Anodes for lithium-based energy storage devices

Abstract

An anode for an energy storage device includes a current collector having a conductive layer and a surface layer disposed on and in contact with the conductive layer. The surface layer can include a transition metalate other than chromate. A lithium storage layer covers and is in contact with the surface layer. The lithium storage layer can have an average thickness of at least 1 μm, includes at least 40 atomic % silicon, germanium, or a combination thereof, and is substantially free of a carbon-based binder. The lithium storage layer can be a continuous porous lithium storage layer.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority and any other benefit of U.S. Provisional Patent Application No. 63 / 294,159, entitled "ANODES FOR LITHIUM-BASED ENERGY STORAGE DEVICES," filed December 28, 2021, the entire disclosure of which is fully incorporated herein by reference for all purposes.

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

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

[0004] The industry has recently turned to nano- or micro-structured silicon, i.e., silicon in the form of spaced apart nano- or microwires, tubes, pillars, particles, etc., to reduce pulverization problems. The theory is that making the structures nano-sized prevents crack propagation, and spacing them apart provides more space for volumetric expansion, thereby allowing the silicon to absorb lithium with reduced stress and improved stability compared to, for example, a macroscopic layer of bulk silicon.

[0005] Although various approaches are being researched, silicon-based batteries have yet to make a significant impact on the market due to unresolved issues. Summary of the Invention

[0006] There remains a need for anodes for lithium-based energy storage devices, such as Li-ion batteries, that are easy to manufacture, robust to handling, have high charge capacity suitable for fast charging, e.g., at least 1 C, and have good cycle life.

[0007] According to one embodiment of the present disclosure, an anode for an energy storage device includes a current collector having a conductive layer and a surface layer disposed on and in contact with the conductive layer. The surface layer can include a transition metalate other than chromate. A lithium storage layer covers and is in contact with the surface layer. The lithium storage layer can have an average thickness of at least 1 μm, includes at least 40 atomic % silicon, germanium, or a combination thereof, and is substantially free of a carbon-based binder. The lithium storage layer can be a continuous porous lithium storage layer.

[0008] According to another embodiment of the present disclosure, a method of making an anode for use in an energy storage device is provided. The method may include providing a current collector having a conductive layer and a surface layer covering and in contact with the conductive layer. The surface layer may include or be formed from a transition metalate other than chromate. A lithium storage layer is deposited on the surface layer by a vapor deposition process. The lithium storage layer has an average thickness of at least 1 μm, includes at least 40 atomic % silicon, germanium, or a combination thereof, and is in contact with the surface layer. The vapor deposition process may be a PECVD process.

[0009] According to another embodiment of the present disclosure, there is provided a method of making a current collector for use in an energy storage device. The current collector may include a conductive layer and a surface layer. The method includes forming a surface layer on the conductive layer by contacting the conductive layer with a mixture including a transition metalate compound other than chromate and one or more mixed solvents. The current collector is characterized by a surface roughness Ra≧250 nm, and the mixture is substantially free of silicon compounds.

[0010] According to another embodiment of the present disclosure, an anode for an energy storage device may include a current collector made according to the methods of the present disclosure.

[0011] According to another embodiment of the present disclosure, a lithium ion battery is provided that may include an anode of the present disclosure.

[0012] The present disclosure provides anodes for energy storage devices that may have one or more of the following advantages over conventional anodes: improved stability at aggressive 1C or greater charge and / or discharge rates; higher total areal charge capacity; higher charge capacity per gram of lithium storage material (e.g., silicon); improved physical durability; simplified manufacturing process; more reproducible manufacturing process; reduced environmental impact manufacturing process; or reduced dimensional change during operation. [Brief description of the drawings]

[0013] [Figure 1] 2 is a cross-sectional view of a non-limiting example of an anode, according to some embodiments. [Diagram 2] FIG. 1 is a cross-sectional view of a prior art anode. [Diagram 3] 2 is a cross-sectional view of a non-limiting example of an anode, according to some embodiments. [Figure 4] 2 is a cross-sectional view of a non-limiting example of an anode, according to some embodiments. [Figure 5A] 1 is a cross-sectional schematic diagram of a non-limiting example of a current collector having a first type of nanopillars, according to some embodiments. [Figure 5B] 4 is a cross-sectional schematic diagram of a non-limiting example of a current collector having a second type of nanopillars, according to some embodiments. [Figure 6A] 1A-1D are SEM cross-sectional views of non-limiting examples of current collectors having nanopillar or nodular roughened features, according to some embodiments. [Figure 6B] 1A-1D are SEM cross-sectional views of non-limiting examples of current collectors having nanopillar or nodular roughened features, according to some embodiments. [Figure 7] 1A-1C are SEM cross-sectional views of non-limiting examples of current collectors having broad roughness features according to some embodiments. [Figure 8] 1 is a SEM of a non-limiting example of a chemically roughened surface of a current collector according to some embodiments. [Figure 9] 1 is a SEM of a non-limiting example of a current collector having nanopillar-like or nodular roughened features, according to some embodiments; [Figure 10] This is an SEM of copper foil C. [Figure 11] 13 is an SEM of the current collector of example anode E-3 before silicon deposition. [Figure 12] 13 is an SEM of the current collector of example anode E-11 before silicon deposition. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] It is understood that the drawings are for purposes of illustrating the concepts of the present disclosure and may not be to scale. Terms such as "overlaying," "over," and the like include direct contact, but do not necessarily require direct contact (unless such direct contact is indicated or clearly required for functionality). As used herein, "average" may represent a mean, median, or mode, and "average thickness" may be based on at least three measurements (e.g., 3, 4, 5, 6, 7, 8, 9, 10, or more measurements). Further details of certain embodiments of the present application can be found in U.S. Patent No. 10,910,653, U.S. Patent No. 11,024,842, U.S. Patent Application Publication No. 2021 / 0050584, U.S. Patent Application Publication No. 2021 / 0057733, U.S. Patent Application Publication No. 2021 / 0057757, U.S. Patent Application Publication No. 2021 / 0057755, U.S. Patent Application Publication No. 2021 / 0066702, PCT International Publication No. WO2022 / 005999, PCT Application No. PCT / US2021 / 064018, and U.S. Patent Application No. 17 / 526,055, the entire contents of which are incorporated by reference herein for all uses.

[0015] FIG. 1 is a cross-sectional view of an anode according to some embodiments of the present disclosure. Anode 100 includes a current collector 101 and a lithium storage layer 107 overlying the current collector. In some embodiments, the lithium storage layer may be a continuous porous lithium storage layer as described elsewhere herein. Current collector 101 includes a surface layer 105 disposed on a conductive layer 103, e.g., a conductive metal layer. For convenience, the surface of the current collector is shown as flat, but the current collector may have a roughened surface as described below. Lithium storage layer 107 is disposed on surface layer 105. In some embodiments, the top of continuous porous lithium storage layer 107 corresponds to top surface 108 of anode 100. In some embodiments, lithium storage layer 107 is in physical contact with surface layer 105. 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 lithium storage layer comprises at least 40 atomic % silicon, germanium, or a combination thereof. In some embodiments, the lithium storage layer is provided by a physical vapor deposition (PVD) process, such as by sputtering or e-beam, or by a chemical vapor deposition (CVD) process, including, but not limited to, hot wire CVD or plasma enhanced chemical vapor deposition (PECVD).

[0016] In the present disclosure, the lithium storage layer 107, such as a continuous porous lithium storage layer, may be substantially free of high aspect ratio nanostructures, for example, in the form of spaced apart wires, pillars, tubes, or 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 lithium storage nanostructures, such as nanowires 190, nanopillars 192, nanotubes 194, and nanochannels 196, disposed on a current collector 180. Unless otherwise noted, the term "lithium storage nanostructure" herein generally refers to a lithium storage active material structure (e.g., a structure of silicon, germanium, or alloys thereof) having at least one cross-sectional dimension less than about 2,000 nm, other than a dimension substantially perpendicular to the underlying substrate (such as the layer thickness) and excluding dimensions caused by random pores and channels. Similarly, the terms "nanowire", "nanopillar" and "nanotube" refer to wires, pillars and tubes, respectively, at least a portion of which have a diameter less than 2,000 nm. "High aspect ratio" nanostructures have an aspect ratio of greater than 4:1, where the aspect ratio is generally the height or length of the feature (which may be measured along a feature axis aligned at an angle of 45-90° to the underlying current collector surface) divided by the width of the feature (which may be measured generally orthogonal to the feature axis). In some embodiments, a lithium storage layer, e.g., a continuous porous lithium storage layer, is considered to be "substantially free" of lithium storage nanostructures when the anode has an average (e.g., mean, median, or mode) of less than 10 lithium storage nanostructures per 1600 square micrometers (the number of lithium storage nanostructures being the sum of the number of nanowires, nanopillars, and nanotubes in the same unit area), such lithium storage nanostructures having an aspect ratio of 4:1 or greater. Alternatively, there is an average of less than 1 such lithium storage nanostructure per 1600 square micrometers. As discussed below, the current collector may have a high surface roughness or may include nanostructures, but these features are separate from the lithium storage layer and distinct from the lithium storage nanostructures.

[0017] In some embodiments, deposition conditions are selected in combination with a current collector to provide an anode in which the lithium storage layer, e.g., a continuous porous lithium storage layer, is relatively smooth and has a diffuse or total reflectance at 550 nm of at least 10%, or alternatively at least 20% (measured on the continuous porous lithium storage layer side). In some embodiments, an anode having such a diffuse or total reflectance may be less susceptible to damage from physical handling. In some embodiments, an anode that may be substantially free of lithium storage nanostructures may have a lower reflectance and may be more susceptible to damage from physical handling.

[0018] The anode of the present disclosure may optionally be double-sided. For example, FIG. 3 is a cross-sectional view of a double-sided anode according to some embodiments. A current collector 301 may include a conductive layer 303 and surface layers (305a, 305b) disposed on both sides of the conductive layer 303. Lithium storage layers (307a, 307b), which may be continuous porous lithium storage layers, are disposed on both sides to form the anode 300. The surface layers 305a and 305b may be the same or different in terms of composition, thickness, roughness, or any other characteristic. Similarly, the lithium storage layers 307a and 307b may be the same or different in terms of composition, thickness, porosity, or any other characteristic.

[0019] Current Collector In some embodiments, the current collector or conductive layer may be characterized by a tensile strength Rm or a yield strength Re. In some cases, the tensile and yield strength properties of the current collector depend mainly on the conductive layer, which may be thicker than the surface layer in some embodiments. A tensile strength that is too high or too low may cause handling difficulties in manufacturing, such as a roll-to-roll process. During electrochemical cycling of the anode, deformation of the anode may occur if the tensile strength is too low, or the adhesion of the lithium storage layer may be impaired if the tensile strength is too high.

[0020] Deformation of the anode is not necessarily an issue for all products, and such deformation may sometimes occur only at higher capacities, i.e., higher loadings of the lithium storage layer material. For such products, the current collector or conductive layer may have a tensile strength R in the range of 100-150 MPa, alternatively 150-200 MPa, alternatively 200-250 MPa, alternatively 250-300 MPa, alternatively 300-350 MPa, alternatively 350-400 MPa, alternatively 400-500 MPa, alternatively 500-600 MPa, alternatively 600-700 MPa, alternatively 700-800 MPa, alternatively 800-900 MPa, alternatively 900-1000 MPa, alternatively 1000-1200 MPa, alternatively 1200-1500 MPa, or any combination of such ranges. m The present invention may be characterized by the following:

[0021] In some embodiments, significant anode deformation should be avoided, but low battery capacity may not be acceptable. For example, if the anode comprises amorphous silicon of 7 μm or greater and / or the electrochemical cycling capacity is less than 1.5 mAh / cm 2 or more, the current collector or conductive layer has a tensile strength R of at least 500 MPa, alternatively at least 600 MPa. mIn such embodiments, the tensile strength may be in the range of 500-550 MPa, alternatively 550-600 MPa, alternatively 600-650 MPa, alternatively 650-700 MPa, alternatively 700-750 MPa, alternatively 750-800 MPa, alternatively 800-850 MPa, alternatively 850-900 MPa, alternatively 900-950 MPa, alternatively 950-1000 MPa, alternatively 1000-1200 MPa, alternatively 1200-1500 MPa, or any combination of ranges therein. In some embodiments, the current collector or conductive layer may have a tensile strength of greater than 1500 MPa. In some embodiments, the current collector or conductive layer is in the form of a foil having a tensile strength of greater than 600 MPa and an average thickness in the range of 4 to 8 μm, alternatively 8 to 10 μm, alternatively 10 to 15 μm, alternatively 10 to 15 μm, alternatively 15 to 20 μm, alternatively 20 to 25 μm, alternatively 25 to 30 μm, alternatively 30 to 40 μm, alternatively 40 to 50 μm, or any combination of those ranges.

[0022] In some embodiments, the conductive layer comprises at least 10 3 S / m, or at least 10 6 S / m, or at least 10 7The conductive layer may have a conductivity of 10 ... In some embodiments, the conductive layer may include multiple layers of different conductive materials. The conductive layer may be in the form of a layer deposited on an insulating substrate (e.g., a polymer sheet or a ceramic substrate, optionally coated on both sides with a conductive material, including but not limited to nickel or copper). In some embodiments, the conductive layer includes a mesh or sheet of conductive carbon, including but not limited to those formed from bundled carbon nanotubes or nanofibers, or carbon fibers.

[0023] If higher tensile strength is desired, the conductive layer may include nickel (and certain alloys), titanium (and certain alloys), or certain copper alloys, such as brass (an alloy of primarily copper and zinc), bronze (an alloy of primarily copper and tin), CuMgAgP (an alloy of primarily copper, magnesium, silver, and phosphorus), CuFe2P (an alloy of primarily copper, iron, and phosphorus), and CuNi3Si (an alloy of primarily copper, nickel, and silicon). The nomenclature of metal alloys is not a stoichiometric molecular formula used in chemistry, but rather a nomenclature used by those skilled in the art of alloys. For example, CuNi3Si does not mean that for each atom of copper, there are three atoms of nickel and one atom of silicon. In some embodiments, these nickel or copper based high tensile conductive layers may include roll-formed nickel or copper alloy foils.

[0024] Alternatively, a conductive carbon mesh or sheet, including but not limited to those formed from bundled carbon nanotubes or nanofibers, can provide a conductive layer with higher tensile strength, hi some embodiments, a conductive metal intermediate layer can be interposed between the conductive carbon and the surface layer.

[0025] In some embodiments, any of the above-mentioned conductive layers (low or high tensile strength) may act as the primary conductive layer and may further include a conductive intermediate layer, e.g., a metal intermediate layer, disposed between the primary conductive layer and the surface layer. FIG. 4 is a cross-sectional view of such an anode according to some embodiments, in this case for a double-sided anode. The current collector 401 may include a conductive layer 403 and surface layers (405a, 405b) disposed on both sides of the conductive layer 403. Lithium storage layers (407a, 407b), which may be continuous porous lithium storage layers, are disposed on both sides to form the anode 400. The conductive layer 403 includes a primary conductive layer 402, which is disposed on both sides by metal intermediate layers (404a, 404b). The metal intermediate layers 404a and 404b may be the same or different in terms of composition, thickness, roughness, or any other characteristic. Similarly, the surface layers 405a and 405b may be the same or different in terms of composition, thickness, roughness, or any other characteristic. Similarly, lithium storage layers 407a and 407b may be the same or different in terms of composition, thickness, porosity, or any other property.

[0026] The metal interlayer may be applied, for example, by sputtering, vapor deposition, electrolytic or electroless plating, or any convenient method. The metal interlayer generally has an average thickness that is less than 50% of the average thickness of the entire conductive layer, i.e., the thickness of the primary conductive layer and the metal interlayer(s) combined. In some embodiments, the surface layer may be more uniformly formed on the metal interlayer than the primary conductive layer, or may adhere better to the metal interlayer.

[0027] In some embodiments, the current collector may be characterized as having a surface roughness. In some embodiments, the top surface 108 of the lithium storage layer 107 may have a surface roughness that is less than the surface roughness of the current collector 101. Comparisons and measurements of surface roughness herein are made in terms of the roughness average (R a ), RMS roughness (R q ), maximum profile peak height roughness (R p ), the average maximum height of the profile (R z ), or peak density (P cIn some embodiments, the current collector may have a surface roughness R z ≧2.5μm and surface roughness R a In some embodiments, R z is in the range of 2.5 to 3.0 μm, alternatively 3.0 to 3.5 μm, alternatively 3.5 to 4.0 μm, alternatively 4.0 to 4.5 μm, alternatively 4.5 to 5.0 μm, alternatively 5.0 to 5.5 μm, alternatively 5.5 to 6.0 μm, alternatively 6.0 to 6.5 μm, alternatively 6.5 to 7.0 μm, alternatively 7.0 to 8.0 μm, alternatively 8.0 to 9.0 μm, alternatively 9.0 to 10 μm, 10 to 12 μm, 12 to 14 μm, or any combination of ranges therein. a is in the range of 0.25 to 0.30 μm, alternatively 0.30 to 0.35 μm, alternatively 0.35 to 0.40 μm, alternatively 0.40 to 0.45 μm, alternatively 0.45 to 0.50 μm, alternatively 0.50 to 0.55 μm, alternatively 0.55 to 0.60 μm, alternatively 0.60 to 0.65 μm, alternatively 0.65 to 0.70 μm, alternatively 0.70 to 0.80 μm, alternatively 0.80 to 0.90 μm, alternatively 0.90 to 1.0 μm, alternatively 1.0 to 1.2 μm, alternatively 1.2 to 1.4 μm, or any combination of these ranges.

[0028] In some embodiments, some or most of the surface roughness of the current collector may be imparted by the conductive layer and / or the metallic interlayer. Alternatively, some or most of the surface roughness of the current collector may be imparted by the surface layer. Alternatively, a combination of the conductive layer, the metallic interlayer, and a portion of the surface layer may substantially contribute to the surface roughness.

[0029] In some embodiments, the conductive layer may include roughened features, such as electrodeposited roughened features, to increase surface roughness. In some embodiments, the electrodeposited roughened features may include copper features. For example, a relatively smooth copper foil may be provided in a first acidic copper plating solution having 50-250 g / L of sulfuric acid and less than 10 g / L of copper provided as copper sulfate. The copper foil is cathodically polarized and plated at about 0.05-0.3 A / cm. 2 A current density of about 0.05-0.2 A / cm can be applied for a few seconds to a few minutes to deposit the copper roughened features at room temperature. In some embodiments, the copper foil may then be placed in a second acid copper plating solution having 50-200 g / L sulfuric acid and more than 50 g / L copper provided as copper sulfate. The second acid copper bath may optionally be warmed to a temperature of about 30° C.-50° C. Cathodic polarization and a current density of about 0.05-0.2 A / cm are applied to fix the particles to the copper foil. 2 By applying a current density of 1000 .mu.m for a period of a few seconds to a few minutes, a thin copper layer can be electroplated onto the copper features.

[0030] Alternatively, in combination with the electrodeposited roughened features, the conductive layer may be subjected to a separate electrochemical, chemical, or physical treatment to impart the desired surface roughness prior to the formation of the surface layer.

[0031] In some embodiments, metal foils, including but not limited to rolled copper foils, can first be heated in an oven in air (e.g., 100° C.-200° C.) for a period of time (e.g., 10 minutes-24 hours) to remove any volatile material on its surface and to induce some degree of surface oxidation. In some embodiments, the heat-treated foil may then undergo additional chemical treatment, such as immersion in a chemical etchant such as an acid or hydrogen peroxide / HCl solution, optionally followed by a deionized water rinse. The chemical etchant removes the oxidized metal. Such treatments may increase the surface roughness. In some embodiments, there is no heating, but rather treatment with a chemical etchant that includes an oxidizing agent. In some embodiments, the oxidizing agent may be dissolved oxygen, hydrogen peroxide, or some other suitable oxidizing agent. Such chemical etchants may further include organic acids, such as methanesulfonic acid, or inorganic acids, such as hydrochloric acid or sulfuric acid. The chemical etchant may be optionally followed by a deionized water rinse. Such treatments described in this paragraph may be referred to herein as "chemical roughening" treatments.

[0032] In some embodiments, the electrodeposited roughened features can be characterized as nanopillared features. FIG. 5A illustrates a cross-sectional view of a non-limiting example of an electrodeposited copper roughened feature according to some embodiments. In some cases, the current collector 501 can include a plurality of nanopillared features 520 (electrodeposited copper roughened features) disposed on a conductive layer 503. The nanopillared features 520 are distinguished from the nanopillars 192 of FIG. 2 at least by their composition, their layer, their dimensions, the process used to form the nanopillars, their surface density, and / or their orientation. The nanopillared features 520 can include a metal-containing nanopillared core 522 (e.g., a copper-containing core) and a surface layer 505 at least partially disposed on the nanopillared core and optionally disposed on the conductive layer in the gap regions between the nanopillared features. Each nanopillared feature can be characterized by a height H, a base width B, and a maximum width W. The base width B may be the smallest width across the bottom or base of the nanopillared feature. The maximum width W may be measured across the widest portion perpendicular to the nanopillared feature axis. The height H may be measured along the axis of the nanopillared feature from the base to the end of the nanopillared feature. The nanopillared feature axis is the longitudinal axis of the nanopillared feature. In some cases, the nanopillared feature axis may pass through the center of mass of the nanopillared feature.

[0033] In some embodiments, the nanopillar-like features can be characterized as a first type and a second type of nanopillar. In some cases, the first type of nanopillar can be characterized by H ranging from 0.4 μm to 3.0 μm, B ranging from 0.2 μm to 1.0 μm, W / B ratio ranging from 1 to 1.5, H / B (aspect) ratio ranging from 0.8 to 4.0, and an angle of the longitudinal axis of the nanopillar-like feature relative to the plane of the conductive layer ranging from 60° to 90°, e.g., most or all of the nanopillar-like features in FIG. 5A can be the first type of nanopillar. FIG. 6A is an SEM cross-section of a non-limiting example of a current collector having primarily the first type of nanopillar-like features. In some embodiments, upon optical or SEM analysis, a single or average 20 μm long cross section of the current collector may contain at least two nanopillars of the first type, alternatively at least three, at least four, at least five, at least six, at least seven, at least eight, or at least ten nanopillars of the first type. In some embodiments, upon optical or SEM analysis, a single or average 20 μm long cross section of the current collector may contain 2-4, alternatively 4-6, alternatively 6-8, alternatively 8-10, alternatively 10-12, alternatively 12-14, alternatively 14-16, alternatively 16-20, alternatively 20-25, alternatively 25-30 nanopillars of the first type, or any combination of ranges therein. Note that the 20 μm length of analysis refers to the lateral distance 501LD along the length of the current collector, for example as shown in FIG. 5A.

[0034] In some cases, the second type of nanopillars may be characterized by an H of at least 1.0 μm and a W / B ratio of greater than 1.5. That is, the second type of nanopillars tend to widen away from their base. FIG. 5B is a cross-sectional view of a non-limiting example of a second type of nanopillar. For clarity, the nanopillar core and surface layers are not separately defined. The second type of nanopillars may have a significantly wider top (sometimes referred to herein as a "wide top roughened feature"), such as nanopillar-like feature 524. Alternatively, the second type of nanopillars may include a branched or tree-like structure, such as nanopillar-like feature 526. The "trunk" and "branches" are all similar in width, but the entire feature is significantly wider toward the top, as illustrated by effective cross-sectional profile 526'. Effective cross-sectional profile 526' is the shape formed by a line drawn between the outermost points of successive branches or trunks of the nanopillar-like feature. Such branched structures can have the same effect as solid nanopillar-like features such as 524.

[0035] FIG. 6B is an SEM cross section of a non-limiting example of a current collector having some second type nanopillars (circled). The performance of an anode having second type nanopillars may be acceptable in many embodiments. However, in some embodiments, it has been observed that an anode having a large number of second type nanopillars may be inferior in some cases compared to an anode having fewer second type nanopillars. Without being bound by theory, the broad top may prevent the roughened features from being embedded in the silicon. Alternatively, these structures may be structurally weak and may break at the base. In any case, a current collector having too many such structures may not perform well with PECVD deposited lithium storage material in some embodiments. In some embodiments, in optical or SEM analysis, at least one 20 μm long cross section of the current collector may contain fewer second type nanopillars than first type nanopillars. In some embodiments, upon optical or SEM analysis, an average 20 μm long cross-section of the current collector (e.g., obtained from three measurements) may contain fewer nanopillars of the second type than the first type. In some embodiments, upon optical or SEM analysis, at least one 20 μm long cross-section of the current collector may contain fewer than 10, or fewer than 9, 8, 7, 6, 6, 4, 3, 2, or 1 nanopillar(s) of the second type. In some embodiments, upon optical or SEM analysis, an average 20 μm long cross-section of the current collector (e.g., obtained from three measurements) may contain fewer than 10, or fewer than 9, 8, 7, 6, 6, 4, 3, 2, or 1 nanopillar(s) of the second type.

[0036] In some embodiments, the nanopillars may be classified in a category other than a first type nanopillar or a second type nanopillar. In some embodiments, the electrodeposited roughened features may be characterized as nodular features, and in some cases may include particulate features or hemispherical features. In some embodiments, the base of the nodular feature may generally represent the maximum width. In some embodiments, the nodular feature may be characterized as having an H in the range of 0.4-5.0 μm, a W / B ratio in the range of about 1-1.2, and an H / B aspect ratio in the range of about 0.5-1.5. In some cases, the electrodeposited roughened features may be defined as either nodular or a first type nanopillar.

[0037] In some embodiments, the surface roughness is R a or R z Although the features themselves may be relatively large relative to the surface roughness, for example asperities separated by at least about 2 μm microns on average, Figure 7 shows an SEM cross-section of a portion of a current collector having broad roughness features. Current collector 701 includes a conductive layer 703 (the surface layer is not readily discernible by SEM). The surface roughness of this current collector was measured to be R a = 508 nm. The broad roughness features may be characterized by a peak height P and a valley separation V. The ratio P / V represents the aspect ratio of the broad roughness features. In some embodiments, on average, V is at least greater than 3 μm, alternatively at least greater than 4 μm, and P / V is less than 0.8, alternatively less than 0.6. In some embodiments, on average, V is in the range of 3-4 μm, alternatively 4-5 μm, alternatively 5-6 μm, alternatively 6-8 μm, alternatively 8-10 μm, alternatively 10-12 μm, alternatively 12-15 μm, and P / V is in the range of 0.2-0.3, alternatively 0.3-0.4, alternatively 0.4-0.5, alternatively 0.5-0.6, alternatively 0.6-0.7, alternatively 0.7-0.8, or any combination of these ranges for V and P / V. In some embodiments, V is the same as the peak-to-peak separation.

[0038] In some embodiments, the roughened current collector surface may appear pitted, cratered, or corroded. A non-limiting example is shown in FIG. 8, created in this case by chemical roughening, oxidation treatment. Some areas that roughly correspond to the original surface, such as area 881, can still be seen. Lines of the original roll-formed surface can still be discerned. Most of the surface has been etched, resulting in a very rough, random, crater-like topology that is much rougher than the original surface. In some embodiments, at least 50% of the surface of the conductive layer is etched to a depth of at least 0.5 μm, or even at least 1.0 μm, from the original surface, resulting in a surface roughness R ais at least 400 nm, alternatively at least 500 nm, alternatively at least 600 nm, alternatively at least 700 nm. Numerous pits / craters 883 are visible. In some embodiments, when examined by SEM analysis, an average 100 square micron area of ​​the chemically roughened current collector may contain at least one discernible pit, alternatively at least two, three, or four discernible pits. In some embodiments, a "pit" may be a feature characterized by a width and a depth, with a ratio of depth to width being at least 0.25, alternatively at least 0.5. The pit may be a concave surface defined by the current collector. The top of the pit may be the top surface of the current collector. In some embodiments, the pit may be at least 2 μm wide. In some embodiments, the pit may occupy 2%-5%, alternatively 5%-10%, alternatively 10%-20%, alternatively 20%-30%, alternatively 30%-40%, alternatively 40%-50% of the surface area of ​​the current collector. In some embodiments, some etched or pitted areas may have a micro-roughness structure 885 formed from the coalescence of secondary smaller pits or craters. Such secondary pits may have an average width or diameter of less than about 2 μm, alternatively less than about 1 μm. In some embodiments, the secondary pits may occupy 5%-10%, alternatively 5%-10%, alternatively 10%-20%, alternatively 20%-30%, alternatively 30%-40%, alternatively 40%-50%, alternatively 50%-60%, alternatively 60%-70%, alternatively 70%-90% of the surface area of ​​the current collector.

[0039] In some embodiments, roughening of the conductive layer can include, for example, physical abrasion (such as by sandpaper, sandblasting, grinding, etc.), ablation (such as by laser ablation), embossing, stamping, casting, imprinting, chemical processing, electrochemical processing, or thermal processing. In some cases, such roughening can be used to form one or more of the roughened features described above, such as nodular features, nanopillar features, broad roughness features, pit-like features, etc. In some cases, the roughened features can be random or, alternatively, have a predetermined pattern.

[0040] surface layer For example, as disclosed in co-pending International Application PCT / US2021 / 039426, filed June 28, 2021 (herein incorporated by reference for all purposes), chromate has been found to be an effective surface layer in some cases, however such chromate coatings often require the use of Cr(VI) materials, which are subject to environmental regulations and restrictions in many areas. Furthermore, chromate surface layers have been found to be more effective in some cases in combination with an underlying zinc or zinc alloy surface layer. This additional layer or layers are referred to as "sublayers" in International Application PCT / US2021 / 039426. In some cases, it may be desirable to simplify the preparation of the surface layer and use less toxic materials.

[0041] In some embodiments, the surface layer may include or be formed from a transition metalate other than chromate. The surface layer may be provided in direct contact with the conductive layer without the need for an intervening zinc-containing layer. In some embodiments, the surface layer may be formed by electroplating. In some cases, the surface layer may be formed by a so-called "conversion coating" process, where typically some elements of the conductive layer react with a conversion coating mixture (e.g., an aqueous or non-aqueous solution containing a transition metalate compound) to cause direct deposition of the transition metalate or its reaction product. As a non-limiting example, if the conductive layer includes copper, copper(0) can reduce the transition metalate or transition metalate precursor compound in the solution to a lower oxidation state, which may have a lower solubility, and cause direct deposition on the conductive layer. The copper ions formed may dissolve in the solution or may be counterions to the coated transition metalate. Conversion coating processes are known in the art for other (non-battery anode) purposes, and alternative reaction mechanisms are possible, many of which do not require copper.

[0042] In some embodiments, the surface layer may be formed by adsorption of a transition metalate compound onto the surface of a conductive layer. In some embodiments, the surface layer may be formed by coating a transition metalate compound onto a conductive layer and drying.

[0043] In some embodiments, one or more additional layers may be provided on the transition metalate surface layer, with multiple layers (which may be referred to as sublayers) collectively comprising the surface layer. However, to further simplify manufacturing, the lithium storage layer may be deposited directly on (in contact with) the non-chromate transition metalate bearing surface layer.

[0044] Transition metalates generally refer to transition metal compounds that have a negative charge. Anionic transition metalate compounds may be associated with one or more cations ("transition metalate compounds"), which may optionally be an alkali metal, an alkaline earth metal, ammonium, an alkylammonium, another transition metal (which may be the same or different from the transition metal of the anionic transition metalate compound), or some other cationic species. Some non-limiting examples of transition metalates include oxometalates, sulfometalates, cyanometalates, and halometalates, which may be used alone or in combination. Unless otherwise specified, the term "transition metal" as used anywhere in this application includes any element in Groups 3-12 of the Periodic Table, including the lanthanides and actinides.

[0045] In some embodiments, the surface layer (transition metalate) may include scandium, titanium, vanadium, manganese, iron, cobalt, nickel, copper, yttrium, zirconium, niobium, molybdenum, tantalum, or tungsten. In some embodiments, the transition metalate includes an oxometalate. In some cases, the oxometalate includes a titanate, vanadate, molybdate, tungstate, or niobate. In some embodiments, the surface layer may further include some chromium, for example in the form of a chromate. In some cases, the chromate may be present as a sublayer, for example, a non-chromate transition metalate sublayer provided between the chromate sublayer and the lithium storage layer. In some embodiments, the chromium present in the surface layer may be a lower atomic percent than the transition metal present in the non-chromate transition metalate.

[0046] In some embodiments, the amount of transition metal element(s) in the surface layer is at least 0.5 mg / m 2 , or at least 1 mg / m 2 , or at least 2 mg / m 2 In some embodiments, the amount of transition metal element(s) in the surface layer may be 0.5 to 1 mg / cm 2 , or 1-2 mg / m2 , or 2 to 5 mg / m 2 , or 5 to 10 mg / m 2 , or 10-20 mg / m 2 , or 20-50 mg / m 2 , or 50-75 mg / m 2 , or 75-100 mg / m 2 , or 100-250 mg / m 2 , or 250-500 mg / m 2 , or 500 to 750 mg / m 2 , or 750-1000 mg / m 2 or any combination of ranges thereof. In some embodiments, the surface layer containing the transition metalate may be at least 0.2 nm thick, alternatively at least 0.5 nm thick, alternatively at least 1 nm thick, or at least 2 nm thick. In some embodiments, the surface layer containing the transition metalate may have a thickness in the range of 0.2-0.5 nm, alternatively 0.5-1.0 nm, alternatively 1.0-2.0 nm, alternatively 2.0-5.0 nm, alternatively 5.0-10 nm, alternatively 10-20 nm, alternatively 20-50 nm, alternatively 50-100 nm, alternatively 100-200 nm, alternatively 200-500 nm, alternatively 500-750 nm, alternatively 750-1000 nm, or any combination of ranges thereof.

[0047] In some embodiments, the surface layer may be characterized as a single layer without any defined sublayers. In some embodiments, the surface layer may have a uniform composition throughout. In some embodiments, the surface layer may have a non-uniform composition. In some embodiments, the composition of the surface layer may include a gradient in the concentration of one or more chemical components. For example, the chemical reactions involved in a single conversion coating process may change over time as the surface composition changes, resulting in a gradient of components. In some cases, the gradient may be caused by surface oxidation or other reactions. In embodiments where the surface layer includes a gradient, the surface layer may be characterized as having the same chemical components throughout, with some chemical components possibly having zero concentration at some locations at the end of the gradient. The surface layer may not include abrupt changes in the concentration of chemical components.

[0048] In addition to being useful for vapor-deposited lithium storage layers, the current collectors described herein may also be suitable for more conventional slurry-coated anodes, such as those containing graphite, silicon particles, or other anode active materials. In some cases, the current collectors described herein may be suitable for use with lithium metal anodes. For example, instead of a lithium storage layer, a layer of lithium metal is provided on the surface layer as the active anode material. The lithium can be deposited electrochemically, by thermal evaporation, by slurry coating, etc. In some embodiments, the current collectors of the present application may be suitable for use as cathode current collectors.

[0049] Silicon Compounds In some embodiments, the surface layer including the transition metalate may be formed from a coating solution (e.g., electroplating, conversion coating, adsorption, etc.) that includes a silicon compound, such as a silane, siloxane, or silazane compound, any of which may be referred to herein as a silicon compound agent, co-deposited with the transition metalate. Some examples of silicon compounds are disclosed in International Application PCT / US2021 / 039426. Although transition metalates may be effective in combination with such silicon compounds, in some embodiments, non-chromate transition metalates may be used as the surface layer without being mixed or combined with such silicon compounds. In some cases, this may further simplify the manufacturing process by reducing the number of materials to monitor in the electroplating or conversion coating bath. That is, in some embodiments, the surface layer may be substantially free of such silicon compounds. By substantially free, the atomic ratio of transition metal(s) to silicon from the silicon compounds in the surface layer may be at least 5:1, alternatively at least 10:1, alternatively at least 20:1, alternatively at least 50:1, alternatively at least 100:1. It should be noted that in some embodiments, the silicon compound may be provided on the transition metalate in a separate step, for example, by contact with a silicon compound agent.

[0050] Lithium storage layer In some embodiments, the lithium storage layer may be a porous material capable of reversibly incorporating lithium, for example, a continuous porous lithium storage layer. In some embodiments, the lithium storage layer comprises silicon, germanium, antimony, tin, or a mixture of two or more of these elements. In some embodiments, the lithium storage layer is substantially amorphous. In some embodiments, the lithium storage layer comprises substantially amorphous silicon. Such a substantially amorphous storage layer may include a small amount (e.g., less than 20 atomic %) of crystalline material dispersed therein. The storage layer may include a dopant, such as hydrogen, boron, phosphorus, carbon, sulfur, fluorine, aluminum, gallium, indium, arsenic, antimony, bismuth, nitrogen, or a metallic element. In some embodiments, the lithium storage layer may include porous, substantially amorphous hydrogenated silicon (a-Si:H), for example, having a hydrogen content of 0.1 to 20 atomic %, or alternatively, greater than that. In some embodiments, the lithium storage layer may include methylated amorphous silicon. It should be noted that unless hydrogen content is specifically mentioned, any atomic % metrics used herein with respect to lithium storage materials or layers refer to atoms other than hydrogen.

[0051] In some embodiments, the lithium storage layer, e.g., a continuous porous lithium storage layer, comprises at least 40 atomic %, alternatively at least 50 atomic %, alternatively at least 60 atomic %, alternatively at least 70 atomic %, alternatively at least 80 atomic %, alternatively at least 90 atomic %, alternatively at least 95%, alternatively at least 97%, alternatively at least 98%, alternatively at least 99% silicon, germanium, or combinations thereof. In some embodiments, the lithium storage layer, e.g., a continuous porous lithium storage layer, comprises at least 40 atomic %, alternatively at least 50 atomic %, alternatively at least 60 atomic %, alternatively at least 70 atomic %, alternatively at least 80 atomic %, alternatively at least 90 atomic %, alternatively at least 95 atomic %, alternatively at least 97 atomic %, alternatively at least 98%, alternatively at least 99% silicon. Note that in the case of a prelithiated anode, as described below, the lithium content is excluded from this atomic % characterization.

[0052] In some embodiments, the lithium storage layer, e.g., a continuous porous lithium storage layer, comprises less than 10 atomic %, alternatively less than 5 atomic %, alternatively less than 2 atomic %, alternatively less than 1 atomic %, alternatively less than 0.5 atomic %, alternatively less than 0.3 atomic % carbon. In some embodiments, the lithium storage layer, e.g., a continuous porous lithium storage layer, comprises substantially no carbon-based binders, graphitic carbon, graphene, graphene oxide, reduced graphene oxide, carbon black, or conductive carbon (i.e., the lithium storage layer comprises less than 1 wt. %, alternatively less than 0.5 wt. %, alternatively less than 0.3 wt. %, alternatively less than 0.1 wt. %, alternatively less than 0.01 wt. %). Some non-limiting examples of carbon-based binders can include organic polymers such as those based on styrene butadiene rubber, polyvinylidene fluoride, polytetrafluoroethylene, polyacrylic acid, carboxymethylcellulose, or polyacrylonitrile.

[0053] Lithium storage layers, for example continuous porous lithium storage layers, may contain voids or interstices (pores) that may be random or non-uniform with respect to size, shape, and distribution. Such porosity does not result in or results from the formation of any recognizable lithium storage nanostructures, such as nanowires, nanopillars, nanotubes, ordered nanochannels, etc. In some embodiments, the pores may be polydisperse. In some embodiments, the continuous porous lithium storage layer may be characterized as nanoporous. In some embodiments, the continuous porous lithium storage layer may have a porosity of 1.0-1.1 g / cm. 3 , or 1.1 to 1.2 g / cm 3 , or 1.2 to 1.3 g / cm 3 , or 1.3 to 1.4 g / cm 3 , or 1.4 to 1.5 g / cm 3 , or 1.5 to 1.6 g / cm 3 , or 1.6 to 1.7 g / cm 3 , or 1.7 to 1.8 g / cm 3 , or 1.8 to 1.9 g / cm 3 , or 1.9 to 2.0 g / cm 3 , or 2.0 to 2.1 g / cm 3 , or 2.1 to 2.2 g / cm 3 , or 2.2 to 2.25 g / cm 3 , or 2.25 to 2.29 g / cm 3 or any combination of ranges thereof, and containing at least 70 atomic % silicon, or 80 atomic % silicon, or at least 85 atomic % silicon, or at least 90 atomic % silicon, or at least 95 atomic % silicon, or at least 97 atomic % silicon, or at least 98 atomic % silicon, or at least 99 atomic % silicon. 3 Note that the density less than 0.05 is evidence of the porosity of the a-Si containing lithium storage layer.

[0054] In some embodiments, the majority of the active material (e.g., silicon, germanium, or alloys thereof) of the lithium storage layer, e.g., the continuous porous lithium storage layer, has substantial lateral connectivity across the portion of the current collector, such connectivity extending around the random pores and interstices. Referring again to FIG. 1, in some embodiments, "substantial lateral connectivity" means that the active material at one point X in the continuous porous lithium storage layer 107 can be connected to the active material at a second point X' in the layer over a linear lateral distance LD at least as large as the average thickness T of the lithium storage layer, or a lateral distance at least twice the thickness, or a lateral distance at least three times the thickness. Although not shown, the total path distance of the material connectivity, including bypass pores and following the topography of the current collector, may be longer than LD. In some embodiments, the continuous porous lithium storage layer may be described as a matrix of interconnected silicon, germanium, or alloys thereof, with random pores and interstices embedded therein. In some embodiments, the lithium storage layer, e.g., a continuous porous lithium storage layer, may have a sponge-like morphology in cross-sectional view. It is noted that the lithium storage layer, e.g., a continuous porous lithium storage layer, does not necessarily need to extend across the entire anode without lateral breaks, and may include random discontinuities or cracks and still be considered continuous. In some embodiments, such discontinuities may occur more frequently on rough current collector surfaces. In some embodiments, the lithium storage layer, e.g., a continuous porous lithium storage layer, may have abutting columns of active material, such as silicon, in cross-sectional view. The abutting columns may be characterized by an average height and an average width, and generally have a height-to-aspect ratio of less than 4:1, alternatively less than 3:1, alternatively less than 2:1, alternatively less than 1:1. Such abutting columns are laterally continuous. In some embodiments, the lithium storage layer, e.g., a continuous porous lithium storage layer, may include a matrix of connected nanoparticle aggregates.In some embodiments, the lithium storage layer may include a mixture of amorphous and crystalline silicon, such as nanocrystalline silicon having an average grain size of less than about 100 nm, or less than about 50 nm, 20 nm, 10 nm, or 5 nm. In some cases, the lithium storage layer may include up to 30 atomic % nanocrystalline silicon relative to the total silicon in the lithium storage layer.

[0055] In some embodiments, the lithium storage layer, e.g., a continuous porous lithium storage layer, is made of silicon (SiO x ), Germanium (GeO x ) or tin (SnO x ), where the ratio of oxygen atoms to silicon, germanium or tin atoms is less than 2:1, i.e., x<2, or alternatively less than 1:1, i.e., x<1. In some embodiments, x is in the range of 0.02 to 0.95, alternatively 0.02 to 0.10, alternatively 0.10 to 0.50, alternatively 0.50 to 0.95, alternatively 0.95 to 1.25, alternatively 1.25 to 1.50, or any combination of such ranges.

[0056] In some embodiments, the lithium storage layer, for example a continuous porous lithium storage layer, is made of silicon (SiN y ), Germanium (GeN y ) or tin (SnN y ) where 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 is in the range of 0.02 to 0.95, alternatively 0.02 to 0.10, alternatively 0.10 to 0.50, alternatively 0.50 to 0.95, alternatively 0.95 to 1.20, or any combination of ranges therein. Lithium storage layers having substoichiometric nitrides of silicon are sometimes referred to as nitrogen-doped silicon or silicon-nitrogen alloys.

[0057] In some embodiments, the lithium storage layer, e.g., a continuous porous lithium storage layer, is made of silicon (SiO x N y ), Germanium (GeOx N y ), or tin (SnO x N y ), where the ratio of total 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) is in the range of 0.02 to 0.95, alternatively 0.02 to 0.10, alternatively 0.10 to 0.50, alternatively 0.50 to 0.95, or any combination of ranges therein.

[0058] In some embodiments, the substoichiometric oxides, nitrides, or oxynitrides are provided by a CVD process, including but not limited to a PECVD process. The oxygen and nitrogen may be provided uniformly within the continuous porous lithium storage layer, or alternatively, the oxygen or nitrogen content may be varied as a function of the storage layer thickness.

[0059] CVD CVD generally involves flowing a precursor gas, or gasified liquid for direct liquid injection CVD, or gas and liquid into a chamber that typically contains one or more objects to be coated, which is heated. Chemical reactions occur on and near the hot surface, resulting in the deposition of a thin film on the surface. This is accompanied by the production of chemical by-products that are exhausted from the chamber along with unreacted precursor gas. As expected with the wide variety of materials deposited and the wide range of applications, there are many variations of CVD that can be used to form lithium storage layers, surface layers or sublayers, auxiliary layers (see below), or other layers. It may be carried out in hot or cold wall reactors, at sub-torr to above atmospheric total pressures, with and without carrier gas, and at temperatures typically ranging from 100 to 1600°C in some embodiments. There are also various enhanced CVD processes that involve the use of plasma, ion, photon, laser, hot filament, or combustion reactions to increase the deposition rate and / or reduce the deposition temperature. Various process conditions can be used to control the deposition, including, but not limited to, temperature, precursor material, gas pressure, flow rates, substrate voltage bias (if applicable), and plasma energy (if applicable).

[0060] As mentioned above, lithium storage layers, such as continuous porous lithium storage layers, e.g., layers of silicon or germanium or both, may be provided by plasma enhanced chemical vapor deposition (PECVD). Compared to conventional CVD, deposition by PECVD can often be performed at lower temperatures and at higher rates, which may be advantageous for higher manufacturing throughput. In some embodiments, PECVD is used to deposit a substantially amorphous silicon layer (optionally doped) on the surface layer. In some embodiments, PECVD is used to deposit a substantially amorphous continuous porous silicon layer on the surface layer.

[0061] In a PECVD process, according to various implementations, a plasma can be generated in the chamber in which the substrate is located or upstream of the chamber and delivered into the chamber. Various types of plasma 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, combination PECVD, and microwave sources can be used. In some embodiments, magnetron-assisted RF PECVD can be used.

[0062] PECVD process conditions (temperature, pressure, precursor gases, carrier gases, dopant gases, flow rates, energy, etc.) can vary depending on the particular process and tool used, as is well known in the art.

[0063] In some implementations, the PECVD process is an expanding thermal plasma chemical vapor deposition (ETP-PECVD) process. In such a process, a plasma generating gas is passed through a direct current arc plasma generator to form a plasma, and the web or other substrate is optionally in an adjacent vacuum chamber including a current collector. A silicon source gas is injected into the plasma, and radicals are generated. The plasma is expanded through a diverging nozzle and injected into the vacuum chamber toward the substrate. An example of a plasma generating gas is argon (Ar). In some embodiments, ionized argon species in the plasma collide with silicon source molecules to form radical species of the silicon source, resulting in deposition on the current collector. Example voltage and current ranges for the DC plasma source are 60-80 volts and 40-70 amps, respectively.

[0064] Any suitable silicon source can be used to deposit silicon. In some embodiments, the silicon source can be a silane-based precursor gas, including but not limited to silane (SiH4), dichlorosilane (H2SiCl2), monochlorosilane (H3SiCl), trichlorosilane (HSiCl3), silicon tetrachloride (SiCl4), disilane, tetrafluorosilane, triethylsilane, and diethylsilane. Depending on the gas used, the silicon layer can be formed by decomposition, such as by hydrogen reduction, or by reaction with another compound. 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 is substantially free of hydrogen. In some embodiments, the gas can include argon, silane, and hydrogen, and optionally some dopant gases. In some embodiments, the gas flow ratio of argon to the combined gas flow of silane and hydrogen is at least 3.0, or alternatively at least 4.0. In some embodiments, the gas flow ratio of argon to the combined gas flow of silane and hydrogen is in the range of 3 to 5, alternatively 5 to 10, alternatively 10 to 15, alternatively 15 to 20, or any combination of ranges thereof. In some embodiments, the gas flow ratio of hydrogen gas to silane is in the range of 0 to 0.1, alternatively 0.1 to 0.2, alternatively 0.2 to 0.5, alternatively 0.5 to 1, alternatively 1 to 2, alternatively 2 to 5, or any combination of ranges thereof. In some embodiments, increasing the gas flow ratio of silane to the combined gas flow of silane and hydrogen can form more porous silicon and / or increase the rate of silicon deposition. In some embodiments, the dopant gas is borane or phosphine, and may be optionally mixed with a carrier gas.In some embodiments, the gas flow ratio 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 ranges thereof. Such gas flow ratios mentioned above may refer to relative gas flows in, for example, standard cubic centimeters per minute (SCCM). In some embodiments, the PECVD deposition conditions and gases may be varied over the course of the deposition.

[0065] In some embodiments, the temperature at the current collector during at least a portion of the time of the PECVD deposition is in the range of 20° C. to 50° C., 50° C. to 100° C., alternatively 100° C. to 200° C., alternatively 200° C. to 300° C., alternatively 300° C. to 400° C., alternatively 400° C. to 500° C., alternatively 500° C. to 600° C., or any combination of ranges therein. In some embodiments, the temperature may vary during the time of the PECVD deposition. For example, the temperature during an early period of PECVD may be higher than a later period. Alternatively, the temperature during a later period of PECVD may be higher than an earlier period.

[0066] The thickness or mass per unit area of ​​the lithium storage layer, e.g., a continuous porous lithium storage layer, depends on the storage material, the desired charge capacity, and other operational and life considerations. Increasing the thickness typically provides more capacity. If the lithium storage layer becomes too thick, electrical resistance may increase and stability may decrease. In some embodiments, the anode has a thickness of at least 0.2 mg / cm 2 , or 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 2In some embodiments, the lithium storage structure may be characterized as having an active silicon areal density of 0.2-0.5 mg / cm. 2 or 0.5-1.0mg / cm 2 or 1.0-1.5mg / cm 2 or 1.5-2mg / cm 2 or 2-3mg / cm 2 or 3-5mg / cm 2 or 5-10mg / cm 2 or 10-15mg / cm 2 or 15-20mg / cm 2 or any combination of those ranges. "Active silicon" refers to silicon in electrical communication with the current collector that is available for reversible lithium storage at the start of cell cycling, e.g., after anode "electrochemical formation" as described below. "Area density" refers to the surface area of ​​the conductive layer upon 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 silicide or electrically isolated from the current collector.

[0067] In some embodiments, the lithium storage layer, e.g., a continuous porous lithium storage layer, has an average thickness of at least 0.5 μm, alternatively at least 1 μm, alternatively at least 2.5 μm, alternatively at least 5 μm, alternatively at least 6.5 μm. In some embodiments, the lithium storage layer, e.g., a 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 lithium storage layer, e.g., a continuous porous lithium storage layer, comprises at least 80 atomic % amorphous silicon and / or has a thickness of 1 to 1.5 μm, alternatively 1.5 to 2.0 μm, alternatively 2.0 to 2.5 μm, alternatively 2.5 to 3.0 μm, alternatively 3.0 to 3.5 μm, alternatively 3.5 to 4.0 μm, alternatively 4.0 to 4.5 μm, alternatively 4.5 to 5.0 μm, alternatively 5.0 to 5.5 μm. , or 5.5 to 6.0 μm, or 6.0 to 6.5 μm, or 6.5 to 7.0 μm, or 7.0 to 8.0 μm, or 8.0 to 9.0 μm, or 9.0 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 those ranges.

[0068] In some embodiments, the lithium storage material can be formed by a physical vapor deposition (PVD) process, such as sputtering, rather than being deposited by CVD or PECVD. Although the deposition rate of sputtering is typically lower than PECVD, sputtering can be suitable for some applications, such as applications requiring a relatively low loading of active material, such as silicon. For example, in some embodiments, the lithium storage layer formed by a sputtering process, such as a continuous porous lithium storage layer, can have a thickness of less than about 15 μm, alternatively less than about 10 μm, alternatively less than 7 μm, alternatively less than 5 μm, alternatively less than 5 μm.

[0069] Other Anode Features The anode may optionally include various additional layers and features. The current collector may include one or more features to ensure that a reliable electrical connection can be made in the energy storage device. In some embodiments, an auxiliary layer is provided on top of the lithium storage structure. In some embodiments, the auxiliary layer is a protective layer to improve the life or physical durability. The auxiliary layer may be an oxide formed from the lithium storage material itself, for example, silicon dioxide in the case of silicon, or some other suitable material. The auxiliary layer may be deposited, for example, by ALD, S-ALD, CVD, i-CVD, PECVD, MLD, evaporation, sputtering, solution coating, inkjet, or any other method compatible with the anode. In some embodiments, the top surface of the auxiliary layer may correspond to the top surface of the anode.

[0070] The auxiliary layer should be suitably conductive to lithium ions and should allow lithium ions to pass into and out of the patterned lithium storage structure during charging and discharging. 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 sublayer acts as a solid electrolyte.

[0071] Some non-limiting examples of materials used in the help layer include metal oxides, nitrides, or oxynitrides, such as those containing aluminum, titanium, vanadium, zirconium, hafnium, or tin, or mixtures thereof. The metal oxides, metal nitrides, or metal oxynitrides may contain other components, such as phosphorus or silicon. Auxiliary layers include lithium phosphorus oxide (LIPON), lithium phosphate, lithium aluminum oxide, (Li,La) x Ti y O z , or Li x S yThe auxiliary layer may include a lithium-containing material such as Al2O3. In some embodiments, the auxiliary layer includes a metal oxide, metal nitride, or metal oxynitride and has an average thickness of less than about 100 nm, for example, in the range of about 0.1 to about 10 nm, or in the range of about 0.2 nm to about 5 nm. LIPON or other solid electrolyte materials with good lithium transport properties may have a thickness of more than 100 nm, or alternatively, in the range of about 1 to about 50 nm. In some embodiments, LIPON or other solid electrolytes may have a thickness of 0.1 to 0.5 μm, alternatively, 0.5 to 1.0 μm, alternatively, 1 to 1.5 μm, alternatively, 1.5 to 2.0 μm, alternatively, 2.0 to 2.5 μm, alternatively, 2.5 to 3.0 μm, alternatively, 3.0 to 3.5 μm, alternatively, 3.5 to 4.0 μm, alternatively, 4.0 to 4.5 μm, alternatively, 4.5 to 5.0 μm, alternatively, 5.0 to 5.5 μm, alternatively, 5. It may have a thickness in the range of 5 to 6.0 μm, alternatively 6.0 to 6.5 μm, alternatively 6.5 to 7.0 μm, alternatively 7.0 to 8.0 μm, alternatively 8.0 to 9.0 μm, alternatively 9.0 to 10 μm, alternatively 10 to 15 μm, alternatively 15 to 20 μm, alternatively 20 to 25 μm, alternatively 25 to 30 μm, alternatively 30 to 40 μm, alternatively 40 to 50 μm, or any combination of those ranges.

[0072] In some embodiments, the lithium storage layer, e.g., a continuous porous lithium storage layer, may be at least partially prelithiated prior to the first electrochemical cycle after battery assembly, or alternatively prior to battery assembly. That is, some lithium may be incorporated into the lithium storage layer to form a lithiated storage layer even before the first battery cycle. In some embodiments, the lithiated storage layer may be divided into smaller structures, including but not limited to platelets, that remain electrochemically active and continue to reversibly store lithium. Note that "lithiated storage layer" simply means that at least a portion of the potential storage capacity of the lithium storage layer is filled, but not necessarily all of it. In some embodiments, the lithiated storage layer may contain lithium in the range of 1% to 5%, alternatively 5% to 10%, alternatively 10% to 15%, alternatively 15% to 20%, alternatively 20% to 30%, alternatively 30% to 40%, alternatively 40% to 50%, alternatively 50% to 60%, alternatively 60% to 70%, alternatively 70% to 80%, alternatively 80% to 90%, alternatively 90% to 100% of the theoretical lithium storage capacity of the lithium storage layer, or any combination of such ranges. In some embodiments, the surface layer may scavenge some of the lithium, and such scavenge may need to be taken into account in order to achieve the desired lithium range in the lithiated storage layer.

[0073] In some embodiments, prelithiation may include depositing lithium metal onto the lithium storage layer, e.g., a continuous porous lithium storage layer, or between one or more lithium storage sublayers, or both, for example, by evaporation, e-beam, or sputtering. Alternatively, prelithiation may include contacting the anode with a reducible lithium organic compound (e.g., lithium naphthalene, n-butyl lithium, etc.). In some embodiments, prelithiation may include incorporating lithium by electrochemical reduction of lithium ions in a prelithiation solution. In some embodiments, prelithiation may include a heat treatment to promote diffusion of lithium into the lithium storage layer.

[0074] In some embodiments, the anode may be heat treated prior to battery assembly. In some embodiments, heat treating the anode may improve adhesion or electrical conductivity of various layers, for example, by inducing migration of atoms from a metal or optional auxiliary layer from the current collector into the lithium storage layer.

[0075] In some embodiments, the lithium storage layer, e.g., a continuous porous lithium storage layer, comprises at least 0.05 atomic % of one or more transition metals, alternatively at least 0.1 atomic %, alternatively at least 0.2 atomic %, alternatively at least 0.5 atomic %, alternatively at least 1 atomic % of copper. In some embodiments, the lithium storage layer, e.g., a continuous porous lithium storage layer, comprises less than about 10 atomic %, alternatively less than 5 atomic %, alternatively less than 2 atomic %, alternatively less than 1 atomic %, alternatively less than 0.5 atomic %, alternatively less than 3 atomic % of one or more transition metals. In some embodiments, the lithium storage layer, e.g., a continuous porous lithium storage layer, may comprise one or more transition metals in an atomic % range of 0.05-0.1%, alternatively 0.1-0.2%, alternatively 0.2-0.5%, alternatively 0.5-1%, alternatively 1-2%, alternatively 2-3%, alternatively 3-5%, alternatively 5-7%, alternatively 7-10%, or any combination of these ranges. In some embodiments, the aforementioned ranges of atomic percent of the transition metal(s) are at least 1 μm 2The cross-sectional area of ​​the lithium storage layer may correspond to a cross-sectional area of ​​1000 nm, which may be measured, for example, by energy dispersive X-ray spectroscopy (EDS). In some embodiments, the transition metal atomic % values ​​above may represent the atomic % of one transition metal, or alternatively, may correspond to the combined atomic % when a mixture of transition metals is present. Some non-limiting examples of transition metals that may be present in the lithium storage layer include copper, nickel, titanium, vanadium, and molybdenum. In some embodiments, there is a gradient in which the concentration of the transition metal in the portion of the lithium storage layer closer to the current collector is higher than the portion more distant from the current collector. In some embodiments, the lithium storage layer, for example, the continuous porous lithium storage layer, may include the same transition metal as that found in the conductive layer or surface layer transition metalate. In some cases, one or more transition metals may be provided to the lithium storage layer by heat treatment to cause migration of the metal into the lithium storage layer, although other methods such as co-deposition of the lithium storage material and the metal may be used.

[0076] In some embodiments, heat treating the anode may be performed in a controlled environment with low oxygen and water (e.g., partial pressure less than 10 ppm or less than 0.1 Torr, or less than 0.01 Torr to prevent degradation). In some embodiments, the anode heat treatment may be performed using an oven, an infrared heating element, contact with a hot plate, or exposure to a flash lamp. The anode heat treatment temperature and time 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 950°C, alternatively 100°C to 250°C, alternatively 250°C to 350°C, alternatively 350°C to 450°C, alternatively 450°C to 550°C, alternatively 550°C to 650°C, alternatively 650°C to 750°C, alternatively 750°C to 850°C, alternatively 850°C to 950°C, or combinations of these ranges. In some embodiments, the heat treatment may be applied for a period of 0.1 to 120 minutes.

[0077] In some embodiments, one or more of the processing steps described above may be performed using a roll-to-roll process, where the conductive layer or current collector is in the form of a roll of rolled film, such as a metal foil, mesh, or fabric.

[0078] Battery Features The above description is primarily directed to the anode / negative electrode of a lithium ion battery (LIB). A LIB typically includes a cathode / positive electrode, an electrolyte in contact with both the anode and the cathode, and a current separator (if a solid electrolyte is not used) disposed between the anode and the cathode. As is known, a battery can be formed into a multi-layer stack of anodes and cathodes with an intervening separator. In some cases, the multi-layer stack may have active material coated on both sides of the current collectors of the anode and the cathode, respectively. Alternatively, the anode / cathode stack can be formed into a so-called jelly roll. Such a structure is provided in a suitable housing with the desired electrical contacts.

[0079] Cathode Positive electrode (cathode) materials include lithium metal oxides or compounds (e.g., LiCoO2 (also known as "LCO"), LiFePO4 (also known as "LFP"), LiNi x Mn x O4 (also known as "LNMO"), LiMnO2, LiNiO2, LiMn2O4 (also known as "LMO"), LiCoPO4, LiNi x Co y Mn z O2 (also known as "NMC"), LiNi x Co y Al zExamples of cathode active materials include, but are not limited to, O2 (also known as "NCA"), LiFe2(SO4)3, or Li2FeSiO4), fluorinated carbon, metal fluorides such as iron fluoride (FeF3), metal oxides, sulfur, selenium, and combinations thereof. The cathode active material may act, for example, by intercalation, conversion, or combination. The cathode active material is typically provided on or in electrical communication with an electrically conductive cathode current collector. In some embodiments, the cathode current collector may include a metal foil, mesh, or sheet of an electrically conductive material such as aluminum. In some cases, the cathode current collector may include a metal coating, such as aluminum, provided on an electrically insulating polymer (one or both sides). In some cases, the cathode current collector may be a film, paper, fiber, or sheet including conductive carbon such as carbon black, carbon nanotubes, graphene, graphene oxide, reduced graphene oxide, and graphite. In some embodiments, the conductive layer may be in the form of a foil, mesh, or sheet of conductive material. In some embodiments, the cathode current collector may include a conductive layer and a transition metalate surface layer according to the present application.

[0080] Current Separator Current separators allow ions to flow between the anode and cathode but prevent direct electrical contact. Such separators are typically porous sheets that, along with the electrolyte, occupy at least a portion of the space between the anode and cathode. Depending on the cell design, the current separator may be in physical contact with the cathode, the anode, both the anode and the cathode, or may not be in physical contact with either the anode or the cathode. Non-aqueous lithium-ion separators are mono- or multi-layer polymer sheets, typically made of polyolefins, especially for small batteries. Most commonly, they are based on polyethylene or polypropylene, although polyethylene terephthalate (PET) and polyvinylidene fluoride (PVdF) can also be used. For example, the separators can have a porosity of >30%, low ionic resistivity, a thickness of about 10-50 μm, and high bulk pin puncture strength. The separator may alternatively comprise a glass material, a ceramic material, a ceramic material embedded in a polymer, a ceramic coated polymer, or some other composite or multi-layer structure, for example to provide greater mechanical and thermal stability.

[0081] electrolyte The electrolyte in a lithium-ion cell may be liquid, solid, or gel. A typical liquid electrolyte includes one or more solvents and one or more salts, at least one of which contains lithium. During the first few charging cycles (sometimes called formation cycles), the organic solvent and / or electrolyte may partially decompose on the negative electrode surface to form a SEI (solid-electrolyte-interphase) layer. The SEI is generally electrically insulating but ionically conductive, thereby allowing lithium ions to pass through. The SEI may reduce electrolyte decomposition during later charging cycles.

[0082] Some non-limiting examples of suitable non-aqueous solvents for some lithium-ion cells include cyclic carbonates (e.g., ethylene carbonate (EC), fluoroethylene carbonate (FEC), propylene carbonate (PC), butylene carbonate (BC), and vinyl ethylene carbonate (VEC)), vinylene carbonate (VC), lactones (e.g., gamma-butyrolactone (GBL), gamma-valerolactone (GVL), and alpha-angelicalactone (AGL)), linear carbonates (e.g., dimethyl carbonate (DMC), methyl ethyl carbonate (MEC, commonly abbreviated as EMC), diethyl carbonate (DEC), methyl propyl carbonate (MPC), dipropyl carbonate (DPC), methyl ethyl carbonate (MEC), diethyl carbonate (DEC), methyl propyl carbonate (MPC), dipropyl carbonate (DPC), methyl ethyl carbonate (MPC), dipropyl ethyl ... 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.

[0083] Non-aqueous liquid solvents can be used in combination. These combinations include, for example, cyclic carbonate-chain carbonate, cyclic carbonate-lactone, cyclic carbonate-lactone-chain carbonate, cyclic carbonate-chain carbonate-lactone, cyclic carbonate-chain carbonate-ether, cyclic carbonate-chain carbonate-chain ester, and the like. In some embodiments, the cyclic carbonate can be combined with a linear ester. The cyclic carbonate may also be combined with a lactone or a linear ester. In some embodiments, the weight 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.

[0084] Salts for liquid electrolytes include LiPF6, LiBF4, LiClO4LiAsF6, 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 with cyclic alkyl groups (e.g., (CF2)2(SO2) 2x Li and (CF2)3(SO2) 2x Li), LiFSI (lithium bis(fluorosulfonyl)imide), LiTDI (lithium 4,5-dicyano-2-(trifluoromethyl)imidazole), and combinations thereof.

[0085] In some embodiments, the total concentration of the lithium salt in the liquid non-aqueous solvent (or combination of solvents) is at least 0.3 M, alternatively at least 0.7 M. The upper concentration limit may be determined by solubility limits and the operating temperature range. In some embodiments, the concentration of the salt is about 2.5 M or less, alternatively about 1.5 M or less. In some embodiments, the electrolyte may include a saturated solution of a lithium salt and an excess of a solid lithium salt.

[0086] In some embodiments, the battery electrolyte includes a non-aqueous ionic liquid and a lithium salt. Additives may be included in the electrolyte to perform various functions, such as stabilizing the battery. For example, additives such as polymerizable compounds with unsaturated double bonds can be added to stabilize or modify the SEI. Certain amine or borate compounds can act as cathode protectants. Lewis acids can be added to stabilize fluorine-containing anions such as PF6. Safety protectants include those to protect against overcharging, such as anisole, or those that act as flame retardants, such as alkyl phosphates.

[0087] The solid electrolyte may be used without a separator since it itself functions as a separator. It is electrically insulating, ionically conductive, and electrochemically stable. In the solid electrolyte configuration, a lithium-containing salt is used, which can be the same as in the liquid electrolyte cell described above, but is held in a solid polymer composite rather than dissolved in an organic solvent. Examples of solid polymer electrolytes are polyvinylidene fluoride (PVDF) or copolymers of chlorides or their derivatives, poly(chlorotrifluoroethylene), poly(ethylene-chlorotrifluoro-ethylene), or poly(fluorinated ethylene-propylene), polyethylene oxide (PEO) and oxymethylene-linked PEO, PEO-PPO-PEO crosslinked with trifunctional urethane, poly(bis(methoxy-ethoxy-ethoxide))-phosphazene (MEEP), triol-type PEO crosslinked with difunctional urethane, poly((oligo)oxyethylene)methacrylate-co-acrylate ... The electrolyte may be an ionically conductive polymer prepared from monomers containing atoms with lone pairs of electrons available for the lithium ions of the electrolyte salt to attach to and migrate between during conduction, such as alkali metal methacrylates, polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polymethylacrylonitrile (PMAN), polysiloxanes 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 any physical mixtures of polymers. Other low conductive polymers that can 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 include small amounts of organic solvents (e.g., those 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.

[0088] In some embodiments, the original uncycled anode may undergo structural or chemical changes during electrochemical charge / discharge, e.g., from normal battery use or from a previous "electrochemical formation step." As known in the art, the electrochemical formation step is generally used to form the initial SEI layer and involves relatively mild conditions of low current and limited voltage. The modified anode partially prepared from such electrochemical charge / discharge cycles may still have superior performance characteristics, despite such structural and / or chemical changes, compared to the original uncycled anode. In some embodiments, the lithium storage layer of the cycled anode may no longer appear as a continuous layer, but instead as isolated pillars or islands, generally with an average aspect ratio of less than 2. Without being bound by theory, in the case of amorphous silicon, a small amount may exfoliate upon cycling in high stress regions. Alternatively, or in addition, the structural changes upon lithiation and delithiation may be asymmetric, resulting in such islands or columns.

[0089] In some embodiments, the electrochemical cycling conditions may be set to utilize only a portion of the theoretical charge / discharge capacity of silicon (3600 mAh / g). In some embodiments, the electrochemical charge / discharge cycle may be configured to utilize 400-600 mAh / g, alternatively 600-800 mAh / g, alternatively 800-1000 mAh / g, alternatively 1000-1200 mAh / g, alternatively 1200-1400 mAh / g, alternatively 1400-1600 mAh / g, alternatively 1600-1800 mAh / g, alternatively 1800-2000 mAh / g, alternatively 2000-2200 mAh / g, alternatively 2200-2400 mAh / g, alternatively 2400-2600 mAh / g, alternatively 2600-2800 mAh / g, alternatively 2800-3000 mAh / g, alternatively 3000-3200 mAh / g, alternatively 3200-3400 mAh / g, or any combination of ranges therein. EXAMPLES

[0090] PECVD Silicon was deposited on various current collectors using an Oxford Plasmalabs System 100 PECVD tool. Unless otherwise noted, depositions were performed at approximately 300 °C and RF powers ranging from approximately 225 to 300 W. The deposition gas was a mixture of silane and argon with a gas flow ratio of approximately 1 to 12, respectively. Unless otherwise noted, deposition time was 60 minutes, resulting in a porous amorphous silicon layer approximately 10 to 12 μm thick on the current collectors.

[0091] Comparison anode C-1 The current collector sample CC-1 is R a = 0.164 μm and R z The copper foils were 26 μm thick with a surface roughness of =1.54 μm. CC-1 did not have the surface layer of the present disclosure. An attempt was made to deposit silicon on one side of CC-1 using the PECVD conditions described above. In this comparative example, silicon deposition was stopped after 30 minutes. The silicon did not adhere sufficiently for electrochemical testing and was not further characterized.

[0092] Comparison Anode C-2 This test shows that the electrodeposited copper roughening feature alone is generally not sufficient to improve silicon adhesion. Copper foil A (high purity copper) had a thickness of 25 μm, a tensile strength of about 275 MPa, and a starting surface roughness R a The thickness of the foil was 167 nm. Copper foil A was first cleaned in acetone, then in IPA with sonication for 10 min, then rinsed with DI water. The foil was treated with 10% concentrated sulfuric acid for 30 s, rinsed with DI water, and placed in an electrodeposition fixture. The fixture was immersed in a bath of 0.01 M CuSO4(aq) containing 1 M H2SO4. Electrodeposition on the foil was carried out using a plating fixture such that only one side of the foil was exposed for electrodeposition. The counter electrode was a platinum / niobium mesh 1.9 cm away from the foil. The current was 100 mA / cm 2 for 100 seconds (conditions suitable for depositing copper roughened features), the foil was removed, rinsed with DI water, and air dried. Surface Roughness R a is 246 nm, and the surface roughness R z The thickness was 2.3 μm. When the silicon was deposited by PECVD as described above, it peeled off easily.

[0093] Example Anode In some tests, the current collector was 20 μm thick, had a tensile strength in the range of about 690 to 860 MPa, a yield strength greater than about 655 MPa, and an initial surface roughness R of 280 nm. a A copper foil was prepared from copper foil B (rolled C70250 alloy, sometimes referred to as CuNi3Si) having a thickness of 100 nm. Copper foil B was first cleaned by rubbing both sides of the foil with a melamine-formaldehyde foam soaked in tri(propylene glycol) methyl ether to remove the organic corrosion resistant layer. Copper foil B was sonicated for 10 min in acetone and then for 10 min in ethyl alcohol. The sample was rinsed in DI water, immersed in 10% sulfuric acid for 30 s, and rinsed with water. The foil was placed in an electrodeposition fixture designed for double-sided deposition. The fixture was immersed in a bath of 0.01 M CuSO4(aq) with 1 M H2SO4. The current was 20 mA / cm 2The foil was then supplied with a current of 10 mA / cm for 500 s (conditions suitable for depositing copper roughened features). The fixture was then placed in a bath of 0.4 M CuSO(aq) and 1 M HSO and supplied with a current of 10 mA / cm. 2 A current density of 100 μm was applied for 100 seconds. This second copper deposition may serve to overcoat the copper roughened features and bond them to the foil. The fixture was then removed and rinsed with DI water. Modified copper foil B′ was then used to perform the surface layer formation process described below. In some cases, copper foil B′ may have a SEM cross section similar to that shown in FIG. 6A or may have a perspective view as shown in FIG. 9 produced in a similar manner.

[0094] In some tests, the current collector included a copper roughened feature and a chromate corrosion-resistant coating, was 18 μm thick, had a tensile strength of about 414 MPa, and had a surface roughness R of 406 nm. a A copper foil was prepared from copper foil C having a surface roughness of 100 nm. An SEM of copper foil C is shown in FIG. 10 and reveals copper roughening features, which can be characterized as nodular or nanopillar-like features. Copper foil C may have an SEM cross section similar to that shown in FIG. 6B. To clean and remove the chromate corrosion resistant coating, copper foil C was sonicated in acetone for 10 minutes and then in ethyl alcohol for 10 minutes. The sample was rinsed with DI water, immersed in 10% sulfuric acid for 30 seconds, and rinsed with water to form copper foil C'. Copper foil C' was then used in subsequent processing to form a surface layer as described below. An SEM of copper foil C' was not taken, but is expected to be similar to that of copper foil C.

[0095] It should be noted that neither copper foil B' nor C' by itself (without further modification) is commercially viable as a current collector due to the absence of any anticorrosive coating, resulting in the formation of a non-uniform copper oxide layer on the surface over time. In some cases, at high temperatures and low pressures such as those sometimes used in PECVD, the copper oxide can cause potential contamination of the PECVD equipment. Furthermore, while the copper oxide may allow for some adhesion of silicon, the non-uniformity can cause quality control issues. In some embodiments, the surface layer of the present disclosure can also act as an anticorrosive coating. Also, all of the anode current collectors in the following examples are R a It should also be noted that the surface had a roughness of >250 nm.

[0096] Example Anode E-1 Copper foil C' was treated with a coating solution containing vanadate as the transition metalate to form a surface layer. Specifically, the treatment included immersing copper foil C' in a solution containing 10 g / L H3PO4, 4 g / L NaVO3, 7 g / L ZnCl2, and 2 mL / L ammonia solution at 50°C for 5 minutes without forced convection. The sample was then rinsed with DI water and dried in air. Silicon was deposited on the surface layer modified current collector using the conditions described above.

[0097] Example Anode E-2 This sample was similar to E-1 except that the immersion time was 10 minutes instead of 5 minutes.

[0098] Example Anode E-3 This sample was similar to E-1, except that the immersion time was 15 minutes instead of 5 minutes. Chemical analysis of the treated foil prior to silicon deposition revealed a surface layer of approximately 350 mg / m 2 of vanadium and about 150 mg / m 2 An SEM of the foil before silicon deposition is shown in Figure 11. While the roughened features are still clearly evident, the coating process in this example has significantly changed the physical appearance, making it rounder and slightly wider than before the conversion process.

[0099] Example Anode E-4 Copper foil C' was treated with a coating solution containing vanadate and molybdate as transition metalates to form a surface layer. Specifically, the treatment included immersing copper foil C' in a solution containing 10 g / L H3PO4, 4 g / L NaVO3, 7 g / L ZnCl2, 2 mL / L ammonia solution, and 1.8 g / L ammonium molybdate tetrahydrate at 50°C for 5 minutes without forced convection. The sample was then rinsed with DI water and dried in air. Silicon was deposited on the surface layer modified current collector using the conditions described above.

[0100] Example Anode E-5 This sample was similar to E-4, except that the immersion time was 10 minutes instead of 5 minutes. Chemical analysis of the treated foil prior to silicon deposition revealed a surface layer of approximately 170 mg / m 2 of vanadium and about 90 mg / m 2 Molybdenum may be present, but at about 7 mg / m 2 was below the detection limit.

[0101] Example Anode E-6 Copper foil C' was treated with a coating solution containing tungstate as the transition metalate to form a surface layer. Specifically, the treatment involved immersion for 10 minutes at room temperature in a sodium tungstate solution prepared by combining 49.48 g of Na2WO4.2H2O with up to 500 ml of DI water adjusted to pH 3 with concentrated H3PO4. The foil was turned over every minute. The sample was then rinsed with DI water and dried in air. Chemical analysis revealed that the tungsten in the surface layer was approximately 30 mg / m 2 The results showed that the concentration of Cr in the surface layer was below the detection limit of 1000 ppm. Silicon was deposited onto the surface layer modified current collector using the conditions described above.

[0102] Example Anode E-7 The copper foil C' was treated with a coating solution containing tungstate as a transition metalate to form a surface layer. Specifically, the treatment was carried out using sodium tungstate. . 10g / L Tungstate (WO4) from 2H2O, Manganese Acetate . 5g / L manganese from 4H2O and zinc acetate . The test included immersion in a zinc / manganese / tungstate solution containing 2 g / L zinc from 2H2O (all in DI water, pH adjusted to 2 with H2SO4) for 10 minutes with turning every minute. The samples were then rinsed with DI water and dried in air. Silicon was deposited onto the surface layer modified current collector using the conditions described above.

[0103] Example Anode E-8 This sample was similar to E-7 except that the temperature of the solution was 60°C.

[0104] Example Anode E-9 This sample was similar to E-8 except that Copper Foil B' was used instead of Copper Foil C'.

[0105] Example Anode E-10 The copper foil C' was treated with a coating solution containing molybdate as a transition metalate to form a surface layer. Specifically, the treatment consisted of 81 mg / L Ca from calcium acetate, 97 mg / L Zn from zinc acetate, 190 mg / L MoO4 from sodium molybdate, and 2- , 3.27 mg / L PO4 from sodium phosphate 3- The procedure involved immersion at room temperature for 30 minutes with stirring in a calcium zinc molybdate solution containing 100% phosphate, ...

[0106] Example Anode E-11 This sample was similar to E-10, except that the temperature of the solution was 60° C. and the immersion time was 10 minutes. Chemical analysis of the treated foil revealed that the molybdenum in the surface layer was approximately 7 mg / m 2 The SEM of the foil before silicon deposition is shown in Figure 12. The roughening features appear very similar to those in Figure 9, suggesting that the coating process forms a relatively thin surface layer, which is also consistent with the chemical analysis.

[0107] Example Anode E-12 The copper foil C' was treated with a coating solution containing molybdate as the transition metalate to form a surface layer. In particular, the treatment consisted of dissolving 2.242 g of sodium phosphate and 1.512 g of sodium molybdate in DI water and dissolving them in diluted HPO 4 Adjust the pH to 7.6 and dilute everything to 500 ml to prepare 3g / L PO4 3- / 2g / L MoO4 2- The process involved immersion in the solution for 1 hour at room temperature. The samples were then rinsed with DI water and dried in air. Silicon was deposited onto the surface layer modified current collector using the conditions described above.

[0108] Example Anode E-13 This sample was similar to E-12 except that the temperature of the solution was 60° C. and the immersion time was 60 minutes.

[0109] Example Anode E-14 The copper foil C' was treated with a coating solution containing niobate as a transition metalate to form a surface layer. Specifically, the treatment consisted of 32.6 g of C4H4NNbO9 per liter of solution. . The deposition conditions included immersion at 60 °C for 5 min in an ammonium niobate oxalate solution prepared by dissolving 1,000 niobium phosphate (XHO). The pH of the solution was 0.9. The samples were then rinsed with DI water and dried in air. Silicon was deposited on the surface layer modified current collectors using the conditions described above.

[0110] Example Anode E-15 This sample was similar to E-14 except that the immersion time was 10 minutes.

[0111] Example Anode E-16 Copper foil C' was treated with a coating solution containing hexafluorotitanate as the transition metalate to form a surface layer. Specifically, the treatment involved immersion at 60 °C for 8 min in a solution containing 12.1 g / L K2TiF6 at pH 2.5 (with the addition of HNO3). Silicon was deposited on the surface layer modified current collector using the conditions described above except that the Si deposition time was 40 min instead of 60 min, resulting in a porous amorphous silicon layer current collector approximately 7-8 μm thick.

[0112] Example Anode E-17 This sample was similar to E-16, but prepared on a different day.

[0113] Example Anode E-18 This sample was similar to E-12, but was prepared on a different day.

[0114] Example Anode E-19 This sample was similar to E-10 except that the immersion time was 5 minutes.

[0115] Example Anode E-20 This sample was similar to E-19 except that the pH was adjusted to 3.5 and the soak time was 10 minutes.

[0116] Example Anode E-21 This sample was similar to E-12 except the immersion time was 1 minute.

[0117] Example Anode E-22 This sample was similar to E-21 except that the immersion time was 35 seconds.

[0118] Example Anode E-23 This sample was similar to E-21 except that the pH was adjusted to 3.5 and the soak time was 4 minutes.

[0119] Example Anode E-24 This sample was similar to E-23 except the temperature was increased to 60° C. and the soak time was 5 minutes.

[0120] Example Anode E-25 This sample was similar to E-23 except the temperature was increased to 45° C. and the immersion time was 9 seconds.

[0121] Example Anode E-26 This sample was similar to E-25 except the temperature was increased to 45° C. and the soak time was 18 seconds.

[0122] Electrochemical Testing - Half Cell Half-cells were constructed using a 0.80 cm diameter punch for each anode. Lithium metal served as a counter electrode separated from the test anode using a Celgard™ separator. The standard electrolyte solution ("Standard") contained a) 88 wt% 1.2 M LiPF6 in 3:7 EC:EMC (by weight), b) 10 wt% FEC, and 2 wt% VC. The anodes were first subjected to an electrochemical formation step. As is known in the art, the electrochemical formation step is used to form an initial SEI layer. Relatively mild conditions of low current and / or limited voltage may be used to ensure that the anode is not overly stressed. In this example, the electrochemical formation included some cycling over a wide voltage range (0.01 or 0.06 to 1.2 V) with C-rates ranging from C / 20 to C / 10. The total active silicon available for reversible lithiation (mg / cm 2 ) and total charge capacity (mAh / cm 2) was determined from the electrochemical formation step data. Formation losses were calculated by dividing the change in effective areal charge capacity (initial charge capacity minus final formation discharge capacity) by the initial areal charge capacity. Silicon has a theoretical charge capacity of about 3600 mAh / g when used in lithium ion batteries, but it has been found that cycle life can be improved if only a portion of the total capacity is used. For all anodes, the performance cycle was set to use a portion of the total capacity, typically in the range of about 1000-1600 mAh / g. The performance cycle protocol for Examples 1-16a and 17 included a 1C charge (considered in the industry to be an aggressive charge) to approximately 5% state of charge and a 1C discharge (also considered in the industry to be an aggressive discharge). A 10 minute pause was provided between the charge and discharge cycles. In Example 18a, the protocol was similar but used a C / 3 discharge to approximately 15% state of charge. Another example cycling protocol included a 3.2C charge (considered in the industry to be a very aggressive charge) and a C / 3 discharge to approximately 15% state of charge, with a 10 minute rest between charge and discharge cycles.

[0123] Table 1 summarizes the properties and cycling performance of example anodes. In some commercial applications, the anodes have a capacity of at least 1.5 mAh / cm 2and must be capable of being charged at a rate of 1C with a cycle life of at least 100 cycles, meaning that the charge capacity must not drop below 80% of the initial charge capacity after 100 cycles. The number of cycles required for an anode to drop below 80% of the initial charge is generally referred to as its "80% SoH ("state of health") cycle life". All example anodes were found to meet and exceed the above criteria, even with an aggressive 1C discharge. When discharged at C / 3, many examples had cycle lives of over 1000 cycles, at which point testing was stopped. Examples 25 and 26 were past 360 cycles and were still cycling at the time of this application. It should also be noted that the formation loss for all of the example anodes was less than about 25%, which is generally acceptable. Most of the example anodes had formation losses less than about 15%, and many even less than 10%. Generally, formation losses of less than 15% are considered very good and can sometimes indicate a very stable a-Si anode. Although there are exceptions, it has often been observed that high formation losses sometimes indicate an unstable anode. It is noted that the vanadate treated examples generally have higher formation losses than the other samples. In this case, the formation losses may be due to some irreversible reactions involving the surface layer (which may be thicker in the vanadate treated samples than in the other samples) and may not necessarily mean poor stability.

[0124] Surprisingly, it has been found that current collectors with very short surface layer treatment times, for example, 1 minute or less (just 9 seconds) provide effective surface layers. Although longer treatments, such as 1 hour, can be effective, shortening the treatment time can be more compatible with reducing manufacturing costs and enabling roll-to-roll processing. In some cases, the surface layer treatment time can be 10 minutes or less, or 5 minutes or less, or 1 minute or less, or 30 seconds or less, or 10 seconds or less.

[0125] In some embodiments, the anodes of the present disclosure have a charge rate of at least 1C and a discharge rate of at least 1C of at least 2.0 mAh / cm 2 and an 80% SoH cycle life of at least 100 cycles. In some embodiments, the anodes of the present disclosure can provide at least about 2 mAh / cm at 1C charge and 1C discharge. 2 When tested at 1000 V, the cycle life may be at least 200 cycles, or at least 300, 400, or 500 cycles.

[0126] In some embodiments, the anodes of the present disclosure have a capacity of at least 1.5 mAh / cm at a charge rate of at least 3C and a discharge rate of at least C / 3. 2 and an 80% SoH cycle life of at least 300 cycles, or alternatively at least 400, 500, 750, or 1000 cycles. [Table 1]

[0127] Although the present anodes have been discussed with reference to batteries, in some embodiments the present anodes may be used in hybrid lithium ion capacitor devices.

[0128] Enumerated Embodiments Still further embodiments herein include those listed below.

[0129] 1. An anode for an energy storage device, the anode comprising: a) a current collector comprising a conductive layer and a surface layer disposed on and in contact with the conductive layer, the surface layer comprising a transition metalate other than chromate; b) a lithium storage layer covering and in contact with the surface layer; The lithium storage layer is (i) has an average thickness of at least 1 μm; (ii) contains at least 40 atomic percent silicon, germanium, or a combination thereof; (iii) an anode that is substantially free of a carbon-based binder;

[0130] 2. The current collector has a surface roughness R a ≧250 nm.

[0131] 3. The anode of any one of the preceding claims, wherein the transition metalate comprises Sc, Ti, V, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ta, or W.

[0132] 4. The anode of any one of embodiments 1 to 3, wherein the surface layer further comprises chromium.

[0133] 5. The anode of any one of embodiments 1 to 4, wherein the transition metalate comprises an oxometalate.

[0134] 6. The anode of embodiment 5, wherein the oxometalate comprises a titanate, vanadate, molybdate, tungstate, or niobate.

[0135] 7. The anode of embodiment 6, wherein the surface layer comprises molybdate and phosphorus.

[0136] 8. The anode of embodiment 7, wherein the phosphorus is in the form of phosphate.

[0137] 9. The anode of embodiment 7 or 8, wherein the surface layer further comprises calcium and zinc.

[0138] 10. The anode of any one of embodiments 1 to 9, wherein the surface layer comprises a composition gradient.

[0139] 11. An anode as described in any one of embodiments 1 to 10, wherein the conductive layer comprises a plurality of conductive nodular or nanopillar-like features, and the surface layer is disposed at least partially on the nodular or nanopillar-like features.

[0140] 12. The anode of embodiment 11, wherein each of the plurality of nodular or nanopillar-like features comprises copper.

[0141] 13. A current collector comprising a plurality of conductive nanopillar-like features, each nanopillar-like feature characterized by a height H, a base width B, and a maximum width W; The cross section of the current collector with a length of 20 μm is (i) at least five first type nanopillars, each first type nanopillar comprising: A) H in the range of 0.4 μm to 3.0 μm, B) B in the range of 0.2 μm to 1.0 μm; C) W / B ratio in the range of 1 to 1.5; D) H / B aspect ratio in the range of 0.8 to 4.0; E) an angle of the longitudinal axis relative to the plane of the conductive layer ranging from 60° to 90°.

[0142] 14. The cross section of a current collector with a length of 20 μm is (ii) further comprising less than four second-type nanopillars, each second-type nanopillar comprising: A) H of at least 1.0 μm; B) a W / B ratio of greater than 1.5.

[0143] 15. The anode of any one of the preceding embodiments, wherein the conductive layer comprises nickel in the nickel layer.

[0144] 16. The anode of embodiment 15, wherein the conductive layer further comprises a metal intermediate layer interposed between the nickel layer and the surface layer.

[0145] 17. The anode of embodiment 16, wherein the metallic interlayer comprises copper.

[0146] 18. The anode of embodiment 16 or 17, wherein the metallic interlayer has an average interlayer thickness that is less than 50% of the total average thickness of the conductive layers.

[0147] 19. The anode of any one of embodiments 1 to 14, wherein the conductive layer comprises copper.

[0148] 20. The anode of embodiment 19, wherein the conductive layer comprises a copper alloy comprising copper, magnesium, silver, and phosphorus.

[0149] 21. The anode of embodiment 19, wherein the conductive layer comprises a copper alloy containing copper, iron, and phosphorus.

[0150] 22. The anode of embodiment 19, wherein the conductive layer comprises a copper alloy, including brass or bronze.

[0151] 23. The anode of embodiment 19, wherein the conductive layer comprises a copper alloy comprising copper, nickel, and silicon.

[0152] 24. The anode of any one of embodiments 1-14, wherein the conductive layer comprises a titanium alloy.

[0153] 25. The anode of any one of embodiments 1-24, wherein the current collector further comprises an insulating substrate, and the conductive layer covers the insulating substrate.

[0154] 26. The anode of any one of embodiments 1 to 14, wherein the conductive layer comprises a mesh of conductive carbon.

[0155] 27. The anode of embodiment 26, wherein the conductive layer further comprises a metal intermediate layer interposed between the conductive carbon mesh and the surface layer.

[0156] 28. The anode of embodiment 27, wherein the metallic interlayer comprises copper.

[0157] 29. The anode of any one of embodiments 1 to 28, wherein the conductive layer or current collector is characterized by a tensile strength of at least 400 MPa.

[0158] 30. The anode of any one of embodiments 1 to 28, wherein the conductive layer or current collector is characterized by a tensile strength of greater than 500 MPa.

[0159] 31. The anode of any one of embodiments 1 to 28, wherein the conductive layer or current collector is characterized by a tensile strength of at least 600 MPa.

[0160] 32. The anode of any one of embodiments 1 to 28, wherein the conductive layer or current collector is characterized by a tensile strength of at least 700 MPa.

[0161] 33. The anode of any one of the preceding embodiments, wherein the conductive layer comprises a roll-formed metal foil.

[0162] 34. The anode of any one of embodiments 1-33, wherein the lithium storage layer is substantially free of high aspect ratio lithium storage nanostructures.

[0163] 35. The anode of any one of embodiments 1 to 34, wherein the lithium storage layer is a continuous porous lithium storage layer.

[0164] 36. The anode of any one of embodiments 1 to 35, wherein the lithium storage layer comprises a substoichiometric nitride of silicon.

[0165] 37. The anode of any one of embodiments 1-36, wherein the lithium storage layer comprises a substoichiometric oxide of silicon.

[0166] 38. The anode of any one of embodiments 1 to 37, wherein the lithium storage layer comprises at least 80 atomic % amorphous silicon.

[0167] 39. The anode of any one of embodiments 1 to 38, wherein the lithium storage layer comprises at least 90 atomic % amorphous silicon.

[0168] 40. The density of the lithium storage layer is 1.1-2.25 g / cm 3 40. The anode of embodiment 38 or 39, wherein

[0169] 41. The anode of any one of embodiments 1 to 37, wherein the lithium storage layer comprises up to 30% nanocrystalline silicon.

[0170] 42. The anode of any one of embodiments 1 to 41, wherein the lithium storage layer comprises columns of silicon nanoparticle aggregates.

[0171] 43. The anode of any one of embodiments 1-42, wherein the lithium storage layer further comprises boron, phosphorus, carbon, sulfur, fluorine, aluminum, gallium, indium, arsenic, antimony, or bismuth, or a combination thereof.

[0172] 44. The anode of any one of embodiments 1-43, wherein the lithium storage layer further comprises a transition metal distributed throughout at least a portion of the lithium storage layer.

[0173] 45. The anode of embodiment 44, wherein the transition metal in the lithium storage layer is present in a total concentration in the range of 0.5 to 5.0 atomic percent.

[0174] 46. ​​The anode according to embodiment 44 or 45, wherein the transition metal element contained in the lithium storage layer is also present in the conductive layer or surface layer.

[0175] 47. An anode as described in embodiment 46, wherein the transition metal contained in the lithium storage layer has a higher concentration near the surface layer than away from the surface layer.

[0176] 48. The anode of any one of embodiments 1 to 47, wherein the lithium storage layer has an average thickness of at least 2.5 μm.

[0177] 49. The anode of any one of embodiments 1 to 47, wherein the lithium storage layer has an average thickness of at least 5.0 μm.

[0178] 50. The anode of any one of embodiments 1-47, wherein the lithium storage layer has an average thickness of at least 7.0 μm.

[0179] 51. The anode of any one of embodiments 1 to 47, wherein the lithium storage layer has an average thickness in the range of 2.5 μm to 20 μm.

[0180] 52. The anode of any one of embodiments 1-51, wherein the lithium storage layer comprises less than 5 atomic % carbon.

[0181] 53. The anode of any one of embodiments 1-52, wherein the lithium storage layer comprises less than 1 atomic % carbon.

[0182] 54. The anode of any one of embodiments 1 to 53, wherein the lithium storage layer is substantially free of high aspect ratio nanostructures.

[0183] 55. The anode of any one of embodiments 1 to 54, wherein the surface layer is formed non-electrolytically by a conversion coating process.

[0184] 56. An anode according to any one of the preceding embodiments, wherein the surface layer does not contain zinc.

[0185] 57. An anode according to any one of the preceding embodiments, wherein the surface layer does not contain a silicon compound.

[0186] 58. A method of making an anode for use in an energy storage device, the method comprising: a) providing a current collector including a conductive layer and a surface layer covering and in contact with the conductive layer, the surface layer including or formed from a transition metalate other than chromate; b) depositing a lithium storage layer on the surface layer by a vapor deposition process; The lithium storage layer is (i) has an average thickness of at least 1 μm; (ii) contains at least 40 atomic percent silicon, germanium, or a combination thereof; (iii) in contact with the surface layer.

[0187] 59. The method of embodiment 58, wherein the vapor deposition process is a chemical vapor deposition process.

[0188] 60. The method of embodiment 58 or 59, wherein the deposition process is a PECVD process.

[0189] 61. The method of embodiment 60, wherein the PECVD process includes forming a capacitively coupled plasma or an inductively coupled plasma.

[0190] 62. The method of embodiment 60, wherein the PECVD process comprises a DC plasma source, an AC plasma source, an RF plasma source, a VHF plasma source, or a microwave plasma source.

[0191] 63. The method of embodiment 60, wherein the PECVD process comprises magnetron-assisted RF PECVD.

[0192] 64. The method of embodiment 60, wherein the PECVD process comprises thermal expansion plasma chemical vapor deposition.

[0193] 65. The method of embodiment 60, wherein the PECVD process comprises hollow cathode PECVD.

[0194] 66. The method of any one of embodiments 59-65, further comprising forming the lithium storage layer using a silane-based precursor gas.

[0195] 67. The method of embodiment 66, wherein the silane-based precursor gas comprises silane (SiH4).

[0196] 68. The method of embodiment 66 or 67, wherein the silane-based precursor gas comprises dichlorosilane (H2SiCl2), monochlorosilane (H3SiCl), trichlorosilane (HSiCl3), silicon tetrachloride (SiCl4), disilane, tetrafluorosilane, triethylsilane, or diethylsilane.

[0197] 69. The method of any one of embodiments 66-68, further comprising adding hydrogen gas during chemical vapor deposition.

[0198] 70. The method of embodiment 69, wherein the ratio of silane-based precursor gas to hydrogen gas is 2 or less.

[0199] 71. The method of embodiment 58, wherein the deposition process comprises physical vapor deposition.

[0200] 72. The method of embodiment 71, wherein the physical vapor deposition comprises sputtering.

[0201] 73. The method of any one of embodiments 58-72, wherein the lithium storage layer comprises less than 5 atomic % carbon.

[0202] 74. The method of any one of embodiments 58-73, wherein the lithium storage layer is substantially free of high aspect ratio lithium storage nanostructures.

[0203] 75. The method of any one of embodiments 58-74, wherein the lithium storage layer is a continuous porous lithium storage layer.

[0204] 76. The method of any one of embodiments 58-75, wherein the lithium storage layer comprises a substoichiometric nitride of silicon.

[0205] 77. The method of any one of embodiments 58-76, wherein the lithium storage layer comprises a substoichiometric oxide of silicon.

[0206] 78. The method of any one of embodiments 58-77, wherein the lithium storage layer comprises at least 80 atomic % amorphous silicon.

[0207] 79. The method of any one of embodiments 58-78, wherein the lithium storage layer comprises at least 90 atomic % amorphous silicon.

[0208] 80. The density of the lithium storage layer is 1.1-2.25 g / cm 3 80. The method of embodiment 78 or 79, wherein the range is

[0209] 81. The method of any one of embodiments 58-77, wherein the lithium storage layer comprises up to 30% nanocrystalline silicon.

[0210] 82. The method of any one of embodiments 58-81, wherein the lithium storage layer comprises columns of silicon nanoparticle aggregates.

[0211] 83. The method of any one of embodiments 58-82, wherein the lithium storage layer has an average thickness of at least 2.5 μm.

[0212] 84. The method of any one of embodiments 58-82, wherein the lithium storage layer has an average thickness of at least 5.0 μm.

[0213] 85. The anode of any one of embodiments 58-82, wherein the lithium storage layer has an average thickness of at least 7.0 μm.

[0214] 86. The anode of any one of embodiments 58 to 82, wherein the lithium storage layer has an average thickness in the range of 2.5 μm to 20 μm.

[0215] 87. The method of any one of embodiments 58-86, further comprising doping the lithium storage layer with boron, phosphorus, carbon, sulfur, fluorine, aluminum, gallium, indium, arsenic, antimony, or bismuth, or a combination thereof.

[0216] 88. The current collector has a surface roughness of R a 88. The method of any one of embodiments 58 to 87, characterized in that the wavelength is ≧250 nm.

[0217] 89. The method of any one of embodiments 58-88, wherein the transition metalate comprises Sc, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Ta, or W.

[0218] 90. The method of any one of embodiments 58-89, wherein the surface layer further comprises chromium.

[0219] 91. The method of any one of embodiments 58-90, wherein the transition metalate comprises an oxometalate.

[0220] 92. The method of embodiment 91, wherein the oxometalate comprises a titanate, vanadate, molybdate, tungstate, or niobate.

[0221] 93. The method of embodiment 92, wherein the surface layer comprises molybdate and phosphorus.

[0222] 94. The method of embodiment 93, wherein the phosphorus is in the form of phosphate.

[0223] 95. The method of embodiment 93 or 94, wherein the surface layer further comprises calcium and zinc.

[0224] 96. The method of any one of embodiments 58-95, wherein the surface layer comprises a composition gradient.

[0225] 97. The method of any one of embodiments 58 to 96, wherein the conductive layer comprises a plurality of conductive nodular or nanopillar-like features, and the surface layer is at least partially disposed on the nodular or nanopillar-like features.

[0226] 98. The method of embodiment 97, wherein each of the plurality of nodular features or nanopillar features comprises copper.

[0227] 99. A current collector comprising a plurality of conductive nanopillar-like features, each nanopillar-like feature characterized by a height H, a base width B, and a maximum width W; The cross section of the current collector with a length of 20 μm is (i) at least five first type nanopillars, each first type nanopillar comprising: A) H in the range of 0.4 μm to 3.0 μm, B) B in the range of 0.2 μm to 1.0 μm; C) W / B ratio in the range of 1 to 1.5; D) H / B aspect ratio in the range of 0.8 to 4.0; E) an angle of the longitudinal axis relative to the plane of the conductive layer in the range of 60° to 90°.

[0228] 100. The cross section of a current collector with a length of 20 μm is (ii) further comprising less than four second-type nanopillars, each second-type nanopillar comprising: A) H of at least 1.0 μm; 100. The method of embodiment 99, wherein B) a W / B ratio of greater than 1.5.

[0229] 101. The method of any one of embodiments 58-100, wherein the conductive layer comprises nickel in a nickel layer.

[0230] 102. The method of embodiment 101, wherein the conductive layer further comprises a metal intermediate layer interposed between the nickel layer and the surface layer.

[0231] 103. The method of embodiment 102, wherein the metallic interlayer comprises copper.

[0232] 104. The method of embodiment 102 or 103, wherein the metallic interlayer has an average interlayer thickness that is less than 50% of the total average thickness of the conductive layers.

[0233] 105. The method of any one of embodiments 58-100, wherein the conductive layer comprises copper.

[0234] 106. The method of embodiment 105, wherein the conductive layer comprises a copper alloy containing copper, magnesium, silver, and phosphorus.

[0235] 107. The method of embodiment 105, wherein the conductive layer comprises a copper alloy containing copper, iron, and phosphorus.

[0236] 108. The method of embodiment 105, wherein the conductive layer comprises a copper alloy, including brass or bronze.

[0237] 109. The method of embodiment 105, wherein the conductive layer comprises a copper alloy containing copper, nickel, and silicon.

[0238] 110. The method of any one of embodiments 58-100, wherein the conductive layer comprises a titanium alloy.

[0239] 111. The method of any one of embodiments 58-110, wherein the current collector further comprises an insulating substrate, and the conductive layer covers the insulating substrate.

[0240] 112. The method of any one of embodiments 58-100, wherein the conductive layer comprises a mesh of conductive carbon.

[0241] 113. The method of embodiment 112, wherein the conductive layer further comprises a metal intermediate layer interposed between the conductive carbon mesh and the surface layer.

[0242] 114. The method of embodiment 113, wherein the metallic interlayer comprises copper.

[0243] 115. The method of any one of embodiments 58-114, wherein the conductive layer or current collector is characterized by a tensile strength of at least 400 MPa.

[0244] 116. The method of any one of embodiments 58-114, wherein the conductive layer or current collector is characterized by a tensile strength of greater than 500 MPa.

[0245] 117. The method of any one of embodiments 58-114, wherein the conductive layer or current collector is characterized by a tensile strength of at least 600 MPa.

[0246] 118. The method of any one of embodiments 58-114, wherein the conductive layer or current collector is characterized by a tensile strength of at least 700 MPa.

[0247] 119. The method of any one of embodiments 58-118, wherein the conductive layer comprises a roll-formed metal foil.

[0248] 120. The method of any one of embodiments 58 to 119, wherein the surface layer is formed non-electrolytically by a conversion coating process.

[0249] 121. The method of any one of embodiments 58-120, wherein the surface layer does not contain zinc.

[0250] 122. The method of any one of embodiments 58-121, wherein the surface layer does not contain a silicon compound.

[0251] 133. A method of making a current collector for use in an energy storage device, the current collector including a conductive layer and a surface layer, the method comprising: forming a surface layer on the conductive layer by contacting the conductive layer with a mixture comprising a transition metalate compound other than chromate and one or more mixed solvents; (i) the current collector is characterized by a surface roughness Ra ≧ 250 nm; (ii) the mixture is substantially free of silicon compounds.

[0252] 134. The method of embodiment 133, wherein the conductive layer comprises copper.

[0253] 135. The method of embodiment 133 or 134, wherein the conductive layer comprises a plurality of conductive nodular or nanopillar features disposed on the conductive layer, and the surface layer is formed on the nodular or nanopillar features.

[0254] 136. The method of claim 135, further comprising electrochemically forming the conductive nodular or nanopillar-like features, the conductive nodular or nanopillar-like features comprising copper.

[0255] 137. The method of any one of embodiments 133 to 136, wherein forming the surface layer comprises a conversion coating process.

[0256] 138. The method of any one of embodiments 133 to 137, wherein forming the surface layer comprises electroplating.

[0257] 139. The method of any one of embodiments 133 to 138, wherein the transition metalate compound comprises Sc, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Ta, or W.

[0258] 140. The method of any one of embodiments 133-139, wherein the transition metallate compound comprises an oxometalate.

[0259] 141. The method of embodiment 140, wherein the oxometalate comprises a titanate, vanadate, molybdate, tungstate, or niobate.

[0260] 142. The method of embodiment 141, wherein the mixture further comprises a phosphate compound.

[0261] 143. The method of embodiment 142, wherein the mixture further comprises a calcium compound and a zinc compound.

[0262] 144. The method of any one of embodiments 133-143, wherein the pH of the mixture is in the range of 6-8.

[0263] 145. The method of any one of embodiments 133-143, wherein the pH of the mixture is less than 6.

[0264] 146. The method of any one of embodiments 133-145, wherein the contacting is carried out at a mixing temperature in the range of 15°C to 25°C.

[0265] 147. The method of any one of embodiments 133-145, wherein the contacting is carried out with the mixture at greater than 25°C and less than 65°C.

[0266] 148. The method of any one of embodiments 133-147, wherein the one or more mixed solvents comprises water in a concentration of at least 50 mol %.

[0267] 149. The method of claim 148, wherein the concentration of water is at least 90 mol %.

[0268] 150. The method of any one of embodiments 133-149, wherein the surface layer comprises a composition gradient.

[0269] 151. The method of any one of embodiments 133-150, further comprising rinsing the current collector with a rinsing agent after contacting with the mixture, the rinsing agent comprising water or an organic solvent.

[0270] 152. The method of any one of embodiments 133-151, further comprising pretreating the conductive layer prior to contacting with the mixture.

[0271] 153. The method of embodiment 152, wherein the pretreatment comprises contacting the conductive layer with an organic solvent.

[0272] 154. The method of embodiment 153, wherein the organic solvent comprises an alcohol or a ketone.

[0273] 155. The method of any one of embodiments 152-154, wherein the pretreatment comprises contacting the conductive layer with an acid.

[0274] 156. The method of any one of embodiments 152-155, wherein the pretreatment comprises heating the conductive layer to a temperature of at least 100°C.

[0275] 157. The method of any one of embodiments 152 to 156, wherein the pretreatment removes one or more corrosion-resistant layers present on the conductive layer prior to contacting with the mixture.

[0276] 158. The method of any one of embodiments 152-157, wherein the pretreatment removes oil or contaminants on the conductive layer.

[0277] 159. The method of any one of embodiments 152-158, wherein the pretreatment modifies the chemical properties of the surface of the conductive layer.

[0278] 160. The method of any one of embodiments 152-159, wherein the pretreatment increases the surface roughness of the conductive layer.

[0279] 161. The method of any one of embodiments 133-160, wherein the mixture comprises a homogeneous solution.

[0280] 162. The method of any one of embodiments 133 to 160, wherein the mixture comprises a dispersion or emulsion.

[0281] 163. The method of any one of embodiments 133-162, wherein the mixture comprises water.

[0282] 164. The method of any one of embodiments 133-163, wherein the mixture comprises an organic solvent.

[0283] 165. The method of any one of embodiments 133-164, wherein the contacting is carried out for a period ranging from 1 second to 60 seconds.

[0284] 166. The method of any one of embodiments 133-165, further comprising transporting the conductive layer to and through the mixture by roll-to-roll processing.

[0285] 167. An anode for a lithium ion energy storage device, comprising: a current collector made according to any of embodiments 133-166; and a lithium storage layer disposed over the current collector.

[0286] 168. The anode of embodiment 167, wherein the lithium storage layer comprises silicon.

[0287] 169. The anode of embodiment 167 or 168, wherein the lithium storage layer comprises at least 40 atomic % silicon, germanium, or a combination thereof.

[0288] 170. The anode of any one of embodiments 167-169, wherein the lithium storage layer comprises graphite.

[0289] 171. The anode of any one of embodiments 167-170, wherein the lithium storage layer further comprises at least 1 wt. % of a carbon-based binder.

[0290] 172. The anode of any one of embodiments 167-169, wherein the lithium storage layer is substantially free of a carbon-based binder.

[0291] 173. The lithium storage layer contains at least 80 atomic % amorphous silicon and has a density of 1.1 to 2.25 g / cm 3 173. The anode of embodiment 172, having a density in the range of

[0292] 175. The anode of embodiment 172 or 173, wherein the lithium storage layer is a continuous porous lithium storage layer.

[0293] 175. The anode of any one of embodiments 172 to 175, wherein the lithium storage layer is deposited on the current collector by a PECVD process.

[0294] 176. A method of making an anode for use in an energy storage device, the method comprising: a) providing a current collector made according to any of embodiments 133-166; b) depositing a lithium storage layer on the surface layer by a vapor deposition process; The lithium storage layer is (i) has an average thickness of at least 1 μm; (ii) contains at least 40 atomic percent silicon, germanium, or a combination thereof; (iii) in contact with the surface layer.

[0295] 177. The method of embodiment 176, wherein the vapor deposition process is a chemical vapor deposition process.

[0296] 178. The method of embodiment 176 or 177, wherein the deposition process is a PECVD process.

[0297] 179. The method of embodiment 178, wherein the PECVD process includes forming a capacitively coupled plasma or an inductively coupled plasma.

[0298] 180. The method of embodiment 178, wherein the PECVD process comprises a DC plasma source, an AC plasma source, an RF plasma source, a VHF plasma source, or a microwave plasma source.

[0299] 181. The method of embodiment 178, wherein the PECVD process includes magnetron-assisted RF PECVD.

[0300] 182. The method of embodiment 178, wherein the PECVD process comprises thermal expansion plasma chemical vapor deposition.

[0301] 183. The method of embodiment 178, wherein the PECVD process comprises hollow cathode PECVD.

[0302] 184. The method of any one of embodiments 177-183, further comprising forming the lithium storage layer using a silane-based precursor gas.

[0303] 185. The method of embodiment 184, wherein the silane-based precursor gas comprises silane (SiH4).

[0304] 186. The method of embodiment 66 or 67, wherein the silane-based precursor gas comprises dichlorosilane (H2SiCl2), monochlorosilane (H3SiCl), trichlorosilane (HSiCl3), silicon tetrachloride (SiCl4), disilane, tetrafluorosilane, triethylsilane, or diethylsilane.

[0305] 187. The method of any one of embodiments 184-186, further comprising adding hydrogen gas during chemical vapor deposition.

[0306] 188. The method of embodiment 187, wherein the ratio of silane-based precursor gas to hydrogen gas is 2 or less.

[0307] 189. The method of embodiment 176, wherein the vapor deposition process comprises physical vapor deposition.

[0308] 190. The method of embodiment 189, wherein the physical vapor deposition comprises sputtering.

[0309] 191. The method of any one of embodiments 176-190, wherein the lithium storage layer comprises less than 5 atomic % carbon.

[0310] 192. The method of any one of embodiments 176-191, wherein the lithium storage layer is substantially free of high aspect ratio lithium storage nanostructures.

[0311] 193. The method of any one of embodiments 176-192, wherein the lithium storage layer is a continuous porous lithium storage layer.

[0312] 194. The method of any one of embodiments 176-193, wherein the lithium storage layer comprises a substoichiometric nitride of silicon.

[0313] 195. The method of any one of embodiments 176-194, wherein the lithium storage layer comprises a substoichiometric oxide of silicon.

[0314] 196. The method of any one of embodiments 176-195, wherein the lithium storage layer comprises at least 80 atomic % amorphous silicon.

[0315] 197. The method of any one of embodiments 176-195, wherein the lithium storage layer comprises at least 90 atomic % amorphous silicon.

[0316] 198. The density of the lithium storage layer is 1.1-2.25 g / cm 3 198. The method of embodiment 196 or 197, wherein the range is

[0317] 199. The method of any one of embodiments 176-195, wherein the lithium storage layer comprises up to 30% nanocrystalline silicon.

[0318] 200. The method of any one of embodiments 176-199, wherein the lithium storage layer comprises columns of silicon nanoparticle aggregates.

[0319] 201. The method of any one of embodiments 176-200, wherein the lithium storage layer has an average thickness of at least 2.5 μm.

[0320] 202. The method of any one of embodiments 176-200, wherein the lithium storage layer has an average thickness of at least 5.0 μm.

[0321] 203. The anode of any one of embodiments 176 to 200, wherein the lithium storage layer has an average thickness of at least 7.0 μm.

[0322] 204. The anode of any one of embodiments 176 to 200, wherein the lithium storage layer has an average thickness in the range of 2.5 μm to 20 μm.

[0323] 205. The method of any one of embodiments 176-204, further comprising doping the lithium storage layer with boron, phosphorus, carbon, sulfur, fluorine, aluminum, gallium, indium, arsenic, antimony, or bismuth, or a combination thereof.

[0324] 206. A lithium-ion battery, a) a cathode and b) an anode according to any one of embodiments 1 to 57, an anode made according to any one of embodiments 58 to 122, an anode made according to any one of embodiments 167 to 175, or an anode made according to any one of embodiments 176 to 205; c) an electrolyte in contact with the anode and the cathode.

[0325] 207. A lithium ion battery as described in embodiment 206, wherein the anode is prelithiated.

[0326] 208. At least 1.5mAh / cm 2 208. A lithium ion battery as described in embodiment 206 or 207, characterized by operation with an initial charge capacity of at least 100 cycles at a charge rate of at least 1C and a discharge rate of at least 1C at 80% SoH cycle life.

[0327] 209. A lithium ion battery as described in embodiment 208, wherein the cycle life is at least 200 cycles.

[0328] 210. Initial charge capacity must be at least 2.0mAh / cm 2 209. A lithium ion battery as described in embodiment 208 or 209, wherein

[0329] 211. At least 1.5mAh / cm 2208. A lithium ion battery as described in embodiment 206 or 207, characterized by operation with an initial charge capacity of at least 300 cycles at a charge rate of at least 3C and a discharge rate of at least C / 3 and capable of an 80% SoH cycle life of at least 300 cycles.

[0330] 212. The lithium ion battery of any one of embodiments 206-211, wherein the cathode comprises NMC, LCO, LFP, LNMO, LMO, or NCA.

[0331] 213. The lithium ion battery of any one of embodiments 206-211, wherein the cathode comprises sulfur, selenium, or both sulfur and selenium.

[0332] 214. The lithium ion battery of any one of embodiments 206-213, further comprising a separator disposed between the anode and the cathode, and the electrolyte is a liquid.

[0333] 215. The lithium ion battery of any one of embodiments 206-214, wherein the electrolyte is a gel.

[0334] 216. The lithium ion battery of any one of embodiments 206-213, wherein the electrolyte is solid.

[0335] 217. A lithium ion battery as described in embodiment 216, wherein the electrolyte comprises a solid polymer.

[0336] 218. A lithium ion battery comprising an anode and a cathode, the anode being prepared in part by subjecting a non-cycling anode to at least one electrochemical charge / discharge cycle, the non-cycling anode comprising an anode according to any of embodiments 1-57, an anode made according to any of embodiments 58-122, an anode according to any of embodiments or 167-175, or an anode made according to any of embodiments 176-205.

[0337] The specific details of the particular embodiments may be combined in any suitable manner without departing from the spirit and scope of the embodiments of the invention, however, other embodiments of the invention may be directed to certain particular embodiments in relation to each individual aspect, or particular combinations of these individual aspects.

[0338] The above description of exemplary embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to be limited to the precise form described, and many modifications and variations are possible in light of the above teaching.

[0339] In the preceding description, for purposes of explanation, numerous details are set forth in order to provide an understanding of various embodiments of the present technology. However, it will be apparent to one skilled in the art that certain embodiments may be practiced without some of these details or with additional details.

[0340] Although several embodiments have been described, it will be recognized by those skilled in the art that various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the invention. Additionally, some well-known processes and elements have not been described to avoid unnecessarily obscuring the invention. Additionally, the details of any particular embodiment may not always be present in variations of that embodiment or may be added to other embodiments.

[0341] Where a range of values ​​is provided, unless the context dictates otherwise, it is understood that each intervening value between the upper and lower limits of that range is also specifically disclosed to the tenth of the unit of the lower limit. Each subrange between any stated or intervening value in a stated range and any other stated or intervening value in that stated range is included. The upper and lower limits of these smaller ranges may be independently included or excluded in the range, and each range in which either, neither, or both limits are included in the smaller range is also encompassed within the invention, subject to any specifically excluded limits in the stated range. Where a stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included.

[0342] 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, a reference to "a method" includes a plurality of such methods, a reference to "the anode" includes a reference to one or more anodes and equivalents thereof known to those skilled in the art, and so forth. The invention has been described in detail herein for purposes of clarity and understanding. It will be understood, however, that certain changes and modifications can be practiced within the scope of the appended claims.

[0343] All publications, patents, and patent applications cited herein are incorporated by reference in their entirety for all purposes. None is admitted to be prior art.

Claims

1. 1. An anode for an energy storage device, the anode comprising: a) a current collector comprising a conductive layer and a surface layer disposed on and in contact with the conductive layer, the surface layer comprising a transition metalate other than chromate; b) a lithium storage layer covering and in contact with the surface layer; The lithium storage layer is (i) has an average thickness of at least 1 μm; (ii) comprises at least 40 atomic percent silicon, germanium, or a combination thereof; (iii) An anode that is substantially free of carbon-based binders.

2. The current collector has a surface roughness R ａ 2. The anode of claim 1, characterized in that the thickness is ≧250 nm.

3. 2. The anode of claim 1, wherein the transition metalate comprises Sc, Ti, V, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ta, or W.

4. 10. The anode of claim 1, wherein the surface layer further comprises chromium.

5. 10. The anode of claim 1, wherein the transition metalate comprises an oxometalate.

6. 6. The anode of claim 5, wherein the oxometalate comprises a titanate, a vanadate, a molybdate, a tungstate, or a niobate.

7. 7. The anode of claim 6, wherein the surface layer comprises molybdate and phosphorus.

8. 8. The anode of claim 7, wherein the phosphorus is in the form of phosphate.

9. 8. The anode of claim 7, wherein the surface layer further comprises calcium and zinc.

10. 10. The anode of claim 1, wherein the conductive layer comprises a plurality of conductive nodular or nanopillar features, and the surface layer is at least partially disposed on the nodular or nanopillar features.

11. 10. The anode of claim 1, wherein the conductive layer comprises copper, nickel, or titanium.

12. 10. The anode of claim 1, wherein the conductive layer comprises a conductive carbon mesh.

13. 13. The anode of claim 12, wherein the conductive layer further comprises a metal intermediate layer interposed between the conductive carbon mesh and the surface layer.

14. 10. The anode of claim 1, wherein the conductive layer or current collector is characterized by a tensile strength of at least 600 MPa.

15. 10. The anode of claim 1, wherein the lithium storage layer is substantially free of lithium storage nanostructures having an aspect ratio greater than 4:

1.

16. 10. The anode of claim 1, wherein the lithium storage layer is a continuous porous lithium storage layer.

17. 10. The anode of claim 1, wherein the lithium storage layer comprises a substoichiometric nitride of silicon.

18. 10. The anode of claim 1, wherein the lithium storage layer comprises at least 80 atomic percent amorphous silicon.

19. The density of the lithium storage layer is 1.1 to 2.25 g / cm ３ 20. The anode of claim 18, wherein the anode is in the range of

20. 10. The anode of claim 1, wherein the lithium storage layer further comprises a transition metal distributed throughout at least a portion of the lithium storage layer, the transition metal being present in a total concentration in the range of 0.5 to 5.0 atomic percent.

21. 10. The anode of claim 1, wherein the lithium storage layer has an average thickness in the range of 2.5 μm to 20 μm.

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