Improvement of atomic layer deposition for high aspect ratio electrode structures

Abstract

A battery electrode that forms 3D electrode nanostructures using a VACNT forest, and a method for manufacturing the same are described. The VACNT is electrically and mechanically attached to an anode or cathode substrate, providing a large-area 3D surface for coating with active materials and highly conductive electron pathways for the cell current collector. A number of different active materials suitable for the anode and cathode in a lithium-ion battery can be used to coat individual carbon nanotubes. The high surface area provided by the VACNT forest and the nano-dimensions of the coated active materials make it possible to achieve both high energy density and high power density with the same battery. Fully conformal coating of individual CNTs can be achieved by a number of different methods, and coating with multiple active materials can be used to form nanolaminate coatings having improved electrochemical characteristics compared to a single material.

Description

Technology Field Cross-reference regarding related applications

[0001] The present application claims priority under 35 USC § 119(e) to U.S. provisional application serial number 62 / 835,308 filed April 17, 2019, U.S. provisional application serial number 62 / 835,344 filed April 17, 2019, and U.S. provisional application serial number 62 / 957,474 filed January 6, 2020, the entire contents of all said applications are incorporated herein by reference. Field of invention

[0002] The present invention relates to a lithium-ion battery having an electrode comprising vertically aligned carbon nanotubes and a method for coating an active material on the electrode. Background Technology

[0003] A lithium-ion battery comprises at least one anode, at least one cathode, and at least one separator, all of which are contained within a housing or casing. The anode, cathode, and separator may be stacked, or alternatively, the anode, cathode, and separator may be sheets rolled or folded together. The electrolyte fills the container and the space between the cathode and the anode. Lithium-ion batteries generate electricity through oxidation and reduction reactions. Lithium ions are extracted from the cathode and inserted into the anode during the charging process, and the reverse reaction occurs during the discharging process. In a conventional lithium-ion cell, each anode and cathode consists of an active material, a conductive agent, a binder, and a current collector. Electrons between the active material and the current collector can only be transferred through the conductive agent, which can result in poor energy storage performance in conventional anodes and cathodes.

[0004] Vertically aligned carbon nanotubes (VACNTs) possess unique electrical and mechanical properties ideal for use as current collectors, enabling 3D electrodes to be constructed for lithium-ion batteries. VACNTs can be grown to a height of several millimeters on a substrate, which allows for high area loading (mg / cm²) of active material without compromising electrical conductivity within the electrode. High area loading results in high area capacitance (mAh / cm²), which is essential for producing batteries with superior energy densities (Wh / L or Wh / kg) compared to those currently on the market.

[0005] 3D electrode structures, such as VACNTs on planar substrates, are recognized as offering the potential to improve both battery energy density (Wh / L) and power density (W / L), but the structures must be coated completely and uniformly with active material. This can become a problem if the aspect ratio (e.g., the height of carbon nanotubes (CNTs) divided by the space between them) is very high. Coating methods that can be used include Atomic Layer Deposition (ALD), Chemical Vapor Deposition (CVD), precipitation, melting, or sol-gel. All require complete penetration to the entire depth of the structure's "forest." High aspect ratio forests may require long ALD deposition times or multiple sol-gel coatings, both of which increase manufacturing costs. However, if the aspect ratio can be kept low, both ALD and sol-gel coatings can be applied more quickly and uniformly. However, a low aspect ratio entails a lower electrode loading (mg / cm²) of the active material, resulting in a decrease in the battery's energy density.

[0006] It is necessary to completely and uniformly coat the structure with active material. While VACNTs provide a high surface area, they are also densely packed, which makes the incorporation of active material very difficult. Dry processes such as PVD and CVD for depositing active material are unsuitable because precursors cannot penetrate the interior of the VACNT forest due to the very high aspect ratio (e.g., the height of CNTs divided by the space between them). Wet processes, such as sol-gel and hydrothermal methods, utilize harsh conditions that can damage VACNTs, particularly for the synthesis of cathode materials. The use of solvents can also affect mechanical stability and the shape of the VACNT forest, which can be problematic. ALD is considered a deposition method with great potential for producing ultra-thin conformal films where the possible film thickness and composition are controlled at the atomic level. Simple materials such as Al2O3 and TiO2 have been successfully deposited by ALD and have proven to be the best protective layers for improving the cycle life of electrode active materials. Some researchers have demonstrated the deposition of thin layers of active materials for lithium-ion batteries, such as LiMn2O4 and LiCoO2, rather than on flat substrates. However, traditional ALD methods can result in incomplete or non-uniform coating of VACNT.

[0007] Therefore, in order to overcome the aforementioned disadvantages, a method is required to coat VACNT onto an anode and cathode containing VACNT, an active material, and a protective layer. outline

[0008] A battery electrode that forms 3D electrode nanostructures using a VACNT forest, and a method for manufacturing the same are described. The VACNT is electrically and mechanically attached to an anode or cathode substrate, providing a large-area 3D surface for coating with active materials and highly conductive electron pathways for the cell current collector. A number of different active materials suitable for the anode and cathode in a lithium-ion battery can be used to coat individual carbon nanotubes. The high surface area provided by the VACNT forest and the nano-dimensions of the coated active materials make it possible to achieve both high energy density and high power density with the same battery. Fully conformal coating of individual CNTs can be achieved by a number of different methods, and coating with multiple active materials can be used to form nanolaminate coatings having improved electrochemical characteristics compared to a single material.

[0009] The development of ALD recipes for these materials for high aspect ratio structures is essential for achieving high-loading VACNT electrodes. ALD has been identified as an important method enabling high loading of active materials on VACNT and high cycle life. An electrode fabrication method utilizing ALD technology with high aspect ratio VACNT 3D current collectors is described.

[0010] In one embodiment, a lithium-ion battery is described. The battery comprises: an anode comprising a first conductive substrate (e.g., a planar conductive substrate, e.g., a metal foil), a first plurality of vertically aligned carbon nanotubes, and a first active material layer located on the outer surface of each of the first plurality of vertically aligned carbon nanotubes, wherein each of the first plurality of vertically aligned carbon nanotubes has a vertical axis substantially perpendicular to the vertical axis of the first substrate; and a cathode comprising a second conductive substrate, a second plurality of vertically aligned carbon nanotubes, and a second active material layer located on the outer surface of each of the second plurality of vertically aligned carbon nanotubes, wherein each of the second plurality of vertically aligned carbon nanotubes has a vertical axis substantially perpendicular to the vertical axis of the second substrate.

[0011] In another embodiment, a lithium-ion battery is described. The battery comprises a first compressible foam substrate comprising a first plurality of metal ligaments connected to form a plurality of open pores, a first plurality of vertically aligned carbon nanotubes, and a first active material layer, wherein each nanotube of the first plurality of vertically aligned carbon nanotubes has an outer surface, a first end, and a longitudinal axis, the first active material layer is located on the outer surface of each nanotube of the first plurality of vertically aligned carbon nanotubes, the first end of each nanotube of the first plurality of vertically aligned carbon nanotubes is connected to a metal ligament of the first plurality of metal ligaments, and the longitudinal axis of each nanotube is substantially perpendicular to the longitudinal axis of the first compressible foam substrate; A cathode comprising a second compressible foam substrate including a second plurality of metal ligaments connected to form a plurality of open pores, a second plurality of vertically aligned carbon nanotubes, and a second active material layer, wherein each nanotube of the second plurality of vertically aligned carbon nanotubes has an outer surface, a first end, and a longitudinal axis, the second active material layer is located on the outer surface of each nanotube of the first plurality of vertically aligned carbon nanotubes, the first end of each nanotube of the second plurality of vertically aligned carbon nanotubes is connected to a metal ligament of the second plurality of metal ligaments, and the longitudinal axis of each nanotube is substantially perpendicular to the longitudinal axis of the second compressible foam substrate.

[0012] In another embodiment, an anode of a lithium-ion battery is described. The anode comprises a substrate; a current collector comprising a plurality of vertically aligned carbon nanotubes, wherein each nanotube in the plurality of vertically aligned carbon nanotubes has an outer surface and a first end, and the first end is coupled to the substrate; and an active material layer located on the outer surface of each nanotube in the plurality of vertically aligned carbon nanotubes.

[0013] In another embodiment, a cathode of a lithium-ion battery is described. The cathode comprises a substrate; a current collector comprising a plurality of vertically aligned carbon nanotubes, wherein each nanotube in the plurality of vertically aligned carbon nanotubes has an outer surface and a first end, and the first end is coupled to the substrate; and at least one active material layer located on the outer surface of each nanotube in the plurality of vertically aligned carbon nanotubes.

[0014] In another embodiment, a method for manufacturing an anode for a lithium-ion battery is described. The method comprises the step of depositing a catalyst and a sublayer on a substrate (on one or both sides of the substrate), wherein the substrate has a longitudinal axis. A plurality of vertically aligned carbon nanotubes are then grown on the substrate (on one or both sides of the substrate), wherein each nanotube of the plurality of vertically aligned carbon nanotubes has an outer surface and a longitudinal axis, and the longitudinal axis of each nanotube is substantially perpendicular to the longitudinal axis of the metal foil substrate. Subsequently, a protective layer is deposited on the outer surface of each nanotube by atomic layer deposition.

[0015] In another embodiment, a method for manufacturing a cathode for a lithium-ion battery is described. The method comprises the step of depositing a catalyst and a sublayer on a substrate (on one or both sides of the substrate), wherein the substrate has a longitudinal axis. A plurality of vertically aligned carbon nanotubes are grown on the substrate (on one or both sides of the substrate), wherein each nanotube of the plurality of vertically aligned carbon nanotubes has an outer surface and a longitudinal axis, and the longitudinal axis of each nanotube is substantially perpendicular to the longitudinal axis of the substrate. A protective layer is deposited on the outer surface of each nanotube by atomic layer deposition.

[0016] In any embodiment described herein, the substrate may include at least one hole, void, or gap. The hole, void, or gap is about 10 μm 2 to about 500 µm2 , alternatively about 25 µm 2 to about 400 µm 2 , alternatively about 10 µm 2 to about 250 µm 2 , alternatively about 10 µm 2 to about 300 µm 2 The area of ​​can be defined. The distance between holes, voids, or gaps may be about 5 μm to about 150 μm, alternatively about 5 μm to about 100 μm, alternatively about 25 μm to about 100 μm, or alternatively about 50 μm to about 100 μm. The substrate may also be patterned, such as a mesh, screen, or foil. The substrate may be patterned using a shadow mask, photolithography, electron-beam (e-beam) lithography, and etching. For example, in a trench pattern, the stripes may have a width of about 5 μm to about 150 μm, alternatively about 5 μm to about 100 μm, or alternatively about 25 μm to about 100 μm. In the trench pattern, the gap may have a width of about 5 µm to about 50 µm, alternatively about 5 µm to about 20 µm, or alternatively about 10 µm to about 30 µm. In the street pattern, the square is about 1600 µm 2 to about 10,000 µm 2 , alternatively about 1000 µm 2 to about 10,000 µm 2 , alternatively about 1500 µm 2 to about 8,000 µm 2 It may have an area of. The spacing or distance between the squares may be about 5 μm to about 10 μm, alternatively about 2.5 μm to about 10 μm, or alternatively about 2.5 μm to about 8 μm.

[0017] In any embodiment described herein, the substrate may also be a compressible foam made of, for example, copper, nickel, stainless steel, aluminum alloy, nickel alloy, carbon, graphene, and graphite. The compressible foam may comprise a plurality of metal ligaments connected to form a plurality of openings, open pores, or open cells. The number of open pores may be about 40 ppi to about 100 ppi, alternatively about 50 ppi to about 100 ppi, alternatively about 60 ppi to about 100 ppi, alternatively about 40 ppi to about 95 ppi, where PPI is the number of pores per inch. Alternatively, the number of open pores may be > about 40 ppi, alternatively > about 50 ppi, alternatively > about 60 ppi, alternatively > about 70 ppi, alternatively > about 80 ppi, alternatively > about 90 ppi, alternatively > about 100 ppi, alternatively > about 110 ppi, where PPI is the number of pores per inch. The compressible foam may have a porosity or void volume of about 70 to about 98%, alternatively about 75 to about 98%, alternatively about 75 to about 96%, alternatively about 70 to about 99%, or alternatively about 80 to about 97%. The metal ligament forming the compressible foam may have a width of about 10 µm to about 100 µm, alternatively about 10 µm to about 95 µm, alternatively about 10 µm to about 90 µm, alternatively about 15 µm to about 100 µm, alternatively about 15 µm to about 95 µm, alternatively about 15 µm to about 90 µm, or alternatively about 15 µm to about 85 µm.The compression ratio of the foam may be greater than about 30%, alternatively greater than about 40%, alternatively greater than about 60%, alternatively about 30% to about 80%, alternatively about 40% to about 80%, alternatively about 50% to about 80%, alternatively about 30% to about 90%, alternatively about 40% to about 90%, alternatively about 50% to about 90%. The compression ratio of the foam is defined according to the following formula:

[0018] In any embodiment described herein, the VACNT has a first end connected to or coupled to a substrate. The VACNT has a longitudinal axis substantially perpendicular to the longitudinal axis of the substrate to which it is attached.

[0019] In any embodiment described herein, the aspect ratio of a plurality of vertically aligned carbon nanotubes may be about 100 to about 3000, alternatively about 100 to about 2500, alternatively about 100 to about 2000, alternatively about 100 to about 1500, or alternatively about 100 to about 1000.

[0020] In any embodiment described herein, the active material layer is FePO4, LixMn2O4, and Li x V2O5, LiCoO2, V2O5, Co3O4, RuO2, SnO2, TiO2, Cu2S, SiO x It may include , and combinations thereof. The anode active material layer is SnO2, SiO2 x It may include RuO2, TiO2, Cu2S, and combinations thereof. The cathode active material layer is Li xIt may include V2O5, V2O5, LiNiO2, LiMn2O4, LiCoO2, FePO4, LiFePO4, Li(Mn,Ni,Co)O2, Li(Ni,Co,Al)O2, and combinations thereof. The anode and cathode may each have a single layer of active material, or two, alternatively three, alternatively four, alternatively five, alternatively six, or alternatively seven layers of different or alternating active material and / or protective layer.

[0021] In any embodiment described herein, the surface of the VACNT may be functionalized to increase the number of precursor nucleation sites. The surface may be functionalized by using acid functionalization, oxygen plasma treatment, chemical functionalization, or by the application of an adhesive layer.

[0022] In any embodiment described herein, the volumetric energy density of the battery cell may be at least about 1,200 Wh / L, alternatively about 600 to about 1,600 Wh / L, or alternatively about 800 to about 1,600 Wh / L. A battery having a volumetric density of about 600 to about 800 Wh / L may be used in a battery-driven electric vehicle. A battery having a volumetric density of about 20 to about 800 Wh / L may be used for other applications requiring more power and less energy.

[0023] In any embodiment described herein, the specific energy density or gravimetric energy density of the battery cell may be at least about 10 Wh / kg, alternatively at least about 500 Wh / kg, alternatively about 250 Wh / kg to about 600 Wh / kg, alternatively about 500 to about 600 Wh / kg, or alternatively about 550 to about 650 Wh / kg. Brief explanation of the drawing

[0024] Figure 1a is a diagram of an electrode having VACNT on both sides of a substrate.

[0025] Figure 1b is a diagram of a battery cell configuration containing multiple anodes and cathodes.

[0026] Figure 1c is a diagram of a prototype ALD process on a flat substrate.

[0027] Figure 1d is a diagram of the ALD process on VACNT.

[0028] Figure 2a illustrates a method of coating CNTs by enabling lateral penetration of ALD precursor gas into the forest through empty spaces (holes, voids, or gaps) in the VACNT forest.

[0029] Figure 2b illustrates lateral gas diffusion through multiple VACNTs.

[0030] Figure 3a is an SEM image of a VACNT forest created by depositing VACNT on a substrate in a street pattern.

[0031] Figure 3b is an SEM image of a VACNT forest created by depositing VACNT on a substrate in a trench pattern.

[0032] Figure 3c is an SEM image of a VACNT forest created by depositing VACNT on a mesh substrate.

[0033] Figure 3d is an SEM image of a VACNT forest created by depositing VACNT in a natural pattern on a Cu foil.

[0034] Figure 3e is an SEM image of a VACNT forest on a solid substrate having square holes created by patterning a catalyst layer using photolithography.

[0035] Figures 4a to 4c are SEM images of open cell foam substrates containing VACNT at various magnifications.

[0036] Figure 5a is a side view photograph of a foam substrate on a wire mesh platform.

[0037] Figure 5b is a top view diagram of a foam substrate on a wire mesh platform.

[0038] Figures 6a and 6b are SEM images of foam substrates containing VACNT before and after compression, respectively.

[0039] Figures 7a and 7b are SEM images of foam substrates containing VACNT before and after compression, respectively.

[0040] Figure 8 is the charge / discharge profile of Si / SnO2-coated VACNT on nickel foam in a half-cell configuration of C / 10.

[0041] Figure 9 is the charge / discharge profile of LiMn2O4-coated VACNT on graphene foam in a half-cell configuration of C / 10.

[0042] Figure 10 shows the performance of sulfur-coated VACNT on nickel foam in a half-cell configuration of C / 10.

[0043] Figure 11 is a charge / discharge profile of LiMn2O4 coated on a VACNT electrode using the sol-gel method.

[0044] Figures 12a and 12b show the first two cycles of VACNT by the wet method in a half-cell coin cell and the charge / discharge profiles of LiMn2O4-coated VACNT. Figure 12a shows the first two cycles of uncoated VACNT. Figure 12b shows VACNT coated with Al2O3 by ALD before coating with an active material.

[0045] Figure 13 shows the cycling performance of LiMn2O4-coated VACNT in half-cells.

[0046] Figure 14 shows the charge / discharge profile of a LiMn2O4-coated VACNT electrode using the ALD method (the C-rate was C / 10). The LiMn2O4 loading is 9.7 mg / cm².

[0047] Figure 15 is an SEM image of LiMn2O4-coated VACNT using ALD.

[0048] Figure 16 shows the X-ray diffraction pattern of LiMn2O4-coated VACNT.

[0049] Figure 17 shows the charge / discharge profile of a LiMn2O4-coated VACNT electrode using the ALD method on a half-cell.

[0050] A of FIG. 18 is an example of an anode or cathode configuration having a monolayer of material A.

[0051] Figure 18B is an example of an anode or cathode configuration having multiple layers.

[0052] Fig. 18C is an example of an anode or cathode configuration having a nanolamination of materials A and B.

[0053] Figure 19 is an SEM image of SnO2-coated VACNT using ALD.

[0054] Figure 20 shows the performance of VACNT coated with SnO2 by ALD.

[0055] Figure 21 shows the charge / discharge profile of an SnO2-coated VACNT electrode using ALD.

[0056] Figure 22 shows the cycling performance of an ALD SnO2-coated VACNT anode in a full cell coin paired with an LCO cathode.

[0057] Figures 23a and 23b are flowcharts of various methods for manufacturing an anode for a lithium-ion battery.

[0058] Figures 24a and 24b are flowcharts of various methods for manufacturing a cathode for a lithium-ion battery.

[0059] Figure 25 summarizes various alternative configurations of a lithium-ion battery and methods for configuring them. Specific details for implementing the invention details

[0060] As shown in FIG. 1a, in a typical electrode configuration, VACNT (10) can be grown on one or both sides of a substrate (2), such as a metal foil. An active material (12) covers the outer surface of the VACNT (10). As shown in FIG. 1b, in a typical battery cell configuration, the anode (13) and the cathode (15) are separated by a separator (14). As illustrated, the anode (13), cathode (15), and separator (14) can be stacked. Alternatively, the anode (13), cathode (15), and separator (14) can be a sheet rolled or folded together (not shown).

[0061] FIG. 25 summarizes various materials and manufacturing methods used in the manufacture of a lithium-ion battery (500). The lithium-ion battery includes a conventional cell (503) having a pastetted electrode (e.g., active material, carbon additive, and binder), an electrode (505) having a three-dimensional (3D) structure, and a solid-state cell (507) having an electrode made of a deposited thin film. The 3D electrode structure may be, but is not limited to, an etched material (513), a VACNT (515) with an active material coated thereon, or a pillar or nanorod (517) of the active material. With respect to the electrode having the VACNT, the substrate for the VACNT (520) may include a metal foil (525), a metal foam (523), or the VACNT may be grown as a freestanding forest (527) (not present). The metal foil substrate (525) may be patterned (533), plain and solid (535), or perforated (537). The active material (550) for the anode (553) is SnO2, SiO2 x The active material (550) for the cathode (555) includes, but is not limited to, RuO2, TiO2, Cu2S, and combinations thereof. xThe active material may be coated (540) using a wet (545) and / or dry (543) method. The wet method (545) includes, but is not limited to, V2O5, V2O5, LiNiO2, LiMn2O4, LiCoO2, FePO4, LiFePO4, Li(Mn,Ni,Co)O2, and Li(Ni,Co,Al)O2. The wet method (545) includes, but is not limited to, sol-gel and melting. The dry method (543) includes, but is not limited to, atomic layer deposition (ALD), CVD, PVD, LPCVD, and PECVD.

[0062] Atomic layer deposition

[0063] A method for coating high aspect ratio structures, such as VACNT, via atomic layer deposition is described herein. A method for performing ALD is described in the literature [Miikkulainen, V. et al. "Atomic Layer Deposition of Spinel Lithium Manganese Oxide by Film-Body-Controlled Lithium Incorporation for Thin-Film Lithium-Ion Batteries." J. Phys. Chem. C 118: 1258-1268 (2014)], the entire contents of which are expressly incorporated herein by reference for all purposes. These structures with high aspect ratios (height / spacing between adjacent structures) can impede the full-field coating of active materials because precursors cannot easily penetrate into the dense structures.

[0064] As mentioned above, VACNT can be used as a current collector in lithium-ion batteries. VACNT can be grown on a substrate for use as a current collector. The growth of VACNT on a support using chemical vapor deposition (CVD) is described in the literature [Zhao, N. and Kang, J. "Direct Growth of Carbon Nanotubes on Metal Supports by Chemical Vapor Deposition." Carbon Nanotubes - Synthesis, Characterization, Applications, Dr. Siva Yellampalli (Ed.), ISBN: 978-953-307-497-9, InTech, Available from: http: / / www.intechopen.com / books / carbon-nanotubessynthesis-characterization-applications / direct-growth-of-carbon-nanotubes-on-metal-supports-by-chemicalvapor-deposition], the entire contents of which are expressly incorporated herein by reference for all purposes. VACNT can be grown to have a height of 10 µm to about 3 mm, alternatively about 20 µm to about 3 mm, alternatively about 20 µm to about 2 mm, alternatively about 50 µm to about 1 mm, alternatively about 50 µm to 800 µm, alternatively about 100 µm to 600 µm, alternatively about 50 µm to 500 µm, alternatively about 20 µm to about 100 µm, alternatively about 100 µm to 500 µm, alternatively about 100 µm to 400 µm, alternatively about 100 µm to 300 µm, alternatively about 100 µm to 200 µm, alternatively about 40 µm to about 200 µm. VACNT for the anode can have a height of about 20 µm to about 100 µm.The VACNT for the cathode can have a height of about 40 μm to about 300 μm.

[0065] As shown in FIG. 1c, in a prototype ALD process on a flat substrate, the substrate (2) is exposed to reactant A (4) and reactant B (6) in a sequential and non-overlapping manner. Unlike other techniques such as chemical vapor deposition, where reactants are introduced simultaneously and thin film growth proceeds in a steady-state manner, in ALD, each reactant reacts with the surface in a self-limiting manner: reactant molecules can only react with a limited number of reactive (active or nucleating) sites on the surface. Growth is stopped when all reactive (active or nucleating) sites are consumed in the reactor. The remaining reactant molecules are flushed out before reactant B 6 is inserted into the reactor. By alternating exposure of reactant A (4) and reactant B (6), a thin film is deposited. Consequently, when describing the ALD process, this refers to both the input time (the time the surface is exposed to the precursor) and the purge time (the time remaining between inputs to the precursor until the chamber is emptied) for each precursor / reactant. The input-purge-input-purge sequence of the binary ALD process constitutes an ALD cycle. Furthermore, instead of using the concept of a growth rate, the ALD process is typically described in relation to their growth per cycle.

[0066] However, coating VACNT (10) using ALD presents several problems. As illustrated in FIG. 1d, the aspect ratio (e.g., the height of the carbon nanotubes (CNT) (10) divided by the space between them) is very high. Consequently, the VACNT (10) forest exhibits steric hindrance problems in that it can be difficult for various reactants (4, 6) to access and react with various active sites along the length of each VACNT (10). High aspect ratio forests may require long ALD deposition times, which increases manufacturing costs.

[0067] The aspect ratio of the VACNT forest (20) can be about 100 to about 3000, alternatively about 100 to about 2500, alternatively about 100 to about 2000, alternatively about 100 to about 1500, alternatively about 100 to about 1000.

[0068] Gas diffusion

[0069] One way to improve the use of ALD for coating VACNT is to improve gas diffusion through the VACNT forest (20). For example, as shown in FIG. 2a, lateral ALD gas diffusion (24) into the VACNT forest (20) can be achieved by patterning the VACNT forest (20) on a substrate having voids, holes, or gaps (30) within the substrate, which causes the gas to flow vertically (26) downward and into the voids, holes, or gaps (30) and laterally (24) through the VACNT forest (20). As shown in FIG. 2b, lateral ALD gas diffusion (24) will cause the gas to flow through the VACNT forest (20) in a direction approximately perpendicular to the longitudinal axis of the VACNT (10). VACNT-free regions (holes or voids) (30) will increase the effective perimeter of the nanotube forest (20) to provide a large lateral diffusion entry path. Thus, various patterned substrates having empty spaces within the VACNT forest will help increase gas diffusion during ALD. Patterning of the VACNT can be performed by (1) limiting the VACNT forest region by using a mesh (e.g., see FIG. 3c), or a patterned substrate (e.g., see FIG. 3a and 3b) such as a screen, foil (e.g., see FIG. 3d), or perforated foil; (2) patterning the catalyst using photolithography (e.g., see FIG. 3e), e-beam lithography, etching, or a shadow mask; or (3) selectively removing regions on the VACNT layer, such as by laser ablation. Figure 3a is an SEM (scanning electron microscope) image of a VACNT forest created by depositing VACNT on a substrate in a street, square, or cube pattern. Figure 3b is an SEM image of a VACNT forest created by depositing VACNT on a substrate in a trench pattern.The solid surface has a width of about 10 μm to about 13 μm and is separated by gaps of about 5 μm to about 10 μm. Fig. 3c is an SEM image of a VACNT forest with a gap of about 50 μm created by depositing VACNT on a mesh substrate. Fig. 3d is an SEM image of a VACNT forest created by depositing VACNT in a natural pattern on a foil. This Cu foil has a solid surface with different heights and gaps that are almost similar to the steps of a staircase. Fig. 3e is an SEM image of a square hole (approximately 15 μm × 15 μm) in a VACNT forest on a solid substrate created by patterning a catalyst layer using photolithography. As illustrated in FIGS. 2a and 2b, empty spaces (voids, holes, or gaps) seen in the various examples shown in FIGS. 3a through 3e can help promote improved gas diffusion through the VACNT forest by enabling lateral gas diffusion in addition to vertical gas diffusion (26) through the VACNT forest.

[0070] ALD gas diffusion can also be increased by applying ALD to freestanding VACNT carpets. Freestanding nanotube carpets will also enable ALD gas penetration from both the top and bottom of the carpet.

[0071] Similarly, ALD gas diffusion will also be improved by using an open-cell foam substrate (e.g., graphene, carbon, metal, or alloy foam). An open-cell foam substrate can be used to grow VACNTs or other 3D structures in the regurgitation between open cells. SEM images of VACNTs grown on an open-cell foam, for example, nickel foam, are shown in FIGS. 4a through 4c. The height of the VACNTs is controlled by the synthesis time. By increasing the short VACNTs in each layer of the foam, the aspect ratio can be significantly reduced. The use of a foam substrate (32) having multiple openings will consequently reduce the deposition time in a high aspect ratio ALD process, which will shorten the deposition time while maintaining a high loading of the active material. The foam substrate (32) can also be placed on a raised platform (34) inside the ALD chamber. For example, as shown in FIGS. 5a and 5b, a wire mesh screen can be used as a platform (34), which will enable precursor gas penetration from both the upper and lower parts of the foam substrate (32).

[0072] foam substrate

[0073] A method is described herein for maintaining both the high electrode loading (mg / cm²) required for high energy density with low-aspect-ratio 3D structures for easier fabrication. The method comprises using an open-cell metal-foam substrate (e.g., see FIGS. 23b and 24b) together with VACNT or other 3D structures grown on metal ligaments between open cells on these compressible foam substrates. SEM images of the open-cell metal foam are shown in FIGS. 4a through 4c.

[0074] The height of the 3D structure (VACNT) on the foam substrate (32) must be a fraction of the height that is optimally used on a flat foil substrate for manufacturing electrodes, because after coating with an active material, the foam (32) can be compressed to a fraction of its original height. The height of the VACNT on the foam substrate may be about 10 µm to about 100 µm, alternatively about 10 µm to about 50 µm, alternatively about 10 µm to about 80 µm. The height of the VACNT on a flat substrate may be about 10 µm to about 200 µm, alternatively about 20 µm to about 200 µm, alternatively about 20 µm to about 150 µm, alternatively about 20 µm to about 100 µm, alternatively about 10 µm to about 40 µm, alternatively about 10 µm to about 30 µm. For example, the height of the VACNT on the foam substrate may be about 1 / 5, alternatively about 1 / 4, or alternatively about 1 / 3 (e.g., about 20 μm compared to about 100 μm) of the height of the VACNT on a flat substrate. By selecting the optimal combination of the VACNT (10) height, the number of cells per unit area, the ligament width, and the subsequent foam compression, the resulting electrode will retain the same important characteristics (loading and thickness) as an ideal flat electrode. FIGS. 6a and 7a are SEM images of a foam substrate containing VACNT before compression, and FIGS. 6b and 7b are SEM images of a foam substrate containing VACNT after compression. Additionally, the use of a metal-foam substrate (32) with shorter VACNT will result in a lower aspect ratio and a larger void area surrounding the VACNT forest (20) before compression, which will significantly improve the conditions for coating the (VACNT) structure (10) with the active material. Since the ALD deposition time of the active material will be proportional to the square of the aspect ratio, the ALD deposition time on the foam substrate (32) can be expected to be about 1 / 16 of the time for the planar electrode.

[0075] The number of open cells per unit on the compressible foam is about 400 to about 10,000 per square inch, alternatively about 500 to about 10,000 per square inch, alternatively about 1,000 to about 10,000 per square inch, alternatively about 600 to about 9,000 per square inch. The porosity (void volume) may vary from about 70 to about 98%, alternatively about 75 to about 98%, alternatively about 75 to about 96%, alternatively about 70 to about 99%, and alternatively about 80 to about 97%.

[0076] The width of the metal ligaments connecting to form the metal foam may be about 10 µm to about 100 µm, alternatively about 10 µm to about 95 µm, alternatively about 10 µm to about 90 µm, alternatively about 15 µm to about 100 µm, alternatively about 15 µm to about 95 µm, alternatively about 15 µm to about 90 µm, or alternatively about 15 µm to about 85 µm.

[0077] The compressible foam (32) may be any conductive material (metal or carbon) capable of withstanding the thermal and chemical environment required for subsequent coating, along with the growth of the 3D structure and any annealing of the active electrode material component. The conductive material must also be able to withstand the chemical and electrochemical environment in the battery cell and must be able to collapse into thinner dimensions while maintaining sufficient structural integrity and electrical conductivity to be useful as a battery electrode.

[0078] Examples of compressible foam materials that can be used for electrodes in lithium-ion batteries include, but are not limited to, stainless steel, aluminum, or nickel alloys for the cathode; copper or nickel for the anode; and carbon, graphene, or graphite for the cathode or anode. In one embodiment, the foam material will have a high porosity and a high specific surface area. These electrodes typically have the highest specific surface area (cm³ of foam) available for the growth of CNTs or other 3D structures. 3 To provide the ligament (cm²), a foam having a high, e.g., >40 ppi to >100 ppi, ideally as high as possible, will be required. The number of cells (pores) per inch may be about 40 ppi to about 100 ppi, alternatively about 50 ppi to about 100 ppi, alternatively about 60 ppi to about 100 ppi, alternatively about 40 ppi to about 95 ppi, alternatively > about 40 ppi, alternatively > about 50 ppi, alternatively > about 60 ppi, alternatively > about 70 ppi, alternatively > about 80 ppi, alternatively > about 90 ppi, alternatively > about 100 ppi, alternatively > about 110 ppi, where PPI is the number of pores per inch.

[0079] The foam material may also be coated with a thin layer of other material to enhance or provide necessary surface features. For example, the foam may be coated with a thin layer of titanium, chromium, aluminum, copper, nickel, or ceramic, such as Al2O3. Polymers / conductive carbon may be used as a matrix to mechanically and electronically connect the foam structure. The polymer must be stable over the desired voltage range and compatible with the electrolyte. Examples include polymers such as polyvinylidene fluoride (PVDF), styrene butadiene copolymer, polyacrylic acid (PAA), and carboxymethyl cellulose (CMC).

[0080] The foam may also be compressible. In other words, the foam has the ability to be flattened or reduced in height to approximately a fraction or percentage of its original height. The compression ratio of the foam should be > about 30%, alternatively > about 40%, alternatively > about 60%, alternatively about 30% to about 80%, alternatively about 40% to about 80%, alternatively about 50% to about 80%, alternatively about 30% to about 90%, alternatively about 40% to about 90%, alternatively about 50% to about 90%. The foam can be reduced to about 50% of its uncompressed thickness or height, alternatively about 40%, alternatively about 30%, alternatively about 20%, alternatively about 10%, alternatively about 10% to about 70%, alternatively about 10% to about 60%, alternatively about 10% to about 50%, alternatively about 10% to about 40%, alternatively about 10% to about 30%.

[0081] While this embodiment envisions using VACNT for 3D structures, it is recognized that other high aspect ratio structures, such as freestanding nanorods of active material, can be used.

[0082] The open cell foam substrate (32) can be reduced by compression to about 1 / 3 of its original (uncompressed) thickness by applying downward pressure, for example, to an appropriate electrode thickness after ALD deposition. Table 1 shows a comparison of the increase in weight of the active material for various substrates after the same process. Although the electrode thickness is the same, the open cell foam substrate obtains a higher loading when processed under the same conditions.

[0083] Table 1 : Weight of active material of various samples after the same coating process (same sample batch undergoes low-pressure chemical vapor deposition (LPCVD) followed by ALD)

[0084] Additionally, as shown in Table 1, the foam electrode thickness before compression is approximately 600 μm, and the foam electrode thickness after compression is approximately 210 μm. Therefore, the % compression ratio of the foam substrate is approximately 65%. Polymers / conductive carbon can be used as a matrix to mechanically and electronically connect the structure. The polymer must be stable over the desired voltage range and compatible with the electrolyte. Examples include polymers such as polyvinylidene fluoride (PVDF), styrene butadiene copolymer, polyacrylic acid (PAA), and carboxymethyl cellulose (CMC). During the compression of the foam, some of the attached VACNTs may be destroyed or detached, but at least 70%, alternatively at least 80%, alternatively at least 90%, and alternatively at least 95% of the VACNTs remain intact and are not destroyed. In the case of brittle carbon foam, some of the ligament itself may be destroyed. In both cases, separation or destruction can reduce the internal electronic conductivity of the electrode. These effects can be improved by using a polymer / conductive-carbon coating.

[0085] The coating can be applied by ALD as described in U.S. Patent No. 7,582,544, the entire contents of which are expressly incorporated herein by reference for all purposes, and the use of foam provides similar advantages to methods for improving ALD for high aspect ratio structures. Table 1 shows the total loading of various samples after the same coating process, a combination of LPCVD and ALD. As shown in Table 1, the foam substrate contained a much higher loading than a typical flat substrate (e.g., stainless steel (SS) disk). As shown in Fig. 8, which is the charge / discharge profile of Si / SnO2-coated VACNT on nickel foam in a C / 10 half-cell configuration, very high loading of the active material can be achieved to create a very high-capacity electrode (anode). The electrode thickness is 110 μm. The performance of the high-loading anode material Si / SnO2-coated VACNT on Ni foam was tested in a half-cell coin cell for lithium metal and is presented in Fig. 8. The total capacity achieved (over 15 mAh / cm²) is much higher than that of current lithium-ion anode electrodes.

[0086] Coating can be applied by a combination of ALD and wet methods. While the sol-gel method is easier and faster for synthesizing active cathode materials, incorporating the actual amount of active material into dense VACNT electrodes is very difficult. On the other hand, the ALD method provides highly conformal coatings and can deliver actual loading of the active material, but producing thick layers can take a very long time. However, combining these two methods offers advantages. MnO x The layer can be applied by ALD on VACNT in the first step, and then MnO₂ by dip coating, drop coating, or spin coating with a solution of a lithium precursor such as LiOH, LiNO₃, or LiClO₄. xIt is incorporated into the / VACNT electrode. The organic solution must be completely infiltrated into the VACNT forest until stoichiometry is reached to form LiMn2O4. After the evaporation of the organic solvent, the lithium precursor layer is reacted at a temperature exceeding 300°C under air or an inert atmosphere. For example, manganese oxide was deposited on the VACNT against the graphene foam by ALD and subsequently dip-coated in a LiOH solution. The resulting electrode was heated in air at 400°C to form LiMn2O4 ("LMO") and further tested in a half-battery coin cell. Figure 9 shows the high capacitance obtained with the foam substrate. Figure 9 is the charge / discharge profile of the LMO-coated VACNT on the graphene foam in a half-battery coin cell configuration of C / 10 (2 cycles). LMO was formed on the VACNT by a combination of ALD and solution methods.

[0087] Coating can also be applied by a melting method. For example, refer to the literature [Hagen, M. et al. "Lithium-sulfur batteries - binder-free carbon nanotubes electrode examined with various electrolytes." J. Power Sources 213; 239-48 (Sept. 1, 2012)], the entire contents of which are expressly incorporated herein by reference for all purposes. For example, materials such as sulfur, which have a low melting point and high affinity for carbon, can be easily coated onto foam substrates to form VACNTs. The performance of high-loading sulfur-coated VACNTs on coin cell-type Ni foam is presented in FIG. 10. Sulfur was coated using a melting method. Here again, the foam structure enables high loading and high capacitance.

[0088] Functionalization of VACNT surface

[0089] Improved application of active material to the VACNT surface on the cathode and anode can also be achieved by increasing surface functionalization. Increasing the number of precursor nucleation sites and the overall affinity of the VACNT surface for the active material will increase the amount of active material that can be coated on the VACNT. This can be achieved, for example, by acid functionalization, which requires high vapor pressure acids such as fuming sulfuric acid to avoid liquid damage to the nanotubes and substrates. Oxygen plasma treatment can also be used, for which the exposure time and RF power (about 5 to about 100 watts) must be adjusted to prevent complete destruction of the nanotubes (e.g., from about 1 second to 2 minutes). Chemical functionalization treatment can be used with trimethylaluminum (TMA) or tetrakis(dimethylamido) titanium (TDMAT) inside an ALD chamber at a temperature below 300°C. Before applying ALD to the active material, a thick layer of adhesive material (about 2 nm or less), such as Al2O3 or SnO2TiO2, may also be applied.

[0090] Anti-degradation protective layer

[0091] To protect the primary active material from chemical or structural degradation and thereby improve cycle life, stratification of the active or other different materials may be used.

[0092] A protective layer can be applied to prevent damage from any subsequent fabrication processes requiring high temperatures or other corrosive environments. A thin coating (approximately 1 to 4 nm) of an inert material (e.g., Al2O3, ZnO, V2O5, …) can be applied to VACNTs, nanotubes, or other 3D structures by ALD. For subsequent processing by methods such as sol-gel, this protective coating will preserve substrate conductivity and structure by protecting the CNTs from oxidation and degradation. Figure 11 shows the charge / discharge profile for the first cycle of the LiMn2O4 / VACNT electrode. The C-rate was C / 5. A thin layer of Al2O3 was coated prior to the deposition of LiMn2O4.

[0093] Although VACNT is very stable at very high temperatures under an inert atmosphere, it will begin to decompose in air at 420°C. Furthermore, wet processes for the synthesis of high-voltage cathode materials (e.g., LiMn2O4, LiCoO2, NMC, LFP) generally involve the calcination of precursors in air at high temperatures. These conditions will damage VACNT, causing it to lose its properties / benefits. Damage to VACNT is also observed in the case of LiMn2O4 (LMO), where precursor decomposition occurs at lower temperatures (below 400°C). The application of a conformal and uniform protective layer is required to prevent damage from any subsequent fabrication processes that require high temperatures or other corrosive environments. A thin coating (approximately 1 to 5 nm) of an inert material (e.g., Al2O3, ZnO, V2O5, …) can be applied to VACNT, nanotubes, and / or other 3D structures by ALD. For subsequent treatment by wet methods such as sol-gel, this protective coating will preserve the substrate conductivity and structure by protecting the CNTs from oxidation and degradation.

[0094] For example, LiMn2O4 was formed on two types of VACNTs by the sol-gel method: i) uncoated VACNTs, and ii) Al2O3 (4 nm) coated VACNTs. The resulting LMO / VACNT electrodes were tested for Li metal in half-cell coin cells. Figures 12a and 12b show the charge / discharge profiles of the first two cycles of the LiMn2O4 / VACNT electrode (cycling at C / 6). The VACNTs in Figure 12a were not coated with a protective layer before being coated with the active material. In Figure 12b, the VACNTs were coated with Al2O3 by ALD before being coated with the active material. Figure 12b shows a large capacitance from the LMO cathode material, whereas Figure 12a shows no capacitance from the LMO material due to the loss of electronic conductivity of the 3D carbon nanostructures after the LMO formation process. The sol-gel method is described in the literature [Ming, H. "Gradient V2O5 surface-coated LiMn2O4 cathode towards enhanced performance in Li-ion battery applications." Electrochimica Acta 120: 390-97 (Feb. 20, 2014)], which is expressly incorporated herein by reference for all purposes.

[0095] LiMn on VACNT directly grown on a metal substrate 2 O 4 Method of forming:

[0096] LiMn2O4 spinel material was synthesized on VACNT using a wet chemical method. In the first step, Li(CH3COO)·H2O and Mn(CH3COO)2.4H2O in appropriate molar ratios were dissolved in a mixture of distilled water and isopropanol. Subsequently, the prepared solution was added dropwise to the top of the VACNT. This process was carried out by aging at room temperature for 10 hours without covering to obtain a gel-coating composite. Finally, the obtained gel-coating composite was calcined in air at 350°C for 30 minutes, followed by annealing at 500°C for 1 hour.

[0097] Alternatively, a protective layer can be applied to the active material using ALD. Very thin layers (about 0.25 nm to 10 nm) of inorganic compounds, such as SnO2, TiO2, Al2O3, and ZnO, can be applied to the anode and cathode materials. These layers act as a "solid electrolyte interface (SEI)," meaning they passivate the surface to prevent further reduction or oxidation of the electrolyte at high and low voltages. Furthermore, these layers prevent the active material from dissolving, which leads to poor cycle life. For example, manganese dissolution from LMO occurs during cycling and results in poor cycle life. A thin protective layer of Al2O3 deposited by ALD can solve this problem. As shown in Fig. 13, the addition (▲) of an ALD Al2O3 thin layer on LMO stabilizes the electrode compared to uncoated VACNT (■).

[0098] Direct deposition of active material on VACNT by ALD

[0099] The ALD process offers several advantages, including excellent thickness control along with high uniformity, excellent conformal deposition, and low-temperature growth (typically below 300°C; some materials can be deposited at room temperature). For example, FePO4, LixMn2O4, and Li xV2O5, LiCoO2, V2O5, Co3O4, RuO2, SnO2, and TiO2, Cu2S, SiO x Several ALD cathode and anode materials for lithium-ion batteries (LIBs), including those for lithium-ion batteries (LIBs), have been studied on flat substrates and low aspect ratio structures.

[0100] The electrode (cathode or anode) may have a single active layer or multiple active layers. In the case of multiple active layers, the last active layer may also act as a protective layer to prevent further decomposition of the electrolyte at low electrochemical potentials. Alternatively, the active material may be sequentially layered, for example, by ALD, or applied using nanolamination of various materials. FIGS. 18A to 18C show examples of three different electrode configurations for a single CNT monolayer (Fig. 18A), a multilayer (Fig. 18B), and a nanolamination (Fig. 18C).

[0101] Cathode protection layer

[0102] The cathode is Li x It will include at least one primary active material such as Mn2O4 or LiCoO2, which is Li applied by ALD x It can be protected by a layer of at least one secondary active material such as V2O5 or LiFePO4.

[0103] Lithium-lithiation of the primary material can occur simultaneously at multiple times in a single or multilayer manner during the ALD process. Lithium-lithiation can be controlled at each stage of the active material. This will allow for maximum consistent lithium-lithiation for the cathode. Post-deposition annealing may be applied. Figure 14 shows the charge / discharge profile at cycle 2 of a coated VACNT with LiMn2O4 coated on it using the ALD method. The C-rate was C / 10. The LiMn2O4 loading was 9.7 mg / cm².

[0104] The direct deposition of cathode materials is generally more challenging than that of anode materials because they typically involve a mixture of two or more materials. The cathode active material is Li x It may be V2O5, V2O5, LiNiO2, LiMn2O4, LiCoO2, FePO4, LiFePO4, Li(Mn,Ni,Co)O2, or Li(Ni,Co,Al)O2. The cathode may comprise a single active material layer on the VACNT, or a multilayer of various cathode active materials such as LiMn2O4 / FePO4 or LiMn2O4 / LiNiO2 / FePO4. In the case of a multilayer, the final active layer may also act as a protective layer to prevent the electrolyte from decomposing at high electrochemical potentials. Alternatively, the cathode may be a nanolamination of various materials. Depending on the ALD cycle rate, nanolamination may lead to the formation of new composite compounds. In particular, if additional annealing is required to form the electro-active material, a pre-coating of a thin ALD layer, such as Al2O3, on the VACNT may be applied prior to the ALD deposition of the cathode active material. Nanolamination is similar to ALD except that each cycle may involve 1 to n different precursors. For example, the literature whose entire contents are expressly incorporated herein by reference for all purposes [Donders, ME "Remote Plasma Atomic Layer Deposition of Thin Films of Electrochemically Active LiCoO2." ECS Transactions, Col. 41, 220 th Refer to [ECS Meeting, Oct. 9-14, 2011, Boston, MA, Number 2].

[0105] Monolayer LiMn2O4 can also be applied. A layer of LiMn2O4 (LMO) is obtained by alternating ALD cycles of two binary compounds, Li2O (or LiOH) and MnOx. The resulting thick layer is subsequently heated in air at 300°C for 5 minutes to form LiMn2O4. An SEM image of VACNT coated with the LMO cathode material is shown in Fig. 15. The VACNT structure is completely covered with a conformal and uniform coating. X-ray diffraction (XRD) analysis of the electrode shows that LiMn2O4 spinel has been formed (Fig. 16). The thickness of the material can range from 0.5 nm to 100 nm. Fig. 17 shows the charge / discharge profile of LMO ALD deposited on the VACNT electrode tested for Li metal in a half-cell coin cell. The specific capacitance is approximately 200 mAh / g, which is close to the theoretical specific capacitance of LMO when the voltage range is 4.4 V to 2.5 V relative to Li. The C-rate is C / 10 and the LMO loading is 9.7 mg / cm².

[0106] Anode protection layer

[0107] The anode will comprise at least one primary active material, such as amorphous or polysilicon, which can be deposited on a substrate by LPCVD or PECVD. For example, for all purposes, refer to the literature whose entire contents are expressly incorporated herein by reference [Foreny, MW et al. "High performance silicon free-standing anodes fabricated by low pressure and plasma-enhanced chemical vapor deposition onto carbon nanotube electrodes." J. Power Sources 228: 270-80 (April 15, 2013)]. This primary active material (Si) may subsequently serve as a protective layer using SnO₂ xAlternatively, it may be coated with a second active material such as TiO2. This protective layer will act as a lithium-ion conductive agent and will protect silicon from further reaction with the electrolyte during cycling.

[0108] The protective anode secondary layer may also be an organic material such as alucone applied by molecular layer deposition (MLD). The protective layer may also be a combination of an inorganic layer and an organic layer to produce a protective and partially active secondary layer (applied by MLD + ALD or other methods). The anode may also include a thin (about 2 nm) ALD coating of an adhesive layer (e.g., Si, SnO, or Al2O3), and a low melting temperature active material (< 400°C, e.g., Sn or Sn / Al alloy) that is melted to cover the CNTs by wicking the forest.

[0109] The active materials are SnO2 and SiO2. x , can be RuO2, TiO2, or Cu2S. These active materials are binary compounds. The anode may include a single active material layer covering the VACNT, or SiO x / SnO2, or SiO x It may include various multilayer anode active materials such as / SnO2 / TiO2. In the case of multilayers, the last active layer may also act as a protective layer to prevent further decomposition of the electrolyte at low electrochemical potentials. Alternatively, the anode may be a nanolamination of various materials. FIGS. 18A to 18C show examples of three different anode configurations on a single CNT monolayer, multilayer, or nanolamination.

[0110] SnO 2 Method for manufacturing a monolayer of:

[0111] Tetrakis(dimethylamino)tin(IV) ("TDMASn") was used as the Sn precursor, and H2O was adjusted and optimized as the oxidizing agent to allow for the coating of high aspect ratio VACNT forests. Thermal ALD of SnO2 thin films was deposited at 200°C using TDMASn (99.99%-Sn) and H2O. Ar gas was used as the carrier gas at a flow rate of 120 sccm. The process was performed at a purge pressure of 1.2 Torr and a deposition pressure of 10 Torr. The TDMASn precursor cylinder temperature was maintained at 55°C with a specific Ar flow rate of 30 sccm during cylinder filling and injection. The ALD SnO2 sequence was as follows: ● TDMASn flow-through ampoule filling with Ar gas at 30 sccm (1s). ● TDMASn administration from ampoule at 30 sccm (2s). ● TDMASn exposure to the sample at 10 Torr (45s). ● Purge the chamber using argon at 1.2 Torr (90s). ● Injection of H2O from a vapor-induced ampoule (0.300s). ● Exposure of sample to H2O at 10 Torr (60 s). ● Purge the chamber with argon at 1.2 Torr (90s). The generated SnO2 layer was uniform and conformal from the bottom to the top of the VACNT forest, as shown in Fig. 19.

[0112] The amount of ALD active material can be well controlled with different deposition cycle numbers. The thickness of the deposited material can range from 0.5 nm to 50 nm. An increase in thickness will increase the electrode loading and consequently the area capacity. Due to the high surface area of ​​the 3D VACNT structure and the high VACNT forest coating capability, very high material loading (mg / cm²) can be achieved while maintaining electrochemical performance due to the nano-dimensions of the active material layer and the high electrical conductivity of the nanotubes. Figure 20 shows the cycling performance of VACNT coated with SnO2 by ALD. The C-rate was C / 5. The SnO2 loading was 4.7 mg / cm². Figure 21 shows the charge / discharge profile of SnO2ALD deposited on a VACNT electrode tested for Li metal in a half-cell coin cell. The achieved capacity is over 6 mAh / cm², which is greater than the actual capacity achieved in a conventional LiB. As shown in Fig. 22, these anodes were paired with a LiCoO2 commercial cathode in a coin cell and exhibited excellent area capacity and circulation (C-rate = C / 6).

[0113] Method for fabricating a cathode and anode for a lithium-ion battery

[0114] Referring to FIG. 23a, a method for manufacturing an anode comprising a VACNT forest as a current collector is described. The method comprises the following steps: 110: Provides a metal foil substrate. 120: Pattern a metal foil using, for example, a shadow mask or photolithography. This step is optional and can be omitted when depositing VACNT on a flat metal foil. 130: A catalyst (e.g., Fe, Ni) and a sublayer (e.g., Al2O3, SiO2, Cr, Ti) are deposited on one or both sides of a metal foil substrate by PVD, CVD, or a sol-gel method. 140: A VACNT forest (multiple VACNTs) is grown on one or both sides of a metal foil substrate using a carbonaceous gas by CVD. 150: Silicon active material is deposited on VACNT by LPCVD. 160: A protective layer is deposited by ALD.

[0115] An alternative method is also described in FIG. 23a. The method includes the following steps: 110: Provides a metal foil substrate. 120: Pattern a metal foil using, for example, a shadow mask or photolithography. This step is optional and can be omitted when depositing VACNT on a flat metal foil. 130: A catalyst (e.g., Fe, or Ni) and a sublayer (e.g., Al2O3, Ti, Cr, SiO2) are deposited on one or both sides of a metal foil substrate by PVD, CVD, or a sol-gel method. 140: A VACNT forest (multiple VACNTs) is grown on one or both sides of a metal foil substrate using a carbonaceous gas by CVD. 155: Functionalize VACNT by, for example, UV / ozone, O2 plasma, or acid treatment. 165: Silicon active material is deposited on VACNT by ALD. 175: A protective layer is deposited by ALD.

[0116] Referring to FIG. 23b, a method for manufacturing an anode comprising a VACNT forest as a current collector on a compressible foam substrate is described. The method comprises the following steps: 210: Provides a foam substrate. 220: A catalyst (e.g., Fe, or Ni) and a sublayer (e.g., Al2O3, Ti, Cr, SiO2) are deposited on a foam substrate by PVD, CVD, or a sol-gel method. 230: A VACNT forest (multiple VACNTs) is grown on a foam substrate using a carbonaceous gas by CVD. 240: Silicon active material is deposited on VACNT by LPCVD. 250: A protective layer is deposited on VACNT by ALD. 260: Compress the foam substrate.

[0117] An alternative method is also described in FIG. 23b. The method includes the following steps: 210: Provides a foam substrate. 220: A catalyst (e.g., Fe, or Ni) and a sublayer (e.g., Al2O3Ti, Cr, SiO2) are deposited on a foam substrate by PVD, CVD, or a sol-gel method. 230: A VACNT forest (multiple VACNTs) is grown on a foam substrate using a carbonaceous gas by CVD. 245: Functionalize VACNT by, for example, UV / ozone, O2 plasma, or acid treatment. 255: Silicon active material is deposited on VACNT by ALD. 265: A protective layer is deposited on VACNT by ALD. 275: Compresses foam.

[0118] Referring to FIG. 24a, a method for manufacturing a cathode comprising a VACNT forest as a current collector is described. The method comprises the following steps: 310: Provides a metal foil substrate. 320: Pattern the metal foil using, for example, a shadow mask or photolithography. This step is optional and can be omitted when depositing VACNT on the flat metal foil. 330: A catalyst (e.g., Fe, or Ni) and a sublayer (e.g., Al2O3, Ti, Cr, SiO2) are deposited on one or both sides of a metal foil substrate by PVD, CVD, or a sol-gel method. 340: A VACNT forest (multiple VACNTs) is grown on one or both sides of a metal foil substrate using a carbonaceous gas by CVD. 350: A cathode active material is incorporated into the VACNT by a melting method. 360: A protective layer is deposited by ALD.

[0119] An alternative method is also described in FIG. 24a. The method includes the following steps: 310: Provides a metal foil substrate. 320: Pattern the metal foil using, for example, a shadow mask or photolithography. This step is optional and can be omitted when depositing VACNT on the flat metal foil. 330: A catalyst (e.g., Fe, or Ni) and a sublayer (e.g., Al2O3, SiO2, Ti, Cr) are deposited on one or both sides of a metal foil substrate by PVD, CVD, or a sol-gel method. 340: A VACNT forest (multiple VACNTs) is grown on one or both sides of a metal foil substrate using a carbonaceous gas by CVD. 355: Functionalize VACNT by, for example, UV / ozone, O2 plasma, or acid treatment. 365: A protective layer is deposited on VACNT by ALD. 375: A cathode active material is deposited on VACNT by ALD. 385: An additional protective layer is deposited on the VACNT by ALD.

[0120] An additional alternative method comprising incorporating a cathode active material using a sol-gel method is also described in FIG. 24a. The method comprises the following steps: 310: Provides a metal foil substrate. 320: Pattern the metal foil using, for example, a shadow mask or photolithography. This step is optional and can be omitted when depositing VACNT on the flat metal foil. 330: A catalyst (e.g., Fe, or Ni) and a sublayer (e.g., Al2O3, Ti, Cr, SiO2) are deposited on one or both sides of a metal foil substrate by PVD, CVD, or a sol-gel method. 340: A VACNT forest (multiple VACNTs) is grown on one or both sides of a metal foil substrate using a carbonaceous gas by CVD. 355: Functionalize VACNT by, for example, UV / ozone, O2 plasma, or acid treatment. 365: A protective layer is deposited on VACNT by ALD. 377: An organic solution containing a metal precursor is infiltrated into the VACNT forest. 387: Heat and anneale the VACNT to form a cathode active material. 397: A protective layer is deposited on VACNT by ALD.

[0121] Referring to FIG. 24b, a method for manufacturing a cathode comprising a VACNT forest as a current collector is described. The method comprises the following steps: 410: Provides a foam substrate. 420: A catalyst (e.g., Fe, or Ni) and a sublayer (e.g., Al2O3, Ti, Cr, SiO2) are deposited on a metal foil substrate by PVD, CVD, or a sol-gel method. 430: A VACNT forest (multiple VACNTs) is grown on a foam substrate using a carbonaceous gas by CVD. 440: Functionalize VACNT by, for example, UV / ozone, O2 plasma, or acid treatment. 450: A protective layer is deposited on VACNT by ALD. 460: A cathode active material is deposited on VACNT by ALD. 470: A protective layer is deposited on VACNT by ALD. 480: Compress the foam electrode.

[0122] An alternative method is also described in FIG. 24b. The method includes the following steps: 410: Provides a foam substrate. 420: A catalyst (e.g., Fe, or Ni) and a sublayer (e.g., Al2O3, Ti, Cr, SiO2) are deposited on a metal foil substrate by PVD, CVD, or a sol-gel method. 430: A VACNT forest (multiple VACNTs) is grown on a foam substrate using a carbonaceous gas by CVD. 435: A cathode active material is incorporated into the VACNT by a melting method. 445: A protective layer is deposited on VACNT by ALD. 455: Compress the foam electrode.

[0123] An additional alternative method comprising incorporating a cathode active material using a sol-gel method is also described in FIG. 24b. The method comprises the following steps: 410: Provides a foam substrate. 420: A catalyst (e.g., Fe, or Ni) and a sublayer (e.g., Al2O3, Ti, Cr, SiO2) are deposited on a metal foil substrate by PVD, CVD, or a sol-gel method. 430: A VACNT forest (multiple VACNTs) is grown on a foam substrate using a carbonaceous gas by CVD. 440: Functionalize VACNT by, for example, UV / ozone, O2 plasma, or acid treatment. 450: A protective layer is deposited on VACNT by ALD. 467: An organic solution containing a metal precursor is infiltrated into the VACNT forest. 477: VACNT is heated at a high temperature and annealed to form a cathode active material. 487: A protective layer is deposited on VACNT by ALD. 497: Compress the foam electrode.

[0124] Characterization of lithium-ion batteries including VACNT

[0125] A battery cell is a basic electrochemical unit that provides an electrical energy source through the conversion of chemical energy, and includes an assembly of electrodes (anode and cathode), a separator, an electrolyte, a container, and terminals. A battery cell is a single power generation unit having two electrodes (cathode and anode). The electrolyte is a chemical substance that reacts with the electrodes to generate an electric current. Types of battery cells include cylindrical cells, button or coin cells, prismatic cells, and pouch cells.

[0126] The total volume of the battery cells is calculated according to the following formula: The energy density of a battery (volume energy) is calculated according to the following formula: The volume ratio (VR) between the active material and the inactive material is calculated according to the following formula: To achieve ideal actual battery performance, the volume ratio (VR) between the active electrode material (active material layer) and other battery components (substrate including VACNT forest, separator, foil, and packaging) must be maximized.

[0127] Thin films of active materials can be deposited onto foil current collectors using ALD, CVD, and sputtering methods to create cell electrodes. The film thickness can range from several nanometers to several micrometers. Thicker films are necessary to achieve high loading and consequently high energy density, but they will drastically reduce rate performance (or power density). Furthermore, growing thick films on planar substrates by ALD is time-consuming and expensive to manufacture. While coating a very thin film of active material onto a planar substrate can shorten deposition time, the VR subsequently becomes very small, resulting in lower energy density. In conventional lithium-ion batteries, electrodes are generally much thicker (40 µm to 80 µm) and thus possess higher VR and higher energy density. By using VACNT structures, it is possible to achieve much higher area capacitance (for the same thickness) than conventional electrodes, and consequently higher energy density. In addition, because the material coating thickness is maintained at the nanoscale and VACNT provides a much larger active surface area, the generated electrode also has a much higher power density.

[0128] The volumetric energy density of a battery cell comprising VACNT structures at the anode and cathode may be up to about 1700 Wh / L, alternatively up to about 1600 Wh / L, alternatively about 500 to about 1600 Wh / L, alternatively about 600 to about 1600 Wh / L, alternatively about 750 to about 1600 Wh / L, or alternatively about 750 to about 1400 Wh / L. The volumetric energy density of a lithium-ion battery having a typical electrode structure is typically 300 to 900 Wh / L, typically up to about 720 Wh / L. The volumetric energy density can also be as low as 20 Wh / L when configuring a battery for ultra-high power applications (e.g., 10,000 W / L) that can be used in hybrid electric vehicles, or alternatively, about 20 Wh / L to about 400 Wh / L, alternatively about 20 Wh / L to about 300 Wh / L, or alternatively about 10 Wh / L to about 400 Wh / L.

[0129] The specific energy density or gravimetric energy density of a battery cell comprising VACNT structures at the anode and cathode may be about 250 to about 700 Wh / kg, alternatively about 250 to about 600 Wh / kg, alternatively about 400 to about 600 Wh / kg, alternatively about 500 to about 600 Wh / kg, alternatively about 550 to about 650 Wh / kg, alternatively about 10 to about 600 Wh / kg, alternatively about 10 to about 500 Wh / kg, alternatively about 10 to about 400 Wh / kg, alternatively about 10 to about 300 Wh / kg, alternatively about 5 to about 300 Wh / kg. The energy density of a lithium-ion battery having a typical electrode structure is typically less than 250 Wh / kg.

[0130] The total capacity of a battery cell including VACNT structures at the anode and cathode may be about 2 to about 15 mAh / cm², alternatively about 2 to about 9 mAh / cm², or alternatively about 2 to about 6 mAh / cm².

[0131] Although the foregoing invention has been described in some detail as examples and embodiments for the sake of clarity and understanding, it will be apparent that certain changes and modifications may be made that still fall within the scope of the appended claims.

Claims

Claim 1 A lithium-ion battery comprising a first conductive substrate, a first plurality of vertically aligned carbon nanotubes, and a first active material layer located on the outer surface of each of the first plurality of vertically aligned carbon nanotubes, wherein each of the first plurality of vertically aligned carbon nanotubes has a vertical axis perpendicular to the vertical axis of the first substrate; A cathode comprising a second conductive substrate, a second plurality of vertically aligned carbon nanotubes, and a second active material layer located on the outer surface of each nanotube of the second plurality of vertically aligned carbon nanotubes, wherein each of the second plurality of vertically aligned carbon nanotubes has a vertical axis perpendicular to the vertical axis of the second substrate, wherein at least one of the first substrate or the second substrate comprises at least one hole or void, and at least one of the first plurality of vertically aligned carbon nanotubes or the second plurality of vertically aligned carbon nanotubes does not grow in the at least one hole or void, and the circumference of the at least one hole or void is 10 to 500 μm 2 A lithium-ion battery that defines the area of. Claim 2 delete Claim 3 A battery according to claim 1, wherein at least one of the first substrate or the second substrate is a solid plane. Claim 4 A battery according to claim 1, wherein the first conductive substrate has a first surface and a second surface, a first portion of a first plurality of vertically aligned carbon nanotubes is coupled to the first conductive substrate on the first surface, and a second portion of a first plurality of vertically aligned carbon nanotubes is coupled to the first conductive substrate on the second surface. Claim 5 A battery according to claim 1, wherein the second conductive substrate has a first surface and a second surface, a first portion of a second plurality of vertically aligned carbon nanotubes is coupled to the second conductive substrate on the first surface, and a second portion of a second plurality of vertically aligned carbon nanotubes is coupled to the second conductive substrate on the second surface. Claim 6 delete Claim 7 A battery according to claim 1, wherein at least one of the first substrate or the second substrate is a patterned substrate. Claim 8 A battery according to claim 7, wherein at least one of the first substrate or the second substrate is selected from the group consisting of a mesh, a screen, and a foil. Claim 9 A battery according to claim 1, wherein at least one of the first substrate or the second substrate is a compressible foam. Claim 10 In paragraph 9, a battery having a compressible foam having 400 to 10,000 open cells per inch. Claim 11 In paragraph 9, a battery having a number of open cells with > 40 pores per inch, wherein the compressible foam is compressible foam. Claim 12 In claim 9, a battery having a compressible foam having a porosity of 70% to 90%. Claim 13 A battery according to claim 9, further comprising a plurality of metal ligaments connecting the compressible foam to form a compressible foam, wherein each of the plurality of metal ligaments has a width of 10 μm to 100 μm. Claim 14 A battery according to claim 9, wherein the compressible foam of the first substrate is made of a material selected from the group consisting of copper, nickel, carbon, and aluminum. Claim 15 A battery according to claim 9, wherein the compressible foam of the second substrate is made of a material selected from the group consisting of stainless steel, aluminum alloy, nickel alloy, and carbon. Claim 16 In claim 9, a battery having a compressible foam having a compression ratio of 30% to 90%. Claim 17 A battery according to claim 1, wherein the aspect ratio of the first plurality of vertically aligned carbon nanotubes is 100 to 1500. Claim 18 A battery according to claim 1, wherein the aspect ratio of the second plurality of vertically aligned carbon nanotubes is 100 to 1500. Claim 19 A battery according to claim 1, wherein the volumetric energy density of the battery is 500 to 1600 Wh / L. Claim 20 A battery according to claim 1, wherein the specific energy density of the battery is 250 to 600 Wh / kg. Claim 21 A battery according to claim 1, wherein the first active material layer and the second active material layer are each individually selected from the group consisting of FePO4, LiCoO2, V2O5, Co3O4, RuO2, SnO2, TiO2, and Cu2S. Claim 22 A battery according to claim 1, wherein the first active material layer comprises silicon. Claim 23 A battery according to claim 1, wherein the anode further comprises a second anode active material layer. Claim 24 A battery according to paragraph 23, wherein the second anode active material layer is a protective layer. Claim 25 A battery according to claim 23, wherein the second anode active material layer comprises TiO2. Claim 26 A battery according to claim 1, wherein the first active material layer comprises a material selected from the group consisting of SnO2, RuO2, TiO2, Cu2S, and combinations thereof. Claim 27 A battery according to claim 1, wherein the second active material layer is selected from the group consisting of V2O5, LiNiO2, LiMn2O4, LiCoO2, FePO4, LiFePO4, Li(Mn,Ni,Co)O2, Li(Ni,Co,Al)O2, and combinations thereof. Claim 28 A battery according to claim 1, wherein the cathode further comprises a second cathode active material layer. Claim 29 A battery according to claim 28, wherein the second cathode active material layer is a protective layer. Claim 30 A battery according to claim 28, wherein the second cathode active material layer is LiFePO4. Claim 31 A battery according to claim 1, wherein each of the first plurality of vertically aligned carbon nanotubes comprises a surface, and said surface is functionalized to increase the amount of precursor nucleation sites. Claim 32 A battery according to claim 31, wherein the surface is functionalized using a method selected from the group consisting of acid functionalization, oxygen plasma treatment, chemical functionalization, and the application of an adhesive layer. Claim 33 A battery according to claim 1, wherein a first active material layer is deposited on the outer surface of each nanotube in a first plurality of vertically aligned carbon nanotubes by atomic layer deposition. Claim 34 A battery according to claim 1, wherein a second active material layer is deposited on the outer surface of each nanotube in a plurality of second vertically aligned carbon nanotubes by atomic layer deposition. Claim 35 A lithium-ion battery comprising: a first compressible foam substrate including a first plurality of metal registrars connected to form a plurality of open pores; a first plurality of vertically aligned carbon nanotubes; and a first active material layer, wherein each nanotube of the first plurality of vertically aligned carbon nanotubes has an outer surface, a first end, and a longitudinal axis, and the first active material layer is located on the outer surface of each nanotube of the first plurality of vertically aligned carbon nanotubes, and the first end of each nanotube of the first plurality of vertically aligned carbon nanotubes is connected to a metal registrar of the first plurality of metal registrars, and the longitudinal axis of each nanotube is perpendicular to the longitudinal axis of the metal registrar to which the nanotube is connected; A cathode comprising a second compressible foam substrate including a second plurality of metal ligaments connected to form a plurality of open pores, a second plurality of vertically aligned carbon nanotubes, and a second active material layer, wherein each nanotube of the second plurality of vertically aligned carbon nanotubes has an outer surface, a first end, and a longitudinal axis, the second active material layer is located on the outer surface of each nanotube of the first plurality of vertically aligned carbon nanotubes, the first end of each nanotube of the second plurality of vertically aligned carbon nanotubes is connected to a metal ligament of the second plurality of metal ligaments, and the longitudinal axis of each nanotube is perpendicular to the longitudinal axis of the metal ligament to which the nanotube is connected, wherein at least one of the first compressible foam substrate or the second compressible foam substrate comprises at least one hole or void, and at least one of the first plurality of vertically aligned carbon nanotubes or the second plurality of vertically aligned carbon nanotubes does not grow in the at least one hole or void, and of the at least one hole or void Circumference of 10 to 500 µm 2 A lithium-ion battery that defines the area of. Claim 36 In paragraph 35, a battery having a compressible foam having 400 to 10,000 open pores per square inch. Claim 37 In paragraph 35, a battery having a compressible foam having an open pore count of > 40 pores per inch. Claim 38 In paragraph 35, a battery having a compressible foam having a porosity of 70% to 90%. Claim 39 A battery according to claim 35, wherein each of the plurality of metal ligaments connected to form a first or second compressible foam has a width of 10 μm to 100 μm. Claim 40 A battery according to claim 35, wherein the compressible foam of the first substrate is made of a material selected from the group consisting of copper, nickel, and carbon. Claim 41 A battery according to claim 35, wherein the compressible foam of the second substrate is made of a material selected from the group consisting of stainless steel, aluminum alloy, nickel alloy, and carbon. Claim 42 A battery according to claim 35, wherein the compressible foam has a compression ratio of 30% to 90%. Claim 43 A battery according to claim 35, wherein the aspect ratio of the first plurality of vertically aligned carbon nanotubes is 100 to 1500. Claim 44 A battery according to claim 35, wherein the aspect ratio of the second plurality of vertically aligned carbon nanotubes is 100 to 1500. Claim 45 In paragraph 35, a battery having a volumetric energy density of 500 to 1600 Wh / L. Claim 46 In paragraph 35, a battery having a specific energy density of 250 to 600 Wh / kg. Claim 47 A battery according to claim 35, wherein the first active material layer and the second active material layer are each individually selected from the group consisting of FePO4, LiCoO2, V2O5, Co3O4, RuO2, SnO2, TiO2, and Cu2S. Claim 48 A battery according to claim 35, wherein the first active material layer comprises silicon. Claim 49 A battery according to claim 35, wherein the anode further comprises a second anode active material layer. Claim 50 A battery according to claim 49, wherein the second anode active material layer is a protective layer. Claim 51 A battery according to claim 49, wherein the second anode active material layer comprises TiO2. Claim 52 A battery according to claim 35, wherein the first active material layer comprises a material selected from the group consisting of SnO2, RuO2, TiO2, Cu2S, and combinations thereof. Claim 53 A battery according to claim 35, wherein the second active material layer is selected from the group consisting of V2O5, LiNiO2, LiMn2O4, LiCoO2, FePO4, LiFePO4, Li(Mn,Ni,Co)O2, and Li(Ni,Co,Al)O2. Claim 54 A battery according to claim 35, wherein the cathode further comprises a second cathode active material layer. Claim 55 A battery according to claim 54, wherein the second cathode active material layer is a protective layer. Claim 56 A battery according to claim 54, wherein the second cathode active material layer is LiFePO4. Claim 57 A battery according to claim 35, wherein each of the first plurality of vertically aligned carbon nanotubes comprises a surface, said surface being functionalized to increase the amount of precursor nucleation sites. Claim 58 A battery according to claim 57, wherein the surface is functionalized using a method selected from the group consisting of acid functionalization, oxygen plasma treatment, chemical functionalization, and the application of an adhesive layer. Claim 59 A battery according to claim 35, wherein a first active material layer is deposited on the outer surface of each nanotube in a first plurality of vertically aligned carbon nanotubes by atomic layer deposition. Claim 60 A battery according to claim 35, wherein a second active material layer is deposited on the outer surface of each nanotube in a plurality of second vertically aligned carbon nanotubes by atomic layer deposition. Claim 61 As an anode of a lithium-ion battery, a substrate; as a current collector comprising a plurality of vertically aligned carbon nanotubes, wherein each nanotube of the plurality of vertically aligned carbon nanotubes has an outer surface and a first end, and the first end is coupled to the substrate; and comprising an active material layer located on the outer surface of each nanotube of the plurality of vertically aligned carbon nanotubes, wherein the substrate comprises at least one hole or void, and the plurality of vertically aligned carbon nanotubes do not grow in the at least one hole or void, and the circumference of the at least one hole or void is 10 to 500 μm 2 The anode of a lithium-ion battery that defines the area of. Claim 62 In claim 61, an anode in which the first end of each of the plurality of vertically aligned carbon nanotubes is connected to a substrate, and the longitudinal axis of each nanotube is perpendicular to the longitudinal axis of the substrate. Claim 63 An anode according to claim 61, wherein the substrate has first and second surfaces, a first portion of a plurality of vertically aligned carbon nanotubes is connected to the first surface of the substrate, and a second portion of the plurality of vertically aligned carbon nanotubes is connected to the second surface of the substrate. Claim 64 delete Claim 65 delete Claim 66 In paragraph 61, the anode, wherein the substrate is a patterned substrate. Claim 67 In paragraph 66, the anode, wherein the patterned substrate is selected from the group consisting of mesh, screen, and foil. Claim 68 In paragraph 61, the anode, wherein the substrate is a compressible foam. Claim 69 In paragraph 68, an anode having a compressible foam having 400 to 10,000 open cells per square inch. Claim 70 In paragraph 68, an anode having a number of open cells with > 40 pores per inch, the compressible foam. Claim 71 In paragraph 68, an anode having a porosity of 70% to 90% in a compressible foam. Claim 72 An anode according to claim 68, further comprising a plurality of metal ligaments connecting the compressible foam to form a compressible foam, wherein each of the plurality of metal ligaments has a width of 10 μm to 100 μm. Claim 73 In paragraph 68, an anode in which a compressible foam is made of a material selected from the group consisting of copper, nickel, and carbon. Claim 74 In paragraph 68, an anode having a compressible foam having a compression ratio of 30% to 90%. Claim 75 In claim 61, an anode having an aspect ratio of a plurality of vertically aligned carbon nanotubes of 100 to 1500. Claim 76 In paragraph 61, an anode in which the active material layer comprises silicon. Claim 77 In paragraph 61, the anode further comprises a second active material layer. Claim 78 In paragraph 77, an anode in which the second active material layer is a protective layer. Claim 79 In paragraph 77, an anode in which the second active material layer comprises TiO2. Claim 80 An anode according to claim 61, wherein the first active material layer comprises a material selected from the group consisting of SnO2, RuO2, TiO2, Cu2S, and combinations thereof. Claim 81 In claim 61, an anode in which the outer surface of each nanotube of a plurality of vertically aligned carbon nanotubes is functionalized to increase the amount of precursor nucleation sites. Claim 82 In paragraph 81, an anode in which the outer surface is functionalized using a method selected from the group consisting of acid functionalization, oxygen plasma treatment, chemical functionalization, and the application of an adhesive layer. Claim 83 In claim 61, an anode in which an active material layer is deposited on the outer surface of each nanotube in a plurality of vertically aligned carbon nanotubes by atomic layer deposition. Claim 84 As a cathode of a lithium-ion battery, a substrate; as a current collector comprising a plurality of vertically aligned carbon nanotubes, wherein each nanotube of the plurality of vertically aligned carbon nanotubes has an outer surface and a first end, and the first end is coupled to the substrate; and each of the plurality of vertically aligned carbon nanotubes The substrate comprises at least one active material layer located on the outer surface of the nanotube, wherein the substrate comprises at least one hole or void, and the plurality of vertically aligned carbon nanotubes do not grow in the at least one hole or void, and the circumference of the at least one hole or void is 10 to 500 μm 2 A cathode of a lithium-ion battery that defines the area of. Claim 85 In paragraph 84, a cathode in which the first end of each of the plurality of vertically aligned carbon nanotubes is connected to a substrate, and the longitudinal axis of each nanotube is perpendicular to the longitudinal axis of the substrate. Claim 86 A cathode according to claim 84, wherein the substrate has first and second surfaces, a first portion of a plurality of vertically aligned carbon nanotubes is connected to the first surface of the substrate, and a second portion of the plurality of vertically aligned carbon nanotubes is connected to the second surface of the substrate. Claim 87 delete Claim 88 delete Claim 89 In paragraph 84, the cathode, wherein the substrate is a patterned substrate. Claim 90 In paragraph 89, a cathode in which the patterned substrate is selected from the group consisting of mesh, screen, and foil. Claim 91 In paragraph 84, a cathode in which the substrate is a compressible foam. Claim 92 In paragraph 91, a cathode having a compressible foam having 400 to 10,000 open cells per square inch. Claim 93 In paragraph 91, a cathode having a number of open cells with a compressible foam of > 40 pores per inch. Claim 94 In paragraph 91, a cathode having a compressible foam having a porosity of 70% to 90%. Claim 95 A cathode according to claim 91, further comprising a plurality of metal ligaments connecting the compressible foam to form a compressible foam, wherein each of the plurality of metal ligaments has a width of 10 μm to 100 μm. Claim 96 In paragraph 91, a cathode in which a compressible foam is made of a material selected from the group consisting of copper, nickel, and carbon. Claim 97 In paragraph 91, a cathode having a compressible foam having a compressibility of 30% to 90%. Claim 98 In paragraph 84, a cathode having an aspect ratio of a plurality of vertically aligned carbon nanotubes of 100 to 1500. Claim 99 A cathode according to claim 84, wherein the active material layer is selected from the group consisting of V2O5, LiNiO2, LiMn2O4, LiCoO2, FePO4, LiFePO4, Li(Mn,Ni,Co)O2, and Li(Ni,Co,Al)O2. Claim 100 In paragraph 84, the cathode further comprises a second active material layer. Claim 101 A cathode according to claim 100, wherein the second active material layer is a protective layer. Claim 102 In claim 100, a cathode in which the second active material layer is LiFePO4. Claim 103 In paragraph 84, a cathode in which the outer surface of each nanotube of a plurality of vertically aligned carbon nanotubes is functionalized to increase the amount of precursor nucleation sites. Claim 104 A cathode according to claim 103, wherein the outer surface is functionalized using a method selected from the group consisting of acid functionalization, oxygen plasma treatment, chemical functionalization, and the application of an adhesive layer. Claim 105 A cathode according to claim 84, wherein an active material layer is deposited on the outer surface of each nanotube in a plurality of vertically aligned carbon nanotubes by atomic layer deposition. Claim 106 A method for manufacturing an anode for a lithium-ion battery comprises: a step of depositing a catalyst and a sublayer on a substrate, wherein the substrate has a longitudinal axis; a step of growing a plurality of vertically aligned carbon nanotubes on the substrate, wherein each of the plurality of vertically aligned carbon nanotubes has an outer surface and a longitudinal axis, and the longitudinal axis of each nanotube is perpendicular to the longitudinal axis of a metal foil substrate; and a step of depositing a protective layer on the outer surface of each nanotube by atomic layer deposition, wherein the substrate has at least one hole or void, and the plurality of vertically aligned carbon nanotubes do not grow in at least one hole or void, and the circumference of at least one hole or void is 10 to 500 μm 2 A method for defining the area of. Claim 107 In paragraph 106, the method wherein the substrate is a metal foil substrate. Claim 108 A method according to claim 106, wherein a substrate comprises first and second surfaces, a first portion of a plurality of vertically aligned carbon nanotubes is grown on the first surface of the substrate, and a second portion of the plurality of vertically aligned carbon nanotubes is grown on the second surface of the substrate. Claim 109 In claim 107, a method in which a metal foil substrate is patterned. Claim 110 delete Claim 111 delete Claim 112 In paragraph 106, the method wherein the substrate is a compressible foam. Claim 113 A method according to claim 112, wherein a compressible foam is manufactured from a material selected from the group consisting of copper, nickel, and carbon. Claim 114 In paragraph 112, a method wherein the compressible foam has a compression ratio of 30% to 90%. Claim 115 A method according to claim 112, further comprising the step of compressing a compressible foam. Claim 116 A method according to claim 106, further comprising the step of depositing an active material on the outer surface of each nanotube by LPCVD prior to the step of depositing a protective layer. Claim 117 In paragraph 116, a method in which the active material comprises silicon. Claim 118 A method according to claim 116, wherein the active material is selected from the group consisting of SnO2, RuO2, TiO2, and Cu2S. Claim 119 A method according to claim 106, further comprising the step of functionalizing the outer surface of each nanotube before the step of depositing a protective layer. Claim 120 A method according to claim 119, wherein the step of functionalizing the outer surface of each nanotube includes UV / ozone, O2 plasma, or acid treatment. Claim 121 A method according to claim 119, further comprising the step of depositing an anode active material on a plurality of vertically aligned carbon nanotubes after the functionalization step and before the step of depositing a protective layer by atomic layer deposition. Claim 122 A method according to claim 106, further comprising the step of compressing a compressible foam. Claim 123 A method for manufacturing a cathode for a lithium-ion battery comprises: a step of depositing a catalyst and a sublayer on a substrate, wherein the substrate has a longitudinal axis; a step of growing a plurality of vertically aligned carbon nanotubes on the substrate, wherein each of the plurality of vertically aligned carbon nanotubes has an outer surface and a longitudinal axis, and the longitudinal axis of each nanotube is perpendicular to the longitudinal axis of the substrate; and a step of depositing a protective layer on the outer surface of each nanotube by atomic layer deposition, wherein the substrate has at least one hole or void, and the plurality of vertically aligned carbon nanotubes do not grow in at least one hole or void, and the circumference of at least one hole or void is 10 to 500 μm 2 A method for defining the area of. Claim 124 In paragraph 123, the method wherein the substrate is a metal foil substrate. Claim 125 A method according to claim 123, wherein a substrate comprises first and second surfaces, a first portion of a plurality of vertically aligned carbon nanotubes is grown on the first surface of the substrate, and a second portion of the plurality of vertically aligned carbon nanotubes is grown on the second surface of the substrate. Claim 126 In paragraph 124, a method in which a metal foil substrate is patterned. Claim 127 delete Claim 128 delete Claim 129 In paragraph 123, the method wherein the substrate is a compressible foam. Claim 130 A method according to claim 129, wherein a compressible foam is manufactured from a material selected from the group consisting of copper, nickel, and carbon. Claim 131 In paragraph 129, a method wherein the compressible foam has a compression ratio of 30% to 90%. Claim 132 A method according to claim 129, further comprising the step of compressing a compressible foam. Claim 133 A method according to claim 123, further comprising the step of incorporating a cathode active material onto the outer surface of each nanotube by a melting method prior to the step of depositing a protective layer. Claim 134 A method according to claim 123, further comprising the step of functionalizing the outer surface of each nanotube before the step of depositing a protective layer. Claim 135 A method according to claim 134, wherein the step of functionalizing the outer surface of each nanotube includes UV / ozone, O2 plasma, or acid treatment. Claim 136 A method according to claim 123, further comprising the step of depositing a cathode active material on a plurality of vertically aligned carbon nanotubes after the step of depositing a protective layer. Claim 137 A method according to claim 136, further comprising the step of depositing an additional protective layer on a plurality of vertically aligned carbon nanotubes after the step of depositing a cathode active material. Claim 138 A method according to claim 137, further comprising the step of compressing a compressible foam. Claim 139 A method according to claim 123, further comprising the step of incorporating a cathode active material onto a plurality of vertically aligned carbon nanotubes by a sol-gel method after the step of depositing a protective layer on the outer surface of each nanotube. Claim 140 A method according to claim 139, further comprising the step of depositing an additional protective layer by atomic layer deposition on a plurality of vertically aligned carbon nanotubes after the step of incorporating a cathode active material. Claim 141 A method according to claim 123, further comprising the step of infiltrating a plurality of vertically aligned carbon nanotubes with an organic solution containing a metal precursor. Claim 142 A method according to claim 141, further comprising the step of heating and annealing a plurality of vertically aligned carbon nanotubes to form a cathode active material on the outer surface of each nanotube. Claim 143 A method according to claim 142, further comprising the step of depositing a protective layer on a plurality of vertically aligned carbon nanotubes by ALD. Claim 144 A method according to paragraph 143, further comprising the step of compressing a compressible foam. Claim 145 A method according to claim 123, further comprising the step of incorporating a cathode active material onto the outer surface of each of a plurality of vertically aligned carbon nanotubes by a melting method prior to the step of depositing a protective layer. Claim 146 A method according to claim 145, wherein the active material layer is selected from the group consisting of V2O5, LiNiO2, LiMn2O4, LiCoO2, FePO4, LiFePO4, Li(Mn,Ni,Co)O2, and Li(Ni,Co,Al)O2. Claim 147 A method according to claim 145, further comprising the step of compressing a compressible foam.

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