Nanocomposite structural energy storage devices and related articles, systems, and methods

Abstract

Nanocomposite structural energy storage devices e.g. all-nanocomposite structural energy storage devices such as structural supercapacitors (SSCs) or batteries, and related articles, e.g. comprising a domain comprising an ionically conductive matrix and a plurality of elongated nanostructures, e.g. carbon nanotubes (CNTs), boron nitride nanotubes (BNNT), distributed within the ionically conductive matrix; and methods, e.g. bulk nanocomposite laminating (BNL) processes.

Description

[0001] NANOCOMPOSITE STRUCTURAL ENERGY STORAGE DEVICES AND RELATED ARTICLES, SYSTEMS, AND METHODS

[0002] RELATED APPLICATIONS

[0003] This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 63 / 708,240, filed October 16, 2024, and entitled “All-Nanocomposite Structural Energy Storage,” which is incorporated herein by reference in its entirety for all purposes.

[0004] TECHNICAL FIELD

[0005] Nanocomposite structural energy storage devices (e.g., all-nanocomposite structural energy storage devices), and related articles, systems, and methods, are generally described.

[0006] SUMMARY

[0007] Generally described herein are nanocomposite structural energy storage devices (e.g., all- nanocomposite structural energy storage devices) and related articles, systems, and methods. The subject matter of the present disclosure involves, in some cases, interrelated products, alternative solutions to a particular problem, and / or a plurality of different uses of one or more systems and / or articles.

[0008] This Summary introduces a selection of concepts in simplified form that are described further below in the Detailed Description. This Summary neither identifies key or essential features, nor limits the scope, of the claimed subject matter.

[0009] Certain embodiments relate to composite articles.

[0010] In some embodiments, an article comprises a domain, comprising an ionically conductive matrix; and a plurality of elongated nanostructures distributed within the ionically conductive matrix; wherein: within the domain, the elongated nanostructures occupy a volume fraction of at least 10 vol%; less than or equal to 20 vol% of the domain is occupied by gas / vacuum closedcell voids having a volume of at least 1012nm3; and the ionically conductive matrix has an ionic conductivity, with respect to at least one monovalent ion and / or at least one divalent ion, of at least 10'7S / cm.

[0011] In one embodiment, an article comprises a domain, the domain comprising an ionically conductive matrix and a plurality of elongated nanostructures distributed within the ionically conductive matrix. In certain embodiments, within the domain, the elongated nanostructures occupy a volume fraction of at least 10 vol%, less than or equal to 20 vol% of the domain is occupied by voids having a volume of at least 1012nm3, and the ionically conductive matrix has

[0012] #14504416vl an ionic conductivity, with respect to at least one monovalent ion and / or at least one divalent ion, of at least 10'7S / cm.

[0013] Some embodiments relate to methods of forming a composite article.

[0014] In certain embodiments, the method comprises arranging a plurality of elongated nanostructures at least partially within an ionically conductive matrix and / or an ionically conductive matrix precursor to form an arrangement of elongated nanostructures and ionically conductive matrix and / or ionically conductive matrix precursor; applying pressure to the arrangement to densify the elongated nanostructures; heating the arrangement; and forming a domain of elongated nanostructures distributed within ionically conductive matrix, wherein: within the domain, the elongated nanostructures occupy a volume fraction of at least 10 vol%; less than or equal to 20 vol% of the domain is occupied by gas / vacuum closed-cell voids having a volume of at least 1012nm3; and within the domain, the ionically conductive matrix has an ionic conductivity, with respect to at least one monovalent ion and / or at least one divalent ion, of at least 10'7S / cm.

[0015] In one embodiment, a method comprises: arranging a plurality of elongated nanostructures at least partially within an ionically conductive matrix and / or an ionically conductive matrix precursor to form an arrangement of elongated nanostructures and ionically conductive matrix and / or ionically conductive matrix precursor; applying pressure to the arrangement to densify the elongated nanostructures; heating the arrangement; and forming a domain of elongated nanostructures distributed within ionically conductive matrix. In some embodiments, within the domain, the elongated nanostructures occupy a volume fraction of at least 10 vol%, less than or equal to 20 vol% of the domain is occupied by voids having a volume of at least 1012nm3, and within the domain, the ionically conductive matrix has an ionic conductivity, with respect to at least one monovalent ion and / or at least one divalent ion, of at least 10'7S / cm.

[0016] One aspect of the disclosure herein is a bulk nanocomposite laminating (BNL) process comprising: a. using vertically aligned carbon nanotubes (VA-CNTs) as scaffolds, boron nitride is coated over the VA-CNTs by a thermal catalytic chemical vapor deposition (CVD) process; and b. the CNTs are removed by thermal oxidation process to produce boron nitride nanotubes (BNNTs) that consist of a dense VA-BNNT forest.

[0017] In one embodiment, the disclosed process BNL process further comprises:

[0018] #14504416vl a. placing a non-porous Teflon (GNPT) release film on top of the VA-BNNT forest to produce a VA-BNNT array; b. cutting a single layer of the VA-BNNT array to produce a single ply of knockdown BNNTs (K-BNNTs) stuck to the GNPT film; and c. repeating (a) and (b) to produce vertically aligned BNNTs (VA-BNNTs).

[0019] One aspect of the disclosure herein is a nanocomposite, comprising: a. electrodes comprised of carbon nanotubes (CNTs), wherein the CNTs are horizontally aligned with a high aspect ratio (105length / diameter) and a high (50 vol%) packing fraction; and b. a separator comprised of electrically insulating NTs, nominally aligned boron nitride nanotubes (BNNTs) and an ionically conductive polymer (or ceramic or other) matrix; wherein the nanocomposite is made by the disclosed BNL process.

[0020] In one embodiment of the disclosed nanocomposite, the electrodes and separator are thin (0=10 pm).

[0021] One aspect of the disclosure herein is a supercapacitor comprising the disclosed nanocomposite.

[0022] One aspect of the disclosure herein is a battery comprising the disclosed nanocomposite.

[0023] The following Detailed Description references the accompanying drawings which form a part this application, and which show, by way of illustration, specific example implementations. Other implementations may be made without departing from the scope of the disclosure. Other advantages and novel features of the present disclosure will become apparent from the following detailed description of various non-limiting embodiments of the disclosure when considered in conjunction with the accompanying figures. In cases where the present specification and a document incorporated by reference include conflicting and / or inconsistent disclosure, the present specification shall control.

[0024] BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Non-limiting embodiments of the present disclosure will be described by way of example with reference to the accompanying figures, which are schematic and are not intended to be drawn to scale unless otherwise indicated. In the figures, each identical or nearly identical component illustrated is typically represented by a single numeral. For purposes of clarity, not every component is labeled in every figure, nor is every component of each embodiment of the

[0026] #14504416vl disclosure shown where illustration is not necessary to allow those of ordinary skill in the art to understand the disclosure. In the figures:

[0027] FIG. 1 A shows, according to certain embodiments, a schematic diagram of an article.

[0028] FIG. IB shows, according to certain embodiments, a cross-sectional schematic diagram of the article shown in FIG. 1 A.

[0029] FIG. 1C shows, according to certain embodiments, a cross-sectional schematic diagram of a composite article illustrating the concept of a three-dimensional convex hull.

[0030] FIG. 2A shows, according to certain embodiments, a domain comprising a plurality of elongated nanostructures arranged in an overlapping fashion.

[0031] FIG. 2B shows, according to certain embodiments, a domain comprising a plurality of elongated nanostructures arranged in a non-overlapping fashion.

[0032] FIG. 2C shows, according to certain embodiments, a domain comprising a plurality of elongated nanostructures arranged in an overlapping and non-overlapping fashion.

[0033] FIG. 2D shows, according to certain embodiments, a domain comprising a stacked configuration of a plurality of elongated nanostructures arranged in an overlapping and nonoverlapping fashion.

[0034] FIG. 2E shows, according to certain embodiments, a composite article comprising a layered configuration of a plurality of elongated nanostructures.

[0035] FIG. 3 A shows, according to certain embodiments, an article comprising a first domain and a second domain.

[0036] FIG. 3B shows, according to certain embodiments, a cross-sectional schematic diagram of the article shown in FIG. 3 A.

[0037] FIG. 4A shows, according to certain embodiments, an article comprising a first domain, a second domain, and a second domain.

[0038] FIG. 4B shows, according to certain embodiments, a cross-sectional schematic diagram of the article shown in FIG. 4A.

[0039] FIG. 5A shows, according to certain embodiments, a schematic diagram of a high- tortuosity elongated nanostructure.

[0040] FIG. 5B shows, according to certain embodiments, a schematic diagram of a mediumtortuosity elongated nanostructure.

[0041] FIG. 5C shows, according to certain embodiments, a schematic diagram of a low- tortuosity elongated nanostructure.

[0042] FIG. 6 shows, according to certain embodiments, a cross-sectional schematic illustration of an energy storage device.

[0043] #14504416vl FIGS. 7A-7D show, according to certain embodiments, schematic diagrams of a method of arranging a plurality of elongated nanostructures at least partially within an ionically conductive matrix and / or an ionically conductive matrix precursor.

[0044] FIGS. 7E-7F show, according to certain embodiments, schematic cross-sectional diagrams of a method of applying pressure to an arrangement of elongated nanostructures.

[0045] FIG. 8 shows, in accordance with certain embodiments, a schematic cross-sectional diagram of a method of applying vacuum to an arrangement.

[0046] FIGS. 9A-9B show, in accordance with certain embodiments, schematic cross-sectional diagrams of methods of heating an arrangement.

[0047] FIG. 10A shows, according to certain embodiments, a schematic cross-sectional diagram of a method of forming a domain of elongated nanostructures distributed within an ionically conductive matrix.

[0048] FIG. 10B shows, according to certain embodiments, a schematic cross-sectional diagram of a method of providing a second domain of elongated nanostructures distributed within an ionically conductive matrix over a first domain.

[0049] FIG. 10C shows, according to certain embodiments, a schematic cross-sectional diagram of a method of providing third domain 104 of elongated nanostructures distributed within an ionically conductive matrix over a second domain.

[0050] FIG. 10D shows, according to certain embodiments, a schematic cross-sectional diagram of a method of forming an arrangement of domains.

[0051] FIG. 10E-10F show, according to certain embodiments, a schematic cross-sectional diagram of a method of applying pressure to an arrangement of domains.

[0052] FIG. 10G shows, according to certain embodiments, a schematic cross-sectional diagram of a method of applying vacuum to an arrangement of domains.

[0053] FIG. 10H shows, according to certain embodiments, a schematic cross-sectional diagram of a method of heating an arrangement of domains.

[0054] FIGS. 11 A-l 1C show, in accordance with certain embodiments, a bulk nanocomposite laminating (BNL) process for CNT and BNNT arrays.

[0055] FIG. 12 is, in accordance with certain embodiments, an all-nanocomposite structural energy storage device (BNL electrode / BNL separator). The electrode thickness can be tuned by the number of K-CNT layers (~10 micrometers each) depending on the power density needed while maintaining a high surface area (3 orders of magnitude higher than CFRP). High surface area electrode K-BNNTs reinforce the separator ply with high density of BNNTs and are manufactured in the same way as the K-CNT layer. The electric insulating BNNTs block

[0056] #14504416vl electrons flow while allowing ions to migrate between the tubes. The thickness is lOx lower than glass fiber composite (GFRP) separators.

[0057] FIG. 13 is, in accordance with certain embodiments, an all-nanocomposite structural energy storage device (BNL electrode / VA-separator). VA-BNNTs give a more direct path for the ions to flow from electrode to electrode while adding reinforcement in the Z direction.

[0058] FIG. 14 is, in accordance with certain embodiments, a schematic drawing of a structural supercapacitor (SSC) composite.

[0059] FIG. 15 shows, in accordance with certain embodiments, before and after CNT growth via 2-inch (diameter) quartz tube furnace.

[0060] FIG. 16 shows, in accordance with certain embodiments, a schematic of the A-CNT knockdown process to produce K-CNTs.

[0061] FIG. 17 shows, in accordance with certain embodiments, a SSC nanocomposite depiction with all described SSC components.

[0062] FIG. 18A shows, in accordance with certain embodiments, a photograph of a K-CNT- Celgard-epoxy structural polymer electrolyte device.

[0063] FIG. 18B shows, in accordance with certain embodiments, a schematic diagram of the device shown in FIG. 18 A.

[0064] FIG. 19A shows, in accordance with certain embodiments, a cyclic voltammogram of the device shown in FIG. 18 A.

[0065] FIG. 19B shows, in accordance with certain embodiments, cyclic voltammograms of conventional devices.

[0066] FIG. 19C shows, in accordance with certain embodiments, a photograph of electrical connections to the device shown in FIG. 18 A.

[0067] DETAILED DESCRIPTION

[0068] Described herein are nanocomposite structural energy storage devices (e.g., all- nanocomposite structural energy storage devices) and related articles, systems, and methods. In some embodiments, a nanocomposite article comprises one or more domains comprising a plurality of elongated nanostructures distributed within an ionically conductive matrix. The nanocomposite articles may, in certain embodiments, comprise a high volume fraction of elongated nanostructures and a low volume fraction of gas / vacuum closed-cell voids (or, in some embodiments, other void types) while having advantageous dimensions (e.g., a thin thickness and / or a large overall volume). The high volume fraction of elongated nanostructures, low volume fraction of gas / vacuum closed-cell voids and / or other voids, and advantageous

[0069] #14504416vl dimensions are achieved, according to certain embodiments, by maintaining alignment of the elongated nanostructures during fabrication of the bulk nanocomposite material, which allows for the ionically conductive material (and / or a precursor thereof) to flow through and spread between the elongated nanostructures via capillary action. In certain embodiments, the resulting article with elongated nanostructures distributed within an ionically conductive matrix and / or ionically conductive matrix precursor may subsequently be densified by the application of pressure and cured or otherwise hardened, thereby providing the bulk nanocomposite material.

[0070] A nanocomposite article may include electronically conductive nanostructures (e.g., carbon nanotubes) distributed within an ionically conductive matrix, in some embodiments. Such articles may be suitable for use as one or more electrodes in an energy storage device (e.g., an electrochemical cell, such as a battery or a capacitor). A nanocomposite article includes, in some embodiments, electronically insulating nanostructures (e.g., boron nitride nanotubes) distributed within an ionically conductive matrix. Such articles may be suitable for use as a separator in an energy storage device. In certain embodiments, multiple nanocomposite articles may be combined to fabricate a complete energy storage device. For example, in some embodiments, a nanocomposite separator may be arranged between two nanocomposite articles, and the resulting arrangement is densified by the application of pressure and hardened such that the ionically conductive matrix within each article forms a continuous phase across the boundaries of the resulting device. The articles and methods described herein may advantageously be used to provide all-nanocomposite structural energy storage devices (e.g., supercapacitors) having advantageous performance characteristics and desirable structural properties, including high specific capacitances, mechanical robustness, and multifunctional integration capability.

[0071] The articles, devices, and / or methods described herein may be used in any of a variety of suitable applications, including, for example, structural components of a vehicle and / or transportation system, infrastructure in buildings, and / or electronic devices. In certain embodiments, the articles, devices, and / or methods combine a structural function with an energy storage function while addressing and overcoming issues associated with conventional structural energy storage devices, including, for example, low surface area electrodes (which lowers energy density) and weak and / or thick separators between electrodes (which limits ionic flow), thereby enhancing both electrochemical and mechanical performance.

[0072] According to certain embodiments, an article is described. FIG. 1 A shows, according to certain embodiments, a schematic diagram of article 102a. In some embodiments, article 102a comprises domain 104a. The “domain” of a given article, as the term is used in this application,

[0073] #14504416vl is a geometric volume in which a collection of nanostructures are contained. The “domain” can be any volume (arbitrarily bounded, or bounded by the limits of a material (such as the edges of a layer of ionically conductive polymer)) within which a collection of nanostructures is arranged.

[0074] In some embodiments, the domain corresponds to the three-dimensional convex hull around a collection of nanostructures within the article. The phrase “three-dimensional convex hull” of a given collection of nanostructures is given its ordinary meaning in geometry and refers to the smallest three-dimensional convex set that contains all the nanostructures within a given collection of nanostructures. The three-dimensional convex hull is also sometimes referred to in the field of geometry as the three-dimensional convex envelope or the three-dimensional convex closure, and it can be visualized (with respect to a collection of nanostructures) as the shape enclosed by a deformable sheet that is arranged such that it completely surrounds a three- dimensional depiction of the collection of nanostructures. FIG. 1C is a cross-sectional schematic illustration of a composite article, which can be used to illustrate the concept of a three- dimensional convex hull. In FIG. 1C, the cross-section of the three-dimensional convex hull of the collection of nanostructures 114 is shown as dotted line 160 surrounding nanostructures 114.

[0075] In some embodiments, the domain comprises an ionically conductive matrix. FIG. IB shows, according to certain embodiments, a cross-sectional schematic diagram of article 102a, wherein the cross-section is taken along lines IB shown in FIG. 1 A. Referring to FIG. IB, domain 104a comprises ionically conductive matrix 112, according to some embodiments.

[0076] The ionically conductive matrix may comprise any of a variety of suitable materials. In some embodiments, for example, the ionically conductive matrix comprises a thermoset polymer and an ionic liquid.

[0077] Any of a variety of thermoset polymers may be used, in accordance with certain embodiments. In some embodiments, the thermoset polymer comprises an epoxy (e.g., an epoxy resin). Non-limiting examples of epoxies include glycidyl epoxy, non-glycidyl epoxy, aliphatic epoxy, cycloaliphatic epoxy, bisphenol epoxy, and novolac epoxy. Other examples of thermoset polymers that can be used include polyurethane resins, phenolic resins, melamine formaldehyde resins, bakelite resins, polyimide resins, cyanide ester resins, and unsaturated polyester resins. In some embodiments, the thermoset polymer may include more than one type of thermoset polymer.

[0078] Any of a variety of ionic liquids may be used, in accordance with certain embodiments. Ionic liquids are salts that exist in a liquid state, typically at or below room temperature. In some embodiments, the ionic liquids that are used herein are in a liquid state at 25°C and 1 atm

[0079] #14504416vl of pressure. The ionic liquid can include a variety of cations, such as l-ethyl-3- methylimidazolium (EMIM), l-butyl-3-methylimidazolium (BMIM), l-hexyl-3- methylimidazolium (HMIM), n-butyl-n-methylpyrrolidinium (PYRw), 1 -methyl- 1- propylpyrrolidinium (PYR13), 1 -butyl- 1-methylpiperidinium (PIP14), choline (Ch), and trihexyl(tetradecyl)phosphonium (Peeeu). The ionic liquid can also include a variety of anions, such as bis(trifluoromethylsulfonyl)imide (TFSI), tetrafluorob orate (BF4), bis(fluorosulfonyl)imide (FSI), hexafluorophosphate (PFe), chloride (Cl), lactate (La), and isoleucine (He). Non-limiting examples of ionic liquids that may be used include l-ethyl-3- methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM- TFSI), l-ethyl-3- methylimidazolium tetrafluorob orate (EMIM-BF4), l-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIM-FSI), l-butyl-3-methylimidazolium tetrafluoroborate (BMIM- BF4), l-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PFe), l-hexyl-3- methylimidazolium chloride (HMIM-C1), n-butyl-n-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (PYRM-TFSI), 1 -methyl- 1-propylpyrrolidinium bis(fluorosulfonyl)imide (PYR13-FSI), 1 -butyl- 1-methylpiperidinium bis(trifluoromethylsulfonyl)imide (PIPM-TFSI), choline lactate (Ch-La), choline isoleucine (Chile), trihexyl(tetradecyl)phosphonium chloride (Peeeu-Cl), and trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide (Peeeu-TFSI).

[0080] In some embodiments, the ionically conductive matrix has a relatively high ionic conductivity. In certain embodiments, a relatively high ionic conductivity can make the ionically conductive matrix suitable for use as an ion-transporting material (e.g., in the separator of a battery, capacitor, and / or supercapacitor, in a membrane, and / or in other articles).

[0081] According to some embodiments, the ionically conductive matrix has an ionic conductivity, with respect to at least one monovalent ion (e.g., at least one monovalent cation) and / or at least one divalent ion (e.g., at least one divalent cation), of greater than or equal to 10'7S / cm, greater than or equal to 5x1 O'7S / cm, greater than or equal to 10'6S / cm, greater than or equal to 5xl0'6S / cm, greater than or equal to 10'5S / cm, greater than or equal to 5xl0'5S / cm, greater than or equal to 10'4S / cm, greater than or equal to 5x1 O'4S / cm, greater than or equal to 10'3S / cm, greater than or equal to 5x1 O'3S / cm, greater than or equal to 10'2S / cm, or greater than or equal to 5xl0'2S / cm. According to some embodiments, the ionically conductive matrix has an ionic conductivity, with respect to at least one monovalent ion (e.g., at least one monovalent cation) and / or at least one divalent ion (e.g., at least one divalent cation), of less than or equal to 10'1S / cm, less than or equal to 5xl0'2S / cm, less than or equal to 10'2S / cm, less than or equal to 5xl0'3S / cm, less than or equal to 10'5S / cm, less than or equal to 5xl0'6S / cm,

[0082] #14504416vl less than or equal to 10'6S / cm, or less than or equal to 5xl0'7S / cm. Combinations of these ranges are possible (e.g., greater than or equal to 10'7S / cm and less than or equal to IxlO'1S / cm, or greater than or equal to 10'6S / cm and less than or equal to 10'3S / cm). Other ranges are also possible. In certain embodiments, the ionic conductivity of the ionically conductive matrix may be determined by electrochemical impedance spectroscopy (EIS).

[0083] According to some embodiments, the ionically conductive matrix has an ionic conductivity, with respect to lithium ions, sodium ions, magnesium ions, and / or potassium ions, of greater than or equal to 1 O’7S / cm, greater than or equal to 5x1 O'7S / cm, greater than or equal to 10'6S / cm, greater than or equal to 5xl0'6S / cm, greater than or equal to 10'5S / cm, greater than or equal to 5x1 O'5S / cm, greater than or equal to 10'4S / cm, greater than or equal to 5x1 O'4S / cm, greater than or equal to 10'3S / cm, greater than or equal to 5x1 O'3S / cm, greater than or equal to 1 O’2S / cm, or greater than or equal to 5xl0'2S / cm. According to some embodiments, the ionically conductive matrix has an ionic conductivity, with respect to lithium ions, sodium ions, magnesium ions, and / or potassium ions, of less than or equal to 10'1S / cm, less than or equal to 5xl0'2S / cm, less than or equal to 10'2S / cm, less than or equal to 5xl0'3S / cm, less than or equal to 10'5S / cm, less than or equal to 5xl0'6S / cm, less than or equal to 10'6S / cm, or less than or equal to 5xl0'7S / cm. Combinations of these ranges are possible (e.g., greater than or equal to 1 O’7S / cm and less than or equal to IxlO'1S / cm, or greater than or equal to 10'6S / cm and less than or equal to 10'3S / cm). Other ranges are also possible.

[0084] According to some embodiments, the ionically conductive matrix has an ionic conductivity, with respect to lithium ions (e.g., Li+), of greater than or equal to 10'7S / cm, greater than or equal to 5x1 O'7S / cm, greater than or equal to 10'6S / cm, greater than or equal to 5x1 O'6S / cm, greater than or equal to 10'5S / cm, greater than or equal to 5x1 O'5S / cm, greater than or equal to 1 O’4S / cm, greater than or equal to 5xl0'4S / cm, greater than or equal to 10'3S / cm, greater than or equal to 5x1 O'3S / cm, greater than or equal to 10'2S / cm, or greater than or equal to 5xl0'2S / cm. According to some embodiments, the ionically conductive matrix has an ionic conductivity, with respect to lithium ions (e.g., Li+), of less than or equal to 10’1S / cm, less than or equal to 5xl0'2S / cm, less than or equal to 10'2S / cm, less than or equal to 5xl0'3S / cm, less than or equal to 10'5S / cm, less than or equal to 5xl0'6S / cm, less than or equal to 10'6S / cm, or less than or equal to 5xl0'7S / cm. Combinations of these ranges are possible (e.g., greater than or equal to 10'7S / cm and less than or equal to IxlO'1S / cm, or greater than or equal to 10'6S / cm and less than or equal to 10'3S / cm). Other ranges are also possible.

[0085] In some embodiments, the ionically conductive matrix has a relatively high Young’s modulus. In certain embodiments, a relatively high Young’s modulus can make the ionically

[0086] #14504416vl conductive matrix suitable for use as a structural material (e.g., in the separator of a battery, capacitor, and / or supercapacitor, in a membrane, and / or in other articles).

[0087] According to some embodiments, the Young’s modulus of the ionically conductive matrix is greater than or equal to 100 MPa, greater than or equal to 500 MPa, greater than or equal to 700 MPa, greater than or equal to 1 GPa, greater than or equal to 1.65 GPa, or greater than or equal to 5 GPa. According to some embodiments, the Young’s modulus of the ionically conductive matrix is less than or equal to 10 GPa, less than or equal to 5 GPa, or less than or equal to 2 GPa. Combinations of these ranges are possible (e.g., greater than or equal to 100 MPa and less than or equal to 10 GPa). Other ranges are also possible. In certain embodiments, the Young’s modulus of the ionically conductive matrix is determined using a Zwick Mechanical Tester.

[0088] According to some embodiments, the domain comprises a plurality of elongated nanostructures. Referring, for example, to FIG. IB, domain 104a comprises a plurality of elongated nanostructures 114. As used herein, the term “elongated nanostructure” refers to a structure having a maximum cross-sectional diameter of less than or equal to 1 micrometer and a length resulting in an aspect ratio greater than or equal to 10. In some embodiments, the elongated nanostructure can have an aspect ratio greater than or equal to 100, greater than or equal to 1000, greater than or equal to 10,000, or greater. Those skilled in the art would understand that the aspect ratio of a given structure is measured along the longitudinal axis of the elongated nanostructure, and is expressed as the ratio of the length of the longitudinal axis of the nanostructure to the maximum cross-sectional diameter of the nanostructure. The “longitudinal axis” of an article corresponds to the imaginary line that connects the geometric centers of the cross-sections of the article as a pathway is traced, along the longest length of the article, from one end to another. See, for example, longitudinal axis 116 of nanostructures 114 in FIG. IB.

[0089] In some cases, the elongated nanostructure may have a maximum cross-sectional diameter of less than or equal to 1 micrometer, less than or equal to 100 nanometers, less than or equal to 50 nanometers, less than or equal to 25 nanometers, less than or equal to 10 nanometers, or, in some cases, less than or equal to 1 nanometer. A “maximum cross-sectional diameter” of an elongated nanostructure, as used herein, refers to the largest dimension between two points on opposed outer boundaries of the elongated nanostructure, as measured perpendicular to the length of the elongated nanostructure (e.g., the length of a carbon nanotube). The “average of the maximum cross-sectional diameters” of a plurality of structures refers to the number average.

[0090] #14504416vl In certain embodiments, the elongated nanostructures described herein have relatively low geometric tortuosities. For example, in certain embodiments, at least a portion (e.g., at least 10%, at least 25%, at least 50%, at least 75%, at least 90%, at least 95%, at least 99%, or all) of the elongated nanostructures have geometric tortuosities of less than or equal to 3, less than or equal to 2.5, less than or equal to 2, less than or equal to 1.5, less than or equal to 1.2, or less than or equal to 1.1 (and, in certain embodiments, down to substantially 1).

[0091] The geometric tortuosity of a particular elongated nanostructure is calculated as the effective path length divided by the projected path length. Examples are shown in FIGS. 5A-5C. FIG. 5A shows an example of a high-tortuosity elongated nanostructure, where the geometric tortuosity is calculated by dividing the length of longitudinal axis 502 by projected path length 504. FIG. 5B shows an example of a medium-tortuosity elongated nanostructure, and FIG. 5C shows an example of a low-tortuosity elongated nanostructure. One of ordinary skill in the art would be capable of determining the geometric tortuosity of a given elongated nanostructure by examining an image (e.g., a magnified image such as a scanning electron micrograph, a microscope enhanced photograph, or an unmagnified photograph), determining the effective path length by tracing a pathway from one end of the elongated nanostructure to the other end of the elongated nanostructure along the longitudinal axis of the elongated nanostructure, and determining the projected path length by measuring the straight-line distance between the ends of the elongated nanostructure.

[0092] According to certain embodiments, the plurality of elongated nanostructures has an average geometric tortuosity of less than or equal to 3, less than or equal to 2.5, less than or equal to 2, less than or equal to 1.5, less than or equal to 1.2, or less than or equal to 1.1 (and, in certain embodiments, down to substantially 1). The average geometric tortuosity of a plurality of elongated nanostructures is calculated as the number average of the geometric tortuosities of the individual elongated nanostructures.

[0093] The elongated nanostructure can have a cylindrical or pseudo-cylindrical shape, in some embodiments. In some embodiments, the elongated nanostructure can be a nanotube, such as a carbon nanotube (CNT) and / or a boron nitride nanotube (BNNT). Other examples of elongated nanostructures include, but are not limited to, nanofibers and nanowires. In some embodiments, for example, the elongated nanostructures comprise nanotubes, nanofibers, and / or nanowires.

[0094] Elongated nanostructures can be single molecules (e.g., in the case of some nanotubes) or can include multiple molecules bound to each other (e.g., in the case of some nanofibers).

[0095] As used herein, the term “nanotube” refers to a substantially cylindrical elongated nanostructure comprising a fused network of primarily six-membered rings (e.g., six-membered

[0096] #14504416vl aromatic rings). Nanotubes may include, in some embodiments, a fused network of at least 10, at least 100, or at least 1000 rings (e.g., six-membered rings such as six-membered aromatic rings), or more. In some cases, nanotubes may resemble a sheet of graphite formed into a seamless cylindrical structure. It should be understood that the nanotube may also comprise rings or lattice structures other than six-membered rings. According to certain embodiments, at least one end of the nanotube may be capped, i.e., with a curved or nonplanar aromatic group.

[0097] Elongated nanostructures may be formed of a variety of materials, in some embodiments. In certain embodiments, the elongated nanostructures comprise carbon (e.g., carbon-based nanostructures) or boron nitride (e.g., boron nitride nanostructures). Other non-limiting examples of materials from which elongated nanostructures may be formed include silicon, alumina, indium-gallium-arsenide materials, silicon nitride (e.g., SisN4), silicon carbide, dichalcogenides (WS2), oxides (e.g., titanium dioxide, molybdenum trioxide), and boron-carbon- nitrogen compounds (e.g., BC2N2, BC4N). In some embodiments, the elongated nanostructure may be formed of one or more inorganic materials. Non-limiting examples include semiconductor nanowires such as silicon (Si) nanowires, indium-gallium-arsenide (InGaAs) nanowires, and nanotubes comprising boron nitride (BN), silicon nitride (SisN4), silicon carbide (SiC), dichalcogenides such as (WS2), oxides such as titanium dioxide (TiCh) and molybdenum trioxide (MoOs), and boron-carbon-nitrogen compositions such as BC2N2 and BC4N.

[0098] In certain embodiments, the plurality of elongated nanostructures are distributed within the ionically conductive matrix. For example, referring to FIG. IB, plurality of elongated nanostructures 114 are distributed within ionically conductive matrix 112.

[0099] The plurality of elongated nanostructures may be distributed within the ionically conductive matrix in any of a variety of suitable configurations. In some embodiments, for example, the longitudinal axes (e.g., longitudinal axes 116) of the plurality of elongated nanostructures (e.g., elongated nanostructures 114) are substantially aligned with each other. Those skilled in the art would understand that elongated nanostructures may have some inherent deviation along their length such as waviness. Accordingly, for the purposes of determining the alignment of elongated nanostructures with each other, one would draw a line from one end of the elongated nanostructure to the other end of the elongated nanostructure, such as line 504 shown in FIG. 5 A. Alignment of the elongated nanostructures with each other can be determined by 3-dimensional electron tomography.

[0100] In some embodiments, at least 50%, at least 75%, at least 90%, at least 95%, at least 99%, or all of the elongated nanostructures within the collection of nanostructures are within 30 degrees, within 20 degrees, within 10 degrees, within 5 degrees, or within 2 degrees of parallel

[0101] #14504416vl to at least 50%, at least 75%, at least 90%, at least 95%, at least 99%, or all of the other elongated nanostructures within the collection.

[0102] In some embodiments, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 99%, or all of the elongated nanostructures within the collection of nanostructures are parallel to within 30 degrees, within 20 degrees, within 10 degrees, within 5 degrees, or within 2 degrees of a common vector. One example is shown in FIG. IB, where longitudinal axes 116 are all horizontally arranged. Another example is shown in the upper right-hand portion of FIG. 7C, in which nanostructures 114 remain aligned with a common vector (and with each other) after they have been knocked over but prior to penetration by ionically conductive matrix and / or ionically conductive matrix precursor 122. As noted above, those skilled in the art would understand that elongated nanostructures may have some inherent deviation along their length such as waviness. Accordingly, for the purposes of determining the alignment of elongated nanostructures with respect to a common vector, one would draw a line from one end of the elongated nanostructure to the other end of the elongated nanostructure, such as line 504 shown in FIG. 5A. Alignment of the elongated nanostructures with a common vector can be determined by 3-dimensional electron tomography. As noted above, the high volume of elongated nanostructures, low volume of gas / vacuum closed-cell voids and / or other types of voids, and large scale in at least two dimensions in the final composite can be achieved, in accordance with certain embodiments, by maintaining alignment of the elongated nanostructures during fabrication of the bulk nanocomposite materials, which allows for an ionically conductive matrix and / or an ionically conductive matrix precursor to flow through and spread between the elongated nanostructures via capillary action.

[0103] According to certain embodiments, the first dimension of the domain is substantially parallel to the longitudinal axes of the elongated nanostructures. Referring, for example, to FIG. IB, first dimension 106 of domain 104a is substantially parallel to (i.e., within 30 degrees, within 20 degrees, within 10 degrees, within 5 degrees, within 2 degrees, or within 1 degree of parallel to) longitudinal axes 116 of elongated nanostructures 114.

[0104] FIG. 2A shows, according to certain embodiments, a domain comprising a plurality of elongated nanostructures arranged in an overlapping fashion. In some embodiments, for example, within domain 104, at least a portion of the plurality of elongated nanostructures 114 are arranged in ionically conductive matrix 112 such that first portion of elongated nanostructures 114a at least partially overlaps second portion of elongated nanostructures 114b.

[0105] FIG. 2B shows, according to certain embodiments, a domain comprising a plurality of nanostructures arranged in a non-overlapping fashion. In some embodiments, for example,

[0106] #14504416vl within domain 104, first portion of elongated nanostructures 114a and second portion of elongated nanostructures 114b are arranged in ionically conductive matrix 112 in a nonoverlapping fashion. In some embodiments, the plurality of elongated nanostructures arranged in a non-overlapping fashion may be arranged in an end-to-end fashion, as shown in FIG. 2B.

[0107] FIG. 2C shows, according to certain embodiments, a domain comprising a plurality of nanostructures arranged in an overlapping and non-overlapping fashion. In some embodiments, within domain 104, at least a portion of the plurality of elongated nanostructures 114 are arranged in ionically conductive matrix 112 such that first portion of elongated nanostructures 114a at least partially overlaps second portion of elongated nanostructures 114b and at least a portion of the plurality of elongated nanostructures 114b are arranged in a non-overlapping (e.g., an end-to-end) fashion.

[0108] FIG. 2D shows, according to certain embodiments, a domain comprising a stacked configuration of a plurality of nanostructures arranged in an overlapping and non-overlapping fashion. In some embodiments, the configuration of elongated nanostructures shown in FIG. 2A may extend such that at a least portion of the plurality of elongated nanostructures are arranged in an overlapping and non-overlapping fashion. In some embodiments, for example, within domain 104, at least a portion of the plurality of elongated nanostructures 114 are arranged in ionically conductive matrix 112 such that first portion of elongated nanostructures 114a at least partially overlaps second portion of elongated nanostructures 114b, which at least partially overlap third portion of elongated nanostructures 114c, which at least partially overlaps fourth portion of elongated nanostructures 114d, which at least partially overlaps fifth portion of elongated nanostructures 114e. In certain embodiments, first portion of elongated nanostructures 114a are arranged in a non-overlapping fashion with fifth portion of elongated nanostructures 114e. Although five portions of elongated nanostructures are shown in FIG. 2D, more portions (e.g., six portions, eight portions, ten portions, or more) or less portions (e.g., four portions, three portions, or less) may be arranged in a stacked configuration in an overlapping and non-overlapping fashion, in accordance with certain embodiments.

[0109] FIG. 2E shows, according to certain embodiments, a composite article comprising a layered configuration of a plurality of elongated nanostructures. In certain embodiments, within article 102’, at least a portion of the plurality of elongated nanostructures 114 are arranged in ionically conductive matrix 112 such that first layer 115a containing first domain 104a comprising elongated nanostructures 114 (e.g., 114a and 114b) is positioned over second layer 115b containing second domain 104b comprising elongated nanostructures 114 (e.g., 114c and 114d). In certain embodiments, as shown in FIG. 2E, first layer 115a comprises first portion of

[0110] #14504416vl elongated nanostructures 114a and second portion of elongated nanostructures 114b arranged such that first portion of elongated nanostructures 114a at least partially overlaps second portion of elongated nanostructures 114b (e.g., as described herein in greater detail with respect to FIG.

[0111] 1 A). In some embodiments, second layer 115b comprises third portion of elongated nanostructures 114c and fourth portion of elongated nanostructures 114d arranged such that third portion of elongated nanostructures 114c at least partially overlaps fourth portion of elongated nanostructures 114d.

[0112] In some embodiments, a combination of a first domain and a second domain, together, define a third domain. For example, referring to FIG. 2E, the combination of first domain 104a and second domain 104b, together, define third domain 104c.

[0113] According to some embodiments, a composite article (and / or a domain within a composite article) comprising a layered configuration of a plurality of elongated nanostructures may include a first layer having any of the elongated nanostructure configurations shown in FIGS. 2A-2D and a second layer having any of the elongated nanostructure configurations shown in FIGS. 2A-2D. In some embodiments, a composite article (and / or a domain within a composite article) comprising a layered configuration of a plurality of elongated nanostructures may comprise more than two layers of elongated nanostructures (e.g., three layers, four layers, five layers, or more), each of which may independently have any of the configuration shown in FIGS. 2A-2D.

[0114] According to certain embodiments, the elongated nanostructures are electronically conductive. Referring, for example, to FIG. IB, the plurality of elongated nanostructures 114 are electronically conductive, in accordance with certain embodiments. The electronically conductive elongated nanostructures may comprise any of a variety of suitable materials. In some embodiments, for example, the electronically conductive elongated nanostructures comprise carbon (e.g., carbon based nanostructures, such as carbon nanotubes), as described herein in greater detail.

[0115] The electronically conductive elongated nanostructures may have any of a variety of suitable electronic conductivities. According to some embodiments, the electronic conductivity of the electronically conductive elongated nanostructures is greater than or equal to 0.001 S / micrometer, greater than or equal to 0.005 S / micrometer, greater than or equal to 0.01 S / micrometer, greater than or equal to 0.05 S / micrometer, greater than or equal to 0.1 S / micrometer, greater than or equal to 0.5 S / micrometer, greater than or equal to 1 S / micrometer, greater than or equal to 5 S / micrometer, greater than or equal to 10 S / micrometer, or greater than or equal to 50 S / micrometer. According to some embodiments, the electronic conductivity of the

[0116] #14504416vl electronically conductive elongated nanostructures is less than or equal to 100 S / micrometer, less than or equal to 50 S / micrometer, less than or equal to 10 S / micrometer, less than or equal to 5 S / micrometer, less than or equal to 1 S / micrometer, less than or equal to 0.5 S / micrometer, less than or equal to 0.1 S / micrometer, less than or equal to 0.05 S / micrometer, less than or equal to 0.01 S / micrometer, or less than or equal to 0.005 S / micrometer. Combinations of these ranges are possible (e.g., greater than or equal to 0.001 S / micrometer and less than or equal to 100 S / micrometer, or greater than or equal to 0.01 S / micrometer and less than or equal to 0.5 S / micrometer). Other ranges are also possible.

[0117] According to some embodiments, an article comprising electronically conductive elongated nanostructures may be an electrode. For example, referring to FIGS. 1 A-1B, article 102a comprising a plurality of electronically conductive elongated nanostructures 114 distributed within ionically conductive matrix 112 may be an electrode, in accordance with certain embodiments.

[0118] In some embodiments, the elongated nanostructures are electronically insulating. For example, referring to FIG. IB, the plurality of elongated nanostructures 114 are electronically insulating, in some embodiments. The electronically insulating elongated nanostructures may comprise any of a variety of suitable materials. For example, in certain embodiments, the electronically insulating elongated nanostructures comprise boron nitride (e.g., boron nitride nanostructures, such as boron nitride nanotubes), as described herein in greater detail.

[0119] In certain embodiments an article comprising electronically insulating elongated nanostructures may be a separator (e.g., of an electrochemical device such as an electrochemical cell, a fuel cell, a battery, and / or a capacitor). Referring, for example, to FIGS. 1 A-1B, article 102a comprising a plurality of electronically insulating elongated nanostructures 114 distributed within ionically conductive matrix 112 may be a separator, in accordance with certain embodiments.

[0120] In some embodiments, an article described herein comprises a first domain (e.g., any of the domains described above), and the article further comprises at least a second domain over the first domain. FIG. 3 A shows, according to certain embodiments, article 102b comprising first domain 104a and second domain 104b. As shown in FIG. 3 A, second domain 104b is over first domain 104a. In certain embodiments, first domain 104a and second domain 104b are arranged within layers that are at least partially in contact (e.g., directly in contact) with each other. In some embodiments, first domain 104a and second domain 104b are at least partially in contact (e.g., directly in contact) with each other.

[0121] #14504416vl In some embodiments, first domain 104a comprises a first plurality of elongated nanostructures distributed within an ionically conductive matrix, and second domain 104b comprises a second plurality of elongated nanostructures distributed within the ionically conductive matrix. FIG. 3B shows, according to certain embodiments, a cross-sectional schematic diagram of article 102b, wherein the cross-section is taken along lines 3B shown in FIG. 3 A. As shown in FIG. 3B, first domain 104a comprises a first plurality of elongated nanostructures 114 (e.g., 114a and 114b) distributed within ionically conductive matrix 112, and second domain 104b comprises a second plurality of elongated nanostructures 114 (e.g., 114a’ and 114b’) distributed within ionically conductive matrix 112.

[0122] In certain embodiments, there is no discernable interface between first domain 104a and second domain 104b. In some embodiments, for example, there is no change in chemical composition, no physical discontinuity, or no other discernable interface between first domain 104a and second domain 104b. In other embodiments, there is a discernable interface between first domain 104a and second domain 104b (e.g., there is a change in chemical composition, a physical discontinuity, and / or another type of discernable interface between first domain 104a and second domain 104b.

[0123] According to some embodiments, the ionically conductive matrix forms a continuous phase across the first domain and the second domain. Referring, for example, to FIG. 3B, ionically conductive matrix 112 forms a continuous phase across first domain 104a and second domain 104b. In certain embodiments wherein ionically conductive matrix 112 forms a continuous phase across first domain 104a and second domain 104b, there is no discernable interface between first domain 104a and second domain 104b (e.g., there is no change in chemical composition, no physical discontinuity, or no other discernable interface between first domain 104a and second domain 104b).

[0124] Second domain 104b may have any of a variety of suitable configurations, as described herein (e.g., any of the configurations shown in FIGS. 2A-2E). In certain embodiments, first domain 104a and second domain 104b have the same or substantially the same configuration. In other embodiments, first domain 104a and second domain 104b are configured differently (e.g., as shown in FIG. 3B).

[0125] According to some embodiments, first domain 104a has electrode properties. In some embodiments, for example, first domain 104a comprises a plurality of electronically conductive elongated nanostructures 114 (e.g., a plurality of electronically conductive elongated carbon nanotubes) distributed within ionically conductive matrix 112. In certain embodiments, second domain 104b has separator properties. For example, in some embodiments, second domain 104b

[0126] #14504416vl comprises a plurality of electronically insulating nanostructures 114 (e.g., a plurality of electronically insulating boron nitride nanotubes) distributed within ionically conductive matrix 112. In some embodiments, first domain 104a may be an electrode and second domain 104b may be a separator.

[0127] In some embodiments, an article described herein comprises a first domain (e.g., any of the domains described above), a second domain (e.g., any of the domains described above), and the article further comprises at least a third domain over the second domain. FIG. 4A shows, according to certain embodiments, article 102c comprising first domain 104a, second domain 104b, and third domain 104c. As shown in FIG. 4A, third domain 104c is over second domain 104b (which is over first domain 104a). In some embodiments, second domain 104b and third domain 104c are arranged within layers that are at least partially in contact (e.g., directly in contact) with each other. In some embodiments, second domain 104b and third domain 104c are at least partially in contact (e.g., directly in contact) with each other.

[0128] In some embodiments, first domain 104a comprises a first plurality of elongated nanostructures distributed within an ionically conductive matrix, second domain 104b comprises a second plurality of elongated nanostructures distributed within the ionically conductive matrix, and third domain 104c comprises a third plurality of elongated nanostructures distributed within the ionically conductive matrix. FIG. 4B shows, according to certain embodiments, a cross- sectional schematic diagram of article 102c, wherein the cross-section is taken along lines 4B shown in FIG. 4A. As shown in FIG. 4B, first domain 104a comprises a first plurality of elongated nanostructures 114 (e.g., 114a and 114b) distributed within ionically conductive matrix 112, second domain 104b comprises a second plurality of elongated nanostructures 114 (e.g., 114a’ and 114b’) distributed within ionically conductive matrix 112, and third domain 104c comprises a third plurality of elongated nanostructures 114 (e.g., 114a” and 114b”) distributed within ionically conductive matrix 112.

[0129] According to certain embodiments, there is no discernable interface between first domain 104a, second domain 104b, and third domain 104c. In some embodiments, for example, there is no change in chemical composition, no physical discontinuity, or no other discernable interface between first domain 104a, second domain 104b, and third domain 104c. In other embodiments, there is a discernable interface between: (i) first domain 104a and second domain 104b; and / or (ii) second domain 104b and third domain 104c (e.g., there is a change in chemical composition, a physical discontinuity, and / or another type of discernable interface between: (i) first domain 104a and second domain 104b; and / or second domain 104b and third domain 104c).

[0130] #14504416vl According to some embodiments, the ionically conductive matrix forms a continuous phase across the first domain, the second domain, and the third domain. Referring, for example, to FIG. 4B, ionically conductive matrix 112 forms a continuous phase across first domain 104a, second domain 104b, and third domain 104c. In some embodiments wherein ionically conductive matrix 112 forms a continuous phase across first domain 104a, second domain 104b, and third domain 104c, there is no discernable interface between first domain 104a, second domain 104b, and third domain 104c (e.g., there is no change in chemical composition, no physical discontinuity, or no other discernable interface between first domain 104a, second domain 104b, and third domain 104c).

[0131] Third domain 104c may have any of a variety of suitable configurations, as described herein (e.g., any of the configurations shown in FIGS. 2A-2E). In certain embodiments, first domain 104a, second domain 104b, and third domain 104c have the same or substantially the same configuration. In other embodiments, first domain 104a, second domain 104b, and third domain 104c are configured differently. In yet other embodiments, two of the three domains have the same or substantially the same configuration, and the other domain is configured differently. For example, in some embodiments, first domain 104a and third domain 104c have the same or substantially the same configuration, and second domain 104b is configured differently (e.g., as shown in FIG. 4B).

[0132] In some embodiments, first domain 104a has electrode properties. For example, in certain embodiments, first domain 104a comprises a plurality of electronically conductive elongated nanostructures (e.g., a plurality of electronically conductive elongated carbon nanotubes) distributed within ionically conductive matrix 112. In some embodiments, second domain 104b has separator properties. In certain embodiments, for example, second domain 104b comprises a plurality of electronically insulating nanostructures 114 (e.g., a plurality of electronically insulating boron nitride nanotubes) distributed within ionically conductive matrix 112. In some embodiments, third domain 104c has electrode properties. For example, in certain embodiments, third domain 104c comprises a plurality of electronically conductive elongated nanostructures 114 (e.g., a plurality of electronically conductive elongated carbon nanotubes) distributed within ionically conductive matrix 112. In certain embodiments, first domain 104a may be a first electrode (e.g., an anode), second domain 104b may be a separator, and third domain 104c may be a second electrode (e.g., a cathode).

[0133] In certain embodiments, an article may comprise any of a variety of suitable domains. In certain embodiments, for example, an article comprises greater than or equal to 6 domains, greater than or equal to 9 domains, greater than or equal to 12 domains, greater than or equal to

[0134] #14504416vl 15 domains, greater than or equal to 30 domains, greater than or equal to 60 domains, greater than or equal to 90 domains, greater than or equal to 120 domains, or more. In some embodiments, an article comprises less than or equal to 150 domains, less than or equal to 120 domains, less than or equal to 90 domains, less than or equal to 60 domains, less than or equal to 30 domains, less than or equal to 14 domains, less than or equal to 12 domains, or less than or equal to 9 domains. Combinations of the above recited ranges are also possible (e.g., the article comprises greater than or equal to 6 domains and less than or equal to 150 domains). Other ranges are also possible.

[0135] One, more, or all of the domain(s) described herein (e.g., the first domain, the second domain, the third domain, and / or additional domain(s)) may have any of a variety of suitable dimensions. In certain embodiments, for example, referring to FIGS. 1 A, 3A, and 4A, domain 104 (e.g., domain 104a, 104b, and 104c) comprises first dimension 106 and second dimension 108. According to certain embodiments, second dimension 108 is perpendicular to first dimension 106.

[0136] The length of first dimension 106 may be any of a variety of suitable lengths. In some embodiments, for example, first dimension 106 has a length of at least 1 centimeter, at least 2 centimeters, at least 5 centimeters, at least 10 centimeters, at least 15 centimeters, at least 20 centimeters, at least 50 centimeters, or more (e.g., at least 1 meter, at least 1 kilometer, etc.). In certain embodiments, first dimension 106 has a length of less than or equal to 100 centimeters, less than or equal to 50 centimeters, less than or equal to 20 centimeters, less than or equal to 15 centimeters, less than or equal to 10 centimeters, less than or equal to 5 centimeters, or less than or equal to 2 centimeters. Combinations of the above recited ranges are possible (e.g., first dimension 106 has a length of at least 1 centimeter and less than or equal to 100 centimeters, first dimension 106 has a length of at least 5 centimeters and less than or equal to 10 centimeters). Other ranges are also possible.

[0137] The length of second dimension 108 may be any of a variety of suitable lengths. In some embodiments, for example, second dimension 108 has a length of at least 1 centimeter, at least 2 centimeters, at least 5 centimeters, at least 10 centimeters, at least 15 centimeters, at least 20 centimeters, at least 50 centimeters, or more (e.g., at least 1 meter, at least 1 kilometer, etc.). In certain embodiments, second dimension 108 has a length of less than or equal to 100 centimeters, less than or equal to 50 centimeters, less than or equal to 20 centimeters, less than or equal to 15 centimeters, less than or equal to 10 centimeters, less than or equal to 5 centimeters, or less than or equal to 2 centimeters. Combinations of the above recited ranges are possible (e.g., second dimension 108 has a length of at least 1 centimeter and less than or equal

[0138] #14504416vl to 100 centimeters, second dimension 108 has a length of at least 5 centimeters and less than or equal to 10 centimeters). Other ranges are also possible.

[0139] According to certain embodiments, one, more, or all of the domain(s) described herein (e.g., the first domain, the second domain, the third domain, and / or additional domain(s)) comprises a third dimension. Referring to FIGS. 1 A, 3A, and 4A, for example, first domain 104a comprises third dimension 110a, second domain 104b comprises third dimension 110b, and third domain 104c comprises third dimension 110c. In some embodiments, the third dimension 110 (e.g., third dimension 110a, 110b, and / or 110c) is perpendicular to first dimension 106 and second dimension 108. In some embodiments, the third dimension 110 (e.g., third dimension 110a, 110b, and / or 110c) is a thickness of the domain.

[0140] The length of the third dimension of one, more, or all of the domain(s) may be any of a variety of suitable lengths. In certain embodiments, the length of the third dimension (e.g., dimension 110) is advantageously thin. In some embodiments, for example, the third dimension has a length of less than or equal to 1000 micrometers, less than or equal to 500 micrometers, less than or equal to 100 micrometers, less than or equal to 50 micrometers, less than or equal to 10 micrometers, less than or equal to 5 micrometers, less than or equal to 2 micrometers, less than or equal to 1 micrometer, less than or equal to 0.5 micrometers, less than or equal to 0.2 micrometers, less than or equal to 0.1 micrometers, or less. In some embodiments, the third dimension has a length greater than or equal to 0.01 micrometers, greater than or equal to 0.1 micrometers, greater than or equal to 0.2 micrometers, greater than or equal to 0.5 micrometers, greater than or equal to 1 micrometer, greater than or equal to 2 micrometers, greater than or equal to 5 micrometers, greater than or equal to 10 micrometers, greater than or equal to 50 micrometers, greater than or equal to 100 micrometers, or greater than or equal to 500 micrometers. Combinations of the above recited ranges are possible (e.g., the third dimension has a length of less than or equal to 1000 micrometers and greater than or equal to 0.01 micrometers, the third dimension has a length of less than or equal to 1 micrometer and greater than or equal to 0.5 micrometers). Other ranges are also possible.

[0141] One, more, or all of the domain(s) described herein (e.g., the first domain, the second domain, the third domain, and / or additional domain(s)) may have any of a variety of suitable volumes. In certain embodiments, for example, the volume of one, more, or all of the domain(s) is greater than or equal to 106pm3, greater than or equal to 108pm3, greater than or equal to 1010pm3, greater than or equal to 1 cm3, greater than or equal to 100 cm3, or greater (e.g., greater than or equal to 10,000 cm3, greater than or equal to 1 m3, etc.). In some embodiments, the volume of one, more, or all of the domain(s) is less than or equal to 10 m3, less than or equal to

[0142] #14504416vl 1 m3, less than or equal to 10,000 cm3, less than or equal to 100 cm3, less than or equal to 1 cm3, less than or equal to 1010pm3, or less than or equal to 108pm3. Combinations of the above recited ranges are possible (e.g., the volume of one, more, or all of the domain(s) is greater than or equal to 106pm3and less than or equal to 10 m3, the volume of one, more, or all the domain(s) is greater than or equal to 1 cm3and less than or equal to 100 cm3). Other ranges are also possible.

[0143] In some embodiments, one, more, or all of the domain(s) described herein (e.g., the first domain, the second domain, the third domain, and / or additional domain(s)) can have a relatively high percentage of their volume fractions occupied by elongated nanostructures. In certain embodiments, for example, the elongated nanostructures occupy a volume fraction of at least 10 vol%, at least 15 vol%, at least 20 vol%, at least 25 vol%, at least 30 vol%, at least 35 vol%, at least 40 vol%, at least 45 vol%, at least 50 vol%, at least 55 vol%, at least 60 vol%, at least 65 vol%, at least 70 vol%, at least 75 vol%, or more within one, more, or all of the domain(s). According to some embodiments, the elongated nanostructures occupy a volume fraction less than or equal to less than or equal to 80 vol%, less than or equal to 75 vol%, less than or equal to 70 vol%, less than or equal to 65 vol%, less than or equal to 60 vol%, less than or equal to 55 vol%, less than or equal to 50 vol%, less than or equal to 45 vol%, less than or equal to 40 vol%, less than or equal to 35 vol%, less than or equal to 30 vol%, less than or equal to 25 vol%, less than or equal to 20 vol%, less than or equal to 15 vol%, or less than or equal to 10 vol% within one, more, or all of the domain(s). Combinations of the above recited ranges are possible (e.g., the elongated nanostructures occupy a volume fraction between at least 10 vol% and less than or equal to 80 vol% within one, more, or all of the domain(s), the elongated nanostructures occupy a volume fraction between at least 30 vol% and less than or equal to 50 vol% within one, more, or all of the domain(s)). Other ranges are also possible.

[0144] One, more, or all of the domain(s) described herein (e.g., the first domain, the second domain, the third domain, and / or additional domain(s)) may have any of a variety of suitable amounts of the elongated nanostructures. In some embodiments, for example, one, more, or all of the domain(s) comprise greater than or equal to 1,000 elongated nanostructures, greater than or equal to 2,000 elongated nanostructures, greater than or equal to 5,000 elongated nanostructures, greater than or equal to 10,000 elongated nanostructures, greater than or equal to 20,000 elongated nanostructures, greater than or equal to 50,000 elongated nanostructures, greater than or equal to 100,000 elongated nanostructures, or greater than or equal to 200,000 elongated nanostructures. In certain embodiments, one, more, or all of the domain(s) comprise less than or equal to 500,000 elongated nanostructures, less than or equal to 200,000 elongated

[0145] #14504416vl nanostructures, less than or equal to 100,000 elongated nanostructures, less than or equal to 50,000 elongated nanostructures, less than or equal to 20,000 elongated nanostructures, less than or equal to 10,000 elongated nanostructures, less than or equal to 5,000 elongated nanostructures, or less than or equal to 2,000 elongated nanostructures. Combinations of the above recited ranges are possible (e.g., one, more, or all of the domain(s) comprise between greater than or equal to 1,000 elongated nanostructures and less than or equal to 500,000 elongated nanostructures, one, more, or all of the domain(s) comprise between greater than or equal to 50,000 and less than or equal to 200,000 elongated nanostructures). Other ranges are also possible.

[0146] One, more, or all of the domain(s) described herein (e.g., the first domain, the second domain, the third domain, and / or additional domain(s)) may have any of a variety of suitable volume fractions occupied by an ionically conductive matrix. In some embodiments, for example, the ionically conductive matrix occupies a volume fraction of at least 20 vol%, at least 25 vol%, at least 30 vol%, at least 35 vol%, at least 40 vol%, at least 45 vol%, at least 50 vol%, at least 55 vol%, at least 60 vol%, at least 65 vol%, at least 70 vol%, at least 75 vol%, at least 80 vol%, or at least 85 vol% within one, more, or all of the domain(s). In certain embodiments, less than or equal to 90 vol%, less than or equal to 85 vol%, less than or equal to 80 vol%, less than or equal to 75 vol%, less than or equal to 70 vol%, less than or equal to 65 vol%, less than or equal to 60 vol%, less than or equal to 55 vol%, less than or equal to 50 vol%, less than or equal to 40 vol%, less than or equal to 35 vol%, less than or equal to 30 vol%, less than or equal to 25 vol%, or less within one, more, or all of the domain(s). Combinations of the above recited ranges are possible (e.g., the ionically conductive matrix occupies at least 20 vol% and less than or equal to 90 vol% within one, more, or all of the domain(s)). Other ranges are also possible.

[0147] In some embodiments, one, more, or all of the domain(s) described herein (e.g., the first domain, the second domain, the third domain, and / or additional domain(s)) can have a relatively high percentage of their volume fractions occupied by a combination of elongated nanostructures and the ionically conductive matrix. In certain embodiments, for example, at least 90 vol%, at least 95 vol%, at least 98 vol%, at least 99 vol%, at least 99.5 vol%, at least 99.9 vol%, at least 99.95 vol%, at least 99.99 vol%, or more (e.g., 100 vol%) of one, more, or all of the domain(s) is occupied by elongated nanostructures or ionically conductive matrix. In certain embodiments, less than or equal to 100 vol%, less than or equal to 99.99 vol%, less than or equal to 99.95 vol%, less than or equal to 99.9 vol%, less than or equal to 99.5 vol%, less than or equal to 99 vol%, less than or equal to 98 vol%, or less than or equal to 95 vol% of one, more, or all of the domain(s) is occupied by elongated nanostructures or ionically conductive matrix.

[0148] #14504416vl In some embodiments, one, more, or all of the domain(s) described herein (e.g., the first domain, the second domain, the third domain, and / or additional domain(s)) can have an advantageously low void volume. As used herein, the term “void volume” refers to the total volume within a domain that is enclosed or open (such as a cavity or open cell that is exposed to the environment outside the solid article containing the domain), that lies outside the elongated nanostructures, and that is occupied by gas, a vacuum, a liquid (e.g., solvent), and / or combinations thereof. In certain embodiments, the void volume is the total volume within a domain that is not occupied by ionically conductive matrix or elongated nanostructures (except for any internal volume within the elongated nanostructures themselves, if present). In some embodiments, one, more, or all of the domain(s) described herein (e.g., the first domain, the second domain, the third domain, and / or additional domain(s)) can have an advantageously low gas / vacuum closed-cell void volume. A “gas / vacuum closed-cell void,” as used herein, refers to a void that is enclosed (as opposed to an open volume, such as a cavity or open cell that is exposed to the environment outside the solid article containing the domain), that lies outside the elongated nanostructures, and that is occupied by gas or a vacuum. In some embodiments, one, more, or all of the domain(s) described herein (e.g., the first domain, the second domain, the third domain, and / or additional domain(s)) can have an advantageously low closed-cell void volume. A “closed-cell void,” as used herein, refers to a void that is enclosed (as opposed to an open volume, such as a cavity or open cell that is exposed to the environment outside the solid article containing the domain) and that lies outside the elongated nanostructures.

[0149] In some embodiments, a relatively small percentage of the volume of one, more, or all of the domain(s) described herein (e.g., the first domain, the second domain, the third domain, and / or additional domain(s)) is occupied by voids having a substantial size. The reduction or elimination of voids having a substantial size was a surprising benefit of certain of the processing methods described herein and has led to composite materials that exhibit enhanced mechanical robustness. In certain embodiments, for example, less than or equal to 20 vol% (or less than or equal to 10 vol%, less than or equal to 5 vol%, less than or equal to 2 vol%, less than or equal to 1 vol%, less than or equal to 0.5 vol%, less than or equal to 0.1 vol%, less than or equal to 0.05 vol%, less than or equal to 0.01 vol%, or less (e.g., none)) of one, more, or all of the domain(s) is occupied by voids having a volume of at least 1012nm3(or having a volume of at least 109nm3, having a volume of at least 106nm3, or having a volume of at least 104nm3). In certain embodiments, greater than or equal to 0.01 vol% (or greater than or equal to 0.05 vol%, greater than or equal to 0.1 vol%, greater than or equal to 0.5 vol%, greater than or equal to 1 vol%, greater than or equal to 2 vol%, greater than or equal to 5 vol%, or greater than or equal to

[0150] #14504416vl 10 vol%) of one, more, or all of the domain(s) is occupied by voids having a volume of at least 1012nm3(or having a volume of at least 109nm3, having a volume of at least 106nm3, or having a volume of at least 104nm3). Combinations of the above recited ranges are also possible (e.g., less than or equal to 20 vol% and greater than or equal to 0.01 vol% of one, more, or all of the domain(s) is occupied by voids having a volume of at least 1012nm3). Other ranges are also possible.

[0151] In some embodiments, a relatively small percentage of the volume of one, more, or all of the domain(s) described herein (e.g., the first domain, the second domain, the third domain, and / or additional domain(s)) is occupied by closed-cell voids having a substantial size. The reduction or elimination of closed-cell voids having a substantial size was a surprising benefit of certain of the processing methods described herein and has led to composite materials that exhibit enhanced mechanical robustness. In certain embodiments, for example, less than or equal to 20 vol% (or less than or equal to 10 vol%, less than or equal to 5 vol%, less than or equal to 2 vol%, less than or equal to 1 vol%, less than or equal to 0.5 vol%, less than or equal to 0.1 vol%, less than or equal to 0.05 vol%, less than or equal to 0.01 vol%, or less (e.g., none)) of one, more, or all of the domain(s) is occupied by closed-cell voids having a volume of at least 1012nm3(or having a volume of at least 109nm3, having a volume of at least 106nm3, or having a volume of at least 104nm3). In certain embodiments, greater than or equal to 0.01 vol% (or greater than or equal to 0.05 vol%, greater than or equal to 0.1 vol%, greater than or equal to 0.5 vol%, greater than or equal to 1 vol%, greater than or equal to 2 vol%, greater than or equal to 5 vol%, or greater than or equal to 10 vol%) of one, more, or all of the domain(s) is occupied by closed-cell voids having a volume of at least 1012nm3(or having a volume of at least 109nm3, having a volume of at least 106nm3, or having a volume of at least 104nm3). Combinations of the above recited ranges are also possible (e.g., less than or equal to 20 vol% and greater than or equal to 0.01 vol% of one, more, or all of the domain(s) is occupied by closed-cell voids having a volume of at least 1012nm3). Other ranges are also possible.

[0152] In some embodiments, a relatively small percentage of the volume of one, more, or all of the domain(s) described herein (e.g., the first domain, the second domain, the third domain, and / or additional domain(s)) is occupied by gas / vacuum closed-cell voids having a substantial size. The reduction or elimination of gas / vacuum closed-cell voids having a substantial size was a surprising benefit of certain of the processing methods described herein and has led to composite materials that exhibit enhanced mechanical robustness. In certain embodiments, for example, less than or equal to 20 vol% (or less than or equal to 10 vol%, less than or equal to 5 vol%, less than or equal to 2 vol%, less than or equal to 1 vol%, less than or equal to 0.5 vol%,

[0153] #14504416vl less than or equal to 0.1 vol%, less than or equal to 0.05 vol%, less than or equal to 0.01 vol%, or less (e.g., none)) of one, more, or all of the domain(s) is occupied by gas / vacuum closed-cell voids having a volume of at least 1012nm3(or having a volume of at least 109nm3, having a volume of at least 106nm3, or having a volume of at least 104nm3). In certain embodiments, greater than or equal to 0.01 vol% (or greater than or equal to 0.05 vol%, greater than or equal to 0.1 vol%, greater than or equal to 0.5 vol%, greater than or equal to 1 vol%, greater than or equal to 2 vol%, greater than or equal to 5 vol%, or greater than or equal to 10 vol%) of one, more, or all of the domain(s) is occupied by gas / vacuum closed-cell voids having a volume of at least 1012nm3(or having a volume of at least 109nm3, having a volume of at least 106nm3, or having a volume of at least 104nm3). Combinations of the above recited ranges are also possible (e.g., less than or equal to 20 vol% and greater than or equal to 0.01 vol% of one, more, or all of the domain(s) is occupied by gas / vacuum closed-cell voids having a volume of at least 1012nm3). Other ranges are also possible.

[0154] As would be understood by those of ordinary skill in the art, the percentage of a domain (or other region) that is occupied by voids having a volume within a size range is determined by adding together the volumes of all voids having a size within that range and dividing that result by the total volume of the domain (or other region). For example, to figure out the percentage of a domain occupied by voids having a volume of at least 109nm3, one would locate all voids having a volume of at least 109nm3within the domain, add together the volumes of the voids having a volume of at least 109nm3within the domain to determine the cumulative volume of all voids over 109nm3, divide the cumulative volume of the voids by the total volume of the domain, and multiply the result by 100%. Voids within a domain (or other region) may be located by analyzing X-ray computed tomography (pCT) images. Briefly, pCT are taken of the domain (or other region), voids in the images are identified by image processing software, and the volume percentage of the domain (or other region) occupied by voids is calculated as described above.

[0155] According to some embodiments, less than or equal to 20 vol% (or less than or equal to 10 vol%, less than or equal to 5 vol%, less than or equal to 2 vol%, less than or equal to 1 vol%, less than or equal to 0.5 vol%, less than or equal to 0.1 vol%, less than or equal to 0.05 vol%, less than or equal to 0.01 vol%, or less (e.g., none)) of the region within the outer boundaries of the ionically conductive matrix is occupied by voids having a volume of at least 1012nm3(or having a volume of at least 109nm3, having a volume of at least 106nm3, or having a volume of at least 104nm3). In certain embodiments, greater than or equal to 0.01 vol% (or greater than or equal to 0.05 vol%, greater than or equal to 0.1 vol%, greater than or equal to 0.5 vol%, greater

[0156] #14504416vl than or equal to 1 vol%, greater than or equal to 2 vol%, greater than or equal to 5 vol%, or greater than or equal to 10 vol%) of the region within the outer boundaries of the ionically conductive matrix is occupied by voids having a volume of at least 1012nm3(or having a volume of at least 109nm3, having a volume of at least 106nm3, or having a volume of at least 104nm3). Combinations of the above recited ranges are possible (e.g., less than or equal to 20 vol% and greater than or equal to 0.01 vol% of the region within the outer boundaries of the ionically conductive matrix is occupied by voids having a volume of at least 1012nm3). Other ranges are also possible.

[0157] According to some embodiments, less than or equal to 20 vol% (or less than or equal to 10 vol%, less than or equal to 5 vol%, less than or equal to 2 vol%, less than or equal to 1 vol%, less than or equal to 0.5 vol%, less than or equal to 0.1 vol%, less than or equal to 0.05 vol%, less than or equal to 0.01 vol%, or less (e.g., none)) of the region within the outer boundaries of the ionically conductive matrix is occupied by closed-cell voids having a volume of at least 1012nm3(or having a volume of at least 109nm3, having a volume of at least 106nm3, or having a volume of at least 104nm3). In certain embodiments, greater than or equal to 0.01 vol% (or greater than or equal to 0.05 vol%, greater than or equal to 0.1 vol%, greater than or equal to 0.5 vol%, greater than or equal to 1 vol%, greater than or equal to 2 vol%, greater than or equal to 5 vol%, or greater than or equal to 10 vol%) of the region within the outer boundaries of the ionically conductive matrix is occupied by closed-cell voids having a volume of at least 1012nm3(or having a volume of at least 109nm3, having a volume of at least 106nm3, or having a volume of at least 104nm3). Combinations of the above recited ranges are possible (e.g., less than or equal to 20 vol% and greater than or equal to 0.01 vol% of the region within the outer boundaries of the ionically conductive matrix is occupied by closed-cell voids having a volume of at least 1012nm3). Other ranges are also possible.

[0158] According to some embodiments, less than or equal to 20 vol% (or less than or equal to 10 vol%, less than or equal to 5 vol%, less than or equal to 2 vol%, less than or equal to 1 vol%, less than or equal to 0.5 vol%, less than or equal to 0.1 vol%, less than or equal to 0.05 vol%, less than or equal to 0.01 vol%, or less (e.g., none)) of the region within the outer boundaries of the ionically conductive matrix is occupied by gas / vacuum closed-cell voids having a volume of at least 1012nm3(or having a volume of at least 109nm3, having a volume of at least 106nm3, or having a volume of at least 104nm3). In certain embodiments, greater than or equal to 0.01 vol% (or greater than or equal to 0.05 vol%, greater than or equal to 0.1 vol%, greater than or equal to 0.5 vol%, greater than or equal to 1 vol%, greater than or equal to 2 vol%, greater than or equal to 5 vol%, or greater than or equal to 10 vol%) of the region within the outer boundaries

[0159] #14504416vl of the ionically conductive matrix is occupied by gas / vacuum closed-cell voids having a volume of at least 1012nm3(or having a volume of at least 109nm3, having a volume of at least 106nm3, or having a volume of at least 104nm3). Combinations of the above recited ranges are possible (e.g., less than or equal to 20 vol% and greater than or equal to 0.01 vol% of the region within the outer boundaries of the ionically conductive matrix is occupied by gas / vacuum closed-cell voids having a volume of at least 1012nm3). Other ranges are also possible.

[0160] In some embodiments, one, more, or all of the domain(s) described herein (e.g., the first domain, the second domain, the third domain, and / or additional domain(s)) can have a relatively high ionic conductivity. The ionic conductivity of a domain is measured across two boundaries of the domain. In certain embodiments, a relatively high ionic conductivity measured across a thickness of the domain is particularly useful for one or more applications described herein. For example, a relatively high ionic conductivity measured across third dimension 110 (e.g., third dimension 110a, 110b, and / or 110c shown in FIGS. 1 A, 3A, and 4A) is particularly useful for one or more applications described herein.

[0161] In accordance with certain embodiments, the ionic conductivity of a domain is distinct from the ionic conductivity of the ionically conductive matrix within the domain, as the ionic conductivity of a domain is measured across the whole domain and includes ionic conductivity contributions from both the plurality of elongated nanostructures and the ionically conductive matrix.

[0162] According to some embodiments, the ionic conductivity, with respect to at least one monovalent ion (e.g., at least one monovalent cation) and / or at least one divalent ion (e.g., at least one divalent cation), of one or more (or all) domains(s) is greater than or equal to 10'7S / cm, greater than or equal to 5x1 O'7S / cm, greater than or equal to 10'6S / cm, greater than or equal to 5xl0'6S / cm, greater than or equal to 10'5S / cm, greater than or equal to 5xl0'5S / cm, greater than or equal to 10'4S / cm, greater than or equal to 5x1 O'4S / cm, greater than or equal to 10'3S / cm, greater than or equal to 5x1 O'3S / cm, greater than or equal to 10'2S / cm, greater than or equal to 5xl0'2S / cm, or greater. According to some embodiments, the ionic conductivity, with respect to at least one monovalent ion (e.g., at least one monovalent cation) and / or at least one divalent ion (e.g., at least one divalent cation), of one or more (or all) domains(s) is less than or equal to 10'1S / cm, less than or equal to 5xl0'2S / cm, less than or equal to 10'2S / cm, less than or equal to 5xl0'3S / cm, less than or equal to 10'5S / cm, less than or equal to 5xl0'6S / cm, less than or equal to 10'6S / cm, less than or equal to 5xl0'7S / cm, or less. Combinations of these ranges are possible (e.g., greater than or equal to 10'7S / cm and less than or equal to IxlO'1S / cm, or greater than or equal to 1 O’6S / cm and less than or equal to 10'3S / cm). Other ranges are also

[0163] #14504416vl possible. In some embodiments, one, more, or all of the domains of the article may have an ionic conductivity property recited in this paragraph across its thickness dimension. The ionic conductivity of a domain may be determined by electrochemical impedance spectroscopy (EIS).

[0164] According to some embodiments, the ionic conductivity, with respect to lithium ions, sodium ions, magnesium ions, and / or potassium ions, of one or more (or all) domains(s) is greater than or equal to 10'7S / cm, greater than or equal to 5x1 O'7S / cm, greater than or equal to 10'6S / cm, greater than or equal to 5x1 O'6S / cm, greater than or equal to 10'5S / cm, greater than or equal to 5x1 O'5S / cm, greater than or equal to 10'4S / cm, greater than or equal to 5x1 O'4S / cm, greater than or equal to 10'3S / cm, greater than or equal to 5x1 O'3S / cm, greater than or equal to 10'2S / cm, greater than or equal to 5xl0'2S / cm, or greater. According to some embodiments, the ionic conductivity, with respect to lithium ions, sodium ions, magnesium ions, and / or potassium ions, of one or more (or all) domains(s) is less than or equal to 10’1S / cm, less than or equal to 5xl0'2S / cm, less than or equal to 10'2S / cm, less than or equal to 5xl0'3S / cm, less than or equal to 10'5S / cm, less than or equal to 5xl0'6S / cm, less than or equal to 10'6S / cm, less than or equal to 5xl0'7S / cm, or less. Combinations of these ranges are possible (e.g., greater than or equal to 10'7S / cm and less than or equal to IxlO'1S / cm, or greater than or equal to 10'6S / cm and less than or equal to 10'3S / cm). Other ranges are also possible. In some embodiments, one, more, or all of the domains of the article may have an ionic conductivity property recited in this paragraph across its thickness dimension.

[0165] According to some embodiments, the ionic conductivity, with respect to lithium ions (e.g., Li+), of one or more (or all) domains(s) is greater than or equal to 10'7S / cm, greater than or equal to 5xl0'7S / cm, greater than or equal to 10'6S / cm, greater than or equal to 5xl0'6S / cm, greater than or equal to 10'5S / cm, greater than or equal to 5x1 O'5S / cm, greater than or equal to 10'4S / cm, greater than or equal to 5x1 O'4S / cm, greater than or equal to 10'3S / cm, greater than or equal to 5x1 O'3S / cm, greater than or equal to 10'2S / cm, greater than or equal to 5x1 O'2S / cm, or greater. According to some embodiments, the ionic conductivity, with respect to lithium ions (e.g., Li+), of one or more (or all) domains(s) is less than or equal to 10'1S / cm, less than or equal to 5xl0'2S / cm, less than or equal to 10'2S / cm, less than or equal to 5xl0'3S / cm, less than or equal to 10'5S / cm, less than or equal to 5xl0'6S / cm, less than or equal to 10'6S / cm, less than or equal to 5xl0'7S / cm, or less. Combinations of these ranges are possible (e.g., greater than or equal to 1 O’7S / cm and less than or equal to IxlO'1S / cm, or greater than or equal to 10'6S / cm and less than or equal to 10'3S / cm). Other ranges are also possible. In some embodiments, one, more, or all of the domains of the article may have an ionic conductivity property recited in this paragraph across its thickness dimension.

[0166] #14504416vl In some embodiments, one, more, or all of the domain(s) described herein (e.g., the first domain, the second domain, the third domain, and / or additional domain(s)) can have a relatively high electronic conductivity. The electronic conductivity of a domain is measured across two boundaries of the domain. In certain embodiments, a relatively high electronic conductivity measured across a thickness of the domain is particularly useful for one or more applications described herein. For example, a relatively high electronic conductivity measured across third dimension 110 (e.g., third dimension 110a, 110b, and / or 110c shown in FIGS. 1 A, 3A, and 4A) is particularly useful for one or more applications described herein.

[0167] In accordance with certain embodiments, the electronic conductivity of a domain is distinct from the electronic conductivity of the plurality of elongated nanostructures within the domain, as the electronic conductivity of a domain is measured across the whole domain and includes electronic conductivity contributions from both the plurality of elongated nanostructures and the ionically conductive matrix.

[0168] According to some embodiments, the electronic conductivity of one or more (or all) domains(s) is greater than or equal to 0.001 S / micrometer, greater than or equal to 0.005 S / micrometer, greater than or equal to 0.01 S / micrometer, greater than or equal to 0.05 S / micrometer, greater than or equal to 0.1 S / micrometer, greater than or equal to 0.5 S / micrometer, greater than or equal to 1 S / micrometer, greater than or equal to 5 S / micrometer, greater than or equal to 10 S / micrometer, or greater than or equal to 50 S / micrometer. According to some embodiments, the electronic conductivity of one or more (or all) domains(s) is less than or equal to 100 S / micrometer, less than or equal to 50 S / micrometer, less than or equal to 10 S / micrometer, less than or equal to 5 S / micrometer, less than or equal to 1 S / micrometer, less than or equal to 0.5 S / micrometer, less than or equal to 0.1 S / micrometer, less than or equal to 0.05 S / micrometer, less than or equal to 0.01 S / micrometer, or less than or equal to 0.005 S / micrometer. Combinations of these ranges are possible (e.g., greater than or equal to 0.001 S / micrometer and less than or equal to 100 S / micrometer, or greater than or equal to 0.01 S / micrometer and less than or equal to 0.5 S / micrometer). Other ranges are also possible. In some embodiments, one, more, or all of the domains of the article may have an electronic conductivity property recited in this paragraph across its thickness dimension.

[0169] In some embodiments, one, more, or all of the domain(s) described herein (e.g., the first domain, the second domain, the third domain, and / or additional domain(s)) can have a relatively high Young’s modulus. According to some embodiments, for example, the Young’s modulus of one or more (or all) domains(s) is greater than or equal to 100 MPa, greater than or equal to 500 MPa, greater than or equal to 700 MPa, greater than or equal to 1 GPa, greater than or equal to

[0170] #14504416vl 1.65 GPa, greater than or equal to 5 GPa, greater than or equal to 10 GPa, greater than or equal to 50 GPa, greater than or equal to 100 GPa, greater than or equal to 150 GPa, or greater than or equal to 200 GPa. According to some embodiments, the Young’s modulus of one or more (or all) domains(s) is less than or equal to 250 GPa, less than or equal to 200 GPa, less than or equal to 150 GPa, less than or equal to 100 GPa, less than or equal to 50 GPa, less than or equal to 10 GPa, less than or equal to 5 GPa, or less than or equal to 2 GPa. Combinations of these ranges are possible (e.g., greater than or equal to 100 MPa and less than or equal to 250 GPa). Other ranges are also possible. In certain embodiments, the Young’s modulus of a domain is determined using a Zwick Mechanical Tester.

[0171] According to certain embodiments, a device is described. In certain embodiments, the device is an energy storage device. In some embodiments, the energy storage device is a capacitor, a supercapacitor (e.g., a structural supercapacitor, an electric double layer capacitor), a pseudocapacitor, a hybrid capacitor, or a battery (e.g., a structural battery, a lithium-ion battery, a lithium-metal battery. Other energy storage devices are also possible.

[0172] FIG. 6 shows, according to some embodiments, a cross-sectional schematic illustration of an energy storage device. As shown in FIG. 6, energy storage device 600 comprises separator 602, first electrode (e.g., anode) 604, and second electrode (e.g., cathode) 606. In some embodiments, energy storage device 600 may also include housing 608, which contains separator 602, first electrode 604, and second electrode 606. According to some embodiments, separator 602 may be configured to electronically insulate first electrode 604 from second electrode 606 while also providing sufficient ionic conductivity (e.g., for Li+or any other working ion of energy storage device 600) to allow the energy storage device to be discharged without short circuiting. In cases where energy storage device 600 is rechargeable, separator 602 may also provide sufficient ionic conductivity to allow the energy storage device 600 to be recharged.

[0173] According to some embodiments, the energy storage device (e.g., energy storage device 600) comprises an article as described herein. In some embodiments, for example, the energy storage devices comprises article 102a as shown in FIGS. 1 A-1B. As described herein in greater detail, article 102a may, in some embodiments, be an electrode comprising a plurality of electronically conductive elongated nanostructures (e.g., a plurality of electronically conductive elongated carbon nanotubes) distributed within an ionically conductive matrix. In some such embodiments, article 102a shown in FIGS. 1A-1B may be used as first electrode (e.g., anode) 604 and / or second electrode (e.g., cathode) 606 in energy storage device 600.

[0174] #14504416vl In certain embodiments, as described herein in greater detail, article 102a shown in FIGS. 1 A-1B may be a separator comprising a plurality of electronically insulating nanostructures (e.g., a plurality of electronically insulating boron nitride nanotubes) distributed within an ionically conductive matrix. In some such embodiments, article 102a shown in FIGS. 1A-1B may be used as separator 602 in energy storage device 600.

[0175] According to some embodiments, the energy storage device (e.g., energy storage device 600) comprises article 102b shown in FIGS. 3A-3B. In certain embodiments, as described herein in greater detail, article 102b comprises first domain 104a and second domain 104b over first domain 104a. In some embodiments, first domain 104a may be an electrode comprising a plurality of electronically conductive elongated nanostructures (e.g., a plurality of electronically conductive elongated carbon nanotubes) distributed within an ionically conductive matrix, and second domain 104b may be a separator comprising a plurality of electronically insulating nanostructures (e.g., a plurality of electronically insulating boron nitride nanotubes) distributed within the ionically conductive matrix. In some such embodiments, first domain 104a shown in FIGS. 3 A-3B may be used as at least one electrode (e.g., first electrode 604 and / or second electrode 606) in energy storage device 600, and second domain 104b shown in FIGS. 3A-3B may be used as separator 602 in energy storage device 600.

[0176] In some embodiments, the energy storage device (e.g., energy storage device 600) comprises article 102c as shown in FIGS. 4A-4B. In certain embodiments, as described herein in greater detail, article 102b comprises first domain 104a, second domain 104b over first domain 104a, and third domain 104c over second domain 104b. In some embodiments, first domain 104a may be an electrode comprising a plurality of electronically conductive elongated nanostructures (e.g., a plurality of electronically conductive elongated carbon nanotubes) distributed within an ionically conductive matrix, second domain 104b may be a separator comprising a plurality of electronically insulating nanostructures (e.g., a plurality of electronically insulating boron nitride nanotubes) distributed within the ionically conductive matrix, and third domain 104c may be an electrode comprising a plurality of electronically conductive elongated nanostructures (e.g., a plurality of electronically conductive elongated carbon nanotubes) distributed within the ionically conductive matrix. In some such embodiments, first domain 104a shown in FIGS. 4A-4B may be used as first electrode (e.g., anode) 604 in energy storage device 600, second domain 104b may be used as separator 602 in energy storage device 600, and third domain 104c may be used as second electrode (e.g., cathode) 606 in energy storage device 600.

[0177] #14504416vl In some embodiments, a device described herein can have a relatively high Young’s modulus. According to some embodiments, for example, the Young’s modulus of the device is greater than or equal to 100 MPa, greater than or equal to 500 MPa, greater than or equal to 700 MPa, greater than or equal to 1 GPa, greater than or equal to 1.65 GPa, or greater than or equal to 5 GPa. According to some embodiments, the Young’s modulus of the device is less than or equal to 10 GPa, less than or equal to 5 GPa, or less than or equal to 2 GPa. Combinations of these ranges are possible (e.g., greater than or equal to 100 MPa and less than or equal to 10 GPa). Other ranges are also possible. In certain embodiments, the Young’s modulus of a device is determined using a Zwick Mechanical Tester.

[0178] According to some embodiments, a device described herein can have a relatively high volumetric energy density. According to some embodiments, for example, the volumetric energy density of the device is greater than or equal to 0.007 mWh / cm3, greater than or equal to 0.01 mWh / cm3, greater than or equal to 0.1 mWh / cm3, greater than or equal to 1 mWh / cm3, greater than or equal to 10 mWh / cm3, greater than or equal to 100 mWh / cm3, greater than or equal to 500 mWh / cm3, greater than or equal to 950 mWh / cm3, or greater. According to some embodiments, the volumetric energy density of the device is less than or equal to 1,000 mWh / cm3, less than or equal to 950 mWh / cm3, less than or equal to 500 mWh / cm3, less than or equal to 100 mWh / cm3, less than or equal to 10 mWh / cm3, less than or equal to 1 mWh / cm3, less than or equal to 0.1 mWh / cm3, or less than or equal to 0.01 mWh / cm3. Combinations of these ranges are possible (e.g., greater than or equal to 0.007 mWh / cm3and less than or equal to 1,000 mWh / cm3). Other ranges are also possible.

[0179] In certain embodiments, the volumetric energy density of the device is determined by: (i) determining the volume of the device; (ii) measuring a cyclic voltammogram of the device; (iii) calculating the total energy of the device from the cyclic voltammogram by integrating the product of current and voltage over the applied potential window; and (iv) calculating the volumetric energy density by dividing the calculated total energy by the volume of the device.

[0180] According to some embodiments, a device described herein can have a relatively high specific energy. According to some embodiments, for example, the specific energy of the device is greater than or equal to 0.006 mWh / kg, greater than or equal to 0.01 mWh / kg, greater than or equal to 0.1 mWh / kg, greater than or equal to 1 mWh / kg, greater than or equal to 10 mWh / kg, greater than or equal to 100 mWh / kg, greater than or equal to 500 mWh / kg, greater than or equal to 750 mWh / kg, greater than or equal to 1,000 mWh / kg, or greater than or equal to 1,500 mWh / kg. According to some embodiments, the specific energy of the device is less than or equal to 1,500 mWh / kg, less than or equal to 1,000 mWh / kg, less than or equal to 750 mWh / kg,

[0181] #14504416vl less than or equal to 500 mWh / kg, less than or equal to 100 mWh / kg, less than or equal to 10 mWh / kg, less than or equal to 1 mWh / kg, less than or equal to 0.1 mWh / kg, or less than or equal to 0.01 mWh / kg. Combinations of these ranges are possible (e.g., greater than or equal to 0.006 mWh / kg and less than or equal to 1500 mWh / kg). Other ranges are also possible.

[0182] In certain embodiments, the specific energy of the device is determined by: (i) determining the weight of the device; (ii) measuring a cyclic voltammogram of the device; (iii) calculating the total energy of the device from the cyclic voltammogram by integrating the product of current and voltage over the applied potential window; and (iv) calculating the specific energy by dividing the calculated total energy by the weight of the device.

[0183] According to some embodiments, a device described herein can have a relatively high specific capacitance. According to some embodiments, for example, the specific capacitance of the device is greater than or equal to 4 mF / g, greater than or equal to 100 mF / g, greater than or equal to 200 mF / g, greater than or equal to 500 mF / g, greater than or equal to 1,000 mF / g, greater than or equal to 5,000 mF / g, greater than or equal to 10,000 mF / g, greater than or equal to 15,000 mF / g, greater than or equal to 20,000 mF / g, or greater than or equal to 25,000 mF / g. According to some embodiments, the specific energy of the device is less than or equal to 30,000 mF / g, less than or equal to 25,000 mF / g, less than or equal to 20,000 mF / g, less than or equal to 15,000 mF / g, less than or equal to 10,000 mF / g, less than or equal to 5,000 mF / g, less than or equal to 1,000 mF / g, less than or equal to 500 mF / g, less than or equal to 200 mF / g, or less than or equal to 100 mF / g. Combinations of these ranges are possible (e.g., greater than or equal to 4 mF / g and less than or equal to 30,000 mF / g). Other ranges are also possible.

[0184] In certain embodiments, the specific capacitance of the device is determined by: (i) determining the weight of the device; (ii) measuring a cyclic voltammogram of the device; (iii) calculating the capacitance of the device from the cyclic voltammogram by integrating the current over the applied potential window; and (iv) calculating the specific capacitance by dividing the calculated capacitance by the weight of the device.

[0185] According to certain embodiments, a device described herein may be used in any of a variety of suitable systems and / or applications. In certain embodiments, a device is used as part of an energy storage system, an energy harvesting system, and / or an energy management system.

[0186] In certain embodiments, a device is used as a structural component of a vehicle and / or transportation system (e.g., a land vehicle such as an electric vehicle; a marine vehicle; and / or an aerospace vehicle such as an aircraft and / or spacecraft), a stationary system (e.g., a building (including walls, floors, roofs and / or infrastructure); industrial equipment; or the like), an electronic device (e.g., a consumer electronic device such as a portable or a wearable electronic

[0187] #14504416vl device), or the like. In some embodiments, a device is integrated within at least a portion of a structural element (e.g., a structural panel) of any of the systems described above, thereby advantageously providing combined structural and energy storage functionality while enhancing system efficiency, reducing weight, and improving overall sustainability and versatility.

[0188] According to certain embodiments, methods of making composite materials (and other methods) are also described. FIGS. 7A-7D show, according to certain embodiments, schematic diagrams of a method of arranging a plurality of elongated nanostructures at least partially within an ionically conductive matrix and / or an ionically conductive matrix precursor. In some embodiments, the method comprises arranging a plurality of elongated nanostructures within an ionically conductive matrix and / or an ionically conductive matrix precursor to form an arrangement of elongated nanostructures and ionically conductive matrix and / or ionically conductive matrix precursor.

[0189] Arranging comprises, in certain embodiments, growing the elongated nanostructures from a substrate. Referring to FIG. 7A, for example, step 302 comprises, in some embodiments, growing a forest of elongated nanostructures 114 from growth substrate 120. Methods of growing nanostructures are explained herein in greater detail.

[0190] According to some embodiments, the ionically conductive matrix precursor may be converted into the ionically conductive matrix during the method of making the composite material. In certain embodiments, for example, the ionically conductive matrix precursor may be hardened, heat treated, and / or pressurized to convert the ionically conductive matrix precursor into the ionically conductive matrix, as explained herein in greater detail.

[0191] As used herein, a “forest” of elongated nanostructures corresponds to a plurality of elongated nanostructures arranged in side-by-side fashion with one another. In some embodiments, the nanostructures within the forest are in contact with at least one other nanostructure within the forest. In some embodiments, the forest of elongated nanostructures comprises at least 5, at least 10, at least 50, at least 100, at least 500, at least 1000, or at least 10,000 elongated nanostructures. In some such embodiments, the forest of elongated nanostructures may comprise at least 106, at least 107, at least 108, at least 109, at least 1010, at least 1011, at least 1012, or at least 1013elongated nanostructures. Those of ordinary skill in the art are familiar with suitable methods for forming forests of elongated nanostructures. For example, in some embodiments, the forest of elongated nanostructures can be catalytically grown (e.g., using a growth catalyst deposited via a chemical vapor deposition process). In some embodiments, the as-grown forest can be used as is, while in other cases, the as-grown

[0192] #14504416vl forest may be mechanically manipulated after growth and prior to subsequent processing steps described elsewhere herein (e.g., folding, shearing, compressing, buckling, etc.).

[0193] In some embodiments, the elongated nanostructures within the forest may be closely spaced. For example, the number average of the nearest neighbor distances of the elongated nanostructures within the forest may be less than or equal to 250 nm, less than or equal to 200 nm, less than or equal to 100 nm, less than or equal to 80 nm, less than or equal to 60 nm, less than or equal to 40 nm, less than or equal to 30 nm, less than or equal to 20 nm, less than or equal to 10 nm, less than or equal to 5 nm, or less. In certain embodiments, the number average of the nearest neighbor distances of the elongated nanostructures within the forest may be at least 1 nm, at least 5 nm, at least 10 nm, at least 20 nm, at least 30 nm, at least 40 nm, at least 60 nm, at least 80 nm, at least 100 nm, or at least 200 nm. Combinations of the above-referenced ranges are possible (e.g., at least 1 nm and less than or equal to 250 nm). Other ranges are also possible.

[0194] In some embodiments in which the nanostructures are grown on a growth substrate, the set of substantially aligned nanostructures may be oriented such that the longitudinal axes of the nanostructures are substantially non-parallel to the surface of the growth substrate, For example, as shown in FIG. 7A, the longitudinal axes of nanostructures 114 are oriented in a substantially perpendicular direction with respect to the surface of growth substrate 120.

[0195] In certain embodiments, the forest of elongated nanostructures 114 are grown from growth substrate 120 using chemical vapor deposition (CVD) (e.g., thermal catalytic CVD). In certain embodiments, growth substrate 120 is a silicon wafer substrate. The surface of the silicon wafer substrate on which the forest of elongated nanostructures are grown may be oxidized to form a SiCh layer (e.g., a 500 nm thick SiCh layer) prior to growing the forest of elongated nanostructures, in accordance with certain embodiments. In some embodiments, at least a portion of the SiCh layer is coated with alumina (AI2O3) (e.g., a 10 nm thick AI2O3 layer), and at least a portion of the AI2O3 is coated with iron (Fe) (e.g., a 1 nm thick Fe layer). In certain embodiments, the AI2O3 layer serves as a diffusion layer between the Fe and the SiO2 (e.g., to inhibit their reaction with each other). In some embodiments, the Fe layer de-wets into globules or particles (e.g., nanoparticles) which serve as initiation sites for nanostructure growth.

[0196] According to certain embodiments, elongated nanostructures (e.g., boron nitride nanotubes) can be synthesized by using another nanostructure as a template. For example, in certain embodiments, a first elongated nanostructure type is grown, after which a second material is formed over the first elongated nanostructure. The second material may be formed over the first elongated nanostructure material as a conformal coating, for example. In some

[0197] #14504416vl embodiments, after the second material has been formed over the first nanostructure material, the first nanostructure material can be removed (e.g., via dissolution, oxidation, etching, or any of a number of other methods). As one specific example, in some embodiments, carbon nanotubes are first grown (e.g., using CVD). After the carbon nanotubes have been grown, boron nitride can be deposited over the carbon nanotubes. After the boron nitride has been deposited, the carbon nanotubes can be removed, for example, via heat treatment and / or oxidation. In some embodiments, the boron nitride can be crystallized during the heat treatment step, resulting in boron nitride-based nanostructures (e.g., boron nitride nanotubes).

[0198] Systems and methods for growing elongated nanostructures (including forests of elongated nanostructures) are described, for example, in International Patent Application Serial No. PCT / US2007 / 011914, filed May 18, 2007, entitled “Continuous Process for the Production of Nanostructures Including Nanotubes,” published as WO 2007 / 136755 on November 29, 2007; U.S. Patent Application Serial No. 12 / 227,516, filed November 19, 2008, entitled “Continuous Process for the Production of Nanostructures Including Nanotubes,” published as US 2009 / 0311166 on December 17, 2009; International Patent Application Serial No. PCT / US07 / 11913, filed May 18, 2007, entitled “Nanostructure-reinforced Composite Articles and Methods,” published as WO 2008 / 054541 on May 8, 2008; International Patent Application Serial No. PCT / US2008 / 009996, filed August 22, 2008, entitled “Nanostructure-reinforced Composite Articles and Methods,” published as WO 2009 / 029218 on March 5, 2009; U.S. Patent Application Serial No. 11 / 895,621, filed August 24, 2007, entitled “Nanostructure- Reinforced Composite Articles and Methods,” published as US 2008 / 0075954 on March 27, 2008; and U.S. Patent Application Serial No. 12 / 618,203, filed November 13, 2009, entitled “Controlled-orientation Films and Nanocomposites Including Nanotubes or Other Nanostructures”, published as US 2010 / 0196695, on August 5, 2010; each of which is incorporated herein by reference in its entirety for all purposes.

[0199] In some embodiments, arranging comprises rearranging the elongated nanostructures from a first position that is non-parallel to the growth substrate to a second position that is substantially parallel to the growth substrate. In certain embodiments, alignment of the nanostructures (e.g., with each other and / or to a common vector, and to any degree referenced above) can be established and / or maintained during the process of arranging the nanostructures in a direction substantially parallel to the growth substrate. As noted above, maintaining alignment of the nanostructures can allow for an ionically conductive matrix and / or an ionically conductive matrix precursor to flow through and spread between the elongated nanostructures via capillary action, which can result in a high volume of elongated nanostructures, low volume

[0200] #14504416vl of gas / vacuum closed-cell voids and / or other types of voids, and large scale in at least two dimensions in the final composite. Referring to FIG. 7B, for example, step 304 comprises, in certain embodiments, rearranging elongated nanostructures 114 from a first position that is nonparallel to growth substrate 120 (e.g., as shown in step 302) to a second position that is substantially parallel to growth substrate 120 (see, e.g., nanostructures 114’). In some embodiments, rearranging comprises knocking over elongated nanostructures 114 using mechanical tool 118. Examples of mechanical tools include, but are not limited to, a roller, a doctor blade, a razor blade, and the like.

[0201] According to some embodiments, arranging comprises transferring the elongated nanostructures from the growth substrate to a second substrate, in accordance with certain embodiments. Referring, for example, to FIG. 7B, arranging comprises transferring elongated nanostructures 114’ from growth substrate 120 to second substrate 121, in certain embodiments. The second substrate may, in some embodiments, comprise a release layer, such as a guaranteed non-porous Teflon (GNPT) release film. In certain embodiments, rearranging the elongated nanostructures form the first position that is non-parallel to the growth substrate to a second position that is substantially parallel to the growth substrate and transferring the elongated nanostructures from the growth substrate to the second substrate occur concurrently, for example, as shown in FIG. 7B.

[0202] In some embodiments, arranging comprises adding the ionically conductive matrix and / or the ionically conductive matrix precursor to the elongated nanostructures. In certain embodiments, an arrangement of elongated nanostructures disposed on a second substrate may be provided, for example, from step 304 as shown in FIG. 7B. In FIG. 7C, step 306 comprises, in some embodiments, adding ionically conductive matrix and / or ionically conductive matrix precursor 122 to arrangement of elongated nanostructures 114’ disposed on second substrate 121. In some embodiments, after adding the ionically conductive matrix and / or the ionically conductive matrix precursor to the elongated nanostructure, the second substrate may be removed from the arrangement of elongated nanostructures, thereby providing, as shown in step 308 of FIG. 7D, a plurality of elongated nanostructures 114’ (not shown in FIG. 7D) arranged within ionically conductive matrix and / or ionically conductive matrix precursor 122. Ionically conductive matrix and / or ionically conductive matrix precursor 122 may be added to the plurality of elongated nanostructures 114’ by any of a variety of suitable means, including, but not limited to, atomic layer deposition (ALD), chemical vapor deposition (CVD), chemical vapor infiltration (CVI), and / or drop-casting (e.g., as shown in FIG. 7C). In some embodiments, the ionically conductive matrix and / or ionically conductive matrix precursor may be added to the

[0203] #14504416vl plurality of elongated nanostructures via capillary action. In certain embodiments, for example, the alignment of elongated nanostructures may allow for the ionically conductive matrix and / or ionically conductive matrix precursor to flow through and spread between the elongated nanostructures via capillary action.

[0204] Although not shown in the figures, the ionically conductive matrix and / or ionically conductive matrix precursor may be added to the elongated nanostructures, in some embodiments, prior to rearranging the elongated nanostructures from a first position that is nonparallel to the substrate to a second position that is substantially parallel to the substrate. In certain embodiments, for example, step 306 in FIG. 7C may precede step 304 in FIG. 7B.

[0205] According to some embodiments, the ionically conductive matrix and / or the ionically conductive matrix may be a solid material, and the arranging comprises arranging the plurality of elongated nanostructures adjacent to the solid material and softening at least a portion of the solid material (e.g., with heating) such that the elongated nanostructures are at least partially arranged within the softened material to form the arrangement of elongated nanostructures at least partially within ionically conductive matrix and / or ionically conductive matrix precursor.

[0206] FIGS. 7E-7F show, according to certain embodiments, a cross-sectional schematic diagram of a method of applying pressure to an arrangement of elongated nanostructures and ionically conductive matrix and / or ionically conductive matrix precursor. In some embodiments, the method comprises applying pressure to the arrangement to densify the nanostructures. Referring to FIG. 7E, for example, an arrangement of elongated nanostructures and ionically conductive matrix and / or ionically conductive matrix may be provided, for example, from step 308 as shown in FIG. 7D.

[0207] In certain embodiments, step 310 comprises applying pressure to the arrangement of elongated nanostructures 114 and ionically conductive matrix and / or ionically conductive matrix 122 to densify elongated nanostructures 114, as shown, for example, in step 312 in FIG. 7F. Pressure may be applied in any of a variety of suitable directions 134. In some embodiments, pressure may be applied by hot pressing the arrangement of elongated nanostructures 114 and ionically conductive matrix and / or ionically conductive matrix 122. In some embodiments, pressure may be applied by clamping the arrangement between graphite blocks. In certain embodiments, the densification process may facilitate the removal of one or more gas / vacuum closed-cell voids and / or other void types and / or fluids (e.g., liquid and / or gaseous solvents) present in the ionically conductive matrix and / or the ionically conductive matrix from the manufacturing process.

[0208] #14504416vl According to certain embodiments, at least one dimension of domain 104 may change as a result of the densification process. Referring, for example, to FIGS. 7E-7F, at least one of first dimension 106’, a second dimension, and / or third dimension 110’ of domain 104’ shown in step 310 may be different from first dimension 106”, a second dimension, and / or third dimension 110” of domain 104” shown in step 312. In certain non-limiting embodiments, for example, third dimension 110” may be shorter than third dimension 110’ after the densification process.

[0209] In certain embodiments, the method comprises applying a vacuum to the arrangement of elongated nanostructures and ionically conductive matrix and / or ionically conductive matrix precursor. FIG. 8 shows, in accordance with certain embodiments, a schematic cross-sectional diagram of a method of step 802 of applying vacuum 804 to an arrangement of elongated nanostructures 114 and ionically conductive matrix and / or ionically conductive matrix precursor 122. In some embodiments, vacuum is applied to the arrangement during and / or after adding the ionically conductive matrix and / or the ionically conductive matrix precursor to the elongated nanostructures. In certain embodiments, for example, an arrangement of elongated nanostructures and ionically conductive matrix and / or ionically conductive matrix precursor is provided from step 306 shown in FIG. 7C or step 308 shown in FIG. 7D, and step 802 shown in FIG. 8 comprises applying vacuum 804 to arrangement of elongated nanostructures 114 and ionically conductive matrix and / or ionically conductive matrix precursor 122 during and / or after adding ionically conductive matrix and / or ionically conductive matrix precursor 122 to elongated nanostructures 114. In some embodiments, applying a vacuum to the arrangement of elongated nanostructures and ionically conductive matrix and / or ionically conductive matrix precursor occurs before applying pressure to the arrangement. For example, in certain embodiments, step 802 in FIG. 8 occurs before step 310 shown in FIG. 7E.

[0210] In some embodiments, applying pressure to arrangement of elongated nanostructures and ionically conductive matrix and / or ionically conductive matrix precursor and applying vacuum to the arrangement of elongated nanostructures and ionically conductive matrix and / or ionically conductive matrix precursor are performed at least partially concurrently. In some embodiments, for example, step 802 shown in FIG. 8 and step 310 shown in FIG. 7E are performed at least partially concurrently.

[0211] The vacuum may be applied to the arrangement of elongated nanostructures and ionically conductive matrix and / or ionically conductive matrix precursor by using any of a variety of suitable techniques. In some embodiments, vacuum is applied to the arrangement using a vacuum source and / or pump (e.g., vacuum source and / or pump 806 shown in FIG. 8).

[0212] #14504416vl The vacuum may be applied to the arrangement of elongated nanostructures and ionically conductive matric and / or ionically conductive matrix precursor at any of a variety of suitable pressures. In some embodiments, the vacuum is applied to the arrangement at an absolute pressure greater than 0 atmospheres, greater than or equal to 0.1 atmospheres, greater than or equal to 0.2 atmospheres, greater than or equal to 0.3 atmospheres, greater than or equal to 0.4 atmospheres, greater than or equal to 0.5 atmospheres, greater than or equal to 0.6 atmospheres, greater than or equal to 0.7 atmospheres, greater than or equal to 0.8 atmospheres, or greater than or equal to 0.9 atmospheres. In certain embodiments, the vacuum is applied to the arrangement at an absolute pressure less than 1 atmosphere, less than or equal to 0.9 atmospheres, less than or equal to 0.8 atmospheres, less than or equal to 0.7 atmospheres, less than or equal to 0.6 atmospheres, less than or equal to 0.5 atmospheres, less than or equal to 0.4 atmospheres, less than or equal to 0.3 atmospheres, less than or equal to 0.2 atmospheres, or less than or equal to 0.1 atmospheres. Combinations of the above recited ranges are possible (e.g., the vacuum is applied to the arrangement at an absolute pressure greater than 0 and less than or equal to 1 atmosphere). Other ranges are also possible.

[0213] In certain embodiments, the method comprises heating the arrangement of elongated nanostructures and ionically conductive matrix and / or ionically conductive matrix precursor. According to some embodiments, heating the arrangement of elongated nanostructures and ionically conductive matrix precursor may at least partially (or fully) harden (e.g., cure) the ionically conductive matrix precursor (e.g., into the ionically conductive matrix). FIGS. 9A-9B show, in accordance with certain embodiments, schematic cross-sectional diagrams of methods of heating arrangement of elongated nanostructures 114 and ionically conductive matrix and / or ionically conductive matrix precursor 122 with heat 906. In some embodiments, heating the arrangement of elongated nanostructures and ionically conductive matrix and / or ionically conductive matrix precursor occurs before applying pressure to the arrangement (e.g., step 902 shown in FIG. 9A occurs before step 310 shown in FIG. 7E). In certain embodiments, for example, an arrangement of elongated nanostructures and ionically conductive matrix and / or ionically conductive matrix precursor is provided from step 308 shown in FIG. 7D, and step 902 shown in FIG. 9A comprises heating arrangement of elongated nanostructures 114 and ionically conductive matrix and / or ionically conductive matrix precursor 122 with heat 906 before applying pressure to the arrangement.

[0214] In some embodiments, applying pressure to the arrangement of elongated nanostructures and ionically conductive matrix and / or ionically conductive matrix precursor and heating the arrangement of elongated nanostructures and ionically conductive matrix and / or ionically

[0215] #14504416vl conductive matrix precursor are performed at least partially concurrently (e.g., step 902 shown in FIG. 9A and step 310 shown in FIG. 7E are performed at least partially concurrently). In certain embodiments, for example, an arrangement of elongated nanostructures and ionically conductive matrix and / or ionically conductive matrix precursor is provided from step 308 shown in FIG. 7D, and step 902 shown in FIG. 9A comprises heating arrangement of elongated nanostructures 114 and ionically conductive matrix and / or ionically conductive matrix precursor 122 with heat 906 while applying pressure to the arrangement of elongated nanostructures 114 and ionically conductive matrix and / or ionically conductive matrix precursor 122 (e.g., as shown in FIG. 7E).

[0216] In some embodiments, heating the arrangement of elongated nanostructures and ionically conductive matrix and / or ionically conductive matrix precursor occurs after applying pressure to the arrangement of elongated nanostructures and ionically conductive matrix and / or ionically conductive matrix precursor. In certain embodiments, for example, an arrangement of densified elongated nanostructures and ionically conductive matrix and / or ionically conductive matrix precursor is provided from step 312 shown in FIG. 7F, and step 904 shown in FIG. 9B comprises heating arrangement of elongated nanostructures 114 and ionically conductive matrix and / or ionically conductive matrix precursor 122 with heat 906 after applying pressure to the arrangement.

[0217] The arrangement of elongated nanostructures and ionically conductive matrix and / or ionically conductive matrix precursor may be heated to any of a variety of suitable temperatures. In some embodiments, the arrangement may be heated to a temperature of less than or equal to 1000 °C, less than or equal to 800 °C, less than or equal to 600 °C, less than or equal to 400 °C, less than or equal to 200 °C, less than or equal to 100 °C, less than or equal to 50 °C, or less than or equal to 30 °C. In some embodiments, the arrangement may be heated to a temperature of greater than or equal to 25 °C, greater than or equal to 30 °C, greater than or equal to 50 °C, greater than or equal to 100 °C, greater than or equal to 200 °C, greater than or equal to 400 °C, greater than or equal to 600 °C, or greater than or equal to 800 °C. Combinations of the abovereferenced ranges are also possible (e.g., greater than or equal to 25 °C and less than or equal to 1000 °C). Other ranges are also possible.

[0218] In certain embodiments, the method comprises forming a domain of elongated nanostructures distributed within ionically conductive matrix. FIG. 10A shows, according to certain embodiments, a schematic cross-sectional diagram of a method of step 1002 comprising forming domain 104’ of elongated nanostructures 114’ distributed within ionically conductive matrix 112. Domain 104’ may be formed, in some embodiments, according to the methods

[0219] #14504416vl described herein and shown in FIGS. 7A-9B. Domain 104’ may have any of the properties of one, more, or all of the domain(s) described herein (e.g., first domain 104a, second domain 104b, and / or third domain 104c), in accordance with certain embodiments.

[0220] According to some embodiments, the domain is a first domain, and the method further comprises providing a second domain of elongated nanostructures distributed within ionically conductive matrix over the first domain. FIG. 10B shows, according to certain embodiments, a schematic cross-sectional diagram of a method of step 1004 comprising providing second domain 104” of elongated nanostructures 114” distributed within ionically conductive matrix 112 over first domain 104’. In some embodiments, second domain 104” is formed according to the methods described herein with respect to domain 104’ (see FIGS. 7A-9B). Second domain 104” may, in some embodiments, have any of the properties of one, more, or all of the domain(s) described herein (e.g., first domain 104a, second domain 104b, and / or third domain 104c).

[0221] According to certain embodiments, the method further comprises providing a third domain of elongated nanostructures distributed within ionically conductive matrix over the second domain. FIG. 10C shows, according to certain embodiments, a schematic cross-sectional diagram of a method of step 1006 comprising providing third domain 104’” of elongated nanostructures 114’” distributed within ionically conductive matrix 112 over second domain 104”. Third domain 104’” may be formed according to the methods described herein with respect to first domain 104’ (see FIGS. 7A-9B). In certain embodiments, third domain 104’” has any of the properties of one, more, or all of the domain(s) described herein (e.g., first domain 104a, second domain 104b, and / or third domain 104c).

[0222] In certain embodiments, providing third domain 104’” of elongated nanostructures 114’” distributed within ionically conductive matrix 112 over second domain 104” forms an arrangement of domains. FIG. 10D shows, according to certain embodiments, a schematic cross-sectional diagram of a method of step 1008 comprising forming arrangement of domains 1104.

[0223] According to some embodiments, the method further comprises applying pressure to the arrangement of domains. FIGS. 10E-10F show, according to some embodiments, a schematic cross-sectional diagram of a method applying pressure to arrangement of domains 1104. In some embodiments, the method comprises applying pressure to the arrangement of domains to density the domains. In certain embodiments, for example, step 1010 shown in FIG. 10E comprises applying pressure to arrangement of domains 1104 to densify domains 104 (e.g., first domain 104’, second domain 104”, and third domain 104’”). Pressure may be applied in any of a variety of suitable directions 134. In some embodiments, pressure may be applied by hot

[0224] #14504416vl pressing arrangement of domains 1104. In certain embodiments, pressure may be applied by clamping arrangement of domains 1104 between graphite blocks. In certain embodiments, the densification process may facilitate the removal of one or more gas / vacuum closed-cell voids and / or other types of voids and / or fluids (e.g., liquid and / or gaseous solvents) present in one or more domain(s) from the manufacturing process.

[0225] According to certain embodiments, at least one dimension of one or more domains 104 (e.g., first domain 104’, second domain 104”, and / or third domain 104’”) may change as a result of the densification process. Referring, for example, to FIGS. 10E-10F, at least one of first dimension 106, a second dimension, and / or third dimension 110 (e.g., third dimension 110’, 110”, and / or 110’”) of one or more domains 104 (e.g., first domain 104’, second domain 104”, and / or third domain 104”’ in arrangement of domains 1104) shown in step 1010 may be different from first dimension 106’, a second dimension, and / or third dimension 110a (e.g. third dimension 110a’, 110a” and / or 110a’”) of one or more domains 104a (e.g., first domain 104a’, second domain 104a”, and / or third domain 104a’” in arrangement of domains 1104’) shown in step 1012. In certain non-limiting embodiments, for example, one or more of third dimension 110a (e.g., third dimension 110a’, 110a”, and / or 110a’”) may be shorter than third dimension 110’ (e.g., third dimension 110’, 110”, and / or 110’”) after the densification process.

[0226] According to some embodiments, the method further comprises applying a vacuum to the arrangement of domains. FIG. 10G shows, according to some embodiments, a schematic cross- sectional diagram of a method of step 1014 of applying vacuum 804 to arrangement of domains 1104.

[0227] In some embodiments, applying pressure to the arrangement of domains and applying vacuum to the arrangement of domains are performed at least partially concurrently. In some embodiments, for example, step 1014 shown in FIG. 10G and step 1010 shown in FIG. 10E are performed at least partially concurrently.

[0228] The vacuum may be applied to the arrangement of domains by using any of a variety of suitable techniques. In some embodiments, vacuum is applied to the arrangement using a vacuum source and / or pump (e.g., vacuum source and / or pump 806 shown in FIG. 10G).

[0229] The vacuum may be applied to the arrangement of domains at any of a variety of suitable pressures. In some embodiments, the vacuum is applied to the arrangement at an absolute pressure greater than 0, greater than or equal to 0.1 atmospheres, greater than or equal to 0.2 atmospheres, greater than or equal to 0.3 atmospheres, greater than or equal to 0.4 atmospheres, greater than or equal to 0.5 atmospheres, greater than or equal to 0.6 atmospheres, greater than or equal to 0.7 atmospheres, greater than or equal to 0.8 atmospheres, or greater than or equal to

[0230] #14504416vl 0.9 atmospheres. In certain embodiments, the vacuum is applied to the arrangement at an absolute pressure less than 1 atmosphere, less than or equal to 0.9 atmospheres, less than or equal to 0.8 atmospheres, less than or equal to 0.7 atmospheres, less than or equal to 0.6 atmospheres, less than or equal to 0.5 atmospheres, less than or equal to 0.4 atmospheres, less than or equal to 0.3 atmospheres, less than or equal to 0.2 atmospheres, or less than or equal to 0.1 atmospheres. Combinations of the above recited ranges are possible (e.g., the vacuum is applied to the arrangement at an absolute pressure greater than 0 and less than or equal to 1 atmosphere). Other ranges are also possible.

[0231] In some embodiments, the method comprises heating the arrangement of domains. FIG. 10H shows, according to some embodiments, a schematic cross-sectional diagram of a method of step 1016 of heating arrangement of domains 1104 with heat 906. In some embodiments, heating the arrangement of domains occurs before applying pressure to the arrangement (e.g., step 1016 shown in FIG. 10H occurs before step 1010 shown in FIG. 10E). In certain embodiments, for example, an arrangement of domains is provided from step 1008 shown in FIG. 10D, and step 1016 shown in FIG. 10H comprises heating arrangement of domains 1104 with heat 906 before applying pressure to the arrangement.

[0232] In some embodiments, applying pressure to the arrangement of domains and heating the arrangement of domains are performed at least partially concurrently (e.g., step 1016 shown in FIG. 10H and step 1010 shown in FIG. 10E are performed at least partially concurrently). In certain embodiments, for example, an arrangement of domains is provided from step 1008 shown in FIG. 10D, and step 1016 shown in FIG. 10H comprises heating arrangement of domains with heat 906 while applying pressure to the arrangement of domains (e.g., as shown in FIG. 10E).

[0233] In some embodiments, heating the arrangement of domains occurs after applying pressure to the arrangement of domains. In certain embodiments, for example, an arrangement of densified domains is provided from step 1012 shown in FIG. 10F, and step 1016 shown in FIG. 10H comprises heating arrangement of domains 1104 with heat 906 after applying pressure to the arrangement.

[0234] The arrangement of domains may be heated to any of a variety of suitable temperatures. In some embodiments, the arrangement of domains is heated to a temperature of less than or equal to 1000 °C, less than or equal to 800 °C, less than or equal to 600 °C, less than or equal to 400 °C, less than or equal to 200 °C, less than or equal to 100 °C, less than or equal to 50 °C, or less than or equal to 30 °C. In some embodiments, the arrangement of domains is heated to a temperature of greater than or equal to 25 °C, greater than or equal to 30 °C, greater than or

[0235] #14504416vl equal to 50 °C, greater than or equal to 100 °C, greater than or equal to 200 °C, greater than or equal to 400 °C, greater than or equal to 600 °C, or greater than or equal to 800 °C.

[0236] Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to 25 °C and less than or equal to 1000 °C). Other ranges are also possible.

[0237] According to certain embodiments, heating the arrangement of domains forms a continuous phase of the ionically conductive matrix across the first domain, the second domain, and the third domain. Referring, for example, to FIG. 10H, heating arrangement of domains 1104 forms a continuous phase of ionically conductive matrix across first domain 104’, second domain 104”, and third domain 104’”. In certain embodiments, there is no discernable interface between first domain 104’, second domain 104”, and third domain 104’”. For example, in some embodiments, there is no change in chemical composition, no physical discontinuity, or no other discernable interface between first domain 104a’, second domain 104”, and third domain 104’”.

[0238] In certain embodiments, the applying pressure to the arrangement of domains and the heating the arrangement of domains are performed at least partially concurrently.

[0239] International Patent Application No. PCT / US2023 / 063728, filed March 3, 2023, and entitled “Bulk Nanocomposite Materials and Methods for Making These,” and U.S. Provisional Patent Application No. 63 / 708,240, filed October 16, 2024, and entitled “All-Nanocomposite Structural Energy Storage,” are incorporated herein by reference in their entirety for all purposes.

[0240] The following disclosure is directed to examples intended to illustrate certain embodiments of the present disclosure related to nanocomposite structural energy storage devices and related articles, systems, and methods. It does not necessarily exemplify the full scope of the disclosure.

[0241] Structural energy storage devices combine the energy storage function (supercapacitor or battery) with structural function (e.g., an advanced composite like carbon fiber reinforced polymer (CFRP)). Outstanding challenges involve electrode surface area (which is directly proportional to energy density), high ionic mobility (e.g., between and around the electrodes, which directly affects power density), scaling, and the separator material between electrodes, which is conventionally both weak structurally and generally too thick, limiting the ionic flow.

[0242] Emerging multifunctional materials are the basis of structural supercapacitors (SSCs), allowing SSCs to bear mechanical load and store electrical energy. Due to this multifunctionality, SSCs have the power to transform the utilization of day-to-day structures by integrating them with an inherent energy storage capability. Vice versa, energy storage devices can also be viewed as a structural unit for more complex constructions. Furthermore,

[0243] #14504416vl supercapacitors can be a sustainable energy storage alternative to batteries due to their long- lasting performance. Since supercapacitors store energy electrostatically (unlike batteries that store energy chemically), they can frequently charge and discharge at high speeds (much quicker and more frequently than batteries) and can undergo hundreds of thousands of charge / discharge cycles (whereas batteries can only handle a few thousand cycles due to chemical degradation). Still, there is much work to be done such that SSCs can be practically employed, particularly due to material multifunctionality limitations. For example, conventional SSCs are either not mechanically robust enough or not ionically conductive enough.

[0244] A SSC generally comprises mainly three constituents: two structural and electrically conductive electrodes; a single structural and ionically conductive separator; and a structural polymer electrolyte. While ionically conductive, a SSC separator should be electrically non- conductive to successfully separate the two electrodes from contacting each other. Since a SSC can simultaneously be an energy storage device and a robust structure, utilizing a multifunctional material in the form of a (nano)composite is an approach to achieving a successful SSC. As such, nanomaterial candidates with great potential as constituents within nanocomposites for SSCs include carbon nanotubes and boron nitride nanotubes due to their exceptional material properties that tailor to SSC needs. See, for example, FIG. 14, showing a schematic drawing of a SSC composite.

[0245] As technology advances, engineering systems are allocating a greater proportion of their total mass and volume to energy storage. Therefore, there is a need to maximize mass- and volume-specific performance across a variety of structural systems, including electric vehicles, buildings, space / aircraft, renewable energy systems, consumer electronics, etc. A solution is a SSC multifunctional device that integrates energy storage into existing structural panels for space efficiency, weight savings, sustainability, and versatility. A limitation for conventional SSCs, however, is simultaneously attaining competitive efficient energy storage and robust structural capabilities; therefore, developing a SSC with multifunctional components in the form of a (nano)composite that surpasses the state-of-the-art SSC of carbon fiber (CF) electrodes, glass fiber composite (GRFP) separators, and MVR444 structural polymer electrolytes (SPEs) is needed.

[0246] The disclosure herein describes, in accordance with certain embodiments, a combination of structural components made from carbon nanotubes (CNTs), boron nitride nanotubes (BNNTs), and structural electrolytes (SEs) whose mechanical and electrical properties can be leveraged so that altogether they provide a viable structural supercapacitor.

[0247] #14504416vl To overcome challenges associated with conventional SSCs, described herein is, in accordance with certain embodiments, a nanocomposite of horizontally aligned nanotubes with high aspect ratio (105length / diameter) and high (50 vol%) packing fraction for both the electrodes and the separator. The electrodes comprise highly electrically-conductive aligned carbon nanotubes and a polymer (or ceramic or other) matrix that is ionically conductive. Similarly, the separator comprises electrically insulating nanotubes (NTs), nominally aligned boron nitride nanotubes (BNNTs), and an ionically conductive polymer (or ceramic or other) matrix. The polymer nanocomposite electrodes and separator are made via a bulk nanocomposite laminating (BNL) process. The electrodes and separator are advantageously thin (0=10 pm) compared to typical electrode CFRP layers (0=lOO’s pm). Thus, a layered / laminated structural energy storage device is introduced that has many advantageous properties relative to conventional SSCs.

[0248] Fabricating CNT-based Structural Electrodes: A challenge for supercapacitors is increasing their energy density such that they become competitive with batteries and can power society’s electronics unaided. Certain aspects of this disclosure use high quality, high surface area (lOOOx that of CF) aligned carbon nanotubes (A-CNTs) as SSC electrodes to increase the electrode’s specific surface area and ability to store more energy through the separation of charge at the interface between the electrode and the electrolyte. Employing a BNL process can produce dense, bulk, void-free, A-CNT reinforced electrodes at scale. The BNL process involves growing A-CNTs via a thermal catalytic chemical vapor deposition (CVD) process and “knocking-down” A-CNTs onto a release film to create individual knockdown CNT (K-CNT) plies that can then be stacked on top of one another to create bulk A-CNT reinforced nanocomposite laminates. By densifying A-CNTs in this way, the overall performance of CNT- based electrodes can be enhanced by increasing their volumetric capacitance. Furthermore, results show that the BNL process produces CNT laminates with significant enhancement in modulus and strength, thereby exploiting the thermal and electrical conductivity, low density, high stiffness (Young’s modulus ~1 TPa), and high strength (~ 150 GPa) of CNTs (FIGS. 11A- 11C).

[0249] Fabricating the BNNT -based Structural Separator: An SSC separator should have good electrical insulation, high ionic conductivity, low thickness, and good mechanical stability to allow for easy and quick transport of ions from one side of the SSC to the other while structurally preventing electrical and physical contact between the two electrodes. It was determined that BNNTs fit these criteria. Conventionally, it has been difficult to synthesize high quality (densely packed and vertically aligned) BNNTs. The disclosure herein, in

[0250] #14504416vl accordance with certain embodiments, resolves this by utilizing a method that produces high quality, dense, vertically aligned BNNTs (VA-BNNTs) in bulk. Using VA-CNTs as scaffolds, boron nitride is coated over the VA-CNTs via a CVD process. Afterwards, the CNTs are removed by a thermal oxidation process. By using the VA-CNTs as a scaffold in this way, BNNTs retain verticality, alignment, and nanotube forest density. Therefore, the BNL process can be applied to separators that are lOx thinner than GFRP separators. As an example of a BNNT structural separator, a multifunctional nanocomposite structural separator made of vertically aligned alumina nanotubes using the fabrication methods described herein had a 140% increase in effective stiffness, 5x increase of ionic conductivity, and 30% increase of capacitance over a commercial GFRP separator.

[0251] Developing a Structural Polymer Electrolyte: Creating a SPE with the right concentrations of structural and ionic mediums that yield high ionic conductivity (IC) and high Young’s modulus (E) is a challenging aspect of SSC development since IC and E are inversely related. An epoxy -based SPE was tailored to have relatively high ionic conductivity and mechanical property values that surpass conventional epoxy / ionic liquid systems. As one example, the SPE can contain EPON 862 with Epikure W (hardener) as to provide structural reinforcement and a solution of LiTFSI (lithium salt) in EMIM-TFSI (ionic liquid) to provide ionic conductivity. Incorporating this SPE as one of the SSC components can yield mechanical and ionic conductive properties that surpass conventional SSCs.

[0252] Structural Supercapacitor Nanocomposite Fabrication: Previously fabricated laminates infused with SPE are stacked on top of one another, with two K-CNT 2-ply laminates sandwiching a single K-BNNT ply laminate in between (FIGs. 11 A-l IC). This stack of laminates is clamped between graphite blocks to further densify the 5-ply laminate. The clamped laminate system is brought inside an oven within the glovebox and left to densify. After this 5-ply laminate densification is complete, the clamped laminate system is left in the glovebox oven to cure. FIGS. 12-13 show examples of all-nano-composite structural energy storage devices. To measure success, two K-CNT / SPE 2-ply laminates can sandwich a commercial separator (instead of the BNNT separator) to set a baseline, quantify CNT increased energy storage, and ensure proper SSC functionality before incorporating the BNNT separator to help quantify its improvements.

[0253] SSC Testing, Imaging, and Analysis: Analyzing cured K-CNTs infused with SPE, K- BNNTs infused with SPE, and SSC nanocomposites is important to understand how the interfacial reaction between each of these materials affects the overall multifunctionality of a structural energy storage device. Characterization methods include X-ray computed

[0254] #14504416vl tomography (pCT) to identify voids and SPE infusion compatibility; laminate level tensile testing for modulus calculation; SEM imaging to view specimen fracture surfaces and morphology; Differential Scanning Calorimetry (DSC) to attain glass transition temperatures; inductance, capacitance, and resistance (LCR) metering to measure capacitance; and Electrochemical Impedance Spectroscopy (EIS) to test ionic conductivity.

[0255] This disclosure describes and analyzes, in accordance with certain embodiments, an all- nanocomposite SSC material to better understand its multifunctional behavior and scientifically maximize it beyond conventional devices, thereby providing a foundation for advancing the science behind specific nanomaterial interactions that yield challenging combinations of high mechanical strength and excellent ionic conductivity within SSCs.

[0256] Integrating energy storage into structural components would have a disruptive effect on society’s technological landscape: for the first time, structural parts would also function as energy storage devices and vice versa. Separate compartments for structural components and energy storage devices would no longer be needed, providing society with serious advantages such as space efficiency, weight savings, sustainability, and versatility. Buildings could be designed with walls or floors that store and manage energy, and parts of a car's body could store energy while enhancing structural reinforcement, performance, and safety.

[0257] A challenging aspect in developing practical and realizable SSC nanocomposites for today’s society is that conventional SSCs have yet to achieve multifunctional components that can provide structural integrity while simultaneously storing electric energy. Therefore, there is a need to develop, research, and implement materials that can serve this dual function.

[0258] To create a functioning SSC cell, an important aspect of development in supercapacitors is increasing their energy density such that they become competitive with batteries and can power society’s electronics unaided. Increasing the energy density of supercapacitors is an immense challenge; this disclosure describes, in accordance with certain embodiments, that using high quality, A-CNTs as electrodes within a supercapacitor increases the electrode’s specific surface area and can therefore store more energy through the separation of charge at the interface between the electrode and the electrolyte. This can be done by employing fabrication methods (via a BNL process) that can produce bulk A-CNT reinforced electrodes at scale that are effectively nanofiber versions of carbon fiber reinforced polymer (CFRP). Apart from utilizing the high electrical conductivity of CNTs in the supercapacitor’s electrodes, CNTs also enhance the structural integrity and minimize the weight of the electrodes with their desirable mechanical properties including high stiffness, high strength, and low density. Due to this dual

[0259] #14504416vl functionality of CNTs that serve to increase energy density and enhance structural reinforcement in the electrodes, an advantageous structural supercapacitor component can be achieved.

[0260] The development of SSCs also includes a structural separator — an electronically non- conductive material that has high ionic conductivity. As such, a SSC separator should have good electrical insulation, high ionic conductivity, low thickness, and good mechanical stability to allow for easy and quick transport of ions from one side of the SSC to the other while structurally preventing electrical and physical contact between the two electrodes. This is a challenging combination of qualities to simultaneously find in a material, and therefore, there is a need to for materials that possesses these electrical and ionic properties in addition to exceptional mechanical robustness. It was determined that the BNNT fits these criteria. Conventionally, the difficulty in applying BNNTs to such work arises from the inability to synthesize high quality BNNTs. The disclosure herein, in accordance with certain embodiments, resolves this by utilizing a method that produces high quality, VA-BNNTs that can then be used to manufacture reliable BNNT-based structural separators within SSCs.

[0261] To create a functioning SSC cell, a structural polymer electrolyte (SPE) that is not only ionically conductive, but also serves to structurally reinforce the SSC as a polymer matrix material, should also be considered as an SSC component. The disclosure herein describes, in accordance with certain embodiments, structural electrolytes that are made from mixing different concentrations of a structural polymer with an ionic liquid-based electrolyte. Multiple SPEs with different concentrations of its constituents are considered and utilized to find useful embodiments for the combination of SSC components. As such, described herein are, in accordance with certain embodiments, methods to synthesize each SSC component — CNT- based electrolytes, BNNT-based structural separator, and SE — to generate a SSC nanocomposite that can store energy and function as a structure, from electric and aerospace vehicles to portable electronics.

[0262] CNTs are hollow cylindrical structures that can be made from rolling graphene (a 2D carbon-based material). CNTs can have a nm-scale diameter and can be characterized as either single-walled (SWCNT) or multi-walled (MWCNT), which consists of concentrically nested SWCNTs. CNTs have good thermal and electrical conductivity in addition to low density, high stiffness, i.e., Young’s modulus ~1 TPa, and high strength (~ 150 GPa) due to their characteristic sp2covalent bonding between carbon atoms. These material properties, in addition to CNTs’ high surface area, are ideal for electrodes within an SSC. Furthermore, CNT arrays are capable of being infiltrated with polymer solutions, such as structural polymer electrolytes, via capillary action.

[0263] #14504416vl BNNTs are also hollow cylindrical structures similar to CNTs with a nanostructure that also entails a hexagonal network of atoms, but instead of carbon atoms, the hexagonal network for BNNTs is composed of boron and nitrogen atoms. It has been a challenge to produce high quality BNNTs for various applications, but with high quality production of BNNTs (e.g., as described herein), the numerous intrinsic properties of BNNT’s can be utilized, such as high mechanical strength, high thermal conductivity, electrically insulating behavior, piezoelectric properties, neutron shielding capabilities, and oxidation resistance. Particularly, high thermal conductivity, chemical stability, electrically insulating, high porosity, and mechanical robustness make BNNTs promising candidates for structural separators.

[0264] Recently, a multifunctional nanocomposite structural separator made of vertically aligned alumina nanotubes was realized, which had a 140% increase in effective stiffness, 5x increase of ionic conductivity, and 30% increase of capacitance over a commercial separator. These vertically aligned alumina nanotubes were, in accordance with certain embodiments, fabricated the same way as the fabrication method for BNNTs as described herein, thereby serving as a proof of concept for the BNNT structural separator.

[0265] This combination of energy storage with structural integrity is a gateway for advanced multifunctional materials such as SSC nanocomposites to be implemented across numerous sectors, including but not limited to automotive, aerospace, portable electronics, building construction, aviation, home appliances, etc. Additionally, SSC nanocomposites reduce the weight and volume of systems without compromising mechanical robustness. All in all, SSC nanocomposites have the ability to revolutionize the intersection between energy storage devices and structures allowing for the integration of advanced technology to meet society’s needs. FIG. 14 shows, in accordance with certain embodiments, a schematic drawing of a SSC composite.

[0266] Thermal Catalytic CVD: VA-CNT Synthesis

[0267] Vertically aligned, multiwalled (MW), and densely packed CNT forests signify high quality CNT growths. This VA-CNT synthesis can be achieved through thermal catalytic CVD.

[0268] In this process, CNTs are grown on silicon wafer substrates that are oxidized to form a 500 nm SiCh layer. The substrates are then coated with 10 nm of alumina (AI2O3) and followed by a 1 nm layer of iron (Fe) via electron beam physical vapor deposition. The function of the 1 nm layer of Fe is to have it de-wet into globules or nanoparticles that serve as initiation sites for CNT growth (which happens at ~700 °C). In this case, the alumina layer functions as a diffusion layer between Fe and SiCh to inhibit their reaction with one another (which forms

[0269] #14504416vl silicates). Alumina also results in more Fe nanoparticles that are smaller in size, which helps tightly pack the growing CNTs.

[0270] Once the silicon substrates are cut to fit on a quartz boat (FIG. 15), the quartz boat carrying silicon wafer substrates is placed into the quartz tube furnace where the CVD process takes place. The CNT growths occur at atmospheric pressure, and the CVD process ensures that A-CNT arrays are grown on the Fe catalyst using acetylene gas (C2H2) as a carbon source precursor. At ~700 °C, the C2H2 gas is broken down to free carbon that forms A-CNTs on the Fe nanoparticles. Therefore, the amount of ethylene gas that flows through the furnace dictates the height of the CNTs and heights of 400 pm - 600 pm may be attained.

[0271] Other precursors during the CVD process include hydrogen and helium. Apart from purging the system from any oxygen (which is reactive and combustible if any is left behind), hydrogen helps to “activate” the iron on the silicon wafer where the CNTs grow. In other words, at high temperatures hydrogen helps iron form into globules whereon CNTs grow.

[0272] Hydrogen does this by etching away at the grain boundaries of iron to then form iron globules.

[0273] Hydrogen also removes any rust. When helium is flowed through the system, it acts as an inert atmosphere as it does not cause any reactions.

[0274] Helium flows through a water bubbler at the beginning of the system to create humidity, and helium also serves to delaminate the CNT forests from the wafer to use them in the SSC fabrication.

[0275] Thermal Catalytic CVD: VA-BNNT Synthesis

[0276] Conventionally, it has been difficult to synthesize high quality BNNTs. To attain high quality BNNT growths, BNNTs should be consistently densely packed and vertically aligned. The method described herein ensures, in accordance with certain embodiments, that the BNNT growths have these qualities. Using VA-CNTs as scaffolds, boron nitride is coated over the V A-CNTs via a low-pressure CVD process. Afterwards, the CNTs are removed by a thermal oxidation process. By using the VA-CNTs as a scaffold in this way, BNNTs retain verticality and alignment, and nanotube forest density. Therefore, these high-quality VA- BNNT arrays can be used to fabricate structural separators within SSCs.

[0277] Knockdown Process of A-CNTs

[0278] The knockdown process of A-CNTs emerged to create individual CNT plies that could then be complied or stacked on top of one another to create bulk A-CNT reinforced nanocomposite laminates (FIG. 16).

[0279] #14504416vl In this process, guaranteed non-porous Teflon (GNPT) release film is placed on top of A-CNT forests that sit on the silicon wafer. A razor blade is then passed uniformly, in a single and clear direction, over the top of the film that sits atop of the A-CNT arrays. This results in a single ply of knockdown CNTs (K-CNTs) that stick to the GNPT film. The process is repeated, with the K-CNT ply on GNPT film and razor-bladed in the opposite direction (for ply geometry) with another A-CNT forest growth to create a 2-ply laminate. This process is possible because CNT-CNT interaction is high, and so CNTs can easily fall over on top of each other in this way. Knockdown Process of VA-BNNTs

[0280] There is no specific knockdown process for VA-BNNTs. One approach is to follow the same knockdown process for A-CNTs (FIG. 16). The challenge is that BNNT-BNNT interaction is low, making it difficult to fully “knockdown” the VA-BNNTs (unlike for VA- CNTs). SEM imaging of K-BNNTs can dictate underlying problems that result in poor K- BNNTs. Experimental tests determined that adding an adhesive layer to the GNPT film helps anchor the BNNTs to the substrate, allowing for proper horizontal alignment.

[0281] Developing a SPE

[0282] To develop an optimal SPE for polymer matrix reinforcement and ionic conductivity in SSCs, concentrations between epoxy resin, ionic liquid electrolyte, and salt were experimented with to create a SPE with concentrations that yield a high IC, high Young’s modulus, and high interfacial reaction with CNTs for proper infusion.

[0283] Specifically, it is proposed to use a combination of Epon 862 and Epikure W (resin base and hardener, respectively) with TFSI-EMIM (as IL) and LiTFSI (as Li salt) for the SSC SPE. These constituents are to be mixed and degassed within a glovebox to avoid oxygen reactions with the SPE.

[0284] Infusion of SPE and Densification of Nanotube 2-Ply Laminates

[0285] The K-CNT 2-ply laminate is infused with SPE inside of a glovebox so that there is negligible humidity and no oxygen present for the SPE to react with. A pipet can be used to hold and disperse SPE onto the K-CNT 2-ply laminate. The SPE is allowed to uniformly set into the laminate. Vacuum can also be applied to help the SPE better infuse into the K-CNT laminates. The same infusion process can be applied to a K-BNNT 2-ply laminate.

[0286] After SPE infusion, the K-CNT 2-ply laminate is clamped between graphite blocks (still within the glovebox) to add pressure for laminate densification. The clamp should have a pressure gauge to monitor and record pressures used for laminate densification. The clamped laminate system is then placed inside an oven within the glovebox. The same clamping and densification process can be applied to an SPE-infused K-BNNT 2-ply laminate.

[0287] #14504416vl Structural

[0288] Previously densified 2-ply laminates are then stacked on top of one another, with 2 K- CNT 2-ply laminates sandwiching a K-BNNT 2-ply laminate in between them from the top and bottom adhering to the structural supercapacitor nanocomposite design.

[0289] This stack of laminates is clamped between graphite blocks to further densify the 6-ply laminate. The clamped laminate system is once again brought inside an oven within the glove box and left to densify (FIG. 17).

[0290] After this 6-ply laminate densification is complete, the clamped laminate system is left in the glovebox oven to cure (with temperature and pressure parameters modified).

[0291] Mechanical Testing, Ionic Conductivity Testing, Imaging and Analysis

[0292] Using the Zwick Mechanical Tester (with testXpert Software), the strain, stress, and modulus (ratio of stress [force per unit area] to corresponding strain [deformation]) can be measured to determine the strength and Young’s modulus of the SSC nanocomposite. These measurements are attained via laminate level tensile testing and digital image correlation (Correlated Solution’s VicSnap and Vic-2D software). Alternatively, the SSC nanocomposite samples can also be nano-indented such that the indentation modulus and hardness are measured; then the Young’s modulus can be obtained.

[0293] To measure ionic conductivity (mS / cm), the SSC nanocomposite (an ionic conductor) can have a sinusoidal AC voltage applied over a particular frequency range while sandwiched between two ion-blocking electrodes such that frequency-dependent impedance data is obtained and analyzed via a Nyquist plot. The semicircle depicted in the plot at the high-frequency range provides a way to calculate the bulk resistance (Rb) of the SSC nanocomposite, which allows the ionic conductivity (G) to be calculated via the equation: G = L / (Rb*A) (where L is the thickness of the SSC nanocomposite and A is the area of the SSC nanocomposite).

[0294] After an SSC nanocomposite specimen has undergone tensile testing, SEM imaging can be used to view the specimen fracture surface and analyze pull out behavior of the nanotubes. SEM imaging can provide insight to composition and morphology, as well as factors behind tensile testing breakage.

[0295] X-ray computed tomography (pCT) can be used to identify porosity and / or voids, within the SSC nanocomposite.

[0296] The thermogravimetric analyzer can be used to characterize the decomposition temperatures for each component of the SSC nanocomposite as well as the SSC nanocomposite itself by measuring the samples’ weight % decrease as a function of temperature.

[0297] #14504416vl Differential scanning calorimeter can be used to characterize the glass transition temperatures for each of our polymeric samples by measuring energy absorption and heat flow through the cured samples as they underwent phase transitions due to temperature increase. Knockdown VA-BNNTs

[0298] A consistent method to properly knockdown VA-BNNTs can be explored. The BNNT- BNNT interaction is low, making it challenging to fully “knockdown” the VA-BNNTs (unlike for VA-CNTs).

[0299] Optimize Structural Polymer Electrolyte for SSC Polymer Matrix

[0300] Concentrations between epoxy resin, ionic liquid electrolyte, and salt, can be explored to create a SPE. Each combination can be tested for Young’s modulus and ionic conductivity. Characterize SPE / CNT Component

[0301] Cured K-CNTs infused with SPE can be analyzed and characterized. Characterization includes pCT to identify porosity and / or voids, and SE infusion compatibility; laminate level tensile testing and digital image correlation for modulus calculation; SEM imaging to view specimen fracture surfaces and morphology; TGA to attain decomposition temperatures; DSC to attain the glass transition temperatures; and ionic conductivity testing.

[0302] Characterize SPE / BNNT Component

[0303] Cured K-BNNTs infused with SPE can be analyzed and characterized. Characterization includes pCT to identify porosity and / or voids, and SPE infusion compatibility; laminate level tensile testing and digital image correlation for modulus calculation; SEM imaging to view specimen fracture surfaces and morphology; TGA to attain decomposition temperatures; DSC to attain the glass transition temperatures; and ionic conductivity testing.

[0304] Choose SPE to Use as Polymer Matrix for SSC

[0305] How each SPE performed when infused into CNTs and BNNTs can be compared. SE selection can be based on prior characterizations and analyses for the best overall SSC polymer matrix, considering its interaction with both CNTs and BNNTs.

[0306] Fabricate Structural Supercapacitor Nanocomposites

[0307] K-CNT / PP / Epoxy SSC

[0308] Following the BNL process, a K-CNT 2-ply laminate layered on top of a polypropylene (PP) commercial separator layered on top of another K-CNT 2-ply laminate all infused and cured with standard epoxy can be fabricated to create a structural reference for the SSC nanocomposite. This step can be done to set a baseline for the SSC nanocomposite work, quantify CNT increased energy storage, and test SSC functionality before incorporating the

[0309] #14504416vl BNNT separator and SPE. This can also help in quantifying the improvements from both the SPE and the BNNT separator in later nanocomposite fabrications.

[0310] K-CNT / PP / SPE SSC

[0311] Following the BNL process, a K-CNT 2-ply laminate layered on top of a K-BNNT 2-ply laminate layered on top of another K-CNT 2-ply laminate all infused and cured with SPE can be fabricated to create a nanocomposite. This step can be done to quantify ionic conductivity enhancement due to incorporating the SPE into the SSC nanocomposite as well as to test SSC functionality before incorporating the BNNT separator, which can set a benchmark for improvements from the BNNT separator in later nanocomposite developments.

[0312] K-CNT / K-BNNT / SPE SSC

[0313] Following the BNL process, a K-CNT 2-ply laminate layered on top of a polypropylene (PP) commercial separator layered on top of another K-CNT 2-ply laminate all infused and cured with SPE can be fabricated to create a nanocomposite.

[0314] Characterize SSC Nanocomposites

[0315] Characterization of SSC nanocomposites, as well as K-CNT / SPE and K-BNNT / SPE laminates, includes pCT to identify porosity and / or voids, and SPE infusion compatibility; laminate level tensile testing and digital image correlation for modulus calculation; SEM imaging to view specimen fracture surfaces and morphology; TGA to attain decomposition temperatures; DSC to attain the glass transition temperatures; and ionic conductivity testing.

[0316] This disclosure also includes, in accordance with certain embodiments, fine-tuning different fabrication parameters, such as curing length or temperature, and adjusting compositional features, such as number of plies for CNT -based electrodes and / or BNNT-based separator.

[0317] The following example is intended to illustrate certain embodiments of the present invention, but does not exemplify the full scope of the invention.

[0318] EXAMPLE

[0319] The following examples describes a SSC for nanocomposite structural energy storage, the SSC comprising an electrode formed by a bulk nanocomposite laminating (BNL) process, a commercial separator, and a structural polymer electrolyte.

[0320] FIG. 18A shows, in accordance with certain embodiments, a photograph of a K-CNT- Celgard-epoxy structural polymer electrolyte device. FIG. 18B shows, in accordance with certain embodiments, a schematic diagram of the device shown in FIG. 18 A. As shown in

[0321] #14504416vl FIGS. 9A-9B, the K-CNT electrode overhangs for improved contact. The defined geometry values of the SSC are:

[0322] Area: 3.2 cm2

[0323] Volume: 1.6 cm x 2.0 cm x 0.0358 cm = 0.11456 cm3

[0324] Weight: 0.14 g

[0325] FIG. 19A shows, in accordance with certain embodiments, a cyclic voltammogram of the device shown in FIG. 18A over a voltage range from -4 V to 4 V. FIG. 19B shows, in accordance with certain embodiments, cyclic voltammograms of conventional materials, including multiwalled carbon nanotubes (MWCNTs), MWCNTs / ABA / polyaniline, and bare carbon fibers.

[0326] Using the cyclic voltammogram in FIG. 19A, capacitance was calculated according to the following formula:

[0327] 71 0.231226 [A.7]

[0328] = 0.02890325 [F]

[0329] = 28.90 [mF]

[0330] Using the calculated capacitance and the defined geometry values of the SSC, the following values were calculated:

[0331] Areal capacitance: -9.03 mF / cm2

[0332] Volumetric capacitance: -252 mF / cm3

[0333] Gravimetric (specific) capacitance: -206 mF / g

[0334] For comparison, the gravimetric (specific) capacitance of several conventional devices are shown below:

[0335] CF / GF / PEGDGE-LiTFSI-IL: -11.1 mF / g

[0336] ACF / FP / Epoxy-TEABF4: -101.6 mF / g

[0337] MWCNTs-CF / GF / PEG-LiTf: -125 mF / g

[0338] FIG. 19C shows, in accordance with certain embodiments, a photograph of electrical connections to the device shown in FIG. 18 A.

[0339] It should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific implementations described above. The specific implementations described above are disclosed as examples only. While several embodiments

[0340] #14504416vl of the present invention have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and / or structures for performing the functions and / or obtaining the results and / or one or more of the advantages described herein, and each of such variations and / or modifications is deemed to be within the scope of the present invention. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and / or configurations will depend upon the specific application or applications for which the teachings of the present invention is / are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, the invention may be practiced otherwise than as specifically described and claimed. The present invention is directed to each individual feature, system, article, material, and / or method described herein. In addition, any combination of two or more such features, systems, articles, materials, and / or methods, if such features, systems, articles, materials, and / or methods are not mutually inconsistent, is included within the scope of the present invention.

[0341] The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.”

[0342] The phrase “and / or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Other elements may optionally be present other than the elements specifically identified by the “and / or” clause, whether related or unrelated to those elements specifically identified unless clearly indicated to the contrary. Thus, as a non-limiting example, a reference to “A and / or B,” when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A without B (optionally including elements other than B); in another embodiment, to B without A (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

[0343] As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and / or” as defined above. For example, when separating items in a list, “or” or “and / or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of’ or “exactly one of,”

[0344] #14504416vl or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e. “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” when used in the claims, shall have its ordinary meaning as used in the field of patent law.

[0345] As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and / or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.

[0346] As used herein, “wt%” is an abbreviation of weight percentage. As used herein, “at%” is an abbreviation of atomic percentage.

[0347] Some embodiments may be embodied as a method, of which various examples have been described. The acts performed as part of the methods may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include different (e.g., more or less) acts than those that are described, and / or that may involve performing some acts simultaneously, even though the acts are shown as being performed sequentially in the embodiments specifically described above.

[0348] Use of ordinal terms such as “first,” “second,” “third,” etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.

[0349] #14504416vl In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of’ and “consisting essentially of’ shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.

[0350] #14504416vl

Claims

CLAIMSWhat is claimed is:

1. An article, comprising: a domain, comprising: an ionically conductive matrix; and a plurality of elongated nanostructures distributed within the ionically conductive matrix; wherein: within the domain, the elongated nanostructures occupy a volume fraction of at least 10 vol%; less than or equal to 20 vol% of the domain is occupied by gas / vacuum closed-cell voids having a volume of at least 1012nm3; and the ionically conductive matrix has an ionic conductivity, with respect to at least one monovalent ion and / or at least one divalent ion, of at least 10'7S / cm.

2. An article, comprising: a domain, comprising: an ionically conductive matrix; and a plurality of elongated nanostructures distributed within the ionically conductive matrix; wherein: within the domain, the elongated nanostructures occupy a volume fraction of at least 10 vol%; less than or equal to 20 vol% of the domain is occupied by voids having a volume of at least 1012nm3; and the ionically conductive matrix has an ionic conductivity, with respect to at least one monovalent ion and / or at least one divalent ion, of at least 10'7S / cm.

3. The article of any one of claims 1-2, wherein the ionically conductive matrix comprises a thermoset polymer and an ionic liquid.#14504416vl4. The article of any one of claims 1-3, wherein the elongated nanostructures comprise nanotubes, nanofibers, or nanowires.

5. The article of any one of claims 1-4, wherein the domain comprises: a first dimension having a length of at least 1 centimeter; and a second dimension that is perpendicular to the first dimension, the second dimension having a length of at least 1 centimeter.

6. The article of claim 5, wherein the domain comprises a third dimension that is perpendicular to the first dimension and the second dimension, the third dimension having a length of at least 1 micrometer.

7. The article of any one of claims 5-6, wherein the first dimension of the domain is substantially parallel to longitudinal axes of the elongated nanostructures.

8. The article of any one of claims 1-7, wherein the elongated nanostructures are electronically conductive.

9. The article of claim 8, wherein the article is an electrode.

10. The article of any one of claims 1-9, wherein the domain is a first domain and the plurality of elongated nanostructures are a first plurality of elongated nanostructures, and wherein the article further comprises: a second domain over the first domain, the second domain comprising: the ionically conductive matrix; and a second plurality of elongated nanostructures distributed within the ionically conductive matrix, wherein: within the second domain, the second plurality of elongated nanostructures occupy a volume fraction of at least 10 vol%; and#14504416vlless than or equal to 20 vol% of the second domain is occupied by gas / vacuum closed-cell voids having a volume of at least 1012nm3.

11. The article of claim 10, wherein the article further comprises: a third domain over the second domain, the third domain comprising: the ionically conductive matrix; and a third plurality of elongated nanostructures distributed within the ionically conductive matrix, wherein: within the third domain, the third plurality of elongated nanostructures occupy a volume fraction of at least 10 vol%; and less than or equal to 20 vol% of the third domain is occupied by gas / vacuum closed-cell voids having a volume of at least 1012nm3.

12. The article of claim 11, wherein the ionically conductive matrix forms a continuous phase across the first domain, the second domain, and the third domain.

13. The article of any one of claims 1-7, wherein the elongated nanostructures are electronically insulating.

14. The article of claim 13, wherein the article is a separator.

15. An energy storage device, comprising: the article of any one of claims 1-14.

16. The energy storage device of claim 15, wherein the energy storage device is a supercapacitor.

17. The energy storage device of claim 15, wherein the energy storage device is a battery.

18. A method, comprising:#14504416vlarranging a plurality of elongated nanostructures at least partially within an ionically conductive matrix and / or an ionically conductive matrix precursor to form an arrangement of elongated nanostructures and ionically conductive matrix and / or ionically conductive matrix precursor; applying pressure to the arrangement to densify the elongated nanostructures; heating the arrangement; and forming a domain of elongated nanostructures distributed within ionically conductive matrix, wherein: within the domain, the elongated nanostructures occupy a volume fraction of at least 10 vol%; less than or equal to 20 vol% of the domain is occupied by gas / vacuum closed-cell voids having a volume of at least 1012nm3; and within the domain, the ionically conductive matrix has an ionic conductivity, with respect to at least one monovalent ion and / or at least one divalent ion, of at least 10'7S / cm.

19. A method, comprising: arranging a plurality of elongated nanostructures at least partially within an ionically conductive matrix and / or an ionically conductive matrix precursor to form an arrangement of elongated nanostructures and ionically conductive matrix and / or ionically conductive matrix precursor; applying pressure to the arrangement to densify the elongated nanostructures; heating the arrangement; and forming a domain of elongated nanostructures distributed within ionically conductive matrix, wherein: within the domain, the elongated nanostructures occupy a volume fraction of at least 10 vol%; less than or equal to 20 vol% of the domain is occupied by voids having a volume of at least 1012nm3; and#14504416vlwithin the domain, the ionically conductive matrix has an ionic conductivity, with respect to at least one monovalent ion and / or at least one divalent ion, of at least 10'7S / cm.

20. The method of any one of claims 18-19, wherein the applying pressure to the arrangement and the heating the arrangement are performed at least partially concurrently.

21. The method of any one of claims 18-20, wherein the method further comprises applying a vacuum to the arrangement.

22. The method of claim 21, wherein the vacuum is applied at an absolute pressure greater than 0 and less than 1 atm.

23. The method of any one of claims 18-22, wherein the arranging comprises: growing the elongated nanostructures from a substrate; rearranging the elongated nanostructures from a first position that is substantially non-parallel to the substrate to a second position that is substantially parallel to the substrate; and adding the ionically conductive matrix and / or the ionically conductive matrix precursor to the elongated nanostructures.

24. The method of any one of claims 18-23, wherein the domain is a first domain, and wherein the method further comprises: providing a second domain of elongated nanostructures distributed within ionically conductive matrix over the first domain, wherein: within the second domain, the elongated nanostructures occupy a volume fraction of at least 10 vol%; less than or equal to 20 vol% of the second domain is occupied by gas / vacuum closed-cell voids having a volume of at least 1012nm3; and#14504416vlwithin the second domain, the ionically conductive matrix has an ionic conductivity, with respect to at least one monovalent ion and / or at least one divalent ion, of at least 10'7S / cm.

25. The method of claim 24, wherein the method further comprises: providing a third domain of elongated nanostructures distributed within ionically conductive matrix over the second domain to form an arrangement of domains, wherein: within the third domain, the elongated nanostructures occupy a volume fraction of at least 10 vol%; less than or equal to 20 vol% of the third domain is occupied by gas / vacuum closed-cell voids having a volume of at least 1012nm3; and within the third domain, the ionically conductive matrix has an ionic conductivity, with respect to at least one monovalent ion and / or at least one divalent ion, of at least 10'7S / cm.

26. The method of claim 25, wherein the method further comprises: applying pressure to the arrangement of domains; and heating the arrangement of domains such that the ionically conductive matrix forms a continuous phase across the first domain, the second domain, and the third domain.

27. The method of claim 26, wherein the applying pressure to the arrangement of domains and the heating the arrangement of domains are performed at least partially concurrently.

28. The method of any one of claims 26-27, wherein the method further comprises applying a vacuum to the arrangement of domains.

29. The method of claim 28, wherein the vacuum is applied at an absolute pressure greater than 0 and less than 1 atm.

30. A bulk nanocomposite laminating (BNL) process comprising:#14504416vla. using vertically aligned carbon nanotubes (VA-CNTs) as scaffolds, boron nitride is coated over the VA-CNTs by a thermal catalytic chemical vapor deposition (CVD) process; and b. the CNTs are removed by thermal oxidation process to produce boron nitride nanotubes (BNNTs) that consist of a dense VA-BNNT forest.

31. The BNL process of claim 30, further comprising: a. placing a non-porous Teflon (GNPT) release film on top of the VA- BNNT forests to produce a VA-BNNT array; b. cutting a single layer of the VA-BNNT array to produce a single ply of knockdown BNNTs (K-BNNTs) stuck to the GNPT film; and c. repeating (a) and (b) to produce vertically aligned BNNTs (VA-BNNTs).

32. A nanocomposite, comprising: a. electrodes comprised of carbon nanotubes (CNTs), wherein the CNTs are horizontally aligned with a high aspect ratio (105length / diameter) and a high (50 vol%) packing fraction; and b. a separator comprised of electrically insulating NTs, nominally aligned boron nitride nanotubes (BNNTs) and an ionically conductive polymer (or ceramic or other) matrix; wherein the nanocomposite is made by the BNL process of claim 30.

33. The nanocomposite of claim 32, wherein the electrodes and separator are thin (0=10 pm).

34. A supercapacitor comprising the nanocomposite of claim 32.

35. A battery comprising the nanocomposite of claim 32.#14504416vl

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