CARBON NANOTUBE AND POLYMER COMPOSITE FOR DRY-PROCESSED BATTERY ELECTRODES

Abstract

A solvent-free process uses a composite comprising carbon nanotubes and a polymer to prepare compositions and electrodes for lithium-ion batteries. The carbon nanotubes in the composite may be multifunctional, providing two or more desirable characteristics, acting, for example, as a conductive carbon additive, as a treatment agent, for example, of fibrillation, and / or as a mechanical reinforcement. The composite may be combined with an electroactive and binder material; the binder may be treated, for example, fibrillated, in the presence of the carbon nanotubes in the composite. The resulting composition may be formed into a film that can be applied to a suitable substrate to form an electrode.

Description

Title of the invention: CARBON NANOTUBE AND POLYMER COMPOSITE FOR DRY-PROCESSED BATTERY ELECTRODES

[0001] REFERENCE TO RELATED APPLICATIONS

[0002] The present application claims the benefit, under 35 USC 119, of U.S. Provisional Application No. 63 / 569,822 filed on March 26, 2024, the disclosure of which is hereby incorporated by reference in its entirety. TECHNICAL BACKGROUND

[0003] Lithium-ion batteries (LIBs) are commonly used electrical power sources for many applications ranging from electronic devices to electric vehicles. A lithium-ion battery typically includes a negative electrode and a positive electrode arranged to allow lithium ions and electrons to move to and from the electrodes during charging and discharging. An electrolyte solution in contact with the electrodes provides a conductive medium in which the ions can move. To prevent a direct reaction between the electrodes, an ion-permeable separator is used to physically and electrically isolate the electrodes.During operation, electrical contact is made between the electrodes, allowing electrons to flow within the device to provide electrical energy, and lithium ions to move within the electrolyte from one electrode to the other.

[0004] Most commercially available lithium-ion batteries have anodes that contain graphite, a material capable of incorporating lithium through an intercalation mechanism. Typically, lithium is added to the graphite anode during the charging cycle and removed as the battery is used. Other anode materials used in addition to or instead of graphite include lithium titanate, tin oxide, silicon (Si), and SiOx (x typically being 1.04, 1.06, etc.). In illustrative examples, the anode comprises graphite and / or a silicon-containing compound.

[0005] The cathodes comprise a conductive substrate supporting a mixture containing at least one electrochemically active material and a binder. The electroactive material, such as a lithium transition metal oxide, is capable of receiving and releasing lithium ions. As with the anode, the binder is used to ensure the mechanical integrity and stability of the electrode.

[0006] Since the electroactive material and the binder often have poor electrical conduction or even insulation properties, the cathodes include often an additive that improves the electrical conductivity of the electrode. Conductive additives, e.g., carbon conductive additives, can also be found in LIB anode compositions

[0007] To manufacture the electrode, the active material of the electrode is mixed with a binder, usually a polymer material or a resin. Many existing manufacturing methods use casting techniques based on wet slurries that contain not only the binder, but also solvents, plasticizers, favorable additives, etc. During manufacturing, the slurry is coated or extruded onto a conductive substrate. Since the solvent is detrimental to the final product, it is removed by drying.

[0008] However, drying operations, especially those aimed at removing solvents, are time-consuming, which slows down the overall production process. In addition, they can lead to costs and environmental problems. With regard to the final product, solvent removal during the drying process often results in binder migration to the electrode surface. While minimal migration may be acceptable in some cases, it is problematic in others. For highly charged electrodes (thick, > 4.5 mAh / g), for example, migration is exacerbated, leading to delamination and poor electrode performance.

[0009] Therefore, "dry" alternatives, aimed at reducing or eliminating the drying step associated with slurry techniques, are being developed. Although dry processes also produce electrodes that generally contain an electroactive material, a binder and a conductive additive, they do not require the use of a solvent.

[0010] Dry approaches that have been proposed include high shear mixing involving a fibrillable binder, the use of a sacrificial binder removed during electrode processing, dry powder spraying, electrostatic spray deposition, cold plasma deposition, sputter deposition, powder printing, to name a few. In some cases, a fibrillation promoter is incorporated into the binder and the resulting formulation is subjected to high shear mixing to fibrillate the binder, thereby generating a web-like structure that can better hold the materials together and support the active material.

[0011] To date, the most commonly used additive to promote binder fibrillation is activated carbon (AC). Generally, AC is derived from carbonaceous materials such as bamboo, coconut bark, willow peat, wood, coir, lignite, coal, and petroleum pitch. Activation is achieved by physical or chemical approaches, as is known in the art. For many applications, the CA powders are ground to particle sizes of tens of microns (pm) before being activated. Summary of the invention

[0012] Although dry manufacturing processes can eliminate many of the problems posed by the addition and / or removal of (often harmful) solvents, problems remain.

[0013] For example, many "dry" manufacturing techniques utilize not only the active electrode material but also many other ingredients such as fibrillation promoters, conductive additives, and binders. Since many of these components do not participate in the electrochemical reactions that generate electrical energy, they can negatively impact certain performance characteristics (e.g., capacity and energy density) of the battery because they effectively reduce the amount of active material that can be contained in a given volume.

[0014] State-of-the-art fibrillating agents, such as CAs, often contain high levels of impurities. In addition, the high surface areas and oxygen-containing surface groups typical of CAs tend to promote significant water absorption. These characteristics can contribute to irreversible capacity losses, thereby decreasing battery performance. Furthermore, CAs do not provide sufficient conductivity, making it necessary to increase the amounts of conductive additives in the overall formulation. Even as a simple fibrillation promoter, CA often requires relatively high loadings (5-10 wt. %, in many cases), which, in itself, also limits the amount of active materials that can be included.

[0015] It has been discovered that CA can be supplemented and often entirely replaced by carbon nanotubes (CNTs), as described, for example, in International Patent Application No. PCT / US24 / 20620, filed March 20, 2024, incorporated herein in its entirety by this reference.

[0016] For many applications, CNTs can have a multifunctional character, providing two or more desirable characteristics. For example, carbon nanotubes can act as a fibrillation aid, serving as a substitute for CA, as a conductive carbon additive (by forming electrically conductive networks), and / or as a mechanical reinforcement, adding mechanical strength and flexibility to a produced film / electrode.

[0017] One of the problems encountered when mixing CNTs with other ingredients without solvent, however, is the potential release of airborne particles, which poses health and safety concerns. With an exposure limit At the total weight average (TWA) of 1 microgram per cubic meter (iig / m3) of particles in 8 hours, CNT-derived particulate emissions can become problematic for industrial-scale manufacturing. The limited dispersibility of CNTs is another challenge.

[0018] There is therefore a need for compositions and processes that address at least some of these problems.

[0019] The ingredients involved in the process, composition, and / or articles described herein include: an electroactive component (a material or combination of materials that participates in the electrochemical charge / discharge reactions of an electrochemical cell, e.g., by absorbing or desorbing lithium); a binder; and CNTs. In some embodiments, the CNTs are provided as components of a CNT-polymer composite. In one example, the polymer of the CNT-polymer composite is PTFE. In another, the polymer is polyvinylpyrrolidone (PVP). Other polymeric materials may be used.

[0020] In many embodiments presented herein, the CNT-polymer composite is prepared in the presence of a liquid, in an aqueous medium, for example. For example, the CNT component, the polymer component, or both may be provided in a dispersion and combined to form a mixture that is then dried. The method may also include an agglomeration step, often performed prior to the drying operation, in which the fine CNT-polymer particles are aggregated or "granulated" to form larger entities. In one example, the CNT-polymer granules have a particle size of between about 0.5 and about 30 millimeters (mm) in either direction.

[0021] The CNT-polymer composite may be used to prepare an electrode composition by a dry or solvent-free process that involves combining the electroactive material, the binder, and the CNT-polymer composite, and treating the binder (and, in some cases, also the polymer in the composite) in the presence of CNTs. In general, the binder may be any semi-crystalline polymer. Accordingly, the method may be carried out with binders conventionally considered "fibrillable" as well as with those conventionally considered "non-fibrillable" binders; combinations thereof may also be used.

[0022] Generally, the dry process described herein is carried out without the use of a liquid (e.g., a solvent). In many cases, the ingredients, including the CNT-polymer composite, are provided as free-flowing particulate materials such as free-flowing or flowable powders, flakes, beads, granules, pellets, etc.

[0023] However, it is possible, in certain cases, to use small quantities of liquid (solvent, for example) to implement the method described herein, generally in a step other than the fibrillation or binder treatment step. Generally, if a liquid is added, the amounts used do not exceed about 10% by weight of the total weight of the ingredients used. Often, the liquid, for example the solvent, is added in an amount not exceeding 1% by weight.

[0024] Thus, in one embodiment, a method of preparing an electrode composition comprises: combining an active electrode material, a fibrillable binder and a CNT-polymer composite; and treating the binder in the presence of the CNT-polymer composite, the method being carried out in the absence of a solvent.

[0025] In another embodiment, a method of preparing an electrode composition comprises: treating a binder (by subjecting the binder to high shear conditions, for example) in the presence of a CNT-polymer composite, and adding an electrode active material before, during, or after treating the binder, the method being carried out without adding a solvent.

[0026] The electroactive material, the binder, for example a fibrillable binder, and the CNT-polymer composite may be combined in a single step, followed by processing of the binder, a fibrillation operation, for example. In other embodiments, the components are combined and / or processed sequentially. For example, the binder, in the presence of the CNT-polymer composite, may be processed, for example fibrillated, first, followed by mixing with the electroactive material. Other sequences are possible.

[0027] Uniform distributions of constituents can be achieved by using conditions other than (often milder) those used in binder processing, for example, fibrillation. Low shear mixing techniques can also prevent particle fragmentation, thereby preserving particle size.

[0028] In some embodiments, the method described herein is carried out without adding any fibrillating agent other than the CNTs in the CNT-polymer composite. In this case, the CNTs perform all of the binder processing functions (e.g., fibrillation), completely replacing conventional fibrillating agents such as activated carbons, for example. It is also possible to use the CNTs in the CNT-polymer composite in combination with various amounts of a conventional fibrillating agent, such as an activated carbon, for example.

[0029] The resulting electrode composition, generally a free-floating particulate material, may be further processed. For example, the composition may be formed into a free-floating film that may be applied to an electrically conductive substrate or support to form an electrode. In one approach, the composition is calendered and laminated to a conductive foil substrate. The calendering operation may be carried out at room temperature or at a higher temperature, for example, at a temperature similar to or close to the temperature of glass transition of the binder polymer. The rolling step can be performed during or after calendering of the composition. The resulting electrode can be assembled into a LIB battery.

[0030] In another aspect, the disclosure relates to a dry-processed film which comprises an active electrode material, a binder, generally processed, for example fibrillated, and CNTs (initially provided as a CNT-polymer composite). The dry-processed film also contains the polymer of the CNT-polymer composite, a component which may be identified in some cases (when using a different polymer than the binder, for example). Before any drying operation, the dry-processed film has a weight equal to or less than 1% by weight (wt%) of its theoretical weight.

[0031] The CNT-polymer composite described herein facilitates the incorporation of CNTs into electrode compositions without the need for slurry-based manufacturing techniques. The provision of CNTs in a dry CNT-polymer composite also addresses health and safety concerns that may arise in the context of solvent-free manufacturing. In some implementations, the polymer of the CNT-polymer composite and the polymer of the binder are compatible with each other, facilitating mixing, elongation, and fibrillation of the binder, and improving the distribution of the binder between other electrode components and throughout the electrode. The use of CNTs bound to a polymer matrix results in products (e.g., films or electrodes) that perform at least as well as products prepared with polymer-free CNTs.

[0032] The use of CNTs can impart a number of desirable properties to a dry-processed electrode film and / or electrode, including, for example, electrical conductivity, desirable physical properties, for example, good tensile strength, thermal stability (sometimes comparable to that of diamond crystals or in-plane graphite sheets), and / or chemical stability, to name a few. The addition of CNTs can reduce the amount of binder and / or conventional processing additives required in the manufacturing process, thereby increasing the potential loading of active materials and leading to higher energy density electrodes and thus batteries.

[0033] The approaches described herein may reduce or eliminate the need for CA. In many cases, smaller amounts of additives are required, increasing the available content allowed for active electrode materials, resulting in batteries with higher energy densities and longer lifetimes. CNTs may improve binder fibrillation and material distribution across the electrode. Improved adhesion and mechanical stability represent yet other potential benefits. Dry-processed electrodes prepared using a CNT-polymer composite are expected to exhibit good transfer Reducing electrode impedance with a CNT-based additive can improve cell capacity and charging performance, opening up opportunities for thicker electrodes and higher energy density batteries with fast charging capabilities.

[0034] In some cases, the initial CNTs present in the composite may be broken or separated into smaller units during processing. It is believed that such fragments, distributed, for example, uniformly, in an electrode composition, may lead to electrodes having improved mechanical properties and / or electrical connectivity (by forming improved electrical pathways) in the resulting electrode.

[0035] While binder migration phenomena are often observed with electrodes prepared from slurry, the method and composition described herein appear to produce uniform distributions throughout the electrode. The fibrillated binder holds the electroactive particles (as well as the conductive additives) together (cohesion), while keeping the electrode film layer attached to the metal substrate (adhesion).

[0036] The solvent-free techniques described herein reduce or eliminate the use of harmful solvents such as N-methyl-2-pyrrolidone (NMP) and others. The ability to bypass the drying step associated with slurry (or other "wet" processes) can simplify and speed manufacturing and reduce the footprint of the electrode production line. These benefits, along with reducing or eliminating the need to recycle solvents or take emission reduction measures, can contribute to an overall cost reduction.

[0037] The above and other features of the disclosure, including various details of construction and combinations of parts, as well as other advantages, will now be more particularly described with reference to the drawings which accompany this document and are pointed out in the claims. It is to be understood that the particular method and apparatus embodying the disclosure are shown by way of illustration and not as a limitation of the disclosure. The principles and features of the present disclosure may be used in numerous and diverse embodiments without departing from the scope of the disclosure. BRIEF DESCRIPTION OF THE FIGURES

[0038] In the accompanying drawings, reference characters refer to the same parts in the different views. The drawings are not necessarily to scale; emphasis has been placed on illustrating the principles of the disclosure. In the drawings:

[0039] [Fig.l] corresponds to figures IA (FIG IA), IB (FIG IB) and IC (FIG IC), where: - FIG IA is a schematic diagram and corresponding photograph of a granulated CNT / polymer composite; - FIG IB is a schematic diagram of an intermediate product; and - FIG IC is a schematic diagram and photograph corresponding to a fibrillated product;

[0040] [Fig. 1D] is a series of photographs of a free-standing film prepared using the fibrillated product of FIG. 1C;

[0041] [Fig.2] shows bar charts comparing the tensile strength of dry cathode films prepared with a granulated CNT1 / PVP composite, a CNT2 / PTFE composite and virgin (ungranulated) CNT1s;

[0042] [Fig. 3] includes bar charts comparing the tensile strength (bottom) and elastic modulus (top) of dry cathode films prepared with ungranulated CNT2, ungranulated CNT3 and a granulated CNT3 / PVP-1 composite;

[0043] [Fig.4] includes bar charts comparing the tensile strength (bottom) and elastic modulus (top) of dry cathode films made with granulated CNT3 / PVP composites at different CNT to PVP weight ratios;

[0044] [Fig.5] is a graph showing the 0.5C / 0.1C discharge capacity retention of complete button cells with dry cathodes prepared using granulated NTC3 / PVP-1 composite and granulated NTC3, compared with ungranulated NTC2 and ungranulated NTC3;

[0045] [Fig.6A] is a graph showing the C / 3 capacity cycle of complete button cells with dry cathodes prepared using NTC3 alone and NTC3 / PVP-1 composite up to 330 cycles;

[0046] [Fig.6B] shows the number of cycles for the cell / battery capacity to decrease by 20%, calculated by fitting the linear region of the curves in [Fig.6A].

[0047] [Fig.6C] is a graph showing the comparison of the capacity retention of cells with dry cathodes prepared with granulated NTC3 / PVP-1 composite, granulated NTC3, ungranulated NTC2 and ungranulated NTC3;

[0048] [Fig.7] shows bar charts comparing the tensile strength of dry cathode films prepared with (i) granulated CNT3 or (ii) virgin (ungranulated) CNT3 using a TSE (twin-screw extruder);

[0049] [Fig.8] shows SEM images of the cross-section of the electrode fabricated with granulated CNT3 and the zoomed surface of an NCM particle (left) in this electrode, as well as the EDS (Energy Dispersive Spectroscopy) mapping of F and C (right);

[0050] [Fig.9] shows the rate capacity of dry cathodes made with granulated NTC3 and ungranulated virgin NTC2 using a TSE, tested in complete button cells.

[0051] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0052] The disclosure will be described in more detail below with reference to the accompanying drawings, in which embodiments of the disclosure are illustrated. This disclosure, however, may be embodied in many different forms and should not be construed as being limited to the embodiments shown herein; rather, these embodiments are provided so that this disclosure is complete and comprehensive, and fully conveys the scope of the disclosure to those skilled in the art.

[0053] As used herein, the term "and / or" includes all combinations of one or more of the listed items. Furthermore, all conjunctions used are to be understood in the broadest possible sense. Thus, the word "or" is to be understood as having the definition of a logical "or" rather than a logical "exclusive or," unless the context clearly requires otherwise. Furthermore, the singular forms and the articles "a" and "the" are intended to include the plural forms as well, unless expressly stated otherwise. It is further understood that the terms: includes, comprises, including, and / or comprising, when used in this specification, specify the presence of the indicated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.Further, it is understood that where an element, including a component or subsystem, is referred to and / or shown as being connected or coupled to another element, it may be directly connected or coupled to the other element or intermediate elements may be present.

[0054] It is understood that, although terms such as "first" and "second" are used herein to describe various elements, such elements are not to be limited by such terms. Such terms are used only to distinguish one element from another. Thus, an element discussed below could be referred to as a second element, and likewise, a second element could be referred to as a first element without departing from the teachings of the present disclosure.

[0055] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by a person of ordinary skill in the art to which this disclosure pertains. It is also understood that terms, as defined in commonly used dictionaries, should be interpreted in a sense consistent with their meaning in the context of the relevant field and should not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0056] The disclosure generally relates to the manufacture of electrodes for electrochemical cells, in many cases for batteries such as, for example, LIBs. In one example, the batteries concerned are rechargeable LIBs. Furthermore, the principles described herein may be applied or adapted to lithium metal batteries, for example, lithium-sulfur batteries that include a sulfur-containing cathode, solid-state batteries (SSBs), or other devices.

[0057] Generally, LIB batteries are named after the acronyms of the electroactive material used to form the cathode, often an intercalator compound. The embodiments described herein may be used or adapted to various types of lithium-ion batteries currently known, such as, for example, LCO (lithium cobalt oxide), LMO (lithium manganese oxide), NCM (lithium nickel cobalt manganese oxide), NCA (nickel cobalt aluminum oxide), LCP (lithium cobalt phosphate), LFP (lithium iron phosphate), LFMP (lithium iron manganese phosphate), LFSF (lithium iron fluorosulfate), LTS (lithium titanium sulfide) batteries, or LIBs currently or in the future under development.

[0058] Many techniques for manufacturing electrodes for use in an electrochemical cell include forming an electrode composition (anode or cathode) that can be applied (coated, extruded, laminated, etc.) to a conductive substrate. In the composition, the active electrode material is mixed with a binder (e.g., polymers, resins, etc.), which serves to combine and hold the active materials together. Liquids used to dissolve or transport the binder, plasticizers, and / or other additives are often included.

[0059] Generally, in a conventional solvent-based process, the polymeric binder and other components are mixed with a suitable liquid to form a slurry which can then be applied to the substrate. Typical amounts of liquid employed are at least about 40% of the total weight of the ingredients used; many wet processes require larger amounts of solvent. As the solvent is removed (e.g., during drying), the binder becomes increasingly sticky and adheres to the particles present and / or the substrate.

[0060] Unlike slurry-based techniques, the embodiments described herein involve a "solvent-free" process also referred to as a "dry" process. In this solvent-free approach, some and generally all of the constituents (e.g., active material, binder, additives, etc.) necessary for preparing the electrode composition are provided as free particulate materials, e.g., powders, flakes, granules, beads, and so on. Embodiments described herein may include one or more operations for mixing these constituents (using, for example, equipment designed to mix loose particulate materials) as well as at least one operation for processing the binder. Subjecting the binder to certain shear conditions, for example, may result in binder deformations, such as binder elongations, binder strands, entanglements, etc. With certain types of binders, this is referred to as "fibrillation" of the binder.

[0061] In many aspects of the disclosure, the ingredients are combined and the binder is processed, e.g., fibrillated, without the addition of liquid, e.g., solvent.

[0062] Although most embodiments involve a process without the addition of liquid and completely solvent-free, small amounts of liquid, e.g., a solvent, may be used in some cases to moisten, e.g., at least some of the mixed particles. This may occur, for example, when forming a premix which is then completely dried before subsequent operations. In one example, any solvent used to form such a premix is ​​removed, e.g., by drying, before the binder is deformed. Processing (e.g., fibrillation) of the binder is then carried out with free-flowing, free-flowing, or flowable / pourable particles, under completely solvent-free conditions.

[0063] The solvent may also be used in a subsequent operation (an operation that occurs after the formation of the dry electrode composition), for example, during film fabrication or electrode lamination, particularly to facilitate film processing. Electrode production protocols provide, in some cases, for the use of a small amount of solvent to "wet" the film during calendering, for example. Processes that involve the use of solvents in a subsequent operation, after the electrode composition has been formed, are also referred to herein as "dry" or "solventless." In general, any solvent used (to spray the film during film fabrication or lamination, for example) is removed, for example, by drying, as the electrode passes through heated calendering rolls.

[0064] Suitable solvents may be selected from those generally encountered in the production of LIBs and include, but are not limited to, N-methylpyrrolidone (NMP), acetone, alcohols, and water.

[0065] For many applications, the amount of solvent used does not exceed about and is often less than 1% by weight of the entire electrode composition (a composition containing an electroactive material, a treated, e.g., fibrillated, binder, and other ingredients, an additive component, for example). In illustrative examples, the amount of solvent used is from about 0 to at most 1% by weight, for example, from about 0 to about 0.2, to about 0.4, to about 0.6, to about 0.8% by weight; or from about 0.2, to about 0.4, to about 0.6, to about 0.8, to about 1% by weight; or from about 0.2 to about 0.4, to about 0.6, to about 0.8, to about 1% by weight; or from about 0.4 to about 0.6, to about 0.8, to about 1% by weight; or from about 0.6 to about 0.8, to about 1.0% by weight; or from about 0.8 to about 1% by weight, based on the total weight of the ingredients used.

[0066] In other situations, the solvent may be added in amounts of between about 0 and about 10% by weight, for example, between about 0 and about 2, about 4, about 6 and about 8% by weight; or between about 2 and about 4, about 6, about 8 and about 10% by weight; or between about 4 and about 6, about 8 and about 10% by weight; or between about 6 and about 8 and about 10% by weight; or between about 8 and about 10% by weight; or between about 8 and about 10% by weight.

[0067] If used, the solvent can be removed by standard drying techniques. The low levels of solvent used should be able to be removed completely or almost completely.

[0068] Finished products, e.g., films or films laminated to a current collector, prepared by the dry or solventless process described herein are recognizable by the absence of detectable processing solvents or processing solvent residues. In contrast to such "dry" products, products obtained by wet (slurry) techniques generally contain detectable processing solvents and / or processing solvent residues. In a different approach, dry electrodes or films prepared according to embodiments of the disclosure are expected to have a uniform or substantially uniform distribution of binder throughout the thickness of the electrode or film; in general, less uniformity is observed with wet techniques, which often lead to migration of binder to the surface of a film.

[0069] With respect to the constituents used, the solvent-free method described herein involves: an electroactive component (a material or combination of materials that participates in the electrochemical charge / discharge reactions of an electrochemical cell, for example by absorbing or desorbing lithium); a binder, which may be a fibrillable or non-fibrillable binder; and a carbon additive component. Certain aspects of the disclosure relate to a carbon additive component that consists of, consists essentially of, or comprises carbon nanotubes (CNTs) and a polymer, in a CNT-polymer composite, for example.

[0070] As is known, carbon nanotubes are carbonaceous materials, generally hydrophobic, characterized by at least one sheet of sp2 hybridized carbon atoms bonded to each other to form a honeycomb network that forms a cylindrical or tubular structure. The carbon atoms of a nanotube carbon are arranged in a hollow (e.g., cylindrical) structure, the length of which is usually greater than the radial diameter.

[0071] CNTs can have different morphologies, including single-walled carbon nanotubes (SWCNTs) or multi-walled carbon nanotubes (MWCNTs). SWCNTs can be considered an allotrope of sp2 hybridized carbon similar to fullerenes. The structure is a cylindrical tube comprising six-membered carbon rings. Double-walled carbon nanotubes (DWCNTs) have similar properties to SWCNTs. The analogous MWCNTs, on the other hand, have multiple tubes in concentric cylinders. The number of these concentric walls can vary, for example, from 2 to 25 or more. Typically, the diameter of MWNTs can be 10 nm or more, compared to 0.7 to 2.0 nm for typical SWCNTs.

[0072] Based on chirality, CNTs are classified into armchair, zigzag and chiral nanotubes.

[0073] Carbon nanotubes can provide excellent electrical and thermal conductivity, as well as good mechanical properties. Due to their high conductivity, carbon nanotubes are increasingly used as conductive additives in lithium-ion battery electrodes. They can improve battery performance such as power, cycle life, and energy density.

[0074] In some of the manufacturing processes described herein, CNTs provide multiple benefits (a characteristic termed "multifunctional"), serving, for example, as binder fibrillating agents (or, in some cases, binder deformation), conductive additives (generating conductive networks, e.g., the long-range conductivity of the electrode), and mechanical strengthening aids (providing mechanical support, stability, and / or flexibility to the electrode product, often the coating, layer, or film typically applied to the conductive substrate to form a battery electrode). In many cases, these multiple benefits can be achieved by supplementing or entirely replacing conventional fibrillating agents (e.g., CAs) with CNTs.

[0075] Single or multi-walled CNTs may be used, as may mixtures of two or more different types of CNTs. The number of walls present if MWCNTs are used, determined, for example, by transmission electron microscopy (TEM), at a magnification sufficient to analyze the number of walls in a particular case, may be between about 2 and about 30, for example: 4 to 30; 6 to 30; 8 to 30; 10 to 30; 12 to 30; 14 to 30; 16 to 30; 18 to 30; 20 to 30; 22 to 30; 24 to 30; 26 to 30; 28 to 30; or 2 to 28; 4 to 28; 6 to 28; 8 to 28; 10 to 28; 12 to 28; 14 to 28; 16 to 28; 18 to 28; 20 to 28; 22 to 28; 24 to 28; 26 to 28; or 2 to 26; 4 to 26; 6 to 26; 8 to 26; 10 to 26; 12 to 26; 14 to 26; 16 to 26; 18 to 26; 20 to 26; 22 to 26; 24 to 26; or 2 to 24; 4 to 24; 6 to 24; 8 to 24; 10 to 24; 12 to 24; 14 to 24; 16 to 24; 18 to 24; 20 to 24; 22 to 24; or 2 to 22; 4 to 22; 6 to 22; 8 to 22; 10 to 22; 12 to 22; 14 to 22; 16 to 22; 18 to 22; 20 to 22; or 2 to 20; 4 to 20; 6 to 20; 8 to 20; 10 to 20; 12 to 20; 14 to 20; 16 to 20; 18 to 20; or 2 to 18; 4 to 18; 6 to 18; 8 to 18; 10 to 18; 12 to 18; 14 to 18; 16 to 18; or 2 to 16; 4 to 16; 6 to 16; 8 to 16; 10 to 16; 12 to 16; 14 to 16; or 2 to 14; 4 to 14; 6 to 14; 8 to 14; 10 to 14; 12 to 14; or 2 to 12; 4 to 12; 6 to 12; 8 to 12; 10 to 12; or 2 to 10; 4 to 10;6 to 10;8 to 10;or 2 to 8;4 to 8;6 to 8;or 2 to 6; 4-6; or 2 to 4.

[0076] In many applications, the CNTs used are conventional (also referred to as "plain", "virgin" or "fresh") CNTs, which are often supplied in individualized form, as commercially manufactured or, in some cases, as custom synthesized or processed.

[0077] In general, CNTs are known to contain significant amounts of catalyst and support residues. These species can be detected by techniques such as SEM, TEM, inductively coupled plasma atomic emission spectroscopy (ICP-AES), etc.

[0078] The CNTs may have a diameter of 100 nanometers (nm) or less, such as, for example, in a range of about 1 to about 100 nm, for example, in a range of about 5 to about: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 nm; or about 10 to about: 20, 30, 40, 50, 60, 70, 80, 90, 100 nm; or about 20 to about: 30, 40, 50, 60, 70, 80, 90, 100 nm; or about 30 to about: 40, 50, 60, 70, 80, 90, 100 nm; or from about 40 to about: 50, 60, 70, 80, 90, 100 nm; or from about 50 to about: 60, 70, 80, 90, 10 nm; or from about 60 to about: 70, 80, 90, 100 nm; or from about 70 to about: 80, 90, 100 nm; or from about 80 to about 90, 100 nm; or from about 90 to about 100 nm.

[0079] Specific embodiments utilize CNTs having a diameter of between about 2 nm and about 50 nm, as determined by TEM. For example, the CNTs utilized may have a diameter of between about 2 and about: 5, 10, 20, 30, 40 nm; or about 5 to about: 10, 20, 30, 40, 50 nm; or about 20 to about: 30, 40, 50 nm; or about 30 to about: 40, 50 nm; or about 40 to about 50 nm. In one example, the CNTs have a diameter of between about 5 and about 25 nm.

[0080] The length of the CNTs can vary from about 10 nanometers (nm) to about 750 microns (pm), or more. Thus, the CNTs can be from 10 nm to 100 nm, from 10 nm to 500 nm, from 10 nm to 750 nm, from 10 nm to 1 micron, from 10 nm to 1.25 microns, from 10 nm to 1.5 microns, from 10 nm to 1.75 microns, from 10 nm to 2 microns, or from 100 nm to 500 nm, from 100 nm to 750 nm, from 100 nm to 1 micron, from 100 to 1.25 micron; from 100 to 1.5 micron; from 100 to 1.75 micron; from 100 to 2 microns; from 500 nm to 750 nm; from 500 nm to 1 micron; from 500 nm to 1 micron; from 500 nm to 1.25 micron; from 500 nm to 1.5 micron; from 500 nm to 1.75 micron; from 500 nm to 2 microns; from 750 nm to 1 micron; from 750 nm to 1.25 micron; from 750 nm to 1.5 micron; from 750 nm to 1.75 microns; from 750 nm to 2 microns; from 1 micron to 1.25 microns; from 1.0 micron to 1.5 microns; from 1 micron to 1.75 microns; from 1 micron to 2 microns; or from 1.25 microns to 1.5 microns; from 1.25 microns to 1.75 microns; from 1 micron to 2 microns; or from 1.5 to 1.75 microns; from 1.5 to 2 microns; or from 1.75 to 2 microns.

[0081] In some cases, the CNTs used in the drying process described herein have an average length of between about 1 micron and about 30 microns, for example, between about 1 and about 5, between about 1 and about 10, between about 1 and about 15, between about 1 and about 20, between about 1 and about 25 microns; or from about 5 to about 10, from about 5 to about 15, from about 5 to about 20, from about 5 to about 25, from about 5 to about 30 microns; or from about 10 to about 15, from about 10 to about 20, from about 10 to about 25, from about 10 to about 30 microns; or from about 15 to about 20, from about 15 to about 25, from about 15 to about 30 microns; or from about 20 to about 25, from about 20 to about 30 microns; or from about 25 to about 30 microns.

[0082] In some embodiments, at least one of the CNTs has a length equal to or greater than 2 microns, as determined by SEM. In some embodiments, more than one, for example, a portion such as a fraction of at least 0.1%, at least 1%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, or even more than half, of the CNTs, as determined by SEM, may have a length greater than 2 microns, for example, within the limits specified above.

[0083] The morphology of CNTs is often characterized by a high aspect ratio, with lengths generally greater than 100 times the diameter, and in some cases much higher.

[0084] CNTs may also be characterized by their surface area. Small diameter single-walled CNTs, for example, may have a specific surface area of ​​up to about 3000 m2 / g, such as up to about 1315 m2 / g, while large diameter multi-walled CNTs are often characterized by a specific surface area of ​​up to about 1000 m2 / g.

[0085] In many embodiments described herein, the CNTs used have a Brunauer-Emmett-Teller (BET) surface area, measured, for example, according to the ASTM standard D6556-10, which is less than about 500 m2 / g, such as, for example, less than or equal to 400 m2 / g; or less than or equal to 300 m2 / g.

[0086] In some embodiments, the CNTs have a BET surface area of ​​about 80 to about 110, about 80 to about 200, about 80 to about 230, about 80 to about 260, about 80 to about 280, about 80 to about 310, about 80 to about 350 m2 / g; or about 110 to about 200, about 110 to about 230, about 110 to about 260, about 110 to about 280, about 110 to about 310, about 110 to about 350 m2 / g; or from about 230 to about 260, from about 230 to about 280, from about 230 to about 310, from about 230 to about 350 m2 / g; or from about 260 to about 280, from about 260 to about 310, from about 260 to about 350 m2 / g; or from about 280 to about 310, from about 280 to about 350 m2 / g; or from about 310 to about 360 m2 / g.

[0087] In some cases, the BET surface area of ​​the CNTs is between about 80 and 500, for example between about 200 and 500 m2 / g. In specific examples, the CNTs have a BET surface area of ​​between about 200 and about 250, 300, 350, 400, 450, 500 m2 / g; or between about 250 and about 300, 350, 400, 450, 500 m2 / g; or between about 250 and about 500 m2 / g: 300, 350, 400, 450, 500 m2 / g; or from about 300 to about: 350, 400, 450, 500 m2 / g; or from about 350 to about: 400, 450, 500 m2 / g; or from about 400 to about: 450, 500 m2 / g; or from about 450 to about 500 m2 / g. In one example, the CNTs used have a BET of between about 190 and about 280 m2 / g.

[0088] The CNTs may have a bulk density, calculated, for example, as the weight of the CNT powder, freely dropped and unpacked into the cylinder, divided by the volume the powder occupies, in a range of about 0.01 to about 0.3, for example, about 0.01 to about 0.2, such as about 0.03 g / cm3. Further consolidation, compaction, or densification, as measured by the packed density, may bring the bulk density to a range of about 0.03 g / cm3 to about 0.5 g / cm3.

[0089] The CNTs used herein may be identified and / or characterized by various techniques. Electron microscopy, including techniques such as transmission electron microscopy (TEM) and scanning electron microscopy (SEM), for example, may provide information on characteristics such as the frequency of the specific number of walls present, the diameter, length and branching of the tube, the presence of catalyst particles, etc.

[0090] Raman spectroscopy is often used to characterize the state of carbon in carbonaceous materials. For example, a D band (around 1350 cm1) is associated with sp3- carbon, while a G band (around 1580 cm1) is associated with sp2- carbon in graphite or CNTs. A G' band (around 2700 cm1) is expected to appear at a frequency about twice that of the D band. In some cases, it may be possible to distinguish between CNTs used in the disclosure practice and other carbon structures by thermogravimetric analysis (TGA).

[0091] Other properties of CNTs to be considered in multifunctional CNT candidates relate to their physical form. The size of CNT particles, for example, is a property that can be determined by particle size distribution (PSD) techniques and / or scanning electron microscopy (SEM). For example, a particle size analyzer can be used to measure the intensity of scattered light by laser diffraction to perform a particle size measurement. The average particle size (D50) is the particle size range based on 50% of the particle size distribution of the dispersion. In specific examples, the CNTs have a D50 of less than or equal to 30, often less than or equal to 20, or in many cases less than or equal to 15 microns.

[0092] Due to strong van der Waals interactions, for example along their length, CNTs can easily form aggregates such as bundles, ropes or agglomerates. CNTs can occur as substantially parallel "forests", masses ("pillows") of randomly entangled structured agglomerations or other types of aggregates.

[0093] In some applications, the aggregates are designed to have sufficient strength to fibrillate the binder, while still disaggregating to some extent, generating smaller fragments that can be distributed throughout the composition, thereby producing a uniform distribution of CNTs.

[0094] In many cases, the CNT material has a CNT purity of 97% or more. Typically, anionic, cationic, or metallic impurities are low, for example, in the order of a few parts per million (ppm). Often, the CNTs used herein do not require further additives to counteract Van der Waals forces.

[0095] Commercially available CNT materials that may be used include, but are not limited to, those available from Cabot Corporation under the brand name ENERMAX® carbon nanotubes, from CNano under the brand name FT, from LG Chem under the brand name Lucan.

[0096] The CNTs used in the CNT-polymer composites described herein may undergo further processing or modification. The CNT granules, for example, may be produced by compressing powder or by mixing a CNT powder with a liquid, usually water, followed by oven drying.

[0097] In some cases, the processing step or modification enhances the multifunctionality of the CNTs. In one approach, the CNT material is pre-ground, using, for example, high shear mixing apparatus such as, for example, jet mills, ball mills, extruders, homogenizers, etc. In Table 1 below, CNT3 is a pre-ground version of CNT2.

[0098] Generally, pre-grinding is performed before the CNTs are mixed with the fibrillable binder and / or the electrode active material, and often before the CNT-polymer composite is prepared. Pre-grinding may be performed dry, with the CNTs being pre-ground into a dry powder form. In some cases, however, the pre-grinding operation may involve a solvent. In this case, the solvent may be removed by thermal drying, freeze-drying, or vacuum drying.

[0099] A pre-grinding operation, possibly combined with a drying step (if a solvent is used), can increase the electrochemical performance and fibrillation potential of the CNTs. Pre-grinding can also have positive mechanical effects on the film and / or electrode. Without wishing to be bound by a particular interpretation, it is believed that the smaller particles of the pre-grinded (also referred to herein as "pulverized") material can be dispersed more uniformly in the composition, thus improving the electrical and mechanical properties of the product (film or electrode).

[0100] An illustrative CNT-polymer composite contains pulverized CNTs having a D50 of no greater than about 15 microns.

[0101] In another approach, the CNTs used in the CNT-polymer composite are entirely free of oxygen-containing surface groups or have a reduced number of oxygen-containing surface groups. The reduction or absence of oxygen-containing groups such as -OH, -O-, -COOH, etc., increases the hydrophobicity of the additive and therefore increases the affinity of the CNTs with a hydrophobic polymer or a fibrillable binder such as PTFE. One technique for removing oxygen-containing groups from the CNTs is heat treatment, which can be carried out in a vacuum oven, for example.

[0102] In addition to improving the hydrophobicity of CNTs, heat treatment can also improve their electrical conductivity and reduce or minimize impurities (such as those left over from CNT manufacturing) that can interfere with and negatively impact cyclic performance, hot storage, and / or battery safety. Other techniques may be employed to remove impurities, including acid washing, a combination of heat treatment and acid washing, or other techniques. In some approaches, the acid treatment includes oxidation with HNO3, H2SO4, HCl, HF, alone or in combination with others, or graphitization. Other possible approaches include wetting MWCNTs with dimethylformamide (DMF), first oxidized, then suspended in nitric acid.

[0103] CNTs can be doped (with boron, for example), provided with a graphene wing or treated in another way.

[0104] More than one process and / or modification may be undertaken. For example, the CNTs may be heat treated and pre-milled.

[0105] Thus, in general, the CNT-polymer composite described herein may utilize CNTs without further processing or modification (e.g., unmilled (e.g., unpulverized), unheat-treated, unacid-washed, etc.), pulverized (pre-milled), modified powders, e.g., heat-treated CNTs, acid-washed CNTs, etc. In some cases, the type of CNTs used may be determined by TEM, X-ray tomography, or other techniques. Good multifunctional properties are often reflected in the quality of the resulting film, electrode, or battery.

[0106] Mixtures of two or more CNTs may be used in some cases. For example, the CNTs may form or be compounded to form mixtures of CNTs with various combinations and distributions of the aforementioned characteristics (number of walls, diameters, lengths, morphologies, orientations, etc.)

[0107] Table 1 below presents the physical properties characterizing the illustrative CNTs, namely CNTs1 to CNTs 10.

[0108] [Tableauxl] NTC Type BET, m2 / g Diameter, nm Apparent Density, g / cm3 PSD (pm) D50 NTC 1 208.41 10-20 0.06 <15 NTC 2 265.6 9-12 0.12 133-135 NTC 3 261.6 9-12 0.0308 15 NTC 4 / 9-12 / <15 NTC 5 300.41 5-10 0.092 60 NTC 6 225.59 10-20 0.16 55 NTC 7 101.22 30-50 0.149 80 NTC 8 268.8 5-10 0.0189 15-16 NTC 9 229.7 10-20 0.0614 11-15 NTC 10 91.2 30-50 0.0511 9-15

[0109] Some embodiments use CNTs in combination with another material, one or more types of carbon black (CB), for example. In specific embodiments, the carbon black is multifunctional, as described, for example, in U.S. Provisional Patent Application No. 63 / 322,074, filed March 21, 2022, and in International Patent Application No. PCT / US23 / 64614, filed March 17, 2023, published as WO2023 / 183754 A1 on September 28, 2023), both entitled Solvent-Free Processes for Preparing Lithium-Ion Batteries and both incorporated herein by this reference.

[0110] The CNTs may also be combined with a polymeric material. In many aspects of the disclosure, the CNTs are a component of a CNT-polymer composite. The polymer present in the CNT-polymer composites described herein serves as a glue, connecting, bonding, and providing connectivity to the CNTs, thereby mitigating health and safety concerns related to the potential release of airborne particles that may arise in solvent-free manufacturing. The presence of polymer in the CNT-polymer composite may further facilitate the incorporation of the CNTs into electrode compositions by interacting with the binder polymer, facilitating mixing, and facilitating the dispersibility of the CNT-polymer composite.

[0111] For many applications, the polymer used in the CNT-polymer composite is a per- and polyfluoroalkyl substance (PFAS), such as polytetrafluoroethylene (PTFE). In other cases, the CNT-polymer composite contains polymers free of per- and polyfluoroalkyl substances (PFAS), such as polyvinylpyrrolidone (PVP) or polyethylene glycol (PEG). It is also possible to use combinations of polymers containing or not containing PFAS.

[0112] Other examples of polymeric constituents that may be employed include, but are not limited to, other fluoropolymers such as poly(vinyldifluoroethylene) (PVDF), poly(vinyldifluoroethylene-co-hexafluoropropylene) (PVDF-HFP), polyimides, and water-soluble binders, such as polyethylene oxide, polyvinyl alcohol (PVA), cellulose, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, and copolymers and blends thereof. In some cases, the CNTs used are treated with PTFE, PVP, CMC, or polyethylene glycol (PEG). As with the binders used (described later), the polymer may be fibrillable or non-fibrillable.

[0113] Polymers such as, for example, epoxy, polyester, vinylester, polyetherimide, polyetherketone, polyphthalamide, polyetherketone, polyetherketone, polyimide, phenol-formaldehyde, bismaleimide, acrylonitrile-butadiene-styrene (ABS), polycarbonate, polyethyleneimine, polyurethane, thermoplastic polyurethane, polyvinyl chloride, polystyrene, polyolefins, polypropylene, polyethylene, polyethylene, polytetrafluoroethylene, elastomers such as, for example, polyisoprene, polybutadiene, butyl rubber, nitrile rubber, polytetrafluoroethylene, polyethylene, etc., polypropylene, polyethylene, polytetrafluoroethylene, elastomers such as, for example, polyisoprene, polybutadiene, butyl rubber, nitrile rubber, hydrogenated nitrile butadiene rubber (HNBR, for “hydrogenated nitrile butadiene rubber” in English), polymers ethylene vinyl acetate, silicone polymers and fluorosilicone polymers, combinations thereof,or other polymers or polymer blends may also be used in some cases. In order to improve electrical conductivity, conductive polymers such as, for example, polyanilines, polypyrroles and polythiophenes may also be used.

[0114] The polymer loading in the CNT-polymer composite may be from about 0.1 wt% to about 50 wt% of the composite, for example, from about 0.1 wt% to about 10 wt%. The amount of polymer relative to that of CNTs may be further refined to mitigate safety concerns or to achieve other desired objectives. In various embodiments, the polymer concentration is expressed as a ratio of CNTs to dispersant polymer by weight. An exemplary CNT-polymer composite has a CNT-polymer weight ratio of about 19:1. In another exemplary CNT-polymer composite, the CNT-polymer weight ratio is 200:1. More generally, the CNT-polymer weight ratio present in the composite is between about 1:1 and about 100:0.1, for example between about 10:1 and about 100:0.1.

[0115] The CNT-polymer composite described herein may be prepared by various techniques. Once formed, the composite material may be further processed. In some cases, the composite material is oven-dried or freeze-dried (for subsequent solvent-free manufacturing). Other possible processing steps include, but are not limited to, sieving and / or granulation.

[0116] In one case, the CNTs in powder form are combined with the polymer, also in powder form, by dry mechanical mixing.

[0117] In other approaches, one or both ingredients (CNTs and / or polymer) may be provided in a dispersion, often an aqueous dispersion. In addition to water, aqueous dispersions may include one or more dispersants, e.g., PVP-based dispersants, and / or other ingredients.Suitable dispersants include poly(vinyl pyrrolidone), poly(vinylpyrrolidone-co-vinyl acetate), poly(vinyl butyral) (or PVB), poly(vinyl alcohol), poly(ethylene oxide), poly(propylene oxide), poly(propylene carbonate), cellulosic dispersants such as methylcellulose, carboxymethylcellulose, ethylcellulose, hydroxymethylcellulose and hydroxypropylcellulose; poly(carboxylic acids) such as poly(acrylic acid), polyacrylate, poly(methylacrylate), poly(acrylamide), amide wax, styrene-maleic anhydride resins, octylphenol ethoxylate, multifunctional codispersants such as AMP™ dispersants, containing 2-amino-2-methyl-l-propanol, various derivatives and others known in the art. The compositions may comprise one or more dispersants or one or more dispersant formulations.In many cases, the aqueous dispersions contain water in an amount of at least 40% by weight, typically in an amount of at least 75, 90, or 95% by weight. The CNT dispersions may be prepared by sonication, high shear mixing, or other suitable techniques. Polymeric dispersions of various specifications may be obtained commercially or may be custom-made by methods known in the art.

[0118] In some cases, stable dispersions can be obtained in the absence of stabilizing surfactants (dispersants), even with water as the solvent. Suitable examples of solvents that may also be used include, but are not limited to, N-methyl pyrrolidone, acetone, a suitable alcohol (e.g., isopropanol, ethanol, methanol), water, or any combination thereof.

[0119] Since the solvent-free manufacturing process described herein uses CNT-polymer composites in a dry, free, fluid or flowable form (e.g. (e.g., powders, pellets, flakes, granules, etc.), any solvent used in the dispersion(s) is removed using an appropriate technique.

[0120] An example of preparing a CNT-polymer composite involves combining a CNT-containing dispersion with a polymer dispersion (e.g., a PTFE dispersion in water), and then freeze-drying the resulting mixture. Freeze-drying of carbon-containing mixtures is described in PCT Application No. PCT / CN2023 / 132882, filed on November 21, 2023 and incorporated by reference. In another example, CNTs in dry powder form are mixed with a polymer dispersion, such as a PTFE or PVP dispersion in water, resulting in a high-viscosity paste-like material. This paste may be granulated (using equipment and techniques known in the art) and then dried, for example, in an oven.

[0121] Although various approaches are available for forming CNT-polymer composites, some have been found to result in a better product. Mixing the same polymer dispersion (e.g., PTFE dispersion 30) with unsputtered CNTs (D50 of about 133 to 135 microns) and pulverized CNTs (D50 of about 15 microns) indicated that the smaller CNT particles produced a smoother, higher quality free film. In contrast, the larger CNTs resulted in a rougher film surface with many undispersed carbon features. Thus, at least in some situations, the smaller (e.g., pulverized) CNTs may be preferred when making CNT-polymer composites from dry CNTs and a polymer dispersion.

[0122] It has also been found that mixing an aqueous dispersion of CNTs with an aqueous dispersion of PTFE binder, followed by freeze-drying, does not appear to improve the dispersibility and / or fibrillation of the binder in at least some dry electrode manufacturing processes. In some cases, mechanical mixing of dry carbon nanotubes and PTFE powders has also been found not to form a nanotube-PTFE composite particularly suited to the needs of dry processing. In contrast, dry CNT powders combined with an aqueous dispersion of polymer (e.g., PTFE or PVP), followed by oven drying, appeared to produce higher quality film electrodes.

[0123] The optionally sieved CNT-polymer composites may be formed into granules by techniques known in the art. In some cases, the CNT-polymer granules have a particle size of between about 0.5 and 30 mm, for example between 3 and 15 mm, in either direction. For example, the cylindrically shaped CNT-polymer granules have a diameter of about 4 mm and a length of about 5 to 15 mm.

[0124] For many solvent-free manufacturing processes, the CNT-polymer composite material is less dusty. As used herein, a "dust-free" CNT-polymer composite is one that exhibits a weight loss of no more than 5 wt%, 4 wt%, 3 wt%, 2 wt%, or 1 wt% when passed through a 20-mesh sieve with an opening of 840 μm.

[0125] In addition to the CNT-polymer composite, the method, composition, and / or articles (e.g., film, electrode, battery) described herein also utilize a binder. In some instances, the binder is a fibrillable binder. The fibrillable binder may be provided in a binder component that consists of, consists essentially of, or includes the fibrillable binder.

[0126] Under certain processing conditions, for example high shear mixing in the presence of a fibrillating / fibrillating agent, a fibrillable binder is capable of producing fibrils, forming a network that can connect and support other particles present in the formulation. More specifically, fibrillation of the binder is believed to generate a matrix, lattice, or network of fibrils that imparts mechanical structure to the electrode. In a product electrode, a fibrillated binder can be detected in SEM images which will show the presence of fibrils wrapped around at least some of the particles present, for example the active material particles.Other indirect techniques can be used to assess the relative degree of binder fibrillation, e.g., energy-dispersive X-ray spectroscopy (EDX), powder rheology, tensile strength, and Young's modulus. EDX can map the distribution of fluorinated elements throughout the dry electrode and assess the effectiveness of binder fibrillation. Powder rheology measures the cohesive interaction between particles in the free-flowing electrode powder mixture, while tensile strength and elastic modulus tests measure the strength and flexibility of the remaining electrode film, all of which are representative of the degree of binder fibrillation.In some cases, little or no fibrillation can be inferred from dry product electrode films that crumble or detach from the substrate.

[0127] In some cases, the fibrillable binder is a fibrillable fluoropolymer, such as, for example, polytetrafluoroethylene or PTFE. Other binders that may be considered fibrillable include, but are not limited to, ultra-high molecular weight polypropylene, polyethylene, copolymers, and any combination thereof.

[0128] The fibrillable binder (alone or as a component of a binder (e.g., in a polymer blend) may be provided in an amount of about 0.1 to about 10 wt. %, e.g., about 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10 wt. %. In one example, the fibrillable binder is provided in an amount of about 5% by weight. In other examples, the fibrillable binder is provided in an amount of between about 0.1 and: about 0.5, about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10% by weight; or about 0.5 to: about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10% by weight; or from about 1 to: about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10% by weight; or from about 2 to: about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10% by weight; or from about 3 to: about 4, about 5, about 6, about 7, about 8, about 9, about 10% by weight; or from about 4 to: about 5, about 6, about 7, about 8, about 9, about 10% by weight; or from about 5 to: about 6, about 7, about 8, about 9, about 10; or from about 6 to: about 7, about 8, about 9, about 10% by weight; or from about 7 to: about 8, about 9, about 10% by weight; or from about 8 to: about 9, about 10% by weight.

[0129] However, not all situations require the use of a fibrillable binder. Thus, some embodiments of the disclosure employ a binder component that consists of, consists essentially of, or includes one or more non-fibrillable binders. As used herein, the term "non-fibrillable binder" refers to a binder that is difficult to fibrillate under the same conditions as those sufficient to fibrillate a "fibrillable" binder. Nevertheless, even without achieving complete fibrillation, the practical aspects of the disclosure (under the same or substantially the same processing conditions as those used for a fibrillable reference product) may still distort, e.g., stretch, elongate, entangle, etc., a non-fibrillable binder, often to a significant extent.

[0130] Without wishing to be bound by any particular interpretation or mechanism, it is believed that fibrillation can be considered an extreme phenomenon, in which the binder polymer (which may initially be a colloidal particle) is stretched very thinly, forming very long (high aspect ratio) strands (ribbons) that can pass through more than two electroactive particles, thus holding them together. Practice of the embodiments described herein may also lead to the stretching (elongation) and / or entanglement of a non-fibrillable binder, the formation of CNT-binder composites and / or the coating of CNTs. Even if not fully fibrillated, such a "treated" non-fibrillable binder can still act as a glue, connecting, binding together and providing connectivity for the electroactive particles and adhesion to the current collector.Deformations of a non-fibrillable binder can be observed by at least some of the techniques mentioned above.

[0131] In one example, the non-fibrillable binder is a fluoropolymer such as polyvinylidene fluoride (PVDF). Other examples of binders that may be considered non-fibrillable include poly(vinyldifluoroethylene-co-hexafluoropropylene) (PVDF-HFP), polyimides, and water-soluble binders, such as polyethylene oxide, polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), polyvinyl acetate, polyethylene-co-vinyl acetate, certain polyolefins, cellulose, cellulose derivatives, to name a few.Other possible non-fibrillable binders include polyethylene and polypropylene other than those of very high molecular weight, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), butyl rubber, nitrile rubber, acrylonitrile-butadiene rubber (NBR) and its derivatives, for example, hydrogenated nitrile-butadiene rubber (HNBR), and fluorinated rubber, as well as copolymers and mixtures thereof. In one example, the non-fibrillable binder is a cellulose ester, a cellulose ether, a cellulose nitrate, a carboxyalkylcellulose, a cellulose salt, and a cellulose salt derivative.In some embodiments, the non-fibrillable microparticulate binder is selected from at least one of the following: cellulose, cellulose acetate, methylcellulose, ethylcellulose, hydroxypropylcellulose (HPC), hydroxyethylcellulose (HEC), cellulose nitrate, carboxymethylcellulose (CMC), carboxyethylcellulose, carboxypropylcellulose, carboxyisopropylcellulose, sodium cellulose, sodium cellulose nitrate, and sodium carboxyalkylcellulose. Other examples use combinations of a non-fibrillable binder, e.g., PVDF, and a fibrillable binder, e.g., PTFE.

[0132] The non-fibrillable binders may be present in the electrode composition in the same amounts as those used for the fibrillable binders. Other suitable amounts may be employed, determined by routine experimentation, for example.

[0133] Fibrillable binders combined with non-fibrillable binders may also be used. Routine experimentation allows suitable amounts to be obtained. In many cases, the total amount of combined binders is the same or similar to the amounts described for fibrillable binders.

[0134] The binder used may be the same as or different from the polymer of the CNT-polymer composite. One example uses a PTFE binder and an CNT-PTFE composite. Choosing composite formulations in which the polymer is the same as or compatible with the binder may improve the affinity of the binder with the particles of the CNT / polymer composite and, therefore, improve the distribution, elongation and / or fibrillation of the polymer binder, facilitate the dispersibility of the CNT / polymer composite, promote a uniform distribution of the electrode constituents for better adhesion inside the electrode and / or to a conductive substrate (current collector). In this document, the term "compatible" refers to compounds that can be mixed, do not undergo decomposition or changes in their chemical properties, and exhibit desirable physical properties when mixed.

[0135] In some cases, the binder may be provided partially or entirely by the CNT-polymer composite.

[0136] For many LIB anodes, the electroactive material (also referred to herein as "active material" or "AM") is graphite, e.g., natural graphite, artificial graphite (e.g., massive artificial graphite (MAG)), or mixtures of both. Mesocarbon microbeads (MCMB), mesophase-pitch-based carbon fiber (MCF), or vapor-grown carbon fiber (VGCF) may also be used. Other anode materials used in addition to or instead of graphite include lithium titanate, tin oxide, silicon (Si), and SiOx (x is typically 1.04, 1.06, etc.). In illustrative examples, the anode comprises graphite and / or a silicon-containing compound.Other active anode materials, such as those known or currently explored, or those to be developed in the future, may be used.

[0137] The amount of active anode material may vary depending on the particular type of energy storage device. In illustrative examples, the amount of active anode material (e.g., graphite) is at least 80 wt. %, for example, at least 85, at least 90, at least 95, or at least 99 wt. %, based on the total weight of the (dry) electrode composition. The active anode material, e.g., graphite, may be provided in an amount of from about 80 to about: 85, 90, 93, 96, 99 wt. %, or from about 85 to about: 90, 93, 96, 99 wt. %, or from about 90 to about: 93, 96, 99 wt. %, or from about 93 to about: 96, 99 wt. or from about 96 to about 99% by weight.

[0138] LIB cathodes may use LCO (lithium cobalt oxide), LMO (lithium manganese oxide), NCM (lithium nickel cobalt manganese oxide), NCA (lithium nickel cobalt aluminum oxide), LCP (lithium cobalt phosphate), LFP (lithium iron phosphate), LFMP (lithium iron manganese phosphate), LFSF (lithium iron fluorosulfate), LTS (lithium titanium sulfide). Materials of this type are generally referred to herein as "lithium transition metal compounds", e.g. "lithium transition metal oxides". In addition to cathode materials based on intercalation chemistry, for example, generally involving reactions chemical compounds that transfer a single electron, other types of cathode materials (with lithium ions inserted into FeF3, for example) can transfer multiple electrons through more complex reaction mechanisms, called conversion reactions. Other active cathode materials known from the state of the art or developed in the future can be used.

[0139] In some cases, the dry process described herein utilizes NCM or NCA cathode compositions. NCM (also referred to as "NMC") and NCA are generally known to those skilled in the art.

[0140] More precisely, the NCMs can be represented by the formula Lii+x(NiyCoi_ y.zMnz)i.x02, in which x ranges from 0 to 1, y ranges from 0 to 1 (e.g., 0.3-0.8), and z ranges from 0 to 1 (e.g., 0.1-0.3). Examples of NCM include Lii+x(Nio,33Co(o,33)Mno,33)i-x02, Lii+x(Nio,4Coo,3Mno.3)i-x02, Lii+x(Nio.4Coo.2Mno.4)i x02, Lii+x(Nio.4Coo.iMno.5)i_x02, Li1+x(Nio.5Coo.iMn0.4)i_x02, Li1+x(Nio.5Coo.3Mn0.2)i_x02, Lii+x(Nio.5Coo.2Mno.3)i_x02, Li1+x(Nio.6Coo.2Mn0.2)i_x02, Li1+x(Nio.sCoo.iMno,i)i_x02et Lii+x(Nio.9Co.o5Mno.o5)i XO2.

[0141] The NCA can be represented by the formula Lii+x(NiyCoi.y.zAlz)i.xO2, where x is between 0 and 1, y is between 0 and 1 and z is between 0 and 1. An example of an NCA is Lii+x(Nioj8Cooji5Alojo5)ix02.

[0142] The amount of electroactive cathode material used may vary depending on the particular type of energy storage device. In illustrative examples, the amount of NCM or NCA is at least 90% by weight, for example at least 93%, at least 96%, at least 98% or at least 99% by weight, based on the total weight of the (dry) electrode composition. The NCM or NCA may be provided in an amount of from about 90 to about: 93, 96, 99% by weight; or from about 93 to about: 96, 99% by weight; or from about 96 to about 99% by weight.

[0143] Electrode compositions generally include ingredients such as conductive additives (e.g., conductive carbon additives or CCAs), plasticizers, etc. In the case of solvent-free processes, common techniques also utilize a fibrillation binder (also known as a "fibrillator / fibrillant") or adjuvant, typically CA.

[0144] It has been discovered that conventional fibrillating additives (e.g., CAs) can be supplemented and often entirely replaced when using the CNT-polymer composite described herein. The CNTs in the composite can provide multiple benefits (a characteristic referred to herein as "multifunctional"), serving, for example, as binder fibrillating agents (or, in some cases, binder deformation agents), conductive additives (generating conductive networks, e.g., example, long-range conductivity of the electrode), and mechanical strengthening aids (providing mechanical support, stability and / or flexibility to the electrode product, often the coating, layer or film typically applied to the conductive substrate to form a battery electrode).

[0145] In many cases, the solventless process is conducted in the absence of any fibrillation aid other than the CNT-polymer composite described above.

[0146] It is also possible to use the CNT-polymer composite in combination with another fibrillation aid or fibrillation agent. As used herein, the terms "fibrillation aid" or "fibrillation agent" refer to a material other than the binder or active electrode material and which promotes the fibrillation of a fibrillable binder; the terms "additional fibrillation aid" or "other" or "additional fibrillation agent" or "other" refer to a material other than the CNTs of the CNT-polymer composite (i.e., a material that excludes CNTs or is not a CNT). Generally, the additional fibrillation agent is not considered multifunctional. In some applications, the CNTs of the composite are combined with the CA, in a ratio that may be between about 95:5 and about 50:50.

[0147] Examples of other or additional materials that may be added to the CNT-polymer composite include hard carbon, graphite, graphenes, other non-fibrillating conductive additives, plasticizers, or any combination thereof.

[0148] FIGS. 1A to 1D show a schematic diagram and corresponding photographs of the typical steps of a preparation procedure starting from the CNT-polymer composite to the free film. More specifically, the CNT-polymer composite of FIG. 1A is sequentially mixed with an electrode active material and a binder to form an intermediate (FIG. 1B) which is subjected to binder deformation (FIG. 1C) and then formed into a film ([Fig. 1D]).

[0149] The ingredients such as the electroactive material, the binder and the CNT-polymer composite described above can be used in the form of free particulate materials (e.g., free-flowing or flowable powders, flakes, beads, granules, pellets) to prepare an electrode composition, an electrode product (e.g., a film, such as a free-flowing film), an electrode (in which the electrode composition or the electrode product (e.g., film) has been coated on a conductive substrate), and / or batteries. In some cases, the CNT-polymer composite is provided in a sponge-like structure.

[0150] Firstly, with regard to the dry process used to prepare the composition of the electrode, this process has at least two objectives: to mix some and generally all of the constituents, generally supplied in the form of particles free (e.g., fluid or flowing); and processing the binder in the presence of the CNTs in the CNT-polymer composite. In some embodiments, each of these two objectives is achieved by one or more mixing operations performed under specific shear conditions, using appropriate equipment.

[0151] Low shear mixing, for example, may be chosen to distribute the ingredients as uniformly as possible, for example by using a roller mill. As used herein, the term "low shear mixing" refers to mixing carried out under conditions that are not sufficient or not substantially sufficient to fibrillate a fibrillable binder. The use of low shear mixing conditions also helps to avoid excessive fragmentation of the particles, which is often the case for certain electroactive materials.

[0152] In many cases, binder processing is carried out under high shear conditions. As used herein, the term "high shear mixing" refers to shear conditions vigorous enough to deform (e.g., elongate, entangle) a binder to a degree sufficient to prepare a film electrode by a solventless technique. In the case of fibrillable binders, high shear mixing refers to mixing under shear conditions sufficient to fibrillate the binder.

[0153] Without wishing to be bound by any particular interpretation, it is believed that in the presence of CNTs, typically provided in a CNT-polymer composite, and under high shear conditions, a binder polymer deforms, stretches, elongates, and entangles. The presence of CNTs in a CNT-polymer composite may facilitate the dispersion of CNT aggregates, improve the distribution of CNTs in the blend for improved electrode conductivity and cell performance, strengthen larger polymer domains and fibrils for improved electrode processability, strength, and flexibility, and / or other benefits. The surface energy, elongated tubular shape, and / or surface roughness attributes may facilitate binder polymer setting; the CNTs may be crushed between the electroactive particles, resulting in stretching of the binder polymer.In the case of a CNT-polymer composite dispersed in the binder or on the binder surface, it is believed that the CNT particles may hold neighboring polymer domains together. Other contributing factors include polymer-polymer interactions (which are expected to increase with polymer elongation and / or multidirectional shear forces), electroactive particle-polymer binder interactions (which may be related to surface energy and / or other factors).

[0154] Under the same or almost the same high shear conditions, these manifestations tend to become more pronounced when the binder used is a binder fibrillable. The surface and other properties of CNTs can promote polymer attachment here and there. As all particles move through a high-shear mixture, both the polymer binder and the polymer in the CNT-polymer composite elongate, forming very long and very thin strands (having a high aspect ratio). In some cases, elongation may be observed only for the binder. Generally, these effects will be less pronounced with a non-fibrillable binder processed under the same or nearly the same high-shear conditions. Or, put another way, a non-fibrillable binder may require higher shear conditions to achieve results close to complete fibrillation.

[0155] In addition to the processing contributions described above, the CNTs in the CNT-polymer composite can improve electrical conductivity and, in many cases, can act as mechanical reinforcement by holding together the fibrillable and non-fibrillable polymer binders that are "deformed" (elongated, entangled, etc.) to a greater or lesser extent or "undeformed" (globular, rounded, spherical, etc.).

[0156] Specific shear values ​​may depend on the magnitude of the operation, the materials involved, the type of mixing equipment, and / or other factors. Low or high mixing settings may be determined or optimized based on prior experience, routine experimentation, etc.

[0157] The constituents may be combined in any order to obtain a mixture, preferably well dispersed, for example with a uniform distribution of the constituents, i.e., a homogeneous mixture. In one example, the CNT-polymer composite, for example in the form of granules, is homogeneously dispersed on the surface of the electroactive material and the binder. If CB is used, it may be mixed with the CNT-polymer composite to form a premix. In another approach, the CNT-polymer composite and the CB may be added individually to one or more other ingredients. This addition may be simultaneous or sequential.

[0158] The binder treatment (e.g., fibrillation) can be carried out on any mixture or premix that brings together the CNTs and the binder. In some cases, the polymer of the CNT-polymer composite is treated, e.g., fibrillated, at the same time as the binder.

[0159] Suitable techniques that may be used or adapted to carry out the steps of mixing and / or processing the binder, e.g., fibrillation, include mechanical agitation, shaking, stirring, etc., and may rely on equipment such as jet mills, tubular mills, acoustic mixers, extruders, planetary mixers, other mixing devices, e.g., laboratory-scale mixers, equipment suitable for pilot-scale evaluations, for large-scale industrial manufacturing, etc.

[0160] Stepwise sequences may use one type of apparatus to perform the first operation (e.g., preparing a premix), and another type of apparatus for the next operation (e.g., fibrillation). The same is true for shear and / or other mixing parameters.

[0161] In one embodiment, the CNT-polymer composite, for example in the form of granules, is first pre-treated using high shear equipment to break the composite and the multifunctional additive particles (granules or other particles capable of being ground under high shear conditions) into smaller fragments. The resulting mixture is then combined with the electroactive material, and then the binder is added; the use of low shear conditions during these steps allows the particle size (of the electroactive material, for example) to be preserved and all the constituents to be thoroughly mixed without fibrillating the binder. The electrochemically active material, the binder, and the CNT-polymer composite mixture are then subjected to high shear conditions to treat, for example, fibrillate, the binder.

[0162] In another embodiment, the CNT-polymer composite, in the form of granules for example, is first combined with the electroactive material in a pre-mixing step carried out under low shear, for example, to obtain a uniform distribution of these two constituents. The binder is then added to this premix and processed, i.e. mixed with other constituents without being fibrillated, under low shear conditions. The mixture is then subjected to high shear conditions to process, for example fibrillate, the binder.

[0163] Other sequences are possible. For example, the electroactive material may first be mixed with the binder, then the CNT-polymer composite may be added, for example in the form of granules, followed by treatment of the binder, for example fibrillation, under high shear conditions.

[0164] The mixing and / or low shear processing (e.g., fibrillation) may be carried out in one or more (two, three, four, five, six, etc.) mixing steps or pulses which may last for a suitable period of time, for example, in a range of about 10 seconds to about 5 minutes, for example, in a range of about 30 seconds to about one minute, to about 90 seconds, to about 2 minutes, to about 2 minutes, in a range of about 30 seconds to about one minute, to about 90 seconds, to about 2 minutes, to about 2.5 minutes, to about 3 minutes, to about 4 minutes, to about 5 minutes; from about 1 minute to about 90 seconds, to about 2 minutes, to about 3 minutes, to about 4 minutes, to about 5 minutes; from about 90 seconds to about 3 minutes, to about 4 minutes, to about 5 minutes; from about 2 minutes to about 3 minutes, to about 4 minutes, to about 5 minutes; from about 3 minutes to about 4 minutes, to about 5 minutes; from about 3 minutes to about 4 minutes, to about 5 minutes; from about 4 minutes to about 5 minutes. Different time intervals can also be used. The duration of two, several, or all pulses can be the same or different.

[0165] A pulse may be followed by a rest or cooling period. The rest periods may be at ambient temperature, for example, room temperature. Cooling may be to a temperature below ambient temperature, often 0°C or lower, for example, to a temperature between about -5 and 5°C.

[0166] The standing or cooling period may depend on the temperatures reached during mixing, the quantities handled, etc. In many cases, cooling lasts a few minutes, for example, from 10 minutes to half an hour or more. Cooling periods may vary in duration and / or temperature conditions.

[0167] For example, a binder-containing composition may be subjected to high shear mixing at about 25,000 revolutions per minute (rpm) to about 10,000 rpm, optionally at about 18,000 rpm for one-half minute, and then cooled to a temperature at or below freezing for 10 minutes, for example, at about -10°C. Low shear mixing may be carried out at about 2,000 rpm to about 4,000 rpm, for 1 minute, followed by cooling for 10 minutes at about 0°C.

[0168] In one example, a premix of CNT-polymer composite and electroactive material is prepared using an acoustic mixer, e.g., for several minutes at a force of 100 G. The resulting mixture is combined with the binder at fibrillation parameters, e.g., using a tube mill (such as an IKA TubeMill 100) at 25,000 rpm in a pulsed approach.

[0169] In another example, all components are mixed in a tube mill (such as an IKA TubeMill 100) at 25,000 rpm, using a pulsed approach in which mixing is alternated with rest periods, followed by a longer duration mixing operation.

[0170] Other techniques or equipment, for example a twin-screw extruder, may be used.

[0171] The CNT-polymer composite entities, pellets, for example, may remain intact or fragment under the effect of the processing conditions. The processing conditions may preserve the integrity of some or all of the initial CNTs present in the composite, which will remain intact. In some cases, however, in high shear conditions, for example, the initial CNTs are broken into smaller CNT units, generating CNT fragments, for example. Except for their reduced size, CNT fragments generally share the properties of intact CNTs and can be identified by electron microscopy and other techniques, as described above. The applied shear can distribute these fragments throughout the composition. Without wishing to be bound by any particular interpretation, it is believed that CNTs, as well as milled CNTs, distributed, for example, uniformly throughout the electrode composition, can result in electrodes with improved electrical conductivity and / or desirable mechanical properties.

[0172] The mixing and / or processing steps, e.g., fibrillation, may be controlled by visual inspection, manual calendering, powder rheology, or any other suitable technique. For example, a small quantity may be manually handled and sheared or passed through a manual calendar. End points may be established based on experience, routine experimentation, visual inspection, etc. The success of these operations may also be determined by SEM, performance, and / or other techniques typically used on the electrode product, e.g., electrode film.

[0173] The resulting electrode composition may be in the form of pellets, powders (often fluffy powders), composites such as polymer-encapsulated granules (masterbatch), or other forms of free-flowing or free-floating particulate materials.

[0174] In an optional step, the electrode composition may be sieved to remove unwanted clumps.

[0175] Electrode compositions prepared as described herein generally include CNTs, an active electrode material, and a "cured" binder, which in some cases includes the cured polymer in the CNT-polymer composite. Some product electrode compositions, particularly those prepared with a fibrillable binder, include a post-fibrillation binder (also referred to herein as a "fibrillated binder"), which often exhibits fibrils of a high aspect ratio. Compositions prepared with non-fibrillable binders will still exhibit a "deformed" binder (elongated, tangled, etc.), but perhaps to a lesser extent than that observed with fibrillable binders under the same or substantially the same fibrillation conditions. A cured, e.g., fibrillated, binder can be detected using the techniques described above.The success of binder processing, e.g., fibrillation, is often reflected in the quality of the resulting electrode (e.g., electrode film). In some cases, electrode compositions prepared with non-fibrillable binders include an "undeformed" binder (globular in shape, . rounded, spherical, etc.). Even in these cases, CNTs can serve as a binder and mechanical reinforcement of the electrode.

[0176] The electrode compositions may be used to form an anode, a cathode, or both an anode and a cathode, for example for assembly into a device such as a LIB. One, several, or all of the properties characterizing the CNT-polymer composite used may be evaluated in the electrode composition (in which the binder has been processed, e.g., fibrillated), in the electrodes (e.g., films), generally obtained by further processing of the electrode composition, in the assembled electrodes (in which the electrode, e.g., the film, has been applied to the appropriate substrate), and / or in the batteries described herein.For example, the electrode may be tested for adhesion (evaluating the attachment of the electrode film to a substrate), cohesion (evaluating the degree of bonding of particles to each other), electrode resistivity, and / or other properties, by techniques known in the art.

[0177] Based on the total weight of the electrode composition, the CNTs in the composite may be present in an amount of between about 0.1 and about 10 wt%, for example between about 0.3 and about 5.0 wt%, for example between about 0.3 and about 3 wt%. In one embodiment, for example, the CNTs represent between 3 and 5 wt% of the product electrode composition, for example, between 3 and: 3.5, 4 or 4.5 wt%; between 3.5 and: 4, 4.5 or 5 wt%; or between 4 and: 4.5 or 5 wt%; or between 4.5 and 5 wt%. In another embodiment, the CNTs are present in an amount of between about 0.3 and about 0.5, about 1.0, about 1.5, about 2.0, about 2.5; or between about 0.5 and about 1.0, about 1.5, about 2.0, about 2.5, about 3; or from about 1.0 to: about 1.5, about 2.0, about 2.5, about 3.0; or from about 1.5 to: about 2.0, about 2.5, about 3.0; or from about 2.0 to: about 2.5, about 3.0; or from about 2.5 to about 3.0. Specific amounts can be chosen within or outside these ranges.

[0178] In many cases, the amount of CNTs is equal to or, preferably, less than the amount of CA required to achieve the same or substantially the same electrode performance. In an alternative approach, achieving a performance level established with CA would require smaller amounts of CNTs, thereby freeing up additional volume for the electroactive material.

[0179] In an exemplary LIB graphite anode composition, for example, the CNT loading is not more than about 5 wt% and often not more than 3 wt%, e.g., not more than 1 wt%. In specific examples, the loading is between about 0.1 wt% and 1.0 wt%, e.g., between about 0.1 and about 0.5, or between about 0.5 and about 1 wt%. Other examples use a filler of between about 1 and about 5% by weight, for example a filler of at least about 4.5, 4.0, 3.5, 3.0, 2.5, 2.0 or 1.5.

[0180] In an exemplary NCM cathode composition, the CNTs are present in amounts less than or equal to about 5 wt%, e.g., not more than 3 wt%, e.g., not more than 1 wt%. In specific examples, the loading of the multifunctional additive is between about 0.1 wt% and 1.0 wt%, e.g., between about 0.1 and about 0.5, or between about 0.5 and about 1 wt%. Other examples use a loading of between about 1 and about 5 wt%, e.g., a loading of at least about 4.5, 4.0, 3.5, 3.0, 2.5, 2.0, or 1.5.

[0181] The relative amounts of CNTs to the fibrillable binder may be in a ratio of 5:1 to 0.1:10, for example about 1:1 to 0.1:10, 0.5:1 to 0.1:10, 5:1 to 0.5:10, 5:1 to 1:5, 5:1 to 5:10 by weight. In some cases, the weight ratio is 1:3.

[0182] In one instance, the electrode composition contains active material in an amount of about 90 wt% to about 99 wt%, e.g., up to 96.0 wt%, polymer (including, e.g., the fibrillable binder and polymer component in the CNT-polymer composite) in an amount of about 1 wt% to about 5 wt%, and CNTs in an amount of about 0.3 wt% to about 5 wt%.

[0183] After mixing and processing, for example fibrillation, the composition, optionally sieved, can be formed into a product electrode by any suitable technique known in the prior art or developed in the future. In one case, the composition is formed into a film by calendering, an operation which can be carried out at room temperature or at a higher temperature, for example at a temperature similar to or close to the glass transition temperature of the polymer. In a typical calendering operation, the composition is subjected to heat and pressure using an extruder. The softened material is passed through calendering rollers (vertical, for example) to prepare an electrode sheet or film.In many cases the film is free-standing, a property that can be described using a 150 pm thick film that stands on its own, with no part of the film in contact with any type of support, e.g. a substrate.

[0184] The desired film thickness can be achieved by adjusting the gap between the rollers and, in some cases, other process parameters.

[0185] The roller temperature may be, for example, between room temperature (20°C) and about 200°C. A high roller temperature may result in a thinner film on the first pass, while the opposite occurs at a lower temperature. The roller speed may vary. In examples illustrative, the roller speed ranges from about 0.17 meters per minute (m / min) to about 1.3 m / min. A slower rolling speed tends to produce a thinner film on the first pass compared to a faster rolling speed. The hydraulic pressure used can range from about 1,000 psi to about 7,000 psi. Again, higher pressure can produce a thinner film on the first pass compared to the thicker films obtained with lower pressure.

[0186] Additional passes through the mill may be used to reduce the film thickness until the desired thickness and load are achieved. In some cases, the film thickness is between about 50 μm and about 300 μm, for example between about 50 and about 200 μm, between about 100 μm and about 150 μm. It is also possible to obtain film thicknesses between 50 and 100, 50 and 150, 50 and 200, 50 and 250; or between 100 and 150, 100 and 200, 100 and 250, 100 and 300; or between 150 and 200, 150 and 250, 150 and 300; or between 200 and 250, 200 and 300; or between 250 and 300; or between 250 and 300 pm. Desired loadings may be from about 10 mg / cm2 to about 50 mg / cm2.

[0187] Free-standing films prepared according to the solvent-free method described herein should have good mechanical properties. One mechanical evaluation technique that can be relied upon is tensile strength and elastic modulus testing. For example, an anode prepared using a CNT-polymer composite should have a tensile strength of at least 100 kPa, while the tensile strength of an NCM cathode film should be at least 500 kPa. In an illustrative example, the free-standing film has a tensile strength of at least 0.1 MPa and / or an elastic modulus of no more than about 1000 MPa. A typical thickness of a film may be about 30 μm to about 500 μm. In many cases, the mechanical performance of the film comprising CNTs from the CNT-polymer composite was at least as good as that of a comparative film made using unbound CNTs.

[0188] In an optional operation, the film is thermally activated, for example to soften the binder and prepare the electrode product for application to a substrate. In the laboratory, this operation may be carried out using a hot plate, at 100° centigrade (C), for example. For larger scale processes, temperature-controlled roller calenders, convection and / or microwave dryers, etc. may be used.

[0189] The film, generally free, contains an active electrode material, CNTs (derived from the CNT-polymer composite) and a treated binder, for example fibrillated. Some films also contain a transformed polymer, for example fibrillated, derived from the CNT-polymer composite.

[0190] To form an electrode, the film is applied to a conductive substrate or support. Anode substrates that may be used include, but are not limited to, copper, nickel, titanium, stainless steel, carbonaceous materials in the form of foils, meshes, foams, etched or coated current collectors. Cathode substrates that may be used include, but are not limited to, aluminum, titanium, carbonaceous materials in the form of foils, meshes, foams, etched or coated current collectors. In one embodiment, the film is laminated to a carbon-coated copper foil by calendering the two together, for example, using a horizontal hot roll at a suitable temperature, speed and hydraulic pressure. Another example uses a carbon-coated aluminum current collector.

[0191] In some cases, an electrically conductive glue (adhesive) may be used to apply the film to the substrate.

[0192] The roller temperature can be between approximately 60 and 120°C. Too high temperatures can promote blistering and poor adhesion, while too low temperatures can impair adhesion.

[0193] The roller speed may be between about 0.17 m / min and about 1.3 m / min, for example about 0.5 m / min, while the hydraulic pressure may be between about 500 psi and about 2,000 psi. Other settings may be used. The pressure may be optimized to be high enough to promote adhesion to the substrate without altering the charge, porosity, or other properties. In some cases, lamination is performed before setting the final thickness and / or porosity of the film electrode.

[0194] In some cases, the formation of the film and its application to the substrate may be accomplished in a single step. For example, a powdered electrode composition and a substrate sheet may be introduced together into calendering rolls under conditions to produce a laminate in which the composition is pressed to film thickness and adheres to the sheet. This approach avoids the formation of a free or self-supporting film.

[0195] The laminated structure may be shaped and / or sized for specific applications such as electrochemical cells, e.g., LIB cells, e.g., rechargeable LIB cells, etc.

[0196] The electrodes prepared as described herein may be incorporated into a lithium-ion battery according to methods known in the art, such as, for example, those described in "Lithium Ion Batteries Fundamentals and Applications", by Yuping Wu, CRC press, (2015). In specific implementations, the batteries are button types such as, for example, 2032 button cells, 18650 cylindrical cells, soft batteries, and the like.

[0197] In an illustrative example, a LIB comprises a cathode prepared by a dry process. The cathode contains CNTs, for example in an amount not exceeding 5% by weight, a cathode active material (e.g., NCM), and a fibrillated binder. In an illustrative anode, the active material and the fibrillated binder may be present in an amount of at least 80% by weight and the CNTs in an amount not exceeding 5% by weight.

[0198] The electrode also contains the polymer derived from the CNT-polymer composite used to prepare the electrode composition. This polymer can be identified by known analytical techniques as an individual constituent in cases where the binder and the polymer of the composite are different. In some examples, the polymer derived from the CNT-polymer composite is in a transformed, e.g., fibrillated, form.

[0199] The second (opposite) electrode of the battery can also be prepared using a solvent-free process. In one case, both electrodes of the battery contain CNTs. It is also possible to prepare the second electrode by a conventional dry process (using alternating current, for example), by a slurry or by another non-dry technique.

[0200] In addition to the two electrodes, the typical LIB comprises a suitable electrolyte. This may be, for example, ethylene carbonate-dimethyl carbonate-ethyl methyl carbonate (EC-DMC-EMC), vinylene carbonate (VC), LiPF6; ethylene diethyl carbonate (EC-DEC), LiPF6; or (EC-DMC), LiPF6. In the laboratory, a separator that absorbs the electrolyte and prevents electrical contact between the electrodes, while allowing diffusion of Li ions, may be a suitable glass fiber microfilter (e.g., Whatman GF / A). Polypropylene / polyethylene membrane separators (e.g., Celgard 2300) may also be used in some cases.

[0201] The composition or morphology of the electrodes and / or batteries described herein may be characterized by various techniques. Examples include, but are not limited to, electron microscopy, e.g., TEM, SEM, X-ray tomography, Raman spectrometry, and other suitable qualitative or quantitative analytical methods. In one example, SEM data for graphite electrodes prepared by a dry process using the multifunctional additive described herein revealed the presence of ribbon-like binder fibrils, indicating efficient fibrillation.

[0202] The amounts of solvent or their absence can be assessed by a weight test. This involves drying the wet-cast electrode until the weight of the electrode reaches the value theoretically calculated on the basis of the known solids loading of the slurry, or until the weight of the electrode stabilizes and does not change for a minimum of 3 minutes. In the case of an electrode produced entirely in the absence of solvent, the weight remains the same during the evaluation period. Or, in other words, the weight of the electrode just prepared (before any drying operation) is equal to or less than 1% by weight of the= weight obtained by adding the weight of the individual ingredients supplied in the process).

[0203] Another approach that could be employed to detect a solvent (e.g., NMP) relies on attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectroscopy, in conjunction with gas chromatography (GC). In many cases, dry-processed electrode films can be distinguished from slurry-based products by very low or undetectable levels of solvent residue. A substantially uniform distribution of binder, without migration of binder to the film surface, is another feature that often characterizes an electrode product prepared by a solventless process.

[0204] The flexibility properties characterizing the electrode (its ability to resist cracking) can be measured by visual inspection when bending a film by hand or using a mandrel bend tester. In specific applications, the electrode is evaluated and must pass a 10 mm diameter mandrel bar test without a crack visible to the naked eye. In one illustration, the electrode successfully passed a bend test using an 8 mm diameter pen as a rod.

[0205] The performance of the electrode may be tested using procedures known in the art, or adapted or developed techniques. Suitable techniques include, for example, in-plane and through-plane electrode conductivity, electrochemical impedance spectroscopy (EIS), constant current charge and discharge capability, hybrid pulse power capability (HPPC), cycle life testing.

[0206] In many cases, electrodes prepared by the solventless process described herein have at least equal and often superior performance (as measured by in-plane resistivity, initial capacitance, or first cycle efficiency, for example) to that of a comparative electrode (also referred to herein as a "reference") containing the same amounts of active electrode material (e.g., NCM), binder, and "polymer-free" or "unbound" CNTs (i.e., CNTs that are not provided in a CNT-polymer composite).

[0207] In one illustration, a dry cathode prepared using the composite described herein at CNT loadings not exceeding about 1 wt%, exhibits performance at least as good (as measured by 0.5C / 0.1C capacity retention, 300th cycle discharge capacity, number of cycles per 20% capacity loss) as a comparative (reference) electrode containing the same amounts (e.g., 1% by weight) of unbound or polymer-free CNTs.

[0208] Electrodes prepared using the solvent-free process described herein are also expected to exhibit good mechanical properties. Mechanical evaluation techniques that can be relied upon include peel tests (e.g., 90°, 180°, “T-peel,” various attachments), tensile tests, and bending tests (mandrel experiments), to name a few. In many cases, the electrode prepared with the CNT-polymer composite performed at least as well as a comparative electrode made using CNTs not bonded to the polymer.

[0209] Without wishing to be bound by any specific interpretation, it is believed that the use of CNTs, provided in a CNT-polymer composite, can produce ribbon-like strands or fibrils of binder that may be long enough to wrap around the particles of the electroactive material and hold them together. Thus, even at relatively low levels, CNTs appear capable of treating, e.g., fibrillating, the binder, generating efficient conductive networks in the electrodes, while also contributing to desirable mechanical properties.

[0210] The electrode compositions and methods described herein may also be used (e.g., incorporated) and / or adapted for the manufacture of other energy storage devices, such as primary alkaline batteries, primary lithium batteries, nickel metal hydride batteries, sodium batteries, lithium-sulfur batteries, lithium-air batteries, and supercapacitors. Methods for manufacturing these devices are known in the art and are described, for example, in "Battery Reference Book," by TR Crompton, Newness (2000).

[0211] The disclosure is illustrated by the following non-limited examples.

[0212] EXAMPLES

[0213] Materials and methods

[0214] The active electrode material used was lithium nickel manganese cobalt oxide NCM622 (SNCM03006) from Targray. The water-soluble polymer binder powders used in these examples to prepare aqueous dispersions and produce CNT-polymer composites included PVP DG1902454E from Zhangzhou HuaFu Chemical Co. Ltd), CMC, PEG. The PTFE suspension Teflon™ PTFE DISP 30 was obtained from Chemours. PTFE powder 601X was obtained from Chemours and used as a fibrillable binder to manufacture the electrode. The fine particles of PTFE dispersed in water, under the designation POLYFLON™ PTFE D-210C, were obtained from Daikin Chemicals.

[0215] All specifications of the NTCs were provided by Cabot Corporation. Their characteristics are summarized in Table 1 above.

[0216] Several methods can be used to obtain granules containing CNTs. For example, granules not containing polymer could be prepared by: (i) compressing the CNT powder, or (ii) combining the CNT powder with a liquid, usually water, granulated by a pasta machine (Baice, ZH-57), and then removing the liquid, for example by oven drying. Granules containing both CNTs and polymer can be prepared by mechanically mixing CNT powder with polymer powder, for example PTFE. The powdered CNTs can be mixed with a polymer dispersion such as a PTFE or PVP dispersion, then granulated and subjected to oven drying (in the case of PVP or PTFE dispersions) or freeze drying (for example for PTFE dispersions).

[0217] Dustiness of the granules was assessed using a 20 mesh sieve with a diameter of 840 µm to separate the loose powder, which was then weighed to determine the weight loss of the granule as a function of dustiness. The crushing force was measured by subjecting the cross-section of the pellet / granule to stress using the probe of a Lotun Science texture analyzer and recording the maximum stress as the crushing force.

[0218] In general, the cathode electrodes were prepared in several steps. In a first step (E1), the pellets containing CNTs were processed under appropriate conditions to maximize the dispersibility of the conductive additives (e.g., by high shear mixing). In a second step (E2), the electrode components were combined and mixed under conditions to fibrillate the binder (e.g., by high shear mixing). The third step (E3) consisted of passing the powder mixture obtained in step E2 through a vertical calender preset at the appropriate gap depending on the desired film thickness. The free films obtained from E3 were laminated onto a current collector in a fourth step (E4).

[0219] A similar sequence of steps can be followed to prepare the anode electrodes.

[0220] The thickness of the solvent-free electrodes was measured using a hand-held drop gauge with a 7.14 mm diameter flat contact head. A hand-held punch was used to punch 15 mm diameter discs for the cathode and 16 mm for the anode.

[0221] The mechanical properties of the free dry films, e.g., tensile strength and Young's (elastic) modulus, were tested using a Mecmesin MultiTest-dV motorized force tester with a load of 10N. After being calendered to the desired thickness, the films were cut into 70 x 20 mm strips using a punch. They were then placed in the apparatus and the tensile test program was run.

[0222] The foil resistance of the solvent-free electrodes was measured with a commercial Signatone Pro4-4400 system (SP4 probe head connected to the back of a Keithley 2410-C source meter). The reported values ​​were normalized by the electrode thickness and reported as electrode resistivity in Ohm«cm (Q«cm).

[0223] Example 1

[0224] Several types of granulated CNTs were prepared, comprising various amounts of different types of CNTs and polymers. The detailed compositions and CNT / polymer ratios as well as the main characteristics of the granules are summarized in Table 2.

[0225] [Tables2] CNT pellet / granule type (CNT type / polymer) CNT / polymer weight ratio Approach Dust (%) Crushing force (g) CNT1 / PVP 100 / 1 CNT1 powder + PVP disp. —> oven drying 0.7 432 CNT2 / PTFE 19 / 1 CNT2 dispersion + PTFE disp. —> freeze drying 0.2 Not applicable CNT3 / PVP-1 200 / 1 CNT3 powder + PVP disp. —> oven drying 0.5 537 CNT3 / PVP-2 100 / 1 CNT3 powder + PVP disp. —> oven drying 0.4 566 CNT3 / PTFE 200 / 1 CNT3 powder + PVP disp. PTFE —> oven drying 0.9 427 NTC3 Not applicable NTC3 powder + water —> oven drying 1.7 364 NTC4 / CMC 100 / 1 NTC4 powder + CMC disp. —> oven drying 0.6 590 NTC4 / PEG 100 / 1 NTC4 powder + PEG disp. —> oven drying 0.38 597 NTC4 / PVP 100 / 1 NTC4 powder + PVP disp. —> oven drying 0.67 492 NTC4 Not applicable NTC4 powder + water —> oven drying 0.84 390 NTC4 Not applicable NTC4 powder —> dry granulated / / NTC4 / PVP 100 / 1 NTC4 powder + PVP powder—> dry granulated / /

[0226] The granules in Table 2 were prepared by different methods. One of them consisted of mixing dry powder of CNTs (e.g., CNTs1, CNTs3 and CNTs4) and a water-based polymer dispersion at different CNT / polymer ratios. The resulting mixture is in the form of a paste-like substance with high viscosity. In the next step, the water-containing CNT-based polymer substance was granulated using a pasta machine (Baice, ZH-57) and then subjected to a drying process in an oven at 150°C. The water-based polymer dispersions were prepared by dissolving polymer powders such as PVP, CMC, PEG in water. Another example of a water-based polymer dispersion used was a commercially available aqueous dispersion of Teflon™ PTFE DISP 30.

[0227] Another method is to mix an aqueous dispersion of CNT2 and a water-based polymer dispersion in a weight ratio of 19:1 between CNTs and PTFE, then freeze-dry them at -45°C for 4 hours and vacuum-dry them for 4 hours. The water-based polymer binder dispersion used for this preparative method included Daikin Chemicals D-210C PTFE suspension.

[0228] For comparison, two series of CNT3 and CNT4 pellets (from Table 2) were prepared without polymer. The method consisted of dispersing the dry CNT powder in water at a CNT loading of 13% by weight, followed by granulation of the CNT-containing paste using a pasta machine and oven drying at 150°C.

[0229] The dry CNT granulation method, which consists of compacting the powder. of CNTs or the mixture of CNT powder and polymer powder using a pharmaceutical tablet machine under high pressure and without any solvent, was also included in Table 1.

[0230] Comparing the CNT4, pelletized in the absence of polymer, with the three CNT4 / polymer composites, pelletized with different polymers as listed in Table 2, it was observed that the combination of the polymer with the CNTs allowed for reduced dusting and increased crushing force. A higher level of integration was also observed in the pellets composed of CNT3 / PTFE, CNT3 / PVP-1 and CNT3 / PVP-2, compared to the pellets consisting of only CNT3. Furthermore, all the pelletized CNTs, including the pelletized CNT / polymer composites, had a significantly reduced dusting rate compared to the unpelletized CNTs (e.g., the dry powder of unpelletized CNT3 has a dusting rate of 99.37%).This suggests that granulated CNTs and granulated CNT / polymer composites mitigate the risks of exposure to airborne CNT nanoparticles and offer the advantage of safe handling of CNTs at manufacturing scale.

[0231] Example 2

[0232] In this example, the dry-processed free cathode films were prepared in two steps.

[0233] As shown schematically in FIGS. 1A to 1C, in the first step (El), the electrode components were mixed in sequence according to an operation in two stages using a Resodyn acoustic mixer and an IKA mill. Specifically, the first stage of El was performed to prepare a uniform distribution of the powdered components in the mixture, which included a 10-minute pre-mixing of a carbon additive and the electrode active material NCM 622 (Targray) in the acoustic mixer at 90% intensity and automatic frequency, followed by the addition of the polymer binder PTFE 60IX (Chemours) and mixing at the same settings for another 20 minutes. The conductive additive in non-granulated (fluff) form was used as is. The conductive additive in granular form (obtained as described in Example 1) was pretreated before being mixed with the active material of the electrode, namely in an IKA tubular mill for 3 minutes at 25,000 rpm for 5 cycles (15 minutes of total mixing) with a rest period of 2 minutes between cycles.

[0234] The second step of El, which consists of fibrillating the mixture, was processed using IKA Tube Mill 100 for 15 seconds at 25,000 rpm for 6 cycles and 3 minutes at 5000 rpm for 1 cycle with a rest period of 45 seconds between cycles.

[0235] In the second step (E2), the powder mixture obtained in E1 was passed through a vertical calender at 100°C to obtain free films, as can be seen in [Fig.lD], with a thickness of between 30 and 130 μm.

[0236] The carbon additives, namely virgin (ungranulated) NTC1 (Table 1), NTC1 / PVP composite and NTC2 / PTFE composite granulated by different methods (Table 2) were used to prepare free-standing cathode films according to the formulations listed in Table 3. All films were prepared by a dry process and contained the carbon additive at a loading of 2 wt%, NCM622 (94 wt%) and PTFE (4 wt%). In Table 3, "pass" indicates that a continuous and flexible film could be formed with a film thickness <150 µm; "fail" indicates that no continuous and flexible film could be formed with a film thickness <150 µm.

[0237] [Tables3] Formulation ID Active ingredient Carbon additive Binder Avg. dry film thickness (pm) Free film quality Al 94% NCM 2% ungranulated NTC1 4% PTFE 110 Pass A2 94% NCM 2% granulated NTC1 / PVP 4% PTFE 113 Pass A3 94% NCM 2% NTC2 / P TFE 4% PTFE 189 Fail

[0238] As shown in [Fig.2], the dry cathode film A2, prepared with the CNT1 / PVP pellet / granule, exhibited higher tensile strength than the cathode film Al made with virgin CNT1 powder. This suggests that there are enhanced interactions between the PTFE binder and CNTs to improve the film reinforcement and quality.

[0239] The dry cathode film (formulation A3) made with the CNT2 / PTFE composite comprising unsputtered / ungranulated CNT material resulted in a thicker electrode of 189 pm and a tensile strength of 250 kPa, significantly lower than the tensile strengths observed with other dry cathodes in this example, and was therefore labeled "fail" in Table 3. This appears to confirm the advantages of using processed (sputtered) CNTs over pristine (unsputtered) CNTs in the CNT / polymer composite.

[0240] Example 3

[0241] The free NCM electrode films of this example were prepared according to the two-step procedure described in Example 2. The carbon additives used were granules of the NTC3 / PVP-1 and NTC3 / PVP-2 composites (from Table 2). NTC2 and NTC3, where NTC3 is the pulverized version of NTC2 were used for comparison.

[0242] The electrode formulations used (labeled B1 to B4) are listed in Table 4 below. All dry electrode films were prepared by a dry process and contained the carbon additive at a loading of 1 wt%, NCM622 (96 wt%) and PTFE (3 wt%).

[0243] [Tables4] Formulation ID Active ingredient Carbon additive Binder Avg. film thickness B1 96% NCM 1% of CNT2 ungranulated 3% PTFE 110 B2 96% NCM 1% of CNT3 ungranulated 3% PTFE 116 B3 96% NCM 1% of CNT3 / P VP-1 granules 3% PTFE 111 B4 96% NCM 1% of CNT3 / P VP-2 granules 3% PTFE 111

[0244] The tensile strength and elastic modulus of the dry cathode films selected from Table 4 are shown in FIGS. 3 and 4.

[0245] As shown in [Fig.3], although the dry electrode film B3 made with the granulated CNT3 / PVP-1 composite had lower tensile strength and higher elastic modulus than the electrode film B2 made with the ungranulated CNT3 powder, its mechanical performance was comparable to that of the dry electrode film B1 made with the ungranulated CNT2 dry powder.

[0246] The influence of polymer loading in the composite is evident when comparing CNT3 / PVP composites with different CNT / polymer ratios in formulations B3 and B4. As shown in [Fig. 4], the electrode derived from formulation B3, which uses a CNT3 / PVP-1 composite with a CNT / polymer weight ratio of 200 / 1, exhibits a lower (improved) elastic modulus compared to formulation B4, which was fabricated with a CNT3 / PVP-2 composite containing a CNT / polymer weight ratio of 100 / 1. This further suggests that lower amounts of polymer in the CNT / polymer composite may be preferred to improve the flexibility of unbonded dry films.

[0247] Example 4

[0248] A series of dry-processed cathodes (labeled C1 to C4) were prepared by laminating dry-processed free cathode films, prepared according to E1-E2 as described in Example 2, onto a current collector (E3). Specifically, the free electrode films obtained in E2 were laminated onto the 17 μm thick carbon-coated aluminum foil by calendering them together through a vertical calender at 100°C to obtain the electrode.

[0249] The electrode formulations employed and the characteristics of the resulting cathodes are listed in Table 5 below. All cathode films dry products contained NCM622 (96% by weight), PTFE (3% by weight) and 1% by weight of carbon additives.

[0250] [Tables5] Electrode ID Formulation Active Material Loading [mg / cm2] Electrode Density [g / cm3] Cl 96% NCM, 1% NTC2 ungranulated, 3% PTFE 25.7 3.6 C2 96% NCM, 1% NTC3 ungranulated, 3% PTFE 24.6 3.8 C3 96% NCM, 1% NTC3 / PVP-1 granulated, 3% PTFE 25.4 3.7 C4 96% NCM, 1% NTC3 granulated, 3% PTFE 25.8 3.7

[0251] The cathodes in Table 5 were tested in complete 2032 button cells. 15 millimeter diameter discs were punched for button cell preparation and dried at 100°C under vacuum for at least 4 hours. The discs were calendered to the desired electrode density using a hand roller press and assembled into 2032 button cells in an argon-filled glove box (M-Braun) for testing against slurry-treated graphite anodes containing 3% CB, 5% PVDF, 92% natural graphite, at an anodic access of 1.2, measured as the capacity ratio between the negative and positive electrodes (N / P). Celgard 2325 film was used as the separator. Lithium hexafluorophosphate (LiPF6) IM in ethylene carbonate-dimethyl carbonate-ethyl methyl carbonate (EC-DMC-EMC, 1:1:1 by weight) with 1 wt% vinylene carbonate (VC) from E-Lyte was used as the electrolyte.The room temperature (25 °C) rate performance of the complete button cells was measured by first forming them through four C / 20-D / 20 charge-discharge cycles, and then charging and discharging them at each rate for four cycles at C / 10, C / 5, C / 3, C / 2, IC, and 2C, respectively. The cycling performance tests of the complete cells / batteries were conducted at 25 °C using the C / 3 charge rate and C / 3 discharge rate after the C rate capacity test. The cells / batteries including the C3 cathode underwent an additional forming cycle at C / 20 charge and C / 20 discharge before the cycling test.

[0252] [Fig.5] summarizes the results of the rate capacity test showing the retention of the 0.5C / 0.1C discharge capacity for the cathodes of Table 5. The results indicate that, in addition to mitigating risks related to handling nanomaterials during production, composite electrodes containing 1% granulated CNT3 / PVP-1 and 1% granulated CNT3 performed comparable to electrodes containing only ungranulated CNTs, showing no adverse effects related to the presence of an additional polymer and / or handling in granulated form.

[0253] [Fig.6A] shows a graph illustrating the room temperature cycling of complete button cells with dry cathodes comprising ungranulated CNT3 and granulated CNT3 / PVP-1 composites up to 330 cycles. The capacity loss rate (in mAh per cycle) was calculated by fitting the linear region of the cycling curves (20-330 cycles) with a simple linear function capacity = a + b • Cycle#, where b is a slope representing the capacity loss rate. The results are summarized in Table 6. The R-squared (R2) of the fit was 0.97. See also [Fig.6B]. Data modeling based on capacitance fading indicates that the electrode fabricated with the granulated CNT3 / PVP-1 composite can have a longer lifetime at the time when its capacitance drops by 20% compared to the electrode fabricated with CNT3 powder alone, which indicates the structural and electrochemical stability of the electrode fabricated with the composite.This prediction was confirmed by experimental data collected after 1000 cycles (see also [Fig.6C]).

[0254] [Tableauxô] Formulation Electro ID Discharge Capacity at 300cyc (mAh) Capacity Loss Rate (mAh / cyc) #Number of cycles per 20% capacity loss C2 96% NCM, 1% NTC3, 3% PTFE 6.06±0.08 0.00134+9.66E- 05 966.80+60.73 C3 96% NCM, 1% NTC3 / PVP-1, 3% PTFE 5.94±0.16 0.00126+1.57E- 04 1120.66+115.52

[0255] [Fig.6C] presents a graph showing the capacity retention at room temperature of complete button cells with dry cathodes Cl to C4 tested up to 1000 cycles. The electrode made with the granulated NTC3 / PVP-1 composite showed an improved capacity retention of 7.3% compared to the electrodes made with the ungranulated NTC3 powder and 8.4% compared to the electrodes made with the commercially available dry NTC2 powders, indicating structural and electrochemical stability and improved performance of the former.

[0256] Example 5

[0257] In this example, a series of dry-processed free-standing cathode films were prepared in two steps (E1, E2) as described below and then laminated onto a current collector (E3) for electrochemical testing. The processing of the E1 electrode powder was carried out in sequential steps as follows, which improved the dispersibility of the CNTs and reduced the binder loading in the electrode formulation.

[0258] Step El-A: Initially, CNT granules or non-granulated CNTs were mixed with the NCM active material in an Eirich mixer at a speed of 25 m / s in counter-rotating mode, and the mixture was processed for 6 minutes to form Mixture 1.

[0259] Step El-B: After initial mixing, Mix 1 was processed with the PTFE binder in the Eirich mixer, but at a lower speed of 5 m / s in co-rotation mode for 3 minutes. The reduced speed and shorter mixing time allowed the binder to be incorporated smoothly without excessively fibrillating it, resulting in the components being effectively bonded without lump formation.

[0260] Step El-C: The mixed material was then subjected to extrusion using a twin-screw extruder (TSE). The screw rotation speed was varied at 400 rpm for all samples. This speed variation allows for adjustment of the shear and mixing intensity, which can be optimized for different formulations to ensure uniformity and good compaction of the material.

[0261] Step El-D: After extrusion, the material was ground into flakes using an IKA mill. Grinding was carried out at 5000 tos / min, with durations of 20 seconds, 40 seconds and 60 seconds. This step reduces the granulated material into finer flakes, which improves the surface area and ensures a more uniform texture, crucial for the next processing step.

[0262] Then, the calendering was similar to that of Example 2 and the lamination on the stages E2 and E3 of the current collector was carried out as described in Example 2 and Example 4, respectively.

[0263] The electrode formulations employed and the characteristics of the resulting cathodes are listed in Table 7 below. All dry cathode films contained NCM622 (97 wt%), PTFE (2 wt%), and 1 wt% carbon additives.

[0264] [Tables7] Electrode ID Formulation Active material loading [mg / cm2] Electrode density [g / cm3] Dl 97% NCM622, 1% NTC3 granulated, 2% PTFE 32.96 0.9 D2 97% NCM622, 1% NTC2 ungranulated, 2% PTFE 33.30 0.9

[0265] Overall, as shown in [Fig.7], the dry electrodes made with the CNT3 granules are comparable to commercially available ungranulated CNT2 with respect to mechanical film tensile strength and exhibit an improved elastic modulus of 9.7%.

[0266] The SEM and elemental mapping images of the DI electrode fabricated with the CNT3 pellet, as shown in [Fig. 8], showed the uniform distribution of CNTs after treatment, which were well dispersed on the surface of the CNT particles in the electrode. The CNTs appear to be homogeneously integrated, which will contribute to the conductivity of the structure. Furthermore, the SEM images combined with the F and C elemental maps clearly showed that the PTFE binder was effectively fibrillated, with the fibrils extending throughout the electrode. This suggests that the fibrillation process was successful in forming a network of PTFE fibrils, promoting structural integrity and improving the overall performance of the electrode fabricated with pelletized CNT3. The rate performance data shown in [Fig.9] showed that electrodes made with CNT3 pellets (electrode D1) performed better than those made with dry, ungranulated CNT2 powder (electrode D2) at lower C rates (C / 5 to C / 2). Overall, the performance suggests that the polymer-free CNT3 pellet also provides a balance between discharge capacity and safety.

[0267] ASPECTS

[0268] Aspect 1. A method of preparing an electrode composition, the method comprising: - the combination of an active electrode material, a binder and a composite of carbon nanotubes and polymer; and - treatment of the binder in the presence of the carbon nanotube-polymer composite,

[0269] wherein the method is carried out in the absence of solvent.

[0270] Aspect 2. The method of aspect 1, wherein the carbon nanotubes in the carbon nanotube-polymer composite are multifunctional multi-walled carbon nanotubes.

[0271] Aspect 3. The method of aspect 1 or 2, wherein the carbon nanotubes in the carbon nanotube-polymer composite have a BET of between about 80 and about 500 m2 / g.

[0272] Aspect 4. The method of aspect 1 or 2, wherein the carbon nanotubes in the carbon nanotube-polymer composite have a BET of between about 200 and about 500 m2 / g.

[0273] Aspect 5. The method of one of aspects 1 to 4, wherein the carbon nanotubes in the carbon nanotube-polymer composite have a diameter of between about 2 and about 50 nanometers.

[0274] Aspect 6. The method of one of aspects 1 to 5, wherein the carbon nanotubes of the carbon nanotube-polymer composite have an average particle size (D50) of between about 5 and about 500 microns, as determined by laser diffraction analysis.

[0275] Aspect 7. The method of one of aspects 1 to 6, wherein the nanotubes of carbon nanotube-polymer composite carbon are pre-ground into dry powder form.

[0276] Aspect 8. The method of any one of aspects 1 to 7, wherein the carbon nanotube-polymer composite is a free-floating, dust-free particulate material.

[0277] Aspect 9. The method of one of aspects 1 to 8, wherein the carbon nanotube-polymer composite is in the form of a pellet.

[0278] Aspect 10. The method of one of aspects 1 to 9, wherein the carbon nanotube-polymer composite contains a fibrillable binder, a non-fibrillable binder, or a combination thereof.

[0279] Aspect 11. The method of one of aspects 1 to 10, wherein the carbon nanotube-polymer composite contains a PFAS polymer.

[0280] Aspect 12. The method of aspect 11, wherein the PFAS polymer is PTFE.

[0281] Aspect 13. The method of one of aspects 1 to 10, wherein the composite Carbon nanotube polymer contains a PFAS-free polymer.

[0282] Aspect 14. The method of aspect 13, wherein the PFAS-free polymer is PVP or HNBR.

[0283] Aspect 15. The method of any one of aspects 1 to 14, wherein the weight % ratio of carbon nanotubes in the composite to polymer in the composite is from about 1:1 to about 100:0.1.

[0284] Aspect 16. The method of any one of aspects 1 to 14, wherein the weight % ratio of carbon nanotubes in the composite to polymer in the composite is from about 10:1 to about 100:0.1.

[0285] Aspect 17. The method of one of aspects 1 to 16, wherein the active electrode material, the binder, the carbon nanotube-polymer composite, and the electrode composition are free particulate materials.

[0286] Aspect 18. The method of one of aspects 1 to 17, wherein the carbon nanotubes in the carbon nanotube-polymer composite are present in an amount not exceeding about 5% by weight based on the total weight of the electrode composition.

[0287] Aspect 19. The method of one of aspects 1 to 18, wherein the active electrode material is a lithium transition metal compound.

[0288] Aspect 20. The method of one of aspects 1 to 18, wherein the active electrode material is graphite, a silicon-containing compound, or a combination thereof.

[0289] Aspect 21. The method of one of aspects 1 to 20, wherein the method is carried out in the presence of carbon nanotubes in the carbon nanotube-polymer composite as the sole fibrillating agent.

[0290] Aspect 22. The method of one of aspects 1 to 21, wherein the binder is a fibrillable binder, a non-fibrillable binder, or a combination thereof.

[0291] Aspect 23. The method of any of aspects 1 to 21, wherein the binder contains polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), or a combination thereof.

[0292] Aspect 24. The method of one of aspects 1 to 23, wherein the binder comprises a polymer that is the same or substantially the same as the polymer in the carbon nanotube-polymer composite.

[0293] Aspect 25. The method of one of aspects 1 to 24, wherein the binder treatment comprises a high shear operation sufficient to fibrillate a fibrillable binder.

[0294] Aspect 26. The method of one of aspects 1 to 24, wherein the binder treatment comprises a high shear operation sufficient to deform a non-fibrillable binder.

[0295] Aspect 27. The method of one of aspects 1 to 26, wherein the electrode composition contains an active material in an amount of about 92 wt% to about 99.8 wt%, a binder in an amount of about 0.1 wt% to about 5 wt%, and a composite of carbon nanotubes and polymers in an amount of about 0.1 wt% to about 3 wt%.

[0296] Aspect 28. A method further comprising applying the electrode composition prepared according to one of the preceding aspects to a conductive substrate, to form a battery electrode.

[0297] Aspect 29. A method further comprising calendering the electrode composition prepared according to one of aspects 1 to 27 to form a film.

[0298] Aspect 30. The method of aspect 29, wherein the film is free and has a thickness of between about 30 and about 500 microns.

[0299] Aspect 31. The method of aspect 30, wherein the film has a tensile strength of at least about 0.1 MPa and / or a modulus of elasticity of not more than about 1000 MPa.

[0300] Aspect 32. A method comprising applying the film according to one of aspects 29 to 31 to a conductive substrate to form a battery electrode.

[0301] Aspect 33. The method of one of aspects 1 to 32, wherein the carbon nanotube-polymer composite is prepared by a method which comprises: - the combination of carbon nanotubes and a polymer to form a mixture, and - removing a liquid from the mixture to obtain the carbon nanotube-polymer composite, wherein the carbon nanotubes, the polymer or both is / are provided in a dispersion.

[0302] Aspect 34. The method of aspect 33, wherein the dispersion is an aqueous dispersion.

[0303] Aspect 35. The method of any of aspects 1 to 32, wherein the carbon nanotube-polymer composite is prepared by combining carbon nanotubes and the polymer, wherein the carbon nanotubes, the polymer, or both are provided in the form of a dry powder.

[0304] Aspect 36. A method of preparing an electrode composition, the method comprising:

[0305] (a) subjecting a binder to high shear conditions in the presence of a carbon nanotube-polymer composite for treating the binder; and

[0306] (b) adding an electrode active material before, during or after step (a),

[0307] in which the method is carried out without adding solvent.

[0308] Aspect 37. The method of aspect 36, wherein the carbon nanotubes Carbon nanotube-polymer composites are multifunctional multi-walled carbon nanotubes.

[0309] Aspect 38. The method of aspect 36 or 37, wherein the carbon nanotubes in the carbon nanotube-polymer composite have a BET of between about 80 and about 500 m2 / g.

[0310] Aspect 39. The method of aspect 36 or 37, wherein the carbon nanotubes in the carbon nanotube-polymer composite have a BET in a range of about 200 to about 500 m2 / g.

[0311] Aspect 40. The method of one of aspects 36 to 39, wherein the carbon nanotubes of the carbon nanotube-polymer composite have a diameter of between about 2 and about 50 nanometers.

[0312] Aspect 4L The method of one of aspects 36-40, wherein the carbon nanotubes in the carbon nanotube-polymer composite have an average particle size (D50) in a range of about 5 to about 500 microns, as determined by laser diffraction analysis.

[0313] Aspect 42. The method of one of aspects 36-41, wherein the carbon nanotubes in the carbon nanotube-polymer composite are pre-ground into a dry powder form.

[0314] Aspect 43. The method of one of aspects 36 to 42, wherein the carbon nanotube-polymer composite is a free-floating, dust-free particulate material.

[0315] Aspect 44. The method of one of aspects 36 to 43, wherein the carbon nanotube-polymer composite is in the form of a pellet.

[0316] Aspect 45. The method of one of aspects 36 to 44, wherein the carbon nanotube-polymer composite contains a fibrillable binder, a non-fibrillable binder, or a combination thereof.

[0317] Aspect 46. The method of one of aspects 36 to 45, wherein the carbon nanotube-polymer composite contains a PFAS polymer.

[0318] Aspect 47. The method of aspect 46, wherein the PFAS polymer is PTFE.

[0319] Aspect 48. The method of one of aspects 36 to 45, wherein the composite Carbon nanotube polymer contains a PFAS-free polymer.

[0320] Aspect 49. The method of aspect 48, wherein the PFAS-free polymer is PVP or HNBR.

[0321] Aspect 50. The method of one of aspects 36-49, wherein the weight % ratio of carbon nanotubes in the composite to polymer in the composite is from about 1:1 to about 100:0.1.

[0322] Aspect 51. The method of one of aspects 36-49, wherein the weight % ratio of carbon nanotubes in the composite to polymer in the composite is from about 10:1 to about 100:0.1.

[0323] Aspect 52. The method of one of aspects 36 to 51, wherein the electrode active material, the binder, the carbon nanotube-polymer composite, and the electrode composition are free particulate materials.

[0324] Aspect 53. The method of one of aspects 36-52, wherein the carbon nanotubes in the carbon nanotube-polymer composite are present in an amount not exceeding about 5% by weight based on the total weight of the electrode composition.

[0325] Aspect 54. The method of one of aspects 36 to 53, wherein the active electrode material is a lithium transition metal compound.

[0326] Aspect 55. The method of one of aspects 36 to 53, wherein the active electrode material is graphite, a silicon-containing compound, or a combination thereof.

[0327] Aspect 56. The method of one of aspects 36 to 55, wherein the method is carried out in the presence of carbon nanotubes in the carbon nanotube-polymer composite as the sole fibrillating / fibrillating agent.

[0328] Aspect 57. The method of one of aspects 36 to 56, wherein the binder is a fibrillable binder, a non-fibrillable binder, or a combination thereof.

[0329] Aspect 58. The method of one of aspects 36 to 57, wherein the binder contains polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), or a combination thereof.

[0330] Aspect 59. The method of one of aspects 36 to 58, wherein the binder comprises a polymer that is the same or substantially the same as the polymer in the carbon nanotube-polymer composite.

[0331] Aspect 60. The method of one of aspects 36 to 59, wherein the binder treatment comprises a high shear operation sufficient to fibrillate a fibrillable binder.

[0332] Aspect 61. The method of one of aspects 36 to 59, wherein the binder treatment comprises a high shear operation sufficient to deform a non-fibrillable binder.

[0333] Aspect 62. The method of any of aspects 36 to 61, wherein a mixing operation combining two or more ingredients is carried out at shear conditions which are lower than the shear conditions employed in processing the binder.

[0334] Aspect 63. A method further comprising applying the electrode composition prepared according to one of aspects 36 to 62 to a conductive substrate, to form a battery electrode.

[0335] Aspect 64. A method further comprising calendering the electrode composition prepared according to one of aspects 36 to 62 to form a film.

[0336] Aspect 65. The method of aspect 63, wherein the film is free and has a thickness of between about 30 and about 500 microns.

[0337] Aspect 66. The method of aspect 65, wherein the film has a tensile strength of at least about 0.1 MPa and / or a modulus of elasticity of not more than about 1000 MPa.

[0338] Aspect 67. A method comprising applying the film according to one of aspects 64 to 66 to a conductive substrate to form a battery electrode.

[0339] Aspect 68. The method of one of aspects 36 to 67, wherein the carbon nanotube-polymer composite is prepared by a method that comprises: - the combination of carbon nanotubes and a polymer to form a mixture, and - removing a liquid from the mixture to obtain the carbon nanotube-polymer composite, wherein the carbon nanotubes, the polymer or both is / are provided in a dispersion.

[0340] Aspect 69. The method of aspect 68, wherein the dispersion is an aqueous dispersion.

[0341] Aspect 70. The method of one of aspects 36 to 67, wherein the carbon nanotube-polymer composite is prepared by combining carbon nanotubes and the polymer, wherein the carbon nanotubes, the polymer, or both are provided in the form of a dry powder.

[0342] Aspect 71. A dry-processed film comprising: an active electrode material, a processed binder, and a carbon nanotube-polymer composite, wherein, prior to any drying operation, the film contains solvent residues in an amount not exceeding 1% by weight based on the weight of the film electrode, wherein the carbon nanotubes in the carbon nanotube-polymer composite have a BET of between about 80 and about 500 m2 / g.

[0343] Aspect 72. The dry-processed film of aspect 71, wherein the carbon nanotubes in the carbon nanotube-polymer composite have a BET of between about 200 and about 500 m2 / g.

[0344] Aspect 73. The dry-processed film of aspect 71 or 72, wherein the dry-processed film is free or laminated to a substrate.

[0345] Aspect 74. The dry-processed film of one of aspects 71-73, wherein the carbon nanotubes of the carbon nanotube-polymer composite are multifunctional multi-walled carbon nanotubes.

[0346] Aspect 75. The dry-processed film of one of aspects 71-74, wherein the carbon nanotubes of the carbon nanotube-polymer composite have a diameter of between about 2 and about 50 nanometers.

[0347] Aspect 76. The dry-processed film electrode of one of aspects 71-75, wherein the carbon nanotubes in the carbon nanotube-polymer composite have a size particle mean (D50) between about 5 and about 500 microns, measured by laser diffraction analysis.

[0348] Aspect 77. The dry-processed film of one of aspects 71-76, wherein the carbon nanotubes of the carbon nanotube-polymer composite are pre-ground into a dry powder form.

[0349] Aspect 78. The dry-processed film of one of aspects 71-77, wherein the electrode active material, binder, carbon nanotubes, and electrode composition are particulate materials.

[0350] Aspect 79. The dry-processed film of one of aspects 71-78, wherein the active electrode material is a lithium transition metal compound.

[0351] Aspect 80. The dry-processed film of one of aspects 71-78, wherein the active electrode material is graphite, a silicon-containing compound, or a combination thereof.

[0352] Aspect 81. The dry-processed film of one of aspects 71-80, wherein the carbon nanotubes in the carbon nanotube-polymer composite are present in an amount not exceeding about 5% by weight based on the total weight of the electrode composition.

[0353] Aspect 82. The dry-processed film of one of aspects 71 to 81, wherein the carbon nanotubes of the carbon nanotube-polymer composite are the sole fibrillating agent.

[0354] Aspect 83. The dry-processed film of one of aspects 71-82, wherein the binder is a fibrillable binder, a non-fibrillable binder, or a combination thereof.

[0355] Aspect 84. The dry-processed film of one of aspects 71-83, wherein the binder contains polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), or a combination thereof.

[0356] Aspect 85. The dry-processed film of one of aspects 71-84, wherein the binder comprises a polymer that is the same or substantially the same as the polymer in the carbon nanotube-polymer composite.

[0357] Aspect 86. The dry-processed film of one of aspects 71-85, wherein the carbon nanotube-polymer composite contains a PFAS polymer.

[0358] Aspect 87. The dry-processed film of aspect 86, wherein the PFAS polymer is PTFE.

[0359] Aspect 88. The dry-processed film of one of aspects 71-85, wherein the carbon nanotube-polymer composite contains a PFAS-free polymer.

[0360] Aspect 89. The dry-processed film of aspect 88, wherein the PFAS-free polymer is PVP or HNBR.

[0361] Aspect 90. The dry-processed film of one of aspects 71-89, wherein the weight % ratio of carbon nanotubes of the composite to polymer of the composite is from about 1:1 to about 100:0.1.

[0362] Aspect 91. The method of one of aspects 71-89, wherein the weight % ratio of carbon nanotubes in the composite to polymer in the composite is from about 10:1 to about 100:0.1.

[0363] Aspect 92. The dry-processed film of one of aspects 71 to 91, wherein the film is free-floating and has a thickness of between about 30 and 500 microns.

[0364] Aspect 93. The dry-processed film of aspect 92, wherein the film has a tensile strength of at least about 0.1 MPa and / or a modulus of elasticity of not more than about 1000 MPa.

[0365] Aspect 94. An electrode comprising the dry-processed film of one of aspects 71 to 93.

[0366] Aspect 95. The electrode of aspect 94, wherein the dry-processed film is applied to a substrate.

[0367] Aspect 96. Battery comprising the electrode of aspect 94 or aspect 95.

[0368] Aspect 97. Carbon nanotube-polymer composite, comprising: - a plurality of multi-walled carbon nanotubes; and - a polymer,

[0369] wherein the carbon nanotube-polymer composite is in the form of granules and exhibits a weight loss of less than or equal to 5% upon passing the carbon nanotube-polymer composite through a 20 mesh sieve with 840 micron openings.

[0370] Aspect 98. The carbon nanotube-polymer composite of aspect 97, wherein the composite has a weight loss of 3% or less upon passing the carbon nanotube-polymer composite through a 20 mesh screen with 840 micron openings.

[0371] Aspect 99. The carbon nanotube-polymer composite of aspect 97, wherein the composite has a weight loss of 1% or less upon passing the carbon nanotube-polymer composite through a 20 mesh screen with 840 micron openings.

[0372] Aspect 100. The carbon nanotube-polymer composite of one of aspects 97-99, wherein the carbon nanotubes have a BET of between about 80 and about 500 m2 / g.

[0373] Aspect 101. The carbon nanotube-polymer composite of one of aspects 97-100, wherein the carbon nanotubes of the carbon nanotube-polymer composite have a diameter of between about 2 and about 50 nanometers.

[0374] Aspect 102. The carbon nanotube-polymer composite of one of aspects 97 to 101, wherein the carbon nanotubes in the carbon nanotube-polymer composite polymer have an average particle size (D50) of between about 5 and about 500 microns, as determined by laser diffraction analysis.

[0375] Aspect 103. The carbon nanotube-polymer composite of one of aspects 97 to 102, wherein the carbon nanotubes of the carbon nanotube-polymer composite are pre-ground into a dry powder form.

[0376] Aspect 104. The carbon nanotube-polymer composite of one of aspects 97-103, wherein the carbon nanotube-polymer composite contains a PFAS polymer.

[0377] Aspect 105. The carbon nanotube-polymer composite of one of aspects 97-104, wherein the carbon nanotube-polymer composite contains a PFAS-free polymer.

[0378] Aspect 106. The carbon nanotube-polymer composite of one of aspects 97-105, wherein the weight % ratio of carbon nanotubes in the composite to polymer in the composite is from about 1:1 to about 100:0.1.

[0379] Aspect 107. The carbon nanotube-polymer composite of one of aspects 97-106, wherein the weight % ratio of carbon nanotubes in the composite to polymer in the composite is from about 10:1 to about 100:0.1.

[0380] Aspect 108: A dry-processed film comprising: an active electrode material, a processed binder, and the carbon nanotube-polymer composite of one of aspects 97 to 107.

[0381] Aspect 109: Electrode comprising the dry-processed film of aspect 108.

[0382] Aspect 110: Battery comprising the electrode of aspect 109.

[0383] Although this disclosure has been particularly illustrated and described with reference to preferred embodiments, those skilled in the art will understand that various modifications in form and detail may be made without departing from the scope of the disclosure covered by the appended claims.

Claims

Claims

1. A method of preparing an electrode composition, the method comprising: - combining an active electrode material, a binder and a carbon nanotube-polymer composite; and - treating the binder in the presence of the carbon nanotube-polymer composite, wherein the method is carried out in the absence of a solvent.

2. A method of preparing an electrode composition, the method comprising: (a) subjecting a binder to high shear conditions in the presence of a carbon nanotube-polymer composite to cure the binder; and (b) adding an electrode active material before, during or after step a), wherein the method is carried out without adding a solvent.

3. The method of claim 1 or 2, wherein the carbon nanotubes of the carbon nanotube-polymer composite are multifunctional multi-walled carbon nanotubes.

4. A method according to any preceding claim, wherein the carbon nanotubes of the carbon nanotube-polymer composite have a BET value of between about 80 and about 500m2 / g.

5. A method according to any preceding claim, wherein the carbon nanotube-polymer composite exhibits a weight loss of 5% or less after passing the carbon nanotube-polymer composite through a 20 mesh sieve with 840 micron openings.

6. A method according to any preceding claim, wherein the carbon nanotube-polymer composite is in the form of granules.

7. A method according to any preceding claim, wherein the carbon nanotube-polymer composite contains a PFAS polymer.

8. A method according to any one of claims 1 to 6, wherein the carbon nanotube-polymer composite contains a PFAS-free polymer.

9. A method according to any preceding claim, wherein the weight % ratio of carbon nanotubes in the composite to polymer in the composite is from about 1:1 to about 100:0.

1.

10. A method according to any preceding claim, wherein the carbon nanotubes in the carbon nanotube-polymer composite are present in an amount not exceeding about 5% by weight based on the total weight of the electrode composition.

11. A method according to any preceding claim, wherein the method is carried out in the presence of the carbon nanotubes in the carbon nanotube-polymer composite as the sole fibrillating agent.

12. A method according to any preceding claim, wherein the binder comprises a polymer that is the same or substantially the same as the polymer in the carbon nanotube-polymer composite.

13. A method according to any preceding claim, wherein the treatment of the binder comprises a high shear operation sufficient to fibrillate a fibrillable binder.

14. A method according to any preceding claim, wherein the treatment of the binder comprises a high shear operation sufficient to deform a non-fibrillable binder.

15. A method further comprising calendering the electrode composition prepared according to any preceding claim to form a film.

16. The method of claim 15, wherein the film is free and has a thickness of between about 30 and about 500 microns.

17. The method of claim 16, wherein the film has a tensile strength of at least about 0.1 MPa and / or a modulus of elasticity of no more than about 1000 MPa.

18. A method comprising applying the film of any one of claims 15 to 17 to a conductive substrate to form a battery electrode.

19. A method according to any preceding claim, wherein the carbon nanotube-polymer composite is prepared by a method which comprises: - combining carbon nanotubes and a polymer to form a mixture, and - removing a liquid from the mixture to obtain the carbon nanotube-polymer composite, wherein the carbon nanotubes, the polymer, or both are provided in a dispersion.

20. A dry-processed film comprising: an active electrode material, a processed binder, and a carbon nanotube-polymer composite, wherein, prior to any drying operation, the film contains solvent residues in an amount not exceeding 1% by weight based on the weight of the film electrode, wherein the carbon nanotubes in the carbon nanotube-polymer composite have a BET value of between about 80 and about 500 m2 / g.

21. The dry-processed film of claim 20, wherein the carbon nanotubes in the carbon nanotube-polymer composite have a BET value of between about 200 and about 500 m2 / g.

22. The dry-processed film of claim 20 or 21, wherein the dry-processed film is free or laminated to a substrate.

23. A dry-processed film according to any one of claims 20 to 22, wherein the carbon nanotubes of the carbon nanotube-polymer composite are multifunctional multi-walled carbon nanotubes.

24. The dry-processed film of any one of claims 20 to 23, wherein the active electrode material, the binder, the carbon nanotubes, and the electrode composition are particulate materials.

25. The dry-processed film of any one of claims 20 to 24, wherein the carbon nanotubes in the carbon nanotube-polymer composite are present in an amount not exceeding about 5% by weight based on the total weight of the electrode composition.

26. A dry-processed film according to any one of claims 20 to 25, wherein the carbon nanotubes of the carbon nanotube-polymer composite are the sole fibrillating agent.

27. ​​The dry-processed film of any one of claims 20 to 26, wherein the binder comprises a polymer that is the same or substantially the same as the polymer in the carbon nanotube-polymer composite.

28. The dry-processed film of any one of claims 20 to 27, wherein the carbon nanotube-polymer composite contains a PFAS polymer.

29. The dry-processed film of any one of claims 20 to 27, wherein the carbon nanotube-polymer composite contains a PFAS-free polymer.

30. The dry-processed film of any one of claims 20 to 29, wherein the weight % ratio of carbon nanotubes in the composite to polymer in the composite is from about 1:1 to about 100:0.

1.

31. A dry-processed film according to any one of claims 20 to 30, wherein the film is free-floating and has a thickness of between about 30 and about 500 microns.

32. The dry-processed film of claim 31, wherein the film has a tensile strength of at least about 0.1 MPa and / or a modulus of elasticity of no more than about 1000 MPa.

33. An electrode comprising the dry-processed film of any one of claims 20 to 32.

34. The electrode of claim 33, wherein the dry-treated film is applied to a substrate.

35. A battery comprising the electrode of claim 33 or claim 34.

36. A carbon nanotube-polymer composite, comprising: - a plurality of multi-walled carbon nanotubes; and - a polymer, wherein the carbon nanotube-polymer composite is in the form of granules and exhibits a weight loss of less than or equal to 5% upon passing the carbon nanotube-polymer composite through a 20-mesh sieve with 840-micron openings.

37. The carbon nanotube-polymer composite of claim 36, wherein the composite exhibits a weight loss of 1% or

38.

39.

40.

41.

42.

43.

44. less after passing the carbon nanotube-polymer composite through a 20 mesh screen with 840 micron openings. The carbon nanotube-polymer composite of claim 36 or 37, wherein the carbon nanotubes have a BET value of between about 80 and about 500 m2 / g. The carbon nanotube-polymer composite of any one of claims 36 to 38, wherein the carbon nanotube-polymer composite contains a PFAS polymer. The carbon nanotube-polymer composite of any one of claims 36 to 39, wherein the carbon nanotube-polymer composite contains a PFAS-free polymer. The carbon nanotube-polymer composite of any one of claims 36 to 40, wherein the weight % ratio of carbon nanotubes in the composite to polymer in the composite is from about 1:1 to about 100:0.

1. A dry-processed film comprising: an active electrode material, a processed binder, and the carbon nanotube-polymer composite of any one of claims 36 to 41. An electrode comprising the dry-processed film of claim 42. A battery comprising the electrode of claim 43.

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