio of about 1 to 11 respectively together with a boron-containing dopant gas. Hydrogen gas was not used. An adhesive boron-doped amorphous silicon film with a thickness of about 14 μm having a density of about 1.7 g / cm 3 was deposited.

[0123] Anodes 11A to 11E After silicon deposition, samples of Anode 11 were transferred to a tube furnace under argon and heat-treated at various times and temperatures to form Anodes 11A to 11E shown in Table 2 below.

[0124] Anodes 11 and 11A to 11E were tested in half-cells as described above, except that the punch size of the cell became smaller due to a larger charge capacity. At the end of the formation cycle, the full charge capacity was measured electrochemically together with the final formation cycle current efficiency. These data are also shown in Table 2.

[0125]

Table 2

[0126] All anodes have a very high areal charge capacity, but the data in Table 2 indicate that anode heat treatment appears to unlock some additional charge capacity when processed at 475 °C or 575 °C (about 8% to 15% more than anode 11 without heat treatment). In lithium-ion batteries, such improvements are commercially important and can be used to increase the charge capacity of the cell, to reduce the weight and / or volume of the cell while maintaining the charge capacity of the cell, to extend the cycle life by reducing the rated capacity while maintaining the total charge capacity of the cell, or for some combination thereof.

[0127] The performance of anodes 11 and 11A - 11E under cycling conditions was tested at C / 3, 1C, and 3.2C charge (all C / 3 discharge) as described above. The anodes had a capacity rating of approximately 1100 mAh / g. For the C / 3 and 1C charge schedules, the cells were cycled to an initial areal charge capacity target of 2.0 mAh / cm 2 The high charge rate 3.2C test was completed at a charge current of 3.2C with a total time limit of 15 minutes. This is a common rapid charge test performed in the industry (see “Battery Test Manual for Electric Vehicles’’, Jon P. Christophersen, June 2015, INL / EXT-15-34184 Revision 3, page 5). If the cell completes all of the constant current charge, the cell reaches 3.2 × 0.25 or 80% of its rated capacity, which in this case is 1.6 mAh / cm 2 Cells that reach the charge voltage limit before 15 minutes charge at both constant current and constant potential. The latter charging portion results in cells that do not reach 80% of their rated capacity. None of these anodes have completed cycling or reached 80% of their initial charge capacity (except for anode 11A at about 400 cycles), but the plots are shown in Figures 12 (C / 3 charge), 13 (1C), and 14 (3.2C). The test cells were not all started at the same time, so they are at various stages of cycling.

[0128] The inspection of FIG. 12 shows that there is still no substantial difference between the anodes during C / 3 charging.

[0129] FIG. 13 reveals the performance degradation of anode 11 in cycles 25 - 60 relative to all other anodes. Anode 11 also appears to exhibit some cycle fade starting at approximately cycle 225. Two heat - treated anodes that reached at least 230 cycles (276 cycles for 11A and 237 cycles for 11B) in this write - up did not exhibit such fade. Thus, at charging rates faster than C / 3, the heat - treated anodes appear to show an improvement in cycle life.

[0130] FIG. 14 shows that non - heat - treated anode 11 never reaches a state of charge of 80% at 3.2C, i.e., not 1.6 mAh / cm 2 but rather that anode 11 only reaches approximately 1.25 mAh / cm 2 Due to higher resistance characteristics, the constant - current charge for 15 minutes is not completed. In contrast, the heat - treated anodes reach a state of charge of 80% for at least several cycles. The fact that their capacities are close to the limiting capacity of 1.6 mAh / cm 2 indicates that most of their charging remains at constant current. The combination of a very fast 3.2C charge combined with a high - capacity silicon anode (for anodes 1 - 10) is hypothesized to have introduced some resistance to the flow of electrons or lithium diffusion. However, note that all of the heat - treated samples, anodes 11A - 11E, were much closer to the target charge capacity than non - heat - treated anode 11. Thus, it appears that anode heat treatment can be used to improve the rapid - charging characteristics of anodes.

[0131] Despite the support of the industry for micro- or nanostructured silicon or other lithium storage materials, it has been found in the present disclosure that an anode can be formed very effectively without such features. Although the present anode has been described with reference to a battery, in some embodiments, the present anode can be used in a hybrid capacitor device. Compared with equivalent micro- or nanostructured anodes, the anodes of the present disclosure can have at least one or more of the following unexpected advantages, namely, equivalent or improved stability at a positive charging rate of ≥ 1C, higher overall charge capacity, higher weight charge capacity, higher volume charge capacity, improved physical durability, simplified manufacturing process, and / or more reproducible manufacturing process.

[0132] Although the present anode has been described with reference to a battery, in some embodiments, the present anode can be used in a hybrid lithium-ion capacitor device. Some non-limiting representative embodiments are listed below. 1. An anode for an energy storage device, comprising a current collector including a metal oxide layer, and a continuous porous lithium storage layer covering the metal oxide layer. 2. The anode of embodiment 1, further comprising a first auxiliary layer covering the continuous porous lithium storage layer, the first auxiliary layer including silicon nitride, silicon dioxide, silicon oxynitride, or a first metal compound. 3. The anode according to embodiment 2, wherein the first auxiliary layer includes silicon nitride having a thickness in the range of about 2 nm to about 50 nm. 4. The anode according to embodiment 2, wherein the first auxiliary layer includes silicon dioxide and has a thickness in the range of about 10 nm to about 150 nm. 5. The anode according to embodiment 2, wherein the first auxiliary layer includes a first metal compound selected from the group consisting of metal oxides, metal nitrides, and metal oxynitrides and has a thickness in the range of about 2 nm to about 50 nm. 6. The anode according to embodiment 5, wherein the first metal compound is a transition metal oxide. 7. The anode according to embodiment 5, wherein the first metal compound is titanium dioxide. 8. The anode according to any one of embodiments 2 to 7, further comprising a second auxiliary layer having a composition different from that of the first auxiliary layer composition and containing silicon dioxide, silicon nitride, silicon oxynitride, or a second metal compound. 9. The anode according to embodiment 8, wherein the second metal compound contains a metal oxide, a metal nitride, or a metal oxynitride, and the second auxiliary layer has a thickness in the range of about 2 nm to about 50 nm. 10. The anode according to embodiment 9, wherein the first auxiliary layer contains silicon nitride and the second auxiliary layer contains titanium dioxide. 11. (i) The first auxiliary contains substantially stoichiometric silicon nitride and has a thickness in the range of about 2 nm to about 50 nm, and (ii) the second auxiliary layer contains titanium dioxide and has a thickness in the range of about 2 nm to about 20 nm. The anode according to embodiment 10. 12. The anode according to embodiment 8, wherein the first auxiliary layer contains titanium dioxide and has a thickness of about 2 nm to about 20 nm. 13. The anode according to embodiment 12, wherein the second auxiliary layer contains aluminum oxide having a thickness of about 2 nm to about 20 nm. 14. (i) The first auxiliary layer does not contain aluminum oxide, (ii) when the first auxiliary layer contains substantially stoichiometric silicon nitride, the second auxiliary layer does not contain aluminum oxide. The anode according to embodiment 8. 15. The anode according to embodiment 8, wherein the second metal compound is a lithium-containing material. 16. The anode according to embodiment 15, wherein the lithium-containing material contains lithium phosphate nitride, lithium phosphate, lithium aluminum oxide, or lithium lanthanum titanate. 17. The anode according to embodiment 8, wherein the second auxiliary layer contains a metal cone. 18. The anode according to any one of embodiments 15 to 17, wherein the second auxiliary layer has a thickness in the range of about 5 nm to about 150 nm. 19. Further comprising one or more additional auxiliary layers covering the first and second auxiliary layers, wherein at least one of the additional layers comprises a metal oxide, a metal nitride, a metal oxynitride, a lithium-containing material, or a metal cone, the anode according to any one of Embodiments 8-18. 20. The continuous porous lithium storage layer includes a first lithium storage sublayer covering the metal oxide layer and a second lithium storage sublayer covering the first lithium storage sublayer, and the first lithium storage sublayer has a composition different from that of the second lithium storage sublayer, the anode according to any one of Embodiments 1-19. 21. The anode according to Embodiment 20, wherein each lithium storage sublayer has a composition containing silicon, germanium, or a combination thereof. 22. The anode according to Embodiment 20 or 21, wherein the first or second lithium storage sublayer contains silicon and oxygen, and the ratio of oxygen to silicon is in the range of 0.02 to 0.95. 23. i) The second lithium storage sublayer contains silicon and oxygen, and the ratio of oxygen to silicon is in the range of 0.02 to 0.95; ii) The first lithium storage sublayer contains a higher atomic percentage of silicon and a lower atomic percentage of oxygen than the second lithium storage sublayer; iii) The thickness of the second lithium storage sublayer is thinner than the thickness of the first lithium storage sublayer, the anode according to Embodiment 20 or 21. 24. The anode according to any one of Embodiments 20-22, wherein the first or second lithium storage sublayer contains silicon and nitrogen, and the ratio of nitrogen to silicon is in the range of 0.02 to 0.95. 25. The anode according to any one of Embodiments 20-22, wherein the first or second lithium storage sublayer contains silicon, oxygen and nitrogen, and the ratio of all oxygen and nitrogen atoms to silicon is in the range of 0.02 to 0.95. 26. The continuous porous lithium storage layer is i) silicon and oxygen, wherein the ratio of oxygen atoms to silicon atoms is in the range of 0.02 to 0.95, ii) silicon and nitrogen, wherein the ratio of nitrogen atoms to silicon atoms is in the range of 0.02 to 0.95, or iii) Silicon, oxygen, and nitrogen in which the total ratio of oxygen atoms and nitrogen atoms to silicon atoms is in the range of 0.02 to 0.95 The anode according to any one of Embodiments 1 to 19, comprising the same. 27. The anode according to any one of Embodiments 1 to 26, wherein the metal oxide layer contains an oxide of an alkali metal or an alkaline earth metal. 28. The anode according to Embodiment 27, wherein the metal oxide layer contains an oxide of lithium. 29. The anode according to any one of Embodiments 1 to 28, wherein the metal oxide layer contains an oxide of a transition metal. 30. The anode according to Embodiment 29, wherein the metal oxide layer contains an oxide of nickel or an oxide of titanium. 31. The anode according to any one of Embodiments 1 to 30, wherein the metal oxide layer further contains a metal hydroxide. 32. The anode according to Embodiment 31, wherein the metal oxide layer has a ratio of oxygen atoms in the form of hydroxide to oxide of less than 0.25. 33. The anode according to any one of Embodiments 1 to 32, wherein the metal oxide layer has an average thickness in the range of about 0.010 μm to about 1.0 μm. 34. The anode according to any one of Embodiments 1 to 33, wherein the continuous porous lithium storage layer has a total content of at least 40 atomic% of silicon, germanium, or a combination thereof. 35. The continuous porous lithium storage layer has a density in the range of about 1.1 g / cm 3 ~2.2 g / cm 3 The anode according to any one of Embodiments 1 to 34, comprising at least 85 atomic% amorphous silicon. 36. The anode according to any one of Embodiments 1 to 35, wherein the continuous porous lithium storage layer has a thickness of at least 3 μm. 37. The anode according to any one of Embodiments 1 to 37, wherein the continuous porous lithium storage layer has a thickness in the range of about 7 μm to about 30 μm. 38. The anode according to any one of Embodiments 1 to 37, wherein the continuous porous lithium storage layer substantially does not contain a nanostructure. 39. The anode according to any one of Embodiments 1 to 38, wherein the continuous porous lithium storage layer contains a carbon-based binder of less than 1% by weight. 40. The anode according to any one of Embodiments 1 to 39, wherein the anode has a total reflectance of at least 10% measured at 550 nm on the upper surface of the anode. 41. The anode according to any one of Embodiments 1 to 40, wherein the continuous porous lithium storage layer contains a metal derived from the metal oxide layer in the range of about 0.05% to about 5% atomic%. 42. The anode according to any one of Embodiments 1 to 41, wherein the current collector further includes a conductive layer, and the metal oxide layer is interposed between the conductive layer and the continuous porous lithium storage layer. 43. The anode according to Embodiment 42, wherein the conductive layer includes stainless steel, titanium, nickel, copper, conductive carbon, or a combination thereof. 44. The anode according to Embodiment 43, wherein the continuous porous lithium storage layer contains a metal from the conductive layer in the range of about 0.05% to about 5% atomic%. 45. A battery comprising the anode according to any one of Embodiments 1 to 44 and a cathode. 46. The battery according to Embodiment 45, further comprising one or more compression members configured to apply pressure to the anode in a direction toward the cathode, or configured to apply pressure to the cathode in a direction toward the anode, or both. 47. The lithium-ion battery according to Embodiment 45 or 46, wherein the anode is prelithiated and the cathode contains sulfur, selenium, or both sulfur and selenium. 48. The lithium-ion battery according to Embodiment 47, wherein the cathode further includes a first carbon material. 49. The lithium-ion battery according to Embodiment 48, wherein the cathode further includes carbon nanotubes. 50. A method of fabricating an anode for use in an energy storage device, comprising: providing a current collector including a conductive layer and a metal oxide layer covering the conductive layer, wherein the metal oxide layer has an average thickness of at least 0.01 μm; and Depositing a continuous porous lithium storage layer on a metal oxide layer by a CVD process A method comprising: 51. The step of providing a current collector comprises: i) depositing a metal oxide precursor composition on a conductive layer to form a deposited metal oxide precursor composition, and ii) forming a metal oxide layer using the deposited metal oxide precursor composition The method according to embodiment 50, comprising: 52. The method according to embodiment 51, wherein the metal oxide precursor composition comprises a sol-gel, a metal carbonate, a metal acetate, a metal organic acetate, a metal hydroxide, a metal oxide dispersion, or a combination thereof. 53. The method according to embodiment 52, wherein the step of forming the metal oxide layer comprises heat-treating the deposited metal oxide precursor composition. 54. The method according to embodiment 53, wherein the step of heat-treating comprises exposing the deposited metal oxide precursor composition to a temperature in the range of 50°C to 250°C for a time in the range of optionally 0.1 to 120 minutes. 55. The method according to any one of embodiments 51 to 54, wherein the step of forming the metal oxide layer comprises exposing the deposited metal oxide precursor composition to a pressure in the range of 0.1 to 100 torr for a time in the range of optionally 0.1 to 120 minutes. 56. The method according to embodiment 51, wherein the metal oxide precursor composition comprises metal-containing particles. 57. The method according to embodiment 56, wherein the step of forming the metal oxide layer comprises oxidizing the metal-containing particles. 58. The method according to embodiment 57, wherein oxidizing comprises exposing the metal particles to an oxygen-containing gas or a solution containing a chemical oxidizing agent. 59. The method according to any one of embodiments 50 to 58, further comprising depositing a lithium metal on the metal oxide layer before depositing the continuous porous lithium storage layer. 60. The method according to embodiment 59, wherein the lithium metal is deposited by evaporation, electron beam or sputtering. 61. The method according to embodiment 59 or 60, wherein the ratio of deposited lithium metal atoms to oxygen atoms in the metal oxide layer is within the range of 0.05 to 1.0. 62. The method according to any one of embodiments 59 to 61, wherein the amount of deposited lithium metal is within the range of 2% to 50% of the maximum lithium surface capacity of the continuous porous lithium storage layer. 63. The method according to any one of embodiments 1 to 62, further comprising the step of forming a lithiated storage layer by incorporating lithium into the continuous porous lithium storage layer prior to the first electrochemical cycle when the anode is assembled into the energy storage device. 64. The method according to embodiment 63, wherein lithium is incorporated before the assembly of the energy storage device. 65. The method according to embodiment 63 or 64, wherein the step of incorporating lithium comprises depositing a lithiated material on the continuous porous lithium storage layer. 66. The method according to embodiment 65, wherein the lithiated material comprises a reducing lithium compound, lithium metal, or stabilized lithium metal powder. 67. The method according to embodiment 65 or 66, further comprising the step of applying heat or pressure to the anode during or after the deposition of the lithiated material. 68. The method according to embodiment 63 or 64, wherein the step of incorporating lithium comprises contacting the lithiated material provided as a coating on a lithium transfer substrate with the anode. 69. The method according to embodiment 68, wherein the lithiated material comprises a reducing lithium compound, lithium metal, or stabilized lithium metal powder. 70. The method according to embodiment 68 or 69, further comprising the step of applying heat or pressure to the anode during or after the contact. 71. The method according to any one of embodiments 68 to 70, wherein the lithium transfer substrate functions as a current separator of the assembled battery. 72. The method according to embodiment 63 or 64, wherein the step of incorporating lithium comprises contacting the continuous porous lithium storage layer with a solution containing a reducing lithium organic compound. 73. The method according to embodiment 63 or 64, in which lithium is electrochemically incorporated. 74. The method according to any one of embodiments 63 to 73, further comprising the step of forming an auxiliary layer on the continuous porous lithium storage layer before forming the lithiated storage layer. 75. The method according to embodiment 74, wherein the auxiliary layer comprises silicon nitride, metal oxide, metal nitride, or metal oxynitride. 76. The method according to any one of embodiments 63 to 75, further comprising the step of heat-treating the continuous porous lithium storage layer during incorporation, after incorporation, or both during and after incorporation. 77. The step of forming the lithiated storage layer comprises (a) depositing a lithium metal layer on the continuous porous lithium storage layer, and (b) depositing a lithium ion conducting layer after depositing the lithium metal layer The method according to embodiment 64. 78. The method according to claim 77, further comprising the step of applying heat to the anode: i) between step (a) and step (b), ii) after step (b), or iii) both (i) and (ii). 79. The method according to embodiment 77 or 78, wherein the lithium ion conducting layer comprises at least one of a lithium-containing material, a metal oxide, or a metal cone. 80. The method according to any one of embodiments 77 to 79, wherein the lithium ion conducting layer comprises at least one of lithium phosphonitride (LIPON), lithium phosphate, lithium aluminum oxide, lithium lanthanum titanate, a cone, or zircon. 81. The method according to any one of embodiments 50 to 80, further comprising treating the anode with a reducing agent before battery assembly. 82. The method according to embodiment 81, wherein the reducing agent has an electrochemical potential sufficient to reduce at least a portion of the metal oxide layer. 83. The method according to embodiment 81 or 82, wherein the reducing agent comprises an inorganic hydride, a substituted or unsubstituted borohydride, an amine-borane, or an anionic organic aromatic compound. 84. The method according to any one of embodiments 81 to 83, wherein treating the anode with the reducing agent comprises treating the anode with a non-aqueous solvent containing the reducing agent. 85. The method according to any one of embodiments 50 to 84, further comprising a step of heat-treating the anode before battery assembly after depositing the continuous porous lithium storage layer. 86. The method according to embodiment 85, wherein the step of heat-treating comprises heating the anode to a temperature in the range of 50°C to 600°C for a time in the range of 0.1 minute to 120 minutes. 87. The method according to embodiment 85 or 86, wherein the step of heat-treating is performed in an environment having an oxygen and moisture pressure of less than 1 Torr each. 88. The method according to embodiment 85 or 86, wherein the step of heat-treating is performed in an environment having an oxygen and moisture pressure of less than 0.1 Torr each. 89. The method according to any one of embodiments 85 to 88, wherein the step of heat-treating comprises heating the anode to a temperature in the range of 350°C to 600°C for a time in the range of 0.1 minute to 30 minutes. 90. The method according to any one of embodiments 85 to 89, wherein the metal oxide layer comprises an oxide of nickel or an oxide of titanium. 91. The method according to any one of embodiments 85 to 89, wherein the conductive layer comprises copper and the metal oxide layer comprises an oxide of titanium having a thickness in the range of 0.01 μm to 0.20 μm. 92. The method according to any one of embodiments 85 to 91, wherein the step of heat-treating comprises moving the anode into an oven, exposing the anode to an IR radiation source, or contacting the anode with a heated surface. 93. The method according to any one of embodiments 85 to 92, wherein the conductivity of the continuous porous lithium storage layer is increased by the step of heat-treating. 94. The method according to any one of embodiments 85 to 93, wherein the step of heat-treating increases the adhesion of the continuous porous lithium storage layer to the current collector. 95. The method according to any one of embodiments 85 to 94, wherein the heat treatment step forms an anode in a lithium ion battery cell having a higher charge capacity than an equivalent anode not subjected to the heat treatment step. 96. The method according to any one of embodiments 85 to 95, wherein the heat treatment step forms an anode in a lithium ion battery cell that can be charged faster than an equivalent anode not subjected to the heat treatment step. 97. The method according to any one of embodiments 45 to 96, wherein the CVD process is a PECVD process. 98. The method according to embodiment 97, wherein the continuous porous lithium storage layer comprises a total content of at least 40 atomic% of silicon, germanium, or a combination thereof. 99. The continuous porous lithium storage layer has a density in the range of about 1.1 g / cm 3 ~2.2 g / cm 3 and comprises at least 85 atomic% amorphous silicon. The method according to embodiment 97 or 98. 100. The anode according to any one of embodiments 50 to 99, wherein the continuous porous lithium storage layer has a thickness of at least 3 μm. 101. The anode according to any one of embodiments 50 to 100, wherein the continuous porous lithium storage layer has a thickness in the range of about 7 μm to about 30 μm. 102. The method according to any one of embodiments 50 to 101, wherein the PECVD process includes using silane gas and optionally hydrogen gas, and the ratio of the flow of hydrogen gas to the flow of silane gas is within the range of 0 to 2. 103. The method according to any one of embodiments 50 to 102, wherein the PECVD process further includes using a doping gas to dope the continuous porous lithium storage layer, and the ratio of the flow of the doping gas to the flow of the silane gas is in the range of 0.001 to 0.05. 104. The method according to embodiment 103, wherein the doping gas is borane or phosphine. 105. The method according to any one of embodiments 97 to 104, wherein the PECVD process is an expanded thermal plasma PECVD process or a hollow cathode tube PECVD process. 106. The method according to any one of embodiments 97 to 105, wherein the PECVD process further includes heating the current collector to a temperature in the range of 200°C to 600°C during at least a part of the process. 107. After depositing at least 50% of the continuous porous lithium storage layer, further comprising the step of adding an oxygen source, a nitrogen source, or both to the silane gas to form a lithium storage sublayer or auxiliary layer containing silicon nitride, silicon oxide, or silicon oxynitride. The method according to any one of embodiments 97 to 106. 108. The method according to embodiment 107, wherein an auxiliary layer containing silicon dioxide having a thickness in the range of about 10 nm to about 150 nm is formed. 109. The method according to embodiment 107, wherein an auxiliary layer containing substantially stoichiometric silicon nitride having a thickness in the range of about 2 nm to about 50 nm is formed. 110. The method according to any one of embodiments 50 to 109, further comprising the step of depositing one or more auxiliary layers containing metal compounds each independently selected. 111. The method according to embodiment 110, wherein the metal compound is a metal oxide, a metal nitride, a metal oxynitride, a lithium-containing material, or a metal cone. 112. The method according to any one of embodiments 50 to 111, wherein one or more deposition or heat treatment steps are performed using a roll-to-roll manufacturing method. 113. A lithium-ion battery comprising an anode fabricated according to any one of embodiments 50 to 112 and a cathode. 114. The lithium-ion battery according to embodiment 113, wherein the anode includes a lithiated storage layer and the cathode includes sulfur, selenium, or both sulfur and selenium. 115. The lithium-ion battery according to embodiment 114, wherein the cathode further includes carbon nanotubes. 116. The lithium-ion battery according to embodiment 114 or 115, wherein the lithiated storage layer contains lithium in the range of 50% to 100% of the theoretical lithium storage capacity of the continuous porous lithium storage layer. 117. A lithium-ion battery including an anode and a cathode, wherein the anode is partially prepared by applying at least one electrochemical charge / discharge cycle to a non-cycling anode, and the non-cycling anode includes i) an anode according to any one of Embodiments 1 to 41, or an anode fabricated according to any one of Embodiments 50 to 112, the lithium-ion battery.

[0133] In the foregoing description, for purposes of explanation, numerous details have been set forth in order to provide an understanding of various embodiments of the present technology. However, it will be apparent to those skilled in the art that a particular embodiment may be practiced without some of these details or with additional details.

[0134] Although several embodiments have been described, it will be recognized by those skilled in the art that various modifications, alternative configurations, and equivalents can be used without departing from the spirit of the invention. Further, to avoid unnecessarily obscuring the present invention, some well-known processes and elements have not been described. Additionally, the details of any particular embodiment are not always present in that embodiment's variations and may be added to other embodiments.

[0135] When a range of values is presented, it is understood that each intervening value, to the tenth of the unit of the lower limit, between the upper and lower limits of that range is also specifically disclosed, unless the context clearly dictates otherwise. Each smaller range between any of the recited values or intervening values in the recited range and any other recited value or intervening value in that recited range is included. The upper and lower limits of these smaller ranges may independently be included in or excluded from the range, and ranges including any of the excluded limits, excluding any of the excluded limits, or including both of the excluded limits are also included in the invention, subject to any specifically excluded limit within the recited range. When the recited range includes one or both of the limits, ranges excluding one or both of those included limits are also included.

[0136] As used in this specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a method" includes a plurality of such methods, reference to "a layer" includes reference to one or more layers known to those skilled in the art and their equivalents, etc. Here, the present invention has been described in detail for purposes of clarity and understanding. However, it will be understood that certain changes and modifications may be made within the scope of the appended claims.

[0137] All publications, patents, and patent applications cited herein are hereby incorporated by reference in their entirety for all purposes. There is no admission that any of the foregoing is prior art.

Claims

1. A method for fabricating an anode for use in an energy storage device, comprising: providing a current collector including a conductive layer and a metal oxide layer covering the conductive layer, wherein the metal oxide layer has an average thickness of at least 0.01 μm; depositing a continuous porous lithium storage layer on the metal oxide layer by a chemical vapor deposition process; after deposition of the continuous porous lithium storage layer is completed, heat-treating the anode before battery assembly; wherein the heat-treating step includes heating the anode at a temperature in the range of 100° C. to 600° C. for a time in the range of 0.1 minute to 120 minutes.

2. The method according to claim 1, wherein the heat-treating step is performed in an environment having an oxygen and moisture pressure of less than 1 Torr each, and the heat-treating step is performed under argon, nitrogen, or vacuum. The method according to claim 1.

3. The method according to claim 1 or 2, wherein the temperature range is 350° C. to 600° C., and the time is in the range of 0.1 to 30 minutes. The method according to claim 1 or 2.

4. The method according to any one of claims 1 to 3, wherein the chemical vapor deposition process is a plasma chemical vapor deposition process, and the continuous porous lithium storage layer contains a total content of at least 40 atomic % of silicon, germanium, or a combination thereof. The method according to any one of claims 1 to 3.

5. The method according to any one of claims 1 to 4, wherein the chemical vapor deposition process is a plasma chemical vapor deposition process. The continuous porous lithium storage layer has at least 85 atomic% amorphous silicon having a density in the range of 1.1 g / cm ３ to 2.2 g / cm ３ and contains The method according to any one of claims 1 to 4.

6. The method according to any one of claims 1 to 5, wherein the conductive layer contains nickel or copper. The method according to any one of claims 1 to 5.

7. The method according to any one of claims 1 to 6, wherein the metal oxide layer contains a transition metal oxide, and the transition metal oxide is an oxide of nickel or titanium. The method according to any one of claims 1 to 6.

8. The method according to any one of claims 1 to 7, further comprising depositing a layer of lithium metal on the continuous porous lithium storage layer before the heat-treating step. The method according to any one of claims 1 to 7.

9. The method according to any one of claims 1 to 8, further comprising forming a lithiated storage layer by incorporating lithium into the continuous porous lithium storage layer before a first electrochemical cycle when the anode is assembled into the energy storage device. The method according to any one of claims 1 to 8.

10. Before forming the lithiated storage layer, the method further includes a step of forming an auxiliary layer on the continuous porous lithium storage layer, wherein the auxiliary layer includes silicon nitride, a metal oxide, a metal nitride, or a metal oxynitride, The method according to claim 9.

11. During the incorporation, after the incorporation, or both during and after the incorporation, the method further includes a step of heat-treating the continuous porous lithium storage layer, The method according to claim 9 or 10.

12. The step of forming the lithiated storage layer is (a) depositing a lithium metal layer on the continuous porous lithium storage layer, and (b) after depositing the lithium metal layer, depositing a lithium ion conducting layer, The method further includes a step of applying heat to the anode at i) between steps (a) and (b), ii) after step (b), or iii) both (i) and (ii), The method according to any one of claims 9 to 11.

13. The lithium ion conducting layer includes at least one of a lithium-containing material, a metal oxide, or an inorganic-organic hybrid structure having an alternating layer of a metal oxide and a crosslinked organic substance, The lithium ion conducting layer includes at least one of lithium phosphonitride (LIPON), a lithium phosphate, a lithium aluminum oxide, a lithium lanthanum titanate, an alcone, or zircon, The alcone is the inorganic-organic hybrid structure in which the metal oxide of the alternating layer contains aluminum, The zircon is the inorganic-organic hybrid structure in which the metal oxide of the alternating layer contains zirconium, The method according to claim 12.

14. A method for manufacturing a lithium ion battery including a cathode and an anode, including fabricating the anode by the method according to any one of claims 1 to 13, A method for manufacturing a lithium ion battery.

15. The cathode includes sulfur, selenium, or both sulfur and selenium, The anode is at least partially prelithiated to form a lithiated storage layer, The method for manufacturing a lithium ion battery according to claim 14.

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