US20170309919A1 - High Capacity Energy Storage - Google Patents

Abstract

An energy storage device includes a nano-structured cathode. The cathode includes a conductive substrate, and underframe and an active layer. The underframe includes structures such as nano-filaments and/or aerogel. The active layer optionally includes a catalyst disposed within the active layer, the catalyst being configured to catalyze the dissociation of cathode active material.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is a continuation of U.S. application Ser. No. 14/176,137, filed Feb. 9, 2014, which claims benefit of and priority to U.S. provisional application Ser. Nos.:
• 61/910,955 filed Dec. 2, 2013,
• 61/904,417 filed Nov. 14, 2013,
• 61/887,447 filed Oct. 7, 2013,
• 61/868,002 filed Aug. 20, 2013, and
• 61/806,819 filed Mar. 29, 2013;
• which application is a continuation in part of U.S. non-provisional application Ser. No. 13/935,334 filed Jul. 3, 2013, issued as U.S. Pat. No. 9,362,549, which in turn is a continuation-in-part of Ser. No. 13/779,409 filed Feb. 27, 2013, issued as U.S. Pat. No. 9,349,544, which claims benefit of U.S. provisional application Ser. Nos. 61/615,179 filed Mar. 23, 2012 and 61/752,437 filed Jan. 14, 2013, and which in turn is a continuation in part of Ser. No. 13/725,969 filed Dec. 21, 2012, issued as U.S. Pat. No. 9,412,998, which in turn claims benefit of provisional applications:
• 61/667,317 filed Jul. 30, 2012,
• 61/667,876 filed Jul. 3, 2012,
• 61/603,833 filed Feb. 27, 2012, and
• 61/578,545 filed Dec. 21, 2011;
• which application is a continuation in part of U.S. non-provisional application Ser. No. 13/725,969 filed Dec. 21, 2012, issued as U.S. Pat. No. 9,412,998, which in turn is a continuation-in-part of U.S. non-provisional application Ser. No. 12/904,113 filed Oct. 13, 2010, issued as U.S. Pat. No. 8,481,214, which in turn claims benefit of U.S. provisional application Ser. No. 61/254,090 filed Oct. 22, 2009 and is a continuation-in-part of U.S. non-provisional application Ser. No. 12/392,525 filed Feb. 25, 2009, issued as U.S. Pat. No. 8,420,258, which in turn claims benefit of U.S. provisional application Ser. No. 61/130,679 filed Jun. 2, 2008 and U.S. provisional application Ser. No. 61/067,018 filed Feb. 25, 2008; U.S. application Ser. No. 14/176,137 is a continuation-in-part of U.S. non provisional application Ser. No. 13/868,957 filed Apr. 23, 2013; and U.S. application Ser. No. 14/176,137 is a continuation-in-part of PCT/US14/11556 filed Jan. 14, 2014. This application is copending with U.S. Patent Application entitled “High Capacity Energy Storage” filed Jul. 10, 2017, attorney docket no. 17619.0016USC8.
• The disclosures of the above provisional, non-provisional, and PCT patent applications are hereby incorporated herein by reference in their entirety.
BACKGROUNDField of the Invention
• The invention is in the field of energy storage technology.
Related Art
• Energy storage is important in many applications. These include, backup power, portable electronic devices, and vehicles. One type of energy storage is the lithium ion battery. This battery is currently used in vehicles and portable electronics. There is, however, a need for improved energy storage capacity.
• For example, prior art cathodes used in lithium ion batteries suffer from low energy density (i.e. lithium cobalt oxide˜180 mAh/g) when compared to the best available anode materials (silicon-4000 mAh/g). To alleviate this issue, there has been focus on developing lithium-air batteries, at the expense of additional complexity of new separators and chemistries to support the battery coming in contact with air. One of the developments is to rely upon the reversible formation/decomposition reaction of Li₂O₂at the cathode upon cycling. [e.g., “A Reversible and Higher-Rate Li—O₂Battery”, Science, vol. 337, pgs 563-566]. One issue with the technique described in this paper is that the materials used to catalyze the reaction (gold), has a weight that creates an effective energy density of ˜300 mAh/g. The technology also suffers from poor charging rates. The charging rates being dependent at least in part on catalyst surface area.
SUMMARY
• Various embodiments of invention disclosed herein include new types of cathodes. These cathodes are optionally used in lithium ion batteries. For example, some embodiments can be used in sealed or un-sealed Lithium-air batteries. These embodiments solve problems with the prior art by provided greater energy storage density per unit mass and per unit volume.
• An energy storage device includes a nano-structured cathode. The cathode includes a conductive substrate, and underframe and an active layer. The underframe includes structures such as nano-filaments and/or aerogel. The active layer optionally includes a catalyst disposed within the active layer, the catalyst being configured to catalyze the dissociation of cathode active material.
• In one embodiment, there is provided an electrochemically active electrode for use in a lithium ion cell, the electrode comprising a substrate and an electrochemically active electrode material comprised of a nanostructured template comprising a metal silicide and a layer of an electrochemically active material coating the nanostructured template, the electrochemically active material configured to take in and release lithium ions during cycling of the lithium ion cell, wherein the nanostructured template facilitates conduction of electrical current to and from the electrochemically active material and provides support to the layer of the electrochemically active material.
• In one embodiment, there is provided an electrochemically active electrode material for use in a lithium ion cell, the electrochemically active electrode material comprising a nanostructured template comprising a metal silicide and a layer of a non-silicide electrochemically active material, the electrochemically active material configured to take in and release lithium ions during cycling of the lithium ion cell, wherein the nanostructured template facilitates conduction of electrical current to and from the electrochemically active material and provides support to the layer of the electrochemically active material. In one embodiment, the metal silicide includes silicon/germanium. In one embodiment, the non-silicide active material has a theoretical lithiation capacity of at least 500 mAh/g coating of the nanostructured template.
• In various embodiments, the electrode can include silicon, graphite, Sn, Sn—C, inter-metallics, phosphides, nitrides, 3D metal oxides, or LiCoPO₄, LiMnPO₄, LiMnPO₄, LiMn₂O₄, LiCoO₂, LiNiO₂, vanadium oxides V₂O₅and LiV₃O₈, polyanionic materials such as Li(1-x)VOPO₄, Li(x)FePO₄), LiMnO₂, Li₂FePO₄F, doped LiMn₂O₄, and/or the like. The material can be deposited or grown on the electrode support.
• Some embodiments of the invention include an energy storage system comprising an electrode disposed in a first region of electrolyte and including a substrate, a plurality of support filaments attached to the substrate, and an ion absorbing material attached to the support filaments and configured to expand in volume at least 5 percent when absorbing ions; a separator configured to separate the first region and a second region of electrolyte; and a cathode disposed in the second region of electrolyte, the cathode, anode and separator configured to operate as a rechargeable battery.
• Some embodiments of the invention include a battery comprising a first cathode electrode comprising a supporting underframe, an active material configured to release oxygen and lithium from the active material in a reduction reaction, the reduction reaction including the reduction of a lithium compound, the active material being disposed on the underframe, and an active catalyzer deposited within the active material, the catalyzer configured to catalyze the reduction reaction; and an anode electrode.
• Some embodiments of the invention include battery comprising an anode; a cathode including a conductive substrate, an underframe attached to the substrate, and a catalyst coated on the underframe, the catalyst being configured to catalyze the dissociation of cathode active material; and an electrolyte including the cathode active material.
• Some embodiments of the invention include battery comprising: an anode; a cathode including a conductive substrate, an underframe, a catalyst coated on the underframe, the catalyst being configured to catalyze the dissociation of cathode active material, and a binder configured to hold the underframe in proximity to the substrate; and an electrolyte including the cathode active material.
• Some embodiments of the invention include battery comprising an anode; a cathode including a conductive substrate, an underframe including an aerogel, and a catalyst disposed within the aerogel, the catalyst being configured to catalyze the dissociation of cathode active material; and an electrolyte including the cathode active material.
• Some embodiments of the invention include method of making a battery, the method comprising providing an anode; producing a cathode by growing an underframe including a plurality of nanofibers on a conductive substrate, and depositing a catalyst on the nanofibers, the catalyst being configured to catalyze dissociation of cathode active material; and adding an electrolyte between the anode and the cathode, the electrolyte including the cathode active material.
• Some embodiments of the invention include method of making a battery, the method comprising providing an anode; producing a cathode by providing an underframe including plurality of nanofibers, depositing a catalyst on the nanofibers, the catalyst being configured to catalyze dissociation of cathode active material, and applying the nanofibers to a conductive substrate using a binder; and adding an electrolyte between the anode and the cathode, the electrolyte including the cathode active material.
• Some embodiments of the invention include a method of making a battery, the method comprising providing an anode; producing a cathode by providing an underframe including an aerogel, depositing a catalyst within the aerogel, the catalyst being configured to catalyze dissociation of cathode active material, and applying the aerogel to a conductive substrate; and adding an electrolyte between the anode and the cathode, the electrolyte including the cathode active material.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1A illustrates a cross section of a single element of an energy storage electrode, according to various embodiments of the invention.
• FIG. 1B is a cross section illustrating details of a seed layer ofFIG. 1A according to various embodiments of the invention.
• FIG. 1C is a cross section of a portion of the energy storage electrode ofFIG. 1A illustrating an underlayer between an underframe and active layer, and an over-layer that optionally encapsulates the active layer, according to various embodiments of the invention.
• FIG. 2A illustrates an underframe including a vertically aligned array of nanotubes or nanowires, according to various embodiments of the invention.
• FIG. 2B illustrates an underframe including a vertically aligned array of nanotubes or nanowires, including diameter variation along the length of the nanotubes or nanowires, according to various embodiments of the invention.
• FIG. 2C illustrates an underframe including a vertically aligned array of nanofibers, with ‘graphitic’ edges exposed, according to various embodiments of the invention.
• FIG. 2D illustrates an underframe including a vertically aligned array of branched nanotubes, branched nanofibers, or branched nanowires, according to various embodiments of the invention.
• FIG. 2E illustrates an underframe including a template formed aerogel, according to various embodiments of the invention.
• FIG. 3 illustrates further details of a cross section of a portion of the energy storage electrode ofFIG. 1A, according to various embodiments of the invention.
• FIG. 4A illustrates a cross section of several elements of an energy storage electrode with stacked-cup nanofibers, according to various embodiments of the invention.
• FIG. 4B illustrates a cross section of several elements of a stacked-cup nanofiber with exposed ‘graphitic’ edges, according to various embodiments of the invention.
• FIG. 5A illustrates a cross section of several elements of an energy storage electrode including a template formed aerogel, according to various embodiments of the invention.
• FIG. 5B illustrates a cross section of an aerogel, according to various embodiments of the invention.
• FIG. 6 illustrates a cross section of a prior art rechargeable battery.
• FIG. 7 illustrates methods of producing an electrode, according to various embodiments of the invention.
DETAILED DESCRIPTION
• FIG. 1A illustrates a cross section of a single element of anenergy storage electrode100, according to various embodiments of the invention. One or more ofelectrode100 may be used in a rechargeable battery, such as the rechargeable (secondary) battery ofFIG. 6, in accordance with various embodiments of the invention. Theelectrode100 includes asubstrate110, anoptional seed layer115, and anenergy storage system190. Theenergy storage system190 includes anunderframe130 and anactive layer150. Theseed layer115 may be used to initiate growth of theunderframe130 and may be used to facilitate connection of theenergy storage system190 to thesubstrate110. In alternative embodiments theenergy storage system190 is coupled directly to thesubstrate110. Theunderframe110 supports theactive layer150, as well as theoptional overlayer154 andoptional underlayer152. Theunderframe130 provides enhanced surface area per unit volume for uptake and/or deposition of additional materials.
• Thesubstrate110 can comprise graphite coated aluminum, graphite, Ni, Ag, Fe, Mg, Pb, W, Al, Hf, Mo, Pd, Ta, Au, In, Nb, Ti, Zr, Cu, Li, Ni, V, Zn, C, carbides of the above elements, silicides of the above elements, oxides of the above elements, nitrides of the above elements, an oxygen permeable membrane, and/or any combination thereof. Note that the substrate can include one material, or a combination of more than one material. (The “above elements” refers to those discussed in this paragraph.) For instance, thesubstrate110 can be composed of both aluminum and an oxygen permeable membrane. Additionally, the thickness of the substrate can range in thickness from approximately 5 microns to approximately 250 microns, 250 microns to 750 microns, 750 microns to 2 mm, and 2 mm to 5 mm, or any combination thereof, depending on the particular application of the secondary battery/cell100.
• In various embodiments, thesubstrate110 includes gold, tin, silver, aluminum, copper, graphite, nickel, and/or the like. Optionally, thesubstrate110 is a semi-conductor material. In various embodiments, the semi-conductor material includes element materials such as silicon and germanium, or compound semiconductors such as gallium arsenide and indium phosphide, or alloys such as silicon germanium or aluminum gallium arsenide.
• In various embodiments, thesubstrate110 includes an oxygen permeable membrane, polymers, porous materials such as aerogel, metal, a semiconductor, and/or an insulator. Thesubstrate110 may be fabricated in a variety of shapes. For example, thesubstrate110 may be planar (single sided and double sided), cylindrical, finned, and/or the like. In some embodiments, the shape ofsubstrate110 is selected so as to maximize available surface area. Finally, theelectrode100 typically includes multipleenergy storage systems190, optionally in an array.
• Theoptional seed layer115 serves one or more of a number of functions and may include several sub-layers. For example, theseed layer115 may comprise aninitial layer117, anintermediate layer118, and/or afinal layer119. Theseed layer115 may be configured to control the cross-sectional area (e.g., diameter) of theunderframe130 by controlling an area in which initial growth of theunderframe130 occurs. The relative and/or absolute thicknesses of theinitial layer117, anintermediate layer118, and/or afinal layer119 can be selected to control the area of initial growth of theunderframe130 and thus the underframe cross sectional area (e.g., diameter) shown inFIGS. 2A, 2B, 2C, 2D, &2E). Those skilled in the art of nanotube, nanofiber, nanowire, and aerogel growth will appreciate that other methods are also available to control the cross-sectional area of theunderframe130. In some embodiments, theseed layer115 may control adhesion of theunderframe130 to thesubstrate110. The spacing betweenadjacent underframe130 and/or the cross section of theunderframe130 may limit the possible thickness of theactive layer150,over-layer154,underlayer152, and vice-versa.
• In various embodiments, theseed layer115 includes Ti, Fe, Co, TiN, and/or Mo.
• Theseed layer115 may control a density of initiation points and/or an areal density of growth initiation points for theunderframe130. The density of initiation points determines the density ofunderframe130 attachment points. The density of attachment points may by between 103/cm²to 10¹¹/cm², generally 10⁷/cm²to 10¹⁰/cm². The initiation density may be expressed as a number of support filament initiation sites per unit area, e.g., number/cm². The areal density is the density ofunderframe130 tips that are distal fromseed layer115 andsubstrate110. The areal density can be greater than the density of attachment points because theunderframe130 may be branched, as discussed further elsewhere herein. The areal density may be expressed as a number of support filament tips per unit area, e.g., number/cm².
• In some embodiments, theseed layer115 is a single material deposited on thesubstrate110 in a single layer. Alternatively, theseed layer115 includes multiple (2, 3 or more) sub-layers of differing materials, e.g.,initial layer117,intermediate layer118, and/orfinal layer119. Each of the sub-layers of theseed layer115 may be configured to perform various functions. For example, one of the sub-layers may include a barrier layer configured to prevent migration of atoms between layers; include an adhesion layer configured to bind two layers together; a protection layer configured to protect underlying or overlying layers from chemical/physical degradation; a conduction layer configured to provide conductivity; a stress/strain layer configured to act as a mechanical buffer between two layers; a binding/release layer configured to bind/release the final seed material to/from the underlying substrate; a layer configured to inhibit the growth of nanotube, nanofiber, nanowire, and/or aerogels, and/or a seed layer to initiate nanotube, nanofiber, nanowire, and/or aerogel growth. Persons having ordinary skill in the art of thin film growth and deposition will recognize that there are other utilities a thin film layered structure ofseed layer115 can serve.
• FIG. 1B is a cross section illustrating details of theseed layer115 ofFIG. 1A, according to various embodiments of the invention. Theseed layer115 illustrated inFIG. 1B includes a stack of sub-layers comprising different materials. As described elsewhere herein, the sub-layers include, for example, aninitial layer117, anintermediate layer118 and afinal layer119. Theinitial layer117 is coupled to the substrate and forms a base for theintermediate layer118. Theintermediate layer118 is deposited on theinitial layer117 and configured to form a base for thefinal layer119. Thefinal layer119 is deposited on theintermediate layer118 and is configured to provide sites for attachment and initiation of growth of theunderframe130. Alternatively, thefinal layer119 is configured to inhibit the growth of a nanotube, nanofiber, nanowire, and/or aerogel.
• In various embodiments, thefinal layer119 includes molybdenum, iron, cobalt, nickel, carbon, graphite, graphene, and/or the like. Various materials in thefinal layer119 may initiate or inhibit growth and/or provide for attachment of the including nanotube, nanofiber, nanowire, and/or aerogel. Theintermediate layer118 may comprise, for example, iron, cobalt, nickel, titanium, titanium nitride, aluminum, and/or the like. Theinitial layer117 may include, for example, platinum, tungsten, titanium, chromium, and/or the like. It will be appreciated that alternative materials may be included in the sub-layers ofseed layer115.
• In various embodiments, theunderframe130 includes nanotube, nanofiber, nanowire, and/or aerogel. More specifically, the nanotube, nanofiber, nanowire, and/or aerogel may comprise materials of metals, carbon, graphene, boron nitride, silicon, TiO₂, copper, transition metals, oxides, nitrides, silicides, carbides, SiO₂, silica, transition metal oxides, TiN, SiC, TiC, and/or any combination thereof. The nanotubes, nanofibers, nanowires, and/or aerogel may be doped with materials, including, but not limited to boron, phosphor, and/or nitrogen. In some embodiments theunderframe130 includes carbon nanotubes or fibers having a stacked-cup structure. In alternative embodiments,underframe130 is in the form of a mesh and each ofenergy storage system190 need not be attached tosubstrate110 and/orseed layer115 by an end. The stacked-cup structure provides variable surface texture of theunderframe130. This surface variation can result in useful variation and/or structure in any of the layers placed on theunderframe130.
• Theunderframe130 provides a mechanical base for deposition and growth of theactive layer150,underlayer152, andoverlayer154. Theunderframe130 may also provide strength (e.g., tensile strength, compression strength, shear strength, and/or the like) to theactive layer150. The additional strength reduces or prevents damage to theenergy storage system190 during expansion and/or contraction of theactive layer150. The nanotubes may include a single wall or multiple walls. The nanofibers may include a cup like stacking structure along its length; the edges of these cups may be described as being ‘graphitic’ with respect to their material properties i.e. the edges act as graphene sheets. In some embodiments, the nanotube, nanofiber, nanowire, and/or aerogel of theunderframe130 is configured to act as an active material in which material is adsorbed and/or reactions catalyzed. In some embodiments, the nanotube, nanofiber, nanowire, and/or aerogel of theunderframe130 is configured to allow for uptake of additional material, such as gases (O₂, CO₂, CO, N₂, NO₂, NO, H2, etc.), nano-particles and/or thin films, such as gold, platinum, MnO_x, CuFe, beta-MnO₂/Pt, Pd, Ru, MoN/NGS, Li₅FeO₄, Li₂MnO₃*LiFeO₂, FeO₄, CoFe₂O₄, TiN, TiC, TiO₂, graphite, Ni, Ag, Fe, Mg, Pb, W, Al, Hf, Mo, Pd, Ta, Au, In, Nb, Ti, Zr, Cu, Li, Ni, V, Zn, C, carbides of the above elements or compounds, silicides of the above elements or compounds, oxides of the above elements or compounds, nitrides of the above elements or compounds, and/or any combination thereof. (The “above elements or compounds” refers to those elements discussed in this paragraph.)
• In some embodiments, theactive layer150 does coat some but not all of the length of theunderframe130. As a result, a portion of theunderframe130 forms anuncoated region135. Theuncoated region135 is configured to provide a region for flex and motion of theunderframe130. This flex can reduce mechanical stress resulting from expansion and contraction of theactive layer150. If not reduced, this stress can cause breakage and/or separation of theunderframe130 from theseed layer115. Additionally, thisuncoated region135 may provide additional volume for gas, e.g., O₂, capture and/or sequestration.
• Unfortunately, silicon breakage substantially compromises adhesion of silicon to an anode, thus, decreasing longevity. Methods have been suggested to improve the lifetime of silicon anodes, for example, growing silicon nano-wires on stainless steel.
• The length of theuncoated region135 may range from several angstroms to several microns. In some embodiments the length of theuncoated region135 is selected such that theactive layer150 does not reach or only just reaches theseed layer115. In various embodiments the length of theuncoated region135 is at least 0.1, 0.25, 0.3, 0.5, or 1.0 micrometers. In some embodiments, the length of theuncoated region135 is substantially greater than a micron. In various embodiments the length of theuncoated region135 is at least 20%, 30%, 40%, 55%, 70%, 85%, 90%, or 95% of the total length of theunderframe130 height. Theuncoated region135 is typically located proximate to the end ofunderframe130 closest to theseed layer115. However,uncoated region135 may be provided at other or alternative parts ofunderframe130. For example,uncoated region135 may be provided proximate to branches withinunderframe130.
• In some embodiments,uncoated region135 is a region that has reduced coating ofactive layer150 relative to other parts ofenergy storage system190, rather than a region having no coat at all. For example,uncoated region135 may have a coating ofactive layer150 whose thickness is less than 10, 25 or 50% of the thickness of theactive layer150 found in other regions ofenergy storage system190.
• FIG. 1C is a cross section of a portion of theenergy storage system190 ofFIG. 1A, according to various embodiments. An exemplary location of this cross section is shown by label “A” inFIG. 1A. In these embodiments,energy storage system190 includes anoptional underlayer152 between theunderframe130 and theactive layer150, and anoptional overlayer154.Overlayer154 optionally encapsulates theactive layer150, forming a barrier betweenactive layer150 and an electrolyte. The electrolyte includes an active material configured to react in an electrochemical reaction at the cathode (a cathode active material). The cathode active material may include, for example, lithium ion or some other cation.
• In some embodiments, theunderlayer152 is configured to provide a seed layer for vapor-liquid-solid (VLS) growth of theactive layer150. Alternatively, theunderlayer152 includes a thin layer (e.g., less than one micrometer) of a metal or a series of metals (e.g., a transition metal, gold, silver, copper, nickel, and/or the like) or a salt (e.g., LiF).Underlayer152 optionally includes a silicide. Other materials may be used to form anunderlayer152 depending on the desired effect. For instance, theunderlayer152 can be composed of a thin film or particulate layer with thicknesses that ranges from about 1 nm to 5 nm, 3 nm to 7 nm, 5 nm to 12 nm, 10 nm to 17 nm, 13 nm to 25 nm, 20 nm to 47 nm, 29 nm to 53 nm, 37 nm to 71 nm, 57 nm to 101 nm, or any combination thereof. This thin film or particulate layer may have a material composition comprising gold, platinum, MnO_x, CuFe, beta-MnO₂/Pt, Pd, Ru, MoN/NGS, Li₅FeO₄, Li₂MnO₃*LiFeO₂, FeO₄, CoFe₂O₄, TiN, TiC, TiO₂, and/or any combination thereof. Additionally,underlayer152 can be comprised of nanoparticles with average diameters of 1 nm, 3 nm, 5 nm, 8 nm, 13 nm, 17 nm, 23 nm, 29 nm, 37 nm, 43 nm, 53 nm, 61 nm, 67 nm, 79 nm, 97 nm, 115 nm, possibly larger, or any range there between.Underlayer152 is optionally comprised of both thin films and nanoparticles.Underlayer152 can also be partially comprised of gel electrolytes, such as P(VDF-HFP)-based polymer electrolytes, poly acrylic acid, and polyfluorene-based conducting polymers, incorporating a carbon-oxygen functional group (carbonyl). In this case the thickness of theunderlayer152 can be as much as 500 nm, 750 nm, 900 nm, 1200 nm, or possibly more.
• Theoverlayer154 may be grown and/or deposited on theactive layer150. Theover-layer154 may partially or fully encapsulate theactive layer150. The materials that comprise theover-layer154 include, for example, metals such as gold, silver, copper, and/or the like. Theover-layer154 can also include a diamond-like coating (DLC), or an insulator, such as SiO₂, a binder, a polymer, and/or the like. The thickness of theover-layer154 is typically less than one micrometer in the case of metals, semiconductors or insulators. In various embodiments, the thickness of theover-layer154 may be larger than a micrometer for a binder or larger for polymers. For instance, theover-layer154 can be composed of a thin film with thicknesses that range from about 1 nm to 5 nm, 3 nm to 7 nm, 5 nm to 12 nm, 10 nm to 17 nm, 13 nm to 25 nm, 20 nm to 47 nm, 29 nm to 53 nm, 37 nm to 71 nm, 57 nm to 101 nm, or an combination thereof. This thin film may have a material composition comprising of gold, platinum, MnO_x, CuFe, beta-MnO₂/Pt, Pd, Ru, MoN/NGS, Li₅FeO₄, Li₂MnO₃*LiFeO₂, FeO₄, CoFe₂O₄, TiN, TiC, TiO₂, and/or any combination thereof. Additionally or alternatively,overlayer154 can be comprised of nanoparticles with average diameters of up to 1 nm, 3 nm, 5 nm, 8 nm, 13 nm, 17 nm, 23 nm, 29 nm, 37 nm, 43 nm, 53 nm, 61 nm, 67 nm, 79 nm, 97 nm, 115 nm, possibly larger, or any range there between. These particles may have a material composition comprising gold, platinum, MnO_x, CuFe, beta-MnO₂/Pt, Pd, Ru, MoN/NGS, Li₅FeO₄, Li₂MnO₃*LiFeO₂, FeO₄, CoFe₂O₄, TiN, TiC, TiO₂, and/or any combination thereof.Overlayer154 is optionally comprised of both thin films and nanoparticles.Overlayer154 can also be partially comprised of gel electrolytes, such as P(VDF-HFP)-based polymer electrolytes, poly acrylic acid, and polyfluorene-based conducting polymers, incorporating a carbon-oxygen functional group (carbonyl). In this case the thickness of theoverlayer154 can be up to 500 nm, 750 nm, 900 nm, 1200 nm, or possibly more.
• Theactive layer150 may be grown/deposited on theunderframe130 using a various methods. These methods include, for example, evaporation, sputtering, PECVD (Plasma-Enhanced Chemical Vapor Deposition), low-pressure chemical vapor deposition (LPCVD), VLS (Vapor Liquid Solid synthesis), electroplating, electro-less deposition, “field-free” chemical vapor deposition (CVD), metal-organic CVD, molecular beam epitaxy (MBE), and/or the like. In some embodiments, theactive layer150 distribution over the surface of theunderframe130 is uniform. Alternatively, theactive layer150 thickness is not uniform over the length of theunderframe130. For example, theuncoated region135 height may vary from 0% to 99% of the height of theunderframe130. In some embodiments, theactive layer150 proximate to thesubstrate110 has a smaller thickness relative to the distal end of theunderframe130. As such, the thickness of theactive layer150 may increase, alongunderframe130, with distance from thesubstrate110.
• Theactive layer150 is optionally comprised of Li₂O₂, Li₂O, lithiated TiS₂, LiOH*H₂O, LiOH, (LiMO₂, M=Mn, Ni, Co), LiFePO₄, lithiated TiO₂, and/or any combination thereof. In various embodiments, the thickness of the active layer is from 1-10 nm, 5-50 nm, 15-75 nm, 25-100 nm, 50-200 nm, 80-350 nm, 120-600 nm, 175-950 nm, 250-1500 nm, 425-2500 nm, 725-4000 nm, any combination thereof, or possibly larger. Nanoparticles are optionally interspersed within theactive layer150. These nanoparticles are comprised of, for example, gold, platinum, MnO_x, CuFe, beta-MnO₂/Pt, Pd, Ru, MoN/NGS, Li₅FeO₄, Li₂MnO₃*LiFeO₂, FeO₄, CoFe₂O₄, TiN, TiC, TiO₂, or any combination thereof. These nanoparticles may have diameters between 1 nm, 3 nm, 5 nm, 8 nm, 13 nm, 17 nm, 23 nm, 29 nm, 37 nm, 43 nm, 53 nm, 61 nm, 67 nm, 79 nm, 97 nm, 115 nm, possibly larger, or any combination thereof. Additionally, theactive layer150 may be partially comprised of gel electrolytes, such as P(VDF-HFP)-based polymer electrolytes, poly acrylic acid, and polyfluorene-based conducting polymers, incorporating a carbon-oxygen functional group (carbonyl).
• A number of methods may be employed to achieve a desired length for theuncoated region135. Examples of such methods include controlling the aspect ratio of theunderframe130 during growth, directional deposition, electro-deposition, electro-less deposition at the bottom layer to isolate the trunk, sputter and light etch of a masking layer to open theunderframe130 toactive layer150 growth/deposition, pre-coupling layer isolation (i.e. mask seed locations) prior to growth of theunderframe130, modifying growth parameters of theunderframe130 to achieve an advantageous aspect ratio (such as a tree like structure), or performing a deposition and directional etch back to free the under-frame130 from coverage byactive layer150.
• FIGS. 2A-2E illustrate various examples of individual nanotubes, nanofibers, nanowires and aerogel in an array. The array is optionally a vertically aligned array. For clarity, the individual nanotubes, nanofibers, nanowires and aerogel are shown without the overlayingactive layer150 etc. that is included on these elements to formEnergy Storage System190, as illustrated inFIGS. 1A-1C. As used herein, the term underframe is used to refer to a single structural element (e.g., a signal support filament including a nanotube, nanofiber, nanowire, or aerogel) and also to an array thereof. In some embodiments,underframe130 includes a mixture of nanotubes, nanowires and/or aerogel.
• FIG. 2A illustrates anunderframe130 of vertically aligned arrays of nanotubes or nanowires. In various embodiments, thediameter210 of an individual nanotube, nanofiber, or nanowire is less than 10 nm, between 10 nm and 50 nm, between 20 nm and 80 nm, between 40 nm and 120 nm, between 80 nm and 300 nm, between 120 nm and 450 nm, between 255 and 710 nm, between 380 nm and 1050 nm, and greater the 900 nm, or any combination thereof. Thediameter210 can vary along the length (height) of the an individual nanotube, nanofiber, or nanowire. Note that the diameters of the individual nanotubes, nanofibers, or nanowires need not be the same for all elements of the vertically aligned array. The variation in diameters can be up to 0.1%, 0.25%, 2%, 5%, 10%, 25%, or possibly greater. In various embodiments, theunderframe height290 of the array is an average height and is about 1 micron to 5 microns, 2 microns to 10 microns, 4 microns to 20 microns, 7 microns to 31 microns, 17 microns to 57 microns, 31 microns to 123 microns, 43 microns to 253 microns, 79 microns to 623 microns, 258 microns to 1289 microns, possibly larger, or any combination thereof. This height may vary as the array of nanotubes, nanofibers, or nanowires tilts or bends. Height variation of the individual nanotubes, nanofibers, or nanowires may also be present.
• FIG. 2B illustrates anunderframe130 of vertically aligned arrays of nanotubes, nanofibers, or nanowires, with diameter variation along the length of the nanotube, nanofibers, or nanowire. In various embodiments, thediameter225 is less than 10 nm, between 10 nm and 50 nm, between 20 nm and 80 nm, between 40 nm and 120 nm, between 80 nm and 300 nm, between 120 nm and 450 nm, between 255 and 710 nm, between 380 nm and 1050 nm, and greater the 900 nm, or any combination thereof. Thediameter225 can vary along the length (height) of the individual nanotube, nanofiber, or nanowire. Note that the diameters of the individual nanotubes, nanofibers, or nanowires need not be the same for all elements of the vertically aligned array. The variation in diameters can be up to 0.1%, 0.25%, 2%, 5%, 10%, 25%, or possibly greater. Additionally, by way of example, thediameter220 can vary as different cross-sectional shapes, such as an oval, tear drop, rectangle, diamond, or trapezoid. Other cross sectional shapes are possible. In some embodiments thediameter220 varies as a result of a stacked-cup structure of individual nanotubes, nanofibers, or nanowires. This structure is discussed further elsewhere herein.
• FIG. 2C illustrates an under-frame130 of vertically aligned arrays of nanofibers, with graphitic edges exposed. This occurs in, for example, the stacked-cup structure of some carbon nanofibers. In various embodiments, thediameter230 is less than 10 nm, between 10 nm and 50 nm, between 20 nm and 80 nm, between 40 nm and 120 nm, between 80 nm and 300 nm, between 120 nm and 450 nm, between 255 and 710 nm, between 380 nm and 1050 nm, greater the 900 nm, or any combination thereof. Thediameter230 can vary along the length (height) of an individual nanotube, nanofiber, or nanowire. Note that the diameters of the individual nanotube, nanofiber, or nanowire need not be the same for all elements of the vertically aligned array. The variation indiameters230 can be up to 0.1%, 0.25%, 2%, 5%, 10%, 25%, or possibly greater.
• FIG. 2D illustrates an under-frame130 of vertically aligned arrays of nanotubes, nanofibers, or nanowires including branches. In various embodiments, thediameter240 andunderframe height290 include characteristics and ranges similar to those discussed above with respect toFIGS. 2A-2C (e.g.,diameter210,diameter225, and diameter230).
• In some embodiments, theactive layer150 may coat all of the underframe, and in other embodiments the active layer may coat some but not all of the underframe. Generally, most of the underframe is coasted with the active layer, however, an uncoated region at the trunk, lower region, can remain uncoated, essentially uncoated or minimally coated. This has the effect of allowing the active layer to flex and move during expansion contraction, while reducing the likelihood of separation of the underframe from the substrate at the seed layer. In various embodiments, the active layer covers between 90 and 99%, 75 and 90%, 25 and 75%, or less than 25% of the underframe.
• FIG. 2E illustrates an under-frame130 of template formed aerogel. The aerogel can be a continuous layer or in an array as illustrated. In some embodiments, the aerogel is formed without the use of a template. In some embodiments the aerogel is mixed with the nanotube, nanofiber, or nanowire structures illustrated inFIGS. 2A-2D. In these embodiments the aerogel can be disposed in an array between the individual nanotubes, nanofibers, or nanowires, or may be deposited on the an individual nanotubes, nanofibers, or nanowires.
• In various embodiments, thetemplate aerogel diameter250 is less than 10 nm, between 10 nm and 50 nm, between 20 nm and 80 nm, between 40 nm and 120 nm, between 80 nm and 300 nm, between 120 nm and 450 nm, between 255 and 710 nm, between 380 nm and 1050 nm, 510 nm and 2300 nm, 1550 nm and 4700 nm, 3380 nm and 7450 nm, 6680 nm and 15500 nm, 9870 nm and 23500 nm, and greater the 50000 nm. Thetemplate aerogel diameter250 can vary along the length (height) of the aerogel and/or between members of the array. The variation in diameters can be up to 0.1%, 0.25%, 2%, 5%, 10%, 25%, or possibly greater.
• FIG. 3 illustrates further details of a cross section of a portion, illustrated inFIG. 1C, of theenergy storage system190, according to various embodiments of the invention. These embodiments include active material catalyzers310 (AMC).Active material catalyzers310 are an example of surface effect dominant sites but optionally or alternatively serve to catalyze electrical chemical reactions. Surface effect dominant sites include surfaces of a nanoparticle configured to adsorb charge carriers in a faradaic interaction, e.g., to undergo redox reactions with charge carriers. They are referred to as “surface effect dominant” because optionally, for these nanoparticles, the faradaic interaction between the charge carriers and the nanoparticle surfaces dominate bulk faradaic interactions. Thus, the charge carriers may be more likely to react at the surface relative to the bulk of the nanoparticles. For example, a lithium ion could more likely adsorb onto the surface of the nanoparticle rather than being absorbed or plate into the bulk of the nanoparticle. These nanoparticles are sometimes referred to as surface redox particles. The faradaic interaction results in a pseudo capacitor that can store a significant amount of loosely bound charge and thus provide a significant power density to an energy storage device. In pseudo capacitance an electron is exchanged (e.g., donated). In this case between the charge carrier to the nanoparticle. While some potentials would result in some intercalation of charge carrier into the nanoparticle, this does not necessarily constitute the bulk of the interaction at Surface Effect Dominant Sites and can degrade some types of nanoparticles. A faradaic interaction is an interaction in which a charge is transferred (e.g., donated) as a result of an electrochemical interaction.AMCs310 are not surface effect dominant sites in some embodiments.
• However, optionallyactive material catalyzers310 are typically more than just surface effect dominant sites. In some embodiments,active material catalyzers310 are configured to catalyze electro-chemical reactions. For example, in some embodimentsactive material catalyzers310 are configured to release oxygen from a compound including lithium and oxygen. In some embodiments thecatalyzers310 are configured to catalyze Li⁺+½O₂+e⁻←→½Li₂O₂and/or Li⁺+¼O₂+e⁻←→½Li₂O, or any other reactions known in the art of lithium based batteries. The interactions that occur atactive material catalyzers310 may be dependent on the potentials applied.
• Active material catalyzers310 can be implemented as nanoparticles and/or thin films.Active materials catalyzers310 are generally comprised of materials such as gold, platinum, MnO_x, CuFe, beta-MnO₂/Pt, Pd, Ru, MoN/NGS, Li₅FeO₄, Li₂MnO₃*LiFeO₂, FeO₄, CoFe₂O₄, TiN, TiC, TiO₂, and/or any combination thereof
• As nanoparticles,active material catalyzers310 can have average diameters of up to 1 nm, 3 nm, 5 nm, 8 nm, 13 nm, 17 nm, 23 nm, 29 nm, 37 nm, 43 nm, 53 nm, 61 nm, 67 nm, 79 nm, 97 nm, 115 nm, possibly larger, and/or any combination thereof. Note that the nanoparticles can have multiple sizes, therefore implying a distribution of particle size. This distribution is not necessarily a normal distribution, e.g., the distribution may be bimodal. These nanoparticles can be found as part of theunderframe130,underlayer152,active layer150, and/oroverlayer154.
• Thin film AMCs310 have an average thickness range from about 1 nm to 5 nm, 3 nm to 7 nm, 5 nm to 12 nm, 10 nm to 17 nm, 13 nm to 25 nm, 20 nm to 47 nm, 29 nm to 53 nm, 37 nm to 71 nm, 57 nm to 101 nm, possibly larger, or any combination thereof.Thin film AMCs310 can be part of theunderlayer152 and/or theoverlayer154. Theactive layer150 is optionally comprised of Li₂O₂, Li₂O, lithiated TiS₂, LiOH*H₂O, LiOH, (LiMO₂, M=Mn, Ni, Co), LiFePO₄, TiO₂, lithiated TiO₂, and/or any combination thereof. In various embodiments, the thickness of the active layer is from 1-10 nm, 5-50 nm, 15-75 nm, 25-100 nm, 50-200 nm, 80-350 nm, 120-600 nm, 175-950 nm, 250-1500 nm, 425-2500 nm, 725-4000 nm, larger, or any combination thereof.
• Note that while the distribution ofAMCs310 within each layer ofFIG. 3 are shown to be relatively uniform, in alternative embodiments theAMCs310 are concentrated at one or the other edge of any of the layers, and/or may be concentrated at a boundary between any two of the layers illustrated. For example, in someembodiments AMCs310 are concentrated around the boundary betweenOverlayer154 andActive Layer150, and/or at the boundary betweenActive Layer150 andUnderlayer152. Such concentrations can be achieved, for example, by depositing the AMCs between steps of generating any two of the illustrated layers and/orunderframe130.AMCs310 may be disposed as a gradient within any of the layers illustrated. In some embodiments,AMCs310 include oxygen adsorbing materials.
• FIG. 4A illustrates a cross section of several elements of an energy storage electrode with stacked-cup nanofibers, according to various embodiments of the invention. Specifically, stacked-cup nanofibers have exposed graphitic edges and planes that act as graphene sheets. These graphene sheets wrap around a central ‘core’. These sheets layer on top of each other, creating increased surface area relative to standard nanotubes (which typically have a smooth surface). Additionally, the stacked sheets create channels to the central core of the cupped nanofiber410. These stacked-cup nanofibers can be in a vertically aligned array as illustrated inFIG. 2C or separated from the surface on which they were grown and attached as a mesh to a new substrate using a binder. Further examples of the stacked-cup structure are illustrated in FIGS. 3A-3C and 4 of U.S. patent application Ser. No. 13/935,334 filed Jul. 3, 2013.
• FIG. 4B illustrates a detailed cross section of several elements (“cup edges”) of a stacked-cup nanofiber with exposed ‘graphitic’ edges, according to various embodiments of the invention. In particular, the exposed graphitic edge sheets allow for incursion of particulateactive material catalyzer310 including the materials and characteristics discussed elsewhere herein, between the graphitic edges. See region “A” inFIG. 4B.
• Optionally, an element ofenergy storage system190 can be created, with all the attributes as listed and shown inFIG. 3, on each exposed graphite edge of stacked-cup nanofiber. See region “B” inFIG. 4B. An additional attribute of the stacked-cup nanofiber structure is the existence of a gas storage channel for gas sequestration. See region “C” inFIG. 4B. This channel optionally provides a path for gasses to reach a hollow central core within the nanofiber. Such gasses can include O₂, CO₂, CO, N₂, NO₂, NO, H₂, etc. By way of example, in some embodiments, an oxygen absorber (not shown) such as strontium cobaltite, is included in thechannel440 between the exposed (graphene like) stacked-cup edges to capture excess oxygen. Other materials can optionally be used to capture and release other gases. Absorbers of the above gasses may also be included within the hollowcentral core450 of a stacked-cup nanofiber or an unzipped nanotube.
• The various features illustrated in regions “A,” “B” and “C” ofFIG. 4 may be including in stacked-cup nanofibers in any combination. For example, one embodiment includes the particulateactive material catalyzer310 illustrated in region “A,” theactive layer150 included in region “B,” and room for oxygen sequestration illustrated in region “C.” These are optionally included within thesame channel440.
• FIG. 5A illustrates a cross section of several elements of an energy storage electrode including a template formed aerogel, according to various embodiments of the invention. Specifically, the aerogel has an average density that ranges from about 0.008 g/cm³to 0.3 g/cm³, a surface area that ranges from about 200 m²/g to 2000 m²/g, a pore volume that ranges from about 0.5 cm³/g to 25 cm³/g, and an average pore diameter that ranges from about 2 nm to 50 nm.
• FIG. 5B illustrates a cross section of anaerogel510, according to various embodiments of the invention. In some embodiments, exposedaerogel pores520 and resulting large surface area allow for incursion ofactive material catalyzer310 within the aerogel. An example is illustrated in region “A” ofFIG. 5B.
• In some embodiments, an energy storage system190 (with or without active material catalyzer310) can be created on surfaces of the aerogel. These embodiments ofenergy storage system190 can include any or all the attributes and characteristics discussed elsewhere herein. An example ofenergy storage system190 is illustrated in region “A” ofFIG. 5B. This example can be included on any or all of the available surfaces of theaerogel510. The surfaces and boundaries between the pores function as theunderframe130. Theactive material catalyzer310 shown in region “A” and theenergy storage system190 shown in region “B” are optionally found together, e.g., theactive material catalyzer310 can be included in theenergy storage system190 as discussed elsewhere herein.
• An additional attribute of the aerogel is the presence of a gas storage channels for gas sequestration. Such gases can be O₂, CO₂, CO, N₂, NO₂, NO, H2, etc. These channels exist within the aerogel pores520 of the aerogel. By way of example, an oxygen absorber (such as strontium cobaltite), can optionally be placed in the channel to capture excess oxygen. Other materials can optionally be used to capture and release other gases. The embodiments described in relation toFIG. 5B may be applied to a continuous aerogel (not shown). In these embodiments, nanofibers are grown on an aerogel substrate (which in turn is on a more solid substrate110). The aerogel substrate may include an oxygen absorber and the nanofibers may support theenergy storage system190 as discussed herein.
• FIG. 6 illustrates a cross section of a prior art rechargeable battery (e.g., a secondary battery/cell600). This battery includes acathode610, ananode620, aseparator630 and anelectrolyte640. The various embodiments illustrated inFIGS. 1-5 and discussed herein may be applied to either thecathode610 oranode620. The secondary battery/cell600 may take many geometric forms and shapes as would be apparent to one of ordinary skill in the art. Thecathode610 may be open to the atmosphere or sealed from the atmosphere.
• FIG. 7 illustrates a method for fabricating an electrode including anenergy storage system190 including anunderframe130. Thefirst step701 is to receive asubstrate110.Substrate110 is optionally graphite coated aluminum, graphite, Ni, Ag, Fe, Mg, Pb, W, Al, Hf, Mo, Pd, Ta, Au, In, Nb, Ti, Zr, Cu, Li, Ni, V, Zn, C, carbides of previously noted materials, silicides of previously noted materials, oxides of previously noted materials, nitrides of previously noted materials, an oxygen permeable membrane, or any combination thereof. Note that thesubstrate110 can include one material, or a combination of several materials. Thesubstrate110 can be of other materials, depending on the desired application. For instance, aerogel, stainless steel or graphite can be used for a substrate. Those skilled in the art of battery design can further specify other materials, depending on the desired application. In someembodiments substrate110 is flexible and configured to be coiled.
• An optionalsecond step703 is to clean thesubstrate110. The purpose of cleaning703 thesubstrate110 is to prepare thesubstrate110 for the subsequent depositions and growth of materials in later process steps. It is meant to remove any undesired organics, oxides, and other contaminates present on thesubstrate110. The methods to clean thesubstrate110 can range from physical (using an abrasive, for instance, to remove a thin layer of material that has been exposed to contaminants), to chemical (using a solvent, such as acetone, iso-propanol, TCE, or methanol) and/or chemical etch (citric acid soak/rinse, which dissolves part of the actual substrate, in the case of copper), or any combination of physical and chemical methods to appropriately prepare thesurface110 for subsequent process steps.
• Athird step705 is an optional seed layer deposition.Seed layer deposition705 is the process step where the base layer, orseed layer115, forunderframe130 growth is created. This process step can be implemented through a gas phase (physical or chemical) deposition/growth, a liquid phase deposition/growth, or a solid phase deposition/growth, or any combination thereof.
• Physical gas phase deposition techniques (where the material to be deposited is transported from the source to the substrate in the gas phase) can include: thermal evaporation, electron beam evaporation, DC sputtering, DC magnetron sputtering, RF sputtering, pulsed laser deposition, cathode arc deposition, and/or the like. It is also possible to use reactive physical vapor deposition, a method by which a ‘contaminate gas’ is injected into the chamber during the growth process, thereby incorporating itself into the layer as it grows.
• Chemical gas phase deposition techniques (where chemical precursors are transported to the surface in the gas phase, and then subsequently undergo a chemical reaction at the surface) can include Low Pressure Chemical Vapor Deposition, Plasma-Enhanced Chemical Vapor Deposition, Atmospheric Pressure Chemical Vapor Deposition, Metal-Organic Chemical Vapor Deposition, Hot-wire Chemical Vapor Deposition, Very High Frequency Plasma Enhanced Chemical Vapor Deposition, Microwave Plasma Enhanced Chemical Vapor Deposition, and/or the like.
• Liquid phase deposition techniques to create theseed layer115 can include plating, electroplating, or chemical solution deposition, etc. Solid phase deposition techniques can include focused ion beam deposition. Another possibility for deposition is a solution that contains a liquid and a suspension of appropriate sized particles that are sprayed onto the current collector, and then the substrate is subsequently ‘cured’ such that the carrier solution is removed, leaving the particles intact on the surface of the substrate.
• Any combination of the above process steps can be used to create anappropriate seed layer115 for creating the initiation sites for theunderframe130 growth.
• Afourth step715 in the process is the creation of the initiation sites, defined as the location where theunderframe130 starts growth on theseed layer115. This step is dependent on methods chosen to create theseed layer115. For instance, the initiation sites separation distance can be determined by the thickness and materials chosen forseed layer deposition705. For instance, a seed layer of 3000 angstroms nickel/300 angstroms chrome will produce a certain number of initiation sites per square centimeter. If the thickness of the nickel is reduced to 2000 angstroms, the number of initiation sites per square centimeter will be different than that for a thickness of 3000 angstroms nickel. If another material is chosen, such as iron to replace nickel, the resultant initiation sites per square centimeter will also be different. Step715 is optionally part ofstep705.
• A solid phase deposition technique can allow for control of the initiation sites per square centimeter. This can be a focused ion beam deposition, where the initiation sites/cm²are directly controlled by the by where the focused ion beam deposits it material, or a nano-particle suspension, where the initiation sites/cm²is controlled by the number of nano-particles contained in a given suspension volume. The number of initiation sites can also be controlled by the size of the focused ion beam deposition site, or the size of the nano-particles in solution, etc.
• The initiation sites are typically created when a reactor in which the electrode is produced reaches the appropriate reaction temperature with the appropriate feedstock gases flowing, and the feedstock gas begins to catalyze with theseed layer115. The initiation sites have thus been created, and theunderframe130 growth has commenced.
• Afifth step720 is to grow theunderframe130. There are a number of growth processes available to grow theunderframe130. For example, chemical Vapor Deposition, Thermal Chemical Vapor Deposition, Vapor-Liquid-Solid growth (a type of CVD), and Plasma Enhanced Chemical Vapor Deposition, are processes by which Nano-Tube (NT), Nano-Fiber (NF), and Nano-Wire (NW) growth has been achieved. Those skilled in the art of filament growth will recognize that there are other growth methods available.
• Examples of feedstock gases that can be used to grow NT/NF are carbon monoxide, methane, ethane, ethylene, acetylene, and/or the like. It is also possible to use other hydrocarbons or inorganic compounds for the growth process.
• Of interest is the Plasma Enhanced Chemical Vapor Deposition (CVD) method, due to the fact that the growth of thesupport filament110 aligns with the electric field of the plasma, thus allowing for the production of vertically alignedunderframe130. Thermal CVD, under certain process conditions, can also produce vertically alignedunderframe130 units. Further, Water-Assisted CVD makes possible very high aspect ratio vertically aligned underframe130 (length vs. diameter roughly equal to 1,000,000), allowing for verytall underframe130.
• It has also been demonstrated that appropriately modified bacteria and viruses have grown to nanowire and nanofiber structures. Such techniques are optionally used to createunderframe130.
• It is also possible to use several of the techniques together at once, with the appropriate choice of material. For instance, bacteria/viruses can be used to grow the NT/NF/NW in the presence of an applied electric field, producing vertically aligned support filaments. Another method ofunderframe130 growth is to apply an electric and/or magnetic field during VLS growth to control the trajectory of the growing NT/NF/NW, this controlling the three dimensional shape of theunderframe130. Another technique is to begin growth of the NT/NF/NW underframe130 with the reactor operating in PECVD mode; after a specified time, the reactor can be converted to Thermal CVD mode; and then again, after a specified time, the reactor is converted back to PECVD mode. Those skilled in the art of NT/NF/NW growth can appreciate that there are other possible combinations that allow for appropriate growth control of thesupport filament110.
• Theunderframe height290 of theunderframe130 is generally determined by the duration of the growth process. The temperature of the reactor, the feedstock gases used, and the combination and strength of applied electric and magnetic fields (or the absence thereof) can influence the speed and amount of filament growth.
• Thediameter210 of theunderframe130 is generally determined by the thickness of theseed layer115, or the size of the nano-particles contained in suspension, if a nano-particle suspension method is chosen to create theseed layer115, or the size of the ion beam, if focused ion beam deposition is chosen to create theseed layer115. The temperature of the reactor, the feedstock gases used, and the combination and strength of applied electric and magnetic fields (or the absence thereof) can influence diameter of theunderframe130 as well. This also applies todiameters225,230, and240.
• During thegrowth step720 ofunderframe130, it is possible to implement a sub-step720a,where the diameter and number of branches can be affected. This can be accomplished by changing temperature of the reactor, the feedstock gases used and their relative compositions and flow rates, direction and strength of applied electric and magnetic fields (or the absence thereof). The duration of the change implicitly determines thediameters210225,230 and240), as well as the amount of branching, as shown inFIG. 2D.
• During thegrowth step720 ofunderframe130, it is possible to implement a sub-step720b,where the diameter and number of branches can be affected. This can be accomplished by changing temperature of the reactor, the feedstock gases used and their relative compositions and flow rates, direction and strength of applied electric and magnetic fields (or the absence thereof). The duration of the change implicitly determines the NT/NF diameter210 (as well as theother diameters225,230, and240), as well as the amount of branching, as shown inFIG. 2D.
• The diameter, thickness, height, and branches ofunderframe130 are largely controlled by the changes in the aforementioned parameters; this can be done on a somewhat continuous basis by changing the input parameters for growth, creating the equivalent sub-steps720c,720d,etc., until it is decided to terminate growth.
• If an aerogel is desired, the growth process requires the preparation and setting of a gel on theoptional seed layer115. In some embodiments, when ageing of the gel is complete, the gel is exchanged into200 proof ethanol (or acetone) about four times over the course of a week. After one week, supercritically dry the gel. Thus, an aerogel is produced. Note that the template size can be defined by mechanically masking the locations where the aerogel is desired. Alternatively, the size of the aerogel template can be defined by photolithography. The thickness of the aerogel template can be defined by the thickness of the originally deposited gel on theseed layer115/substrate110.
• Theeighth process step730 is deposit/grow theenergy storage system190. The growth/deposition of theenergy storage system190 can be implemented through a gas phase (physical or chemical) deposition/growth, a liquid phase deposition/growth, or a solid phase deposition/growth, or any combination thereof.
• Physical gas phase deposition techniques (where the material to be deposited is transported from the source to the substrate in the gas phase) can include: thermal evaporation, electron beam evaporation, DC sputtering, DC magnetron sputtering, RF sputtering, pulsed laser deposition, cathode arc deposition, and/or the like. It is also possible to use reactive physical vapor deposition, a method by which a contaminate gas' is injected into the chamber during the growth process, thereby incorporating itself into the layer as it grows.
• Chemical gas phase deposition techniques (where chemical precursors are transported to the surface in the gas phase, and then subsequently undergo a chemical reaction at the surface) can include Low Pressure Chemical Vapor Deposition, Plasma-Enhanced Chemical Vapor Deposition, Atmospheric Pressure Chemical Vapor Deposition, Metal-Organic Chemical Vapor Deposition, Hot-wire Chemical Vapor Deposition, Very High Frequency Plasma Enhanced Chemical Vapor Deposition, Microwave Plasma Enhanced Chemical Vapor Deposition, and/or the like.
• Note that in any deposition stage more than one material can be deposited at a time. For instance, two (or more) different types of metal can be deposited/grown at the same time, such as tin (Sn) and gold (Au); two (or more) different types of semiconductor can be deposited/grown, such as silicon (Si) and germanium (Ge); two (or more) different types of oxide may be grown/deposited, such as lithium iron phosphate (LiFePO₄) and lithium nickel cobalt manganese (Li(NiCoMn)O₂). Additionally, it is possible to mix material types, such as a metal and a semiconductor, or a semiconductor and an oxide, or a metal and an oxide, or a metal, semiconductor, and oxide. Examples include silicon (Si) and lithium (Li) co-depositions, silicon (Si) and LiO₂(or SiO₂) co-depositions, and silicon (Si), lithium (Li), and LiO₂(or SiO₂) co-depositions. It may be desirable to co-deposit insulating material as well, such as silicon dioxide (SiO₂), or silicon nitride (Si₃N₄). Additionally, it may be desirable to co-deposit carbon (C) as well. Note that depositing of active materials (such as Li₂O₂, Li₂O, lithiated TiS₂, LiOH*H₂O, LiOH, (LiMO₂, M=Mn, Ni, Co), LiFePO₄, lithiated TiO₂, and/or any combination thereof) can optionally be performed simultaneously with catalyst materials (such as gold, platinum, MnO_x, CuFe, beta-MnO₂/Pt, Pd, Ru, MoN/NGS, Li₅FeO₄, Li₂MnO₃*LiFeO₂, FeO₄, CoFe₂O₄, TiN, TiC, TiO₂, or any combination thereof).
• Theenergy storage system190 is optionally created by a liquid phase process, such as electro-less deposition or electro-plating. It is also possible to create theenergy storage system190 by coating theunderframes130 with a solution containing active materials (such as Li₂O₂, Li₂O, lithiated TiS₂, LiOH*H₂O, LiOH, (LiMO₂, M=Mn, Ni, Co), LiFePO₄, lithiated TiO₂, and/or any combination thereof) and/or catalyst materials (such as gold, platinum, MnO_x, CuFe, beta-MnO₂/Pt, Pd, Ru, MoN/NGS, Li₅FeO₄, Li₂MnO₃*LiFeO₂, FeO₄, CoFe₂O₄, TiN, TiC, TiO₂, or any combination thereof), suspended in a binder solvent matrix. After appropriate processing, the solvent is driven out of the matrix, leaving only the binder and active/and/or catalyst material, thus creating anelectrode including underframe130 andenergy storage system190. This technique can be applied to both an anode and cathode, with appropriate choice of materials.
• In some embodiments, the reactivity of theenergy storage system190 is controlled by appropriately choosing the deposition and growth technique. For instance, it is possible include catalyst materials during the deposition process of theactive layer150.
• In some embodiments, the deposited/grown energy storage system is encapsulated. This encapsulation could be gel electrolytes, such as P(VDF-HFP)-based polymer electrolytes, poly acrylic acid, and polyfluorene-based conducting polymers, incorporating a carbon-oxygen functional group (carbonyl).
• Atstep740 the electrode fabrication may be complete. The electrode is optionally included within a battery.
• As used herein, the term “nanofibers” is meant to include nano-ribbon, nano-filaments, unzipped nanotubes, nanowires and/or nanotubes.
• Several embodiments are specifically illustrated and/or described herein. However, it will be appreciated that modifications and variations are covered by the above teachings and within the scope of the appended claims without departing from the spirit and intended scope thereof. For example,energy storage systems190 are optionally formed on both sides ofSubstrate110. The teachings disclosed herein may be applied to both batteries and hybrid battery/capacitors. In someembodiments material catalyzer310 migrates from one layer to another during operation. In some embodiments, the particles discussed herein are multi-layered or hollow particles.
• The embodiments discussed herein are illustrative of the present invention. As these embodiments of the present invention are described with reference to illustrations, various modifications or adaptations of the methods and/or specific structures described may become apparent to those skilled in the art. All such modifications, adaptations, or variations that rely upon the teachings of the present invention, and through which these teachings have advanced the art, are considered to be within the spirit and scope of the present invention. Hence, these descriptions and drawings should not be considered in a limiting sense, as it is understood that the present invention is in no way limited to only the embodiments illustrated.

Claims (17)

What is claimed is:

1. An electrochemically active electrode for use in a lithium ion cell, the electrode comprising a substrate and an electrochemically active electrode material comprised of:

a nanostructured template comprising a metal silicide; and

a layer of an electrochemically active material coating the nanostructured template, the electrochemically active material configured to take in and release lithium ions during cycling of the lithium ion cell,

wherein the nanostructured template facilitates conduction of electrical current to and from the electrochemically active material and provides support to the layer of the electrochemically active material.

2. The electrode ofclaim 1, wherein the metal silicide includes silicon and germanium.

3. The electrode ofclaim 1, wherein the metal silicide includes at least one of nickel, cobalt, chromium, titanium, aluminum, copper, silver, gold, tungsten, molybdenum and iron.

4. The electrode ofclaim 1, wherein the electrochemically active material coating the nanostructured template includes at least one of nickel, cobalt, chromium, titanium, aluminum, copper, silver, gold, tungsten, molybdenum and iron.

5. The electrode ofclaim 1, wherein the metal silicide includes at least one of nickel, cobalt, copper, silver, chromium, titanium, aluminum, zinc and iron.

6. The electrode ofclaim 1, wherein the electrochemically active material coating the nanostructured template comprises a silicon material, a tin containing material or a germanium containing material.

7. The electrode ofclaim 1, wherein the electrochemically active material coating the nanostructured template is a non-silicide material.

8. The electrode ofclaim 1, wherein the electrochemically active material coats some but not all of the template.

9. The electrode material ofclaim 8, wherein the electrochemically active material coats from between 90 and 99%, between 75 and 90%, between 25 and 75%, or less than 25% of the template.

10. An electrochemically active electrode for use in a lithium ion cell, the electrode comprising electrochemically active electrode material comprised of:

a nanostructured template comprising a metal silicide; and

a layer of a non-silicide electrochemically active material, the electrochemically active material configured to take in and release lithium ions during cycling of the lithium ion cell,

wherein the nanostructured template facilitates conduction of electrical current to and from the electrochemically active material and provides support to the layer of the electrochemically active material.

11. The electrode ofclaim 10, wherein the metal silicide includes silicon and germanium.

12. The electrode ofclaim 10, wherein the metal silicide includes at least one of nickel, cobalt, chromium, titanium, aluminum, copper, silver, gold, tungsten, molybdenum and iron.

13. The electrode ofclaim 10, wherein the non-silicide active material includes at least one of nickel, cobalt, chromium, titanium, aluminum, copper, silver, gold, tungsten, molybdenum and iron.

14. The electrode ofclaim 10, wherein the metal silicide includes at least one of nickel, cobalt, copper, silver, chromium, titanium, aluminum, zinc and iron.

15. The electrode ofclaim 10, wherein the non-silicide active material comprises a tin containing material or a germanium containing material.

16. The electrode ofclaim 10, wherein the electrochemically active material coats some but not all of the template.

17. The electrode ofclaim 16, wherein the electrochemically active material coats from between 90 and 99%, between 75 and 90%, between 25 and 75%, or less than 25% of the template.

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