Solvent-free process for preparing lithium-ion batteries

Abstract

Solvent-free processes use carbon nanotubes to prepare compositions and electrodes for lithium-ion batteries. Carbon nanotubes can be multifunctional, providing two or more desirable properties, for example, acting as a conductive carbon additive, a fibrillating agent, and / or a mechanical reinforcing agent. In one example, carbon nanotubes are provided in combination with carbon black. In another example, an electrochemical active material, a fibrillable binder, such as PTFE, and carbon nanotubes are combined in one or more steps. The binder is fibrillated using a high-shear mixture. The resulting composition can be formed into a film that can be applied onto a suitable substrate for forming electrodes.

Description

[Technical Field]

[0001] Government support This invention was made with government support under grant number DE-EE0009109.0000, awarded by the Office of Energy Efficiency and Renewable Energy (EERE) of the United States Department of Energy. The Government reserves certain rights in this invention.

[0002] (Cross-reference of related applications) This application relates to U.S. Provisional Patent Application No. 63 / 491,598, filed on 22 March 2023, and U.S. Provisional Patent Application No. 63 / 583,327, filed on 18 September 2023, both of which are incorporated herein by reference in their entirety. [Background technology]

[0003] Lithium-ion batteries (LIBs) are commonly used as an electrical energy source for a wide range of applications, from electronic devices to electric vehicles. A lithium-ion battery typically includes a negative electrode and a positive electrode, arranged in a way that allows 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 that facilitates ion movement. Separators are used to physically and electrically insulate the electrodes to prevent direct contact between them. During operation, electrical contact is made to the electrodes, allowing electrons to flow through the device to provide power and lithium ions to move through the electrolyte from one electrode to the other.

[0004] Most commercially available lithium-ion batteries have an anode containing graphite, a material that can incorporate lithium via an intercalation mechanism. Typically, lithium is added to the graphite anode during the charging cycle and removed as the battery is used.

[0005] A cathode typically comprises a conductive substrate supporting a mixture containing at least an electrochemical active material and a binder. The electrochemical active material, such as a lithium transition metal oxide, can accept and release lithium ions. Similar to the anode, the binder is used to provide mechanical integrity and stability to the electrode.

[0006] Since electrochemical active materials and binders often have low conductivity or even exhibit insulating properties, cathodes often contain additive components to enhance the conductivity of the electrodes. Conductive additives, such as carbon conductive additives, can also be present in the LIB anode composition.

[0007] When manufacturing electrodes, the electrode active material, such as graphite, is mixed with a binder, typically a polymer or resin material. Many existing manufacturing methods use casting techniques based on a wet slurry that contains not only the binder but also solvents, plasticizers, and conductive additives. During manufacturing, the slurry is coated or extruded onto a conductive substrate. The solvent is removed by drying because it is detrimental to the final product.

[0008] However, drying operations, especially when aimed at solvent removal, are time-consuming and slow down the entire manufacturing process. Solvents can also increase costs and potentially cause environmental problems. Regarding the final product, solvent removal during the drying process often results in binder migration to the electrode surface. Minimal migration may be acceptable in some cases, but it can also be problematic. For example, in high-load (thick, >4.5 mAh / g) electrodes, migration worsens, leading to delamination and insufficient electrode performance.

[0009] As a result, "dry" alternative methods have been developed with the aim of reducing or eliminating the drying process associated with slurry technology. Dry processes also typically produce electrodes containing electrochemical active materials, binders, and conductive additive components, but they do not require the use of solvents.

[0010] Proposed dry techniques include, but are not limited to, high-shear mixing containing a fibrillable binder, the use of a sacrificial binder removed during electrode processing, dry powder spraying, electrostatic spray deposition, low-temperature plasma deposition, sputtering deposition, and powder printing. In some embodiments, a fibrillation accelerator is incorporated into the binder, and the resulting formulation is subjected to high-shear mixing to fibrillate the binder, thereby creating a web-like structure that can better retain the material and support the active material.

[0011] To date, the most common additive used to promote binder fibrillation has been activated carbon (AC). Generally, AC is derived from carbonaceous raw materials such as bamboo, coconut shells, willow peat, wood, coir, lignite, coal, and petroleum pitch. Activation is achieved by physical or chemical methods known in the art. In many applications, AC powder is milled to a particle size of several tens of microns (μm) before activation. [Overview of the project]

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

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

[0014] Advanced fibrillating agents such as AC often contain high levels of impurities. Furthermore, the high surface area and surface oxygen-containing groups typical of AC tend to promote significant water uptake. These characteristics can contribute to irreversible capacity loss and degrade battery performance. Additionally, AC may not provide sufficient conductivity, necessitating an increase in the amount of conductive additives in the overall formulation. Even as a simple fibrillation accelerator, AC often requires relatively high addition amounts (often 5-10% by weight), which also limits the amount of active material that can be included.

[0015] Therefore, compositions and processes are needed that address at least some of the challenges associated with existing approaches.

[0016] In a broad sense, the present invention relates to the use of carbon nanotubes (CNTs or plural CNTs) to bring about the necessary improvements in manufacturing methods, product electrodes and / or assembled batteries. More specifically, the present invention relates to the use of these CNTs in dry or solvent-free electrode manufacturing processes.

[0017] When used in such processes, CNTs have been found to be able to function as binder treatment agents. In fact, carbon nanotubes can be multifunctional, offering two or more desirable properties. For example, carbon nanotubes can act as fibrillation aids (functioning as AC substitutes), as conductive carbon additives (by forming conductive networks); and / or as mechanical strengthening agents (adding mechanical strength and flexibility to product films / electrodes).

[0018] It has been further discovered that specific combinations of CNTs and carbon black (CB) can effectively treat the binder in the solvent-free approach described herein. In many cases, CNT-CB combinations can further impart desirable mechanical properties and / or conductivity to the resulting dry-treated films and / or electrodes. For example, cathodes prepared using CNTs and CB can exhibit short-range and long-range conductivity along with good Li diffusion.

[0019] Accordingly, in some embodiments, the dry process described herein is carried out using a combination of CNTs and CBs (e.g., a blend) comprising one or more CNTs and one or more CBs. At least one of the CBs used may have multifunctional properties (acting, for example, as a conductive additive, a binder processing aid, and a mechanical reinforcing agent).

[0020] Typically, the methods described herein are carried out without the use of liquids (e.g., solvents). The components are provided as loose particulate materials, such as flowable or injectable powders, flakes, beads, granules, pellets, etc.

[0021] However, in some cases, it is possible to use small amounts of liquid (e.g., solvent) to carry out the methods described herein, typically other than the fibrillation or binder treatment steps. Generally, when liquid is added, the amount used is about 10% by weight or less of the total weight of the components used. In many situations, the liquid, such as solvent, is added in an amount of 1% by weight or less.

[0022] One aspect of the present invention is characterized by a method for preparing an electrode composition. This method includes the steps of combining an electrode active material, a binder, and CNTs, and treating the binder in the presence of CNTs. Many embodiments of this method are carried out without the addition of a liquid (typically a solvent). CNTs may be components of a CNT-CB carbon additive component.

[0023] In general, the binder can be any semi-crystalline polymer. Therefore, this method can be carried out using binders that were previously considered "fibrillable," as well as binders that were previously considered "non-fibrillable," and combinations of these can also be used.

[0024] In one example, a method for preparing an electrode composition includes the steps of combining an electrode active material, a fibrillable binder, and CNTs, and subjecting the binder to a fibrillation operation in the presence of CNTs, or optionally in the presence of a combination or blend of CNTs and one or more CBs.

[0025] Another aspect of the present invention is characterized by a method for preparing an electrode composition. This method includes the steps of treating a binder in the presence of CNTs (e.g., subjecting the binder to high shear conditions) and adding an electrode active material before, during, or after the binder treatment. The binder may be a fibrillable binder, a non-fibrillable binder, or any combination thereof. The CNTs may be provided as a CNT-CB component.

[0026] In certain embodiments, the methods described herein are carried out without the addition of fibrillation aids other than CNT or CNT-CB components. In such cases, the CNT (or CNT-CB blend) used provides the entire binder treatment (e.g., fibrillation) function and completely replaces conventional fibrillating agents such as activated carbon. It is also possible to use CNT (or CNT-CB components) in combination with various amounts of conventional fibrillation aids, such as activated carbon.

[0027] The electrochemical active material, binder, e.g., a fibrillable binder, and CNTs (or CNT / CB blend) can be combined in a single step, with binder treatment, e.g., fibrillation, performed thereafter. In other embodiments, the components are combined sequentially. For example, the binder is first treated (e.g., fibrillated) in the presence of a multifunctional additive, and then mixed with the electrochemical active material. Other sequences are also possible.

[0028] A uniform distribution of components can be achieved using conditions other than those used in binder processing (e.g., fibrillation) (often milder conditions). Low-shear mixing techniques can also prevent particle fragmentation and maintain particle size.

[0029] Electrode compositions prepared as described herein can result in self-supporting films or laminated films on a substrate. Thus, in embodiments, electrode compositions containing an electrochemical active material, a treated (e.g., fibrillated) binder, CNTs, and an optional CB, typically loose particulate materials such as a liquid powder, are further processed. In one example, the composition can be formed into a self-supporting film that can be applied to a conductive substrate or support to form an electrode. For example, the composition can be calendered and laminated onto a conductive foil substrate. The calendering operation can be performed above room temperature, for example, at a temperature approximately the same as or close to the glass transition temperature of the polymer. The lamination process can be performed during or after the calendering of the composition. The resulting product electrodes can be assembled into a LIB battery in which one or both electrodes are prepared by a solvent-free process. In one example, both electrodes are prepared according to the techniques described herein.

[0030] In a further embodiment, the present invention features a dry-processed film comprising an electrode active material; a typically treated, e.g., fibrillated binder; and CNTs. In some cases, the dry-processed film further comprises at least one CB (which may be multifunctional). Prior to any drying operation, the dry-processed film has a weight equal to or within 1% by weight of its theoretical weight.

[0031] The use of CNTs can impart several attractive properties to dry-processed electrode films and / or electrodes, including, for example, conductivity, attractive physical properties such as good tensile strength, thermal stability (sometimes comparable to that of diamond crystals or in-plane graphite sheets), and / or chemical stability.

[0032] CNTs can, for example, reduce the amount of binder and / or conventional processing additives required in the manufacturing process, increase the potential load on the active material, and result in electrodes with higher energy density, and therefore batteries. The approach described herein can reduce or eliminate the need for AC. In many cases, the amount of additives required is small, increasing the allowable available content in the electrode active material, resulting in batteries with higher energy density and longer lifespan. CNTs can improve the fibrillation of the binder and the material distribution throughout the electrode. Improved adhesion and mechanical stability represent further potential benefits. Dry-processed electrodes prepared using CNTs exhibit good charge transfer. The reduction in electrode impedance by CNT additives can improve cell rate capacity and charging performance, opening up the possibility of higher energy density batteries with thicker electrodes and faster charging capabilities.

[0033] In some cases, the initial CNTs may be broken down or separated into smaller units during processing. For example, such fragments uniformly distributed throughout the electrode composition may result in an electrode with improved mechanical properties and / or electrical connectivity (by forming enhanced electrical paths).

[0034] Further improvements are possible by combining CNTs with one or more carbon blacks. For example, certain combinations of CNTs and CBs have multifunctional properties and can deform the binder to a degree sufficient to process the components using a solvent-free approach. Combinations of CNTs and CBs can further impart desirable mechanical properties. Regarding electrical properties, CNTs, together with CBs, are thought to be able to strike a favorable balance between CNTs that are long-range conductive but have limited Li+ diffusion and CBs that are short-range conductive but have good Li+ diffusion.

[0035] Binder migration is often observed in slurry-prepared electrodes, but the processes and compositions described herein appear to result in a uniform distribution across the electrode. The fibrillating binder holds the electroactive particles together (along with the conductive additives) (aggregation), while keeping the electrode film layer adhered to the metal substrate (adhesion).

[0036] The solvent-free technologies described herein reduce or eliminate the use of harmful solvents such as N-methyl-2-pyrrolidone (NMP). Bypassing the drying process associated with slurries (or other "wet" processes) simplifies and speeds up manufacturing and reduces the footprint of the electrode production line. These advantages, as well as the reduced or elimination of the need for solvent recycling or emission reduction measures, can contribute to overall cost savings.

[0037] The above and other features of the present invention, including various details of configurations and combinations of components, as well as other advantages, are described in more detail with reference to the accompanying drawings and are pointed out in the claims. Specific methods and apparatus for carrying out the present invention are shown by illustration and will be understood not to limit the invention. The principles and features of the present invention can be used in a variety of numerous embodiments without departing from the scope of the invention. [Brief explanation of the drawing]

[0038] In the attached drawings, reference numerals indicate the same parts across different drawings. The drawings are not necessarily to scale. Instead, the focus is on illustrating the principles of the present invention. The drawings are as follows:

[0039] [Figure 1A] This bar graph compares the tensile strength (bottom) and elastic modulus (top) of dry cathode films prepared using various types of CNTs;CBs; and AC as a reference.

[0040] [Figure 1B] This bar graph compares the in-plane resistivity of dry cathodes prepared using various CNTs with the in-plane resistivity of a reference dry cathode prepared using CB.

[0041] [Figure 2A] This shows the effect of D50 of CNTs on the tensile strength (bottom) and elastic modulus (top) of dry cathode films.

[0042] [Figure 2B] This bar graph shows the in-plane electrode resistivity measured for dry cathodes prepared using pulverized (pre-milled) CNTs and unpulverized (unpre-milled) CNTs.

[0043] [Figure 3A]Cross-sectional SEM images of dry cathode films prepared using unpulverized CNTs (A and C) and pulverized CNTs (B and D) are shown. The left images in Figures A and B are backscattered electron images (AI and BI), and the right images are secondary electron images (A-II and B-II). [Figure 3B] Cross-sectional SEM images of dry cathode films prepared using unpulverized CNTs (A and C) and pulverized CNTs (B and D) are shown. The left images in Figures A and B are backscattered electron images (AI and BI), and the right images are secondary electron images (A-II and B-II). [Figure 3C] Cross-sectional SEM images of dry cathode films prepared using unpulverized CNTs (A and C) and pulverized CNTs (B and D) are shown. The left images in Figures A and B are backscattered electron images (AI and BI), and the right images are secondary electron images (A-II and B-II). [Figure 3D] Cross-sectional SEM images of dry cathode films prepared using unpulverized CNTs (A and C) and pulverized CNTs (B and D) are shown. The left images in Figures A and B are backscattered electron images (AI and BI), and the right images are secondary electron images (A-II and B-II).

[0044] [Figure 4] The image shows a cross-sectional SEM image (A) of a dry cathode film prepared using pulverized carbon nanotubes (CNTs), along with corresponding EDS elemental mappings of fluorine (B) and carbon (C) (scale bar 100 μm).

[0045] [Figure 5A] This shows a comparison of the tensile strength (bottom) and elastic modulus (top) of dry cathode films prepared using two different amounts of pulverized and unpulverized carbon nanotubes (CNTs).

[0046] [Figure 5B] This is a bar graph showing the in-plane resistivity of dry cathodes prepared using two different amounts of pulverized and unpulverized carbon nanotubes (CNTs).

[0047] [Figure 6] This is a comparison of the in-plane (top) and through-plane (bottom) electrode resistivity of dry cathodes prepared using several CNTs.

[0048] [Figure 7A] This is a comparison of the tensile strength of dry cathode films prepared with selected carbon dioxide (CB) only, carbon nanotubes (CNT) only, and two different ratios of CB / CNT blends.

[0049] [Figure 7B] This is a comparison of the tensile strength of dry cathode films prepared with selected carbon dioxide (CB) only, carbon nanotubes (CNT) only, and two different ratios of CB / CNT blends.

[0050] [Figure 8] This is a comparison of the cathode resistivity of dry electrodes prepared with CB only, CNT only, and a CB / CNT blend in a selected ratio.

[0051] [Figure 9] This study compares the elastic moduli of dry cathode films prepared with two different amounts of CB and CNT blends, and with two different amounts of CB alone.

[0052] [Figure 10A] This is a bar graph of the tensile strength of dry cathode films formed from selected ratios of CB / CNT blends, CNT only and CB only as comparative examples, and AC for reference. Cathode films that could not be fabricated are marked with an "x" on the chart.

[0053] [Figure 10B] This study compares the tensile strength of dry cathode films prepared using the same amount of carbon nanotubes (CBs) and carbon nanotubes (CBs), with two different types of CBs combined with the same amount of CBs and CBs.

[0054] [Figure 11]This study compares the tensile strength of dried anode films prepared using three different types of carbon nanotubes (CNTs) with that of AC (Acoustic Anode) as a reference.

[0055] [Figure 12] This plot shows the C / 20, C / 10, C / 5, C / 3, C / 2, 1C, and 2C discharge capacities of full coin cells having dry cathodes prepared using pulverized and unpulverized carbon nanotubes (CNTs).

[0056] [Figure 13] This plot shows the discharge capacity cycles of full coin cells having dry cathodes prepared using pulverized and unpulverized carbon nanotubes (CNTs).

[0057] [Figure 14] This plot shows the C / 20, C / 10, C / 5, C / 3, C / 2, 1C, and 2C discharge capacities of full coin cells with dry cathodes prepared using several CNTs with similar D50 values.

[0058] [Figure 15] This plot shows the discharge capacity cycles of a full coin cell with a dry cathode prepared using several CNTs with similar D50 values.

[0059] [Figure 16] This plot shows the discharge capacity at 2C of a full coin cell with a dry cathode using the same CNTs at two different active material addition amounts and densities.

[0060] [Figure 17] This plot shows the C / 20, C / 10, C / 5, C / 3, C / 2, and 1C discharge capacities of full coin cells with dry cathodes prepared using only selected CB and two different ratios of CB / CNT blends.

[0061] [Figure 18]This plot shows the discharge capacity cycles of full coin cells with dry cathodes prepared using only selected CNTs and CB / CNT blends. [Modes for carrying out the invention]

[0062] The present invention will be described in further detail below with reference to the accompanying drawings illustrating exemplary embodiments of the invention. However, the present invention may be carried out in many different forms and should not be construed as being limited to the embodiments of the present invention described herein. Rather, these embodiments are provided so that the disclosure may be thorough and complete and the scope of the invention may be fully conveyed to those skilled in the art.

[0063] Where used herein, the terms "and / or" include any and all combinations of one or more of the enumerated items associated with them. Furthermore, all conjunctions used should be understood in the most comprehensive sense possible. Thus, the word "or" should be understood as having the logical definition of "or" rather than the logical definition of "exclusive OR," unless the context clearly requires otherwise. Additionally, the singular forms and the articles "a," "an," and "the" are intended to include the plural forms unless otherwise specified. It will be further understood that, where used herein, the terms "includes," "comprises," "including," and / or "comprising" indicate the presence of at least one of the described features, integers, processes, operations, elements, and components, but do not exclude the presence or addition of at least one other feature, integer, process, operation, element, component, or group thereof. Furthermore, if an element containing a component or subsystem is mentioned and / or indicated as being connected to or coupled to another element, it will be understood that it may be directly connected to or coupled to the other element, or that intervening elements may exist.

[0064] While terms such as "first," "second," etc., are used to describe a variety of components, it will be understood that these components should not be limited by these terms. These terms are used solely to distinguish one element from another. Thus, the elements described below may be referred to as the second element, and similarly, the second element may be referred to as the first element without departing from the teachings of the present invention.

[0065] Unless otherwise specified, all terms used herein (including technical and scientific terms) have the same meaning as those commonly understood by those skilled in the art to which this invention pertains. Terms as defined in commonly used dictionaries should be interpreted as having the same meaning as their meaning in the context of the relevant art, and it will be further understood that they should not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0066] In a broad sense, this invention relates to the manufacture of electrodes for electrochemical cells, often for batteries such as lithium-ion batteries (LIBs). In one example, the battery in question is a rechargeable LIB.

[0067] Typically, LIBs are named according to the acronym of the electrochemical active material, often an intercalation compound, used to form the cathode. Embodiments described herein can be implemented or adapted to various types of lithium-ion batteries currently known in the art, such as 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) batteries, or other LIBs that are currently known or may be developed in the future.

[0068] Many electrode manufacturing techniques for use in electrochemical cells involve forming electrode compositions (anodes or cathodes) that can be applied (coating, extrusion, lamination, etc.) onto a conductive substrate. In the composition, the electrode active material is mixed (blended) with a binder (e.g., polymer, resin, etc.), which plays a role in associating and holding the active material together. The binder often contains a liquid used to dissolve or transport the binder material, plasticizer, and / or other additives.

[0069] Generally, conventional solvent-based processes involve mixing polymer binders and other components with a suitable liquid to form a slurry, which is then applied onto a substrate. The typical amount of liquid used is at least about 40% based on the total weight of the components used, and many wet processes require even larger amounts of solvent. As the solvent is removed (e.g., during drying), the binder gradually becomes more viscous and adheres to any present particles and / or the substrate.

[0070] In contrast to slurry-based technologies, the embodiments described herein involve a “solvent-free” process, also known as a “dry” process. In this solvent-free approach, several, typically all, of the components required to prepare the electrode composition (e.g., active material, binder, additives, etc.) are supplied as loose particulate materials, such as free-flowing powders, flakes, pellets, or beads. The embodiments described herein may include one or more operations designed to mix these components (e.g., using equipment designed to blend loose particulate materials), as well as at least one operation designed to process the binder. Exposing the binder to specific shear conditions may result in deformation of the binder, such as binder elongation, binder strand formation, entanglement, etc. In some types of binders, this is called binder “fibrillation.” Typically, the resulting composition is a loose particulate material.

[0071] In many embodiments of the present invention, the components are combined, and the binder is processed (e.g., fibrillated) without the addition of a liquid, such as a solvent.

[0072] Most embodiments involve processes that are carried out without the addition of liquid and are completely solvent-free, however, in some cases, a small amount of liquid, such as a solvent, may be used to moisten, for example, at least some of the particles to be mixed. This may occur when a pre-blend is formed and then completely dried before subsequent operations. In one example, any solvent used to form the pre-blend, etc., is removed, for example, by drying, before the binder is deformed. The processing of the binder (e.g., fibrillation) is then carried out under completely solvent-free conditions using loose, free-flowing, or injectable particles.

[0073] While the components can be mixed and the binder processed (e.g., fibrillated) under completely solvent-free conditions, solvents may be used in post-processing (operations performed after the dry electrode composition has been formed), such as during film production or electrode lamination, for example, to enhance film processability. Processes involving the use of solvents during post-processing are also referred to herein as "dry" or "solvent-free." Generally, any solvents used (e.g., to spray the film during laminated film production) are removed, for example, by drying, as the electrodes pass through a heated calender roll.

[0074] Suitable solvents can be selected from those typically used in LIB production, including but not limited to N-methylpyrrolidone (NMP), acetone, alcohols, and water. If used, the solvent can be removed by standard drying techniques. Such low solvent levels are expected to be completely or nearly completely removed.

[0075] When used, the amount of solvent is less than or equal to about 1% by weight of the entire product electrode composition (e.g., a composition containing a treated electrochemical active material such as fibrillation, a binder and other components, additive components, etc.), and is often less than about 1% by weight. In exemplary examples, the amount of solvent used is within the range of about 0 to a maximum of 1% by weight, for example, about 0 to about 0.2, about 0.4, about 0.6, about 0.8% by weight; or about 0.2 to about 0.4, about 0.6, about 0.8, about 1% by weight; or about 0.2 to about 0.4, about 0.6, about 0.8, about 1% by weight; or about 0.4 to about 0.6, about 0.8, about 1% by weight; or about 0.6 to about 0.8, about 1.0% by weight; or about 0.8 to about 1% by weight, and these are based on the total weight of the components used.

[0076] In other situations, the solvent may be added in amounts ranging from about 0 to about 10% by weight, for example, about 0 to about 2, about 4, about 6 to about 8% by weight; or about 2 to about 4, about 6, about 8, about 10% by weight; or about 4 to about 6, about 8, about 10% by weight; or about 6 to about 8, about 10% by weight; or about 8 to about 10% by weight.

[0077] Finished products prepared by solvent-free or dry processes described herein, such as films or films laminated on current collectors, can be identified by the absence of detectable processing solvents or processing solvent residues. In contrast to these “dry” products, products obtained by wet (slurry) techniques typically contain detectable processing solvents and / or processing solvent residues. In different approaches, dry electrodes or films prepared according to embodiments of the present invention are expected to exhibit a uniform or substantially uniform binder distribution across the thickness of the electrode or film. Generally, lower uniformity is observed with wet techniques, which often results in binder migration to the film surface.

[0078] With respect to the components used, the solvent-free process described herein comprises an electroactive component (a material or combination of materials that participates in the electrochemical charge / discharge reaction of an electrochemical cell, such as by absorbing or desorbing lithium), a binder which may be a fibrillable or non-fibrillable binder, and carbon nanotubes. In some embodiments, the carbon nanotubes are components of the carbon additive component. In further embodiments, this component also contains carbon black (CB).

[0079] For many LIB anodes, the electrochemical active material (also referred to herein simply as “active material” or “AM”) is graphite, e.g., natural graphite, artificial graphite (e.g., massive artificial graphite (MAG)), or a blend of both. Mesocarbon microbeads (MCMB), mesophase pitch carbon fibers (MCF), and vapor-grown carbon fibers (VGCF) can also be used. Other anodic materials that can be used in addition to or instead of graphite include lithium titanate, tin oxide, silicon (Si), and SiO2. x Examples include (where x is typically 1.04, 1.06, etc.). In an exemplary example, the anode may contain graphite and / or a silicon-containing compound.

[0080] The principles described herein can also be used in conjunction with other active anodic materials, such as those that are known, currently under investigation, or to be developed in the future.

[0081] The amount of active anode material can be varied depending on the specific type of energy storage device. In exemplary examples, the amount of active anode material (e.g., graphite) is at least 80% by weight, for example, at least 85, at least 90, at least 95, or at least 99% by weight, relative to the total weight of the (dry) electrode composition. The anode active material, e.g., graphite, can be supplied in amounts of about 80–about 85, about 90, about 93, about 96, about 99% by weight; or about 85–about 90, about 93, about 96, about 99% by weight; or about 90–about 93, about 96, about 99% by weight; or about 93–about 96, about 99% by weight; or about 96–about 99% by weight.

[0082] To give a few examples, LIB cathodes can be LCO (lithium cobaltate), LMO (lithium manganeseate), NCM (lithium nickel cobalt manganeseate), NCA (lithium nickel cobalt aluminate), LCP (lithium cobalt phosphate), LFP (lithium iron phosphate), LFMP (lithium iron manganese phosphate), LFSF (lithium iron fluorosulfate), and LTS (lithium titanium sulfide). Such materials are generally referred to herein as "lithium transition metal compounds," or "lithium transition metal oxides." For example, in addition to cathode materials based on insertion chemistry, which typically involves chemical reactions that transfer a single electron, other types of cathode materials (e.g., those with lithium ions inserted into FeF3) can transfer multiple electrons via more complex reaction mechanisms called conversion reactions. Other cathode active materials known in the art or to be developed in the future can be used.

[0083] In some embodiments, the dry processes described herein utilize NCM or NCA cathode compositions. NCM (also known as "NMC") and NCA are generally known to those skilled in the art.

[0084] More specifically, NCM uses the formula Li 1+x Ni y Co 1-y-z Mn z1-xIt can be represented by O2, where x ranges from 0 to 1, y ranges from 0 to 1 (for example, 0.3 to 0.8), and z ranges from 0 to 1 (for example, 0.1 to 0.3). Examples of NCM include Li 1+x (Ni 0.33 Co 0.33 Mn 0.33 ) 1-x O2, Li 1+x (Ni 0.4 Co 0.3 Mn 0.3 ) 1-x O2, Li 1+x (Ni 0.4 Co 0.2 Mn 0.4 ) 1-x O2, Li 1+x (Ni 0.4 Co 0.1 Mn 0.5 ) 1-x O2, Li 1+x (Ni 0.5 Co 0.1 Mn 0.4 ) 1-x O2, Li 1+x (Ni 0.5 Co 0.3 Mn 0.2 ) 1-x O2, Li 1+x (Ni 0.5 Co 0.2 Mn 0.3 ) 1-x O2, Li 1+x (Ni 0.6 Co 0.2 Mn 0.2 ) 1-x O2, Li 1+x (Ni 0.8 Co 0.1 Mn 0.1 ) 1-x O2, and Li 1+x (Ni 0.9 C 0.05 Mn 0.05 )<00000​​​​​​​​​​​​It can be represented by O2, where x is in the range of 0 to 1, y is in the range of 0 to 1, and z is in the range of 0 to 1. An example of NCA is Li 1+x (Ni 0.8 Co 0.15 Al 0.05 ) 1-x It is O2.

[0086] The amount of electroactive cathode material used may vary depending on the specific type of energy storage device. In exemplary examples, the amount of NCM or NCA is at least 90% by weight, for example, at least 93% by weight, at least 96% by weight, at least 98% by weight, or at least 99% by weight, relative to the total weight of the (dry) electrode composition. NCM or NCA can be supplied in amounts of about 90–about 93, about 96, about 99% by weight; or about 93–about 96, about 99% by weight; or about 96–about 99% by weight.

[0087] In addition to the active material, the dry process described herein uses a binder. Generally, the binder can be any semicrystalline polymer.

[0088] In some embodiments, the binder is a fibrillable binder. The fibrillable binder can be provided as a binder component consisting of, essentially consisting of, or containing the fibrillable binder.

[0089] Under specific processing conditions, for example, under high-shear mixing in the presence of a fibrillating agent, a fibrillable binder can generate fibrils, forming a network that can bind and support other particles present in the formulation. More specifically, binder fibrillation is thought to produce a matrix, lattice, or web (also called "strands," "ribbons," or "strings") of fibrils that impart mechanical structure to the electrode. In the product electrode, fibrillated binder can be detected in SEM images showing the presence of fibrils wrapped around at least some of the present particles (e.g., active material particles). Other indirect techniques that can be used to assess the relative degree of binder fibrillation include, for example, energy-dispersive X-ray spectroscopy (EDX), powder rheology, and tensile strength. For example, EDX maps the distribution of fluorine elements across the entire dry electrode to assess the effectiveness of binder fibrillation. Powder rheology measures the aggregation interactions between particles in a free-flowing electrode powder mixture, and tensile strength testing measures the strength of a self-supporting electrode film; both represent the degree of binder fibrillation. In some cases, for dried product electrode films that crumble or peel off from the substrate, it can be inferred that fibrillation is insufficient or absent.

[0090] In some embodiments, the fibrillable binder is a fibrillable fluoropolymer such as polytetrafluoroethylene or PTFE. Other binders that may be considered fibrillable include, but are not limited to, ultra-high molecular weight polypropylene, polyethylene, and copolymers, and any combination thereof.

[0091] The fibrillable binder can be supplied (either alone or as a component in a binder (e.g., in a polymer blend)) in amounts of about 1 to about 10% by weight, for example, about 1 to 2, 2 to 3, 3 to 4, 4 to 5, 5 to 6, 6 to 7, 7 to 8, 8 to 9, or 9 to 10% by weight. In one example, the fibrillable binder is supplied in an amount of about 5% by weight. In other examples, the fibrillable binder is provided in amounts ranging from about 1 to about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9% by weight; or about 2 to about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10% by weight; or about 3 to about 4, about 5, about 6, about 7, about 8, about 9, about 10% by weight; or about 4 to about 5, about 6, about 7, about 8, about 9, about 10% by weight; or about 5 to about 6, about 7, about 8, about 9, about 10% by weight; or about 6 to about 7, about 8, about 9, about 10% by weight; or about 7 to about 8, about 9, about 10% by weight; or about 8 to about 9, about 10% by weight.

[0092] However, fibrillable binders are not used in all situations. Therefore, some embodiments of the present invention use a binder component consisting of, essentially comprising, or containing one or more nonfibrillable binders. As used herein, the term “nonfibrillable” binder refers to a binder that is difficult to fibrillate under the same conditions as a “fibrillable” binder. Nevertheless, by carrying out embodiments of the present invention (under the same or substantially the same processing conditions as those used for fibrillable counterparts), it is possible, often to a considerable extent, to still deform the nonfibrillable binder, for example, by stretching, elongating, or entangling it, even if complete fibrillation is not achieved.

[0093] While we do not wish to be bound to any particular interpretation or mechanism, fibrillation can be considered an extreme phenomenon in which a binder polymer (which may begin as colloidal particles) is stretched very thin to form very long (high aspect ratio) strands that can crosslink two or more electroactive particles, thereby holding them together. By carrying out the embodiments described herein, non-fibrillable binders can also be stretched (elongated) and / or entangled to form, for example, a composite of the binder and a carbon additive, or a coating on carbon additive particles. Such “treated” non-fibrillable binders, even if not fully fibrillated, can still function as adhesives, connecting and bonding electroactive particles and providing connectivity and adhesion of the electroactive particles to a current collector. Deformations of non-fibrillable binders can be observed by at least some of the techniques described above.

[0094] In one example, a non-fibrillable binder is a fluoropolymer such as polyvinylidene fluoride (PVDF). Other examples of binders that can be considered non-fibrillable include poly(vinyldifluoroethylene-co-hexafluoropropylene) (PVDF-HFP), polyimides, and water-soluble binders, such as poly(ethylene) oxide, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyvinyl acetate, polyethylene-co-vinyl acetate, some polyolefins, cellulose, and cellulose derivatives. Other possible non-fibrillable binders include polyethylene and polypropylene other than ultra-high molecular weight, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), hydrogenated nitrile butadiene rubber (HNBR), fluororubber, copolymers and / or mixtures thereof. In one example, a non-fibrillable binder is cellulose ester, cellulose ether, cellulose nitrate, carboxyalkyl cellulose, cellulose salts, and cellulose salt derivatives. In some embodiments, the particulate non-fibrillable binder is selected from at least one of 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 a combination of a non-fibrillable binder, e.g., PVDF, and a non-fibrillable binder, e.g., PTFE.

[0095] The non-fibrillable binder can be present in the electrode composition in the same amount as the fibrillable binder. Other suitable amounts can be used, for example, according to determination by routine experiments.

[0096] Fibrillable binders can also be used in combination with non-fibrillable binders.

[0097] Electrode compositions typically contain components such as conductive additives (e.g., conductive carbon additives or CCA) and plasticizers. In solvent-free processes, common techniques also require binder fibrillating agents (also known as "fibrillating agents") or auxiliary agents, typically AC.

[0098] It has been discovered that conventional fibrillating additives (e.g., AC) can be supplemented with carbon nanotubes, and in many cases, completely replaced by carbon nanotubes. In many cases, CNTs can offer numerous advantages (a feature referred to herein as "multifunctional"), acting, for example, as a binder fibrillating (or, in some cases, binder deformation) agent, as a conductive additive (generating conductive networks, e.g., long-range conductivity of electrodes), and as a mechanical strengthening aid (providing mechanical support, stability, and / or flexibility to electrode products, often coatings, layers, or films typically applied on conductive substrates to form battery electrodes). It has been further discovered that multiple advantages can be realized by supplementing or completely replacing conventional fibrillating agents (e.g., AC) with CNTs combined with at least one type of carbon black (CB or multiple CBs). In some cases, electrodes prepared by a dry process using a blend (mixture) of CNTs and CBs perform better than electrodes similarly prepared using CNTs alone or CB alone.

[0099] As is well known in the art, carbon nanotubes are typically hydrophobic carbonaceous materials that bond together to form a honeycomb lattice that creates cylindrical or tubular structures. 2 It is characterized by at least one sheet of hybridized carbon atoms. The carbon atoms in carbon nanotubes are generally arranged in hollow (e.g., cylindrical) structures with a length greater than the diameter.

[0100] CNTs can have different morphologies, such as single-walled carbon nanotubes (SWCNTs) or multi-walled carbon nanotubes (MWCNTs). SWCNTs have sp structures similar to fullerenes. 2 It can be considered an allotrope of hybridized carbon. This structure is a cylindrical tube containing a six-membered carbon ring. Double-walled carbon nanotubes (DWCNTs) tend to have similar properties to subwalled carbon nanotubes (SWCNTs). On the other hand, similar subwalled carbon nanotubes (MWCNTs) have multiple tubes within a concentric cylinder. The number of these concentric layers can vary, for example, from 2 to 25 or more. Typically, the diameter of MWNTs can be 10 nm or more, while the diameter of typical SWCNTs is 0.7 to 2.0 nm.

[0101] CNTs are classified into armchair, zigzag, and chiral nanotubes based on their chirality.

[0102] Carbon nanotubes (CNTs) can provide excellent electrical and thermal conductivity, as well as good mechanical properties. Due to their high conductivity, carbon nanotubes are increasingly being used as conductive additives in lithium-ion battery electrodes. These can enhance battery performance, including power output, cycle life, and energy density.

[0103] Both single-walled carbon nanotubes (WACs) and multi-walled carbon nanotubes (WACs) can be used, and mixtures of two or more different types of CNTs can also be used. In many embodiments, the CNTs are MWCNTs. The number of layers present when MWCNTs are used is determined, for example, by transmission electron microscopy (TEM) at a magnification sufficient to analyze the number of layers in a particular case, and is about 2 to about 30, for example 4-30, 6-30, 8-30, 10-30, 12-30, 14-30, 16-30, 18-30, 20-30, 22-30, 24-30, 26-30, 28-30, or 2-28, 4-28, 6-2 8, 8~28, 10~28, 12~28, 14~28, 16~28, 18~28, 20~28, 22~28, 24~28, 26~28, or 2~26, 4~26, 6~26, 8~26, 10~26, 12~26, 14~26, 16~26, 18~26, 20~26, 22~26, 24~26, or 2~24, 4~24, 6~24, 8~24, 10~24, 12~24, 14~24, 16-24, 18-24, 20-24, 22-24, or 2-22, 4-22, 6-22, 8-22, 10-22, 12-22, 14-22, 16-22, 18-22, 20-22, or 2-20, 4-20, 6-20, 8-20, 10-20, 12-20, 14-20, 16-20, 18-20, or 2-18, 4-18, 6-18, 8-18, 10-18, 12-18, 14- It may be within the range of 18, 16-18, or 2-16, 4-16, 6-16, 8-16, 10-16, 12-16, 14-16, or 2-14, 4-14, 6-14, 8-14, 10-14, 12-14, or 2-12, 4-12, 6-12, 8-12, 10-12, or 2-10, 4-10, 6-10, 8-10, or 2-8, 4-8, 6-8, or 2-6, 4-6, or 2-4.

[0104] In many embodiments, the carbon nanotubes (CNTs) used are conventional (also called "ordinary," "early," or "fresh") CNTs, which are often supplied in individualized forms that are commercially manufactured or, in some cases, custom synthesized or custom processed.

[0105] Generally, CNTs are known to contain a considerable amount of catalyst and support residue. These species can be detected by techniques such as SEM, TEM, inductively coupled plasma atomic emission spectroscopy, or ICP-AES.

[0106] CNTs are less than 100 nanometers (nm), for example, in the range of about 1 to about 100 nm, for example, about 5 to about 10, about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90, about 100 nm; or about 10 to about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90, about 100 nm; or about 20 to about 30, about 40, about 50, about 60, about 70, about 80, about 90, about 100 nm; or about 30 It may have a diameter in the range of approximately 40, 50, 60, 70, 80, 90, 100 nm; or approximately 40 to approximately 50, 60, 70, 80, 90, 100 nm; or approximately 50 to approximately 60, 70, 80, 90, 10 nm; or approximately 60 to approximately 70, 80, 90, 100 nm; or approximately 70 to approximately 80, 90, 100 nm; or approximately 80 to approximately 90, 100 nm; or approximately 90 to approximately 100 nm.

[0107] Certain embodiments use CNTs having a diameter in the range of about 2 nm to about 50 nm, as measured by TEM. For example, the CNTs used may have a diameter in the range of about 2 to about 5, about 10, about 20, about 30, about 40 nm; or about 5 to about 10, about 20, about 30, about 40, about 50 nm; or about 20 to about 30, about 40, about 50 nm; or about 30 to about 40, about 50 nm; or about 40 to about 50 nm.

[0108] CNTs can vary in length from approximately 10 nanometers (nm) to approximately 750 microns (μm), or more. Therefore, CNTs can be categorized as follows: 10nm-100nm, 10nm-500nm; 10nm-750nm; 10nm-1 micron; 10nm-1.25 micron; 10nm-1.5 micron; 10nm-1.75 micron; 10nm-2 micron; or 100nm-500nm, 100nm-750nm; 100nm-1 micron; 100nm-1.25 micron; 100nm-1.5 micron; 100nm-1.75 micron; 100nm-2 micron; 500nm-750nm; 500nm-1 micron; 500nm-1 micron; 500nm-1.25 micron; 500nm-1 0.5 microns; 500 nm to 1.75 microns; 500 nm to 2 microns; 750 nm to 1 micron; 750 nm to 1.25 microns; 750 nm to 1.5 microns; 750 nm to 1.75 microns; 750 nm to 2 microns; 1 micron to 1.25 microns; 1.0 micron to 1.5 microns; 1 micron to 1.75 microns; 1 micron to 2 microns; or 1.25 microns to 1.5 microns; 1.25 microns to 1.75 microns; 1 micron to 2 microns; or 1.5 to 1.75 microns; 1.5 to 2 microns; or 1.75 to 2 microns are possible.

[0109] In some cases, the CNTs used in the dry processes described herein have an average length in the range of about 1 micron to about 30 microns, for example, about 1 to about 5, about 1 to about 10, about 1 to about 15, about 1 to about 20, about 1 to about 25 microns; or about 5 to about 10, about 5 to about 15, about 5 to about 20, about 5 to about 25, about 5 to about 30 microns; or about 10 to about 15, about 10 to about 20, about 10 to about 25, about 10 to about 30 microns; or about 15 to about 20, about 15 to about 25, about 15 to about 30 microns; or about 20 to about 25, about 20 to about 30 microns; or about 25 to about 30 microns.

[0110] In some embodiments, at least one of the CNTs has a length of 2 microns or more when determined by SEM. In certain embodiments, more than one of the CNTs, for example, at least about 0.1%, at least about 1%, at least about 10%, at least about 15%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, or even more than half, may have a length greater than 2 microns when determined by SEM, for example, within the above range.

[0111] The morphology of carbon nanotubes (CNTs) is often characterized by a high aspect ratio, where the length is typically more than 100 times the diameter, and sometimes much higher.

[0112] CNTs can also be characterized by their surface area. For example, small-diameter single-walled CNTs have a maximum surface area of ​​approximately 3000 m 2 / g, for example, a maximum of approximately 1315m 2 It can have a specific surface area of ​​such as / g, while large-diameter multilayer CNTs can have a maximum of approximately 1000m 2 It is often characterized by its specific surface area per gram.

[0113] In many of the embodiments described herein, the CNTs used have a Brunauer-Emmett-Teller (BET) surface area of ​​approximately 500 m², measured, for example, according to ASTM D6556-10. 2 Less than / g, for example, 400m 2 / g or less; or 300m 2 This includes values ​​of less than / g, etc.

[0114] In some embodiments, the BET surface area of ​​the CNT is approximately 80 to 500 mm², for example, 200 to 500 mm². 2 The range is within / g. In specific examples, CNTs are approximately 80-100, 150, 200, 250, 300, 350, 400, 450, and 500m. 2 / g; or approximately 100-150, 200, 250, 300, 350, 400, 450, 500m 2 / g; or approximately 150-200, 250, 300, 350, 400, 450, 500m 2 / g; or approximately 200-250, 300, 350, 400, 450, 500m 2 / g; or approximately 250-300, 350, 400, 450, 500m 2 / g; or approximately 300-350, 400, 450, 500m 2 / g; or approximately 350-400, 450, or 500m 2 / g; or approximately 400-450, 500m 2 / g; or approximately 450-500m 2 It has a BET surface area within the range of / g.

[0115] For example, CNTs are approximately 80-110m, 80-200m, 80-230m, 80-260m, 80-280m, 80-310m, and 80-350m. 2 / g; or approximately 110-200, approximately 110-230, approximately 110-260, approximately 110-280, approximately 110-310, approximately 110-350m 2 / g; or approximately 230-260, 230-280, 230-310, 230-350m 2 / g; or approximately 260-280, approximately 260-310, approximately 260-350m 2 / g; or approximately 280-310, approximately 280-350m 2 / g; or approximately 310-350m 2 It has a BET surface area of ​​ / g.

[0116] The bulk density (calculated, for example, by dividing the weight of untapped CNT powder free-falling in a cylinder by the volume occupied by the powder) of the CNTs used may be in the range of approximately 0.01 to 0.3, for example, approximately 0.01 to 0.2. In one example, the CNTs are approximately 0.03 g / cm³. 3It has a bulk density. Further densification, compression or densification, measured by the tap density, can increase the bulk density to a range of about 0.03 g / cm 3 to about 0.5 g / cm 3 .

[0117] The CNTs used herein can be identified and / or characterized by various techniques. For example, electron microscopy techniques including transmission electron microscopy (TEM) and scanning electron microscopy (SEM) can provide information regarding features such as the frequency of presence of a specific number of layers, tube diameter, length, branching, presence of catalyst particles, etc.

[0118] Raman spectroscopy is often used for the characterization of the state of carbon in carbonaceous materials. For example, the D band (about 1350 cm -1 ) is associated with sp3 carbon, whereas the G band (about 1580 cm -1 ) is associated with sp2 carbon in graphite or CNTs. The G’ band (about 2700 cm -1 ) is expected to occur at approximately twice the frequency of the D band. In some cases, thermogravimetric analysis (TGA) can make it possible to distinguish the CNTs used to implement the present invention from other carbon structures.

[0119] Other CNT properties to be considered in multifunctional CNT candidates relate to their physical form. For example, the CNT particle size is a property that can be determined by particle size distribution (PSD) techniques and / or scanning electron microscopy (SEM). Particle size measurement can be performed by using a particle size distribution meter to measure the intensity of scattered light by laser diffraction. When a laser beam is directed through a dispersed particulate sample, large particles scatter light at small angles and small particles scatter light at larger angles. The average particle size (D 50 ) is the particle size range based on 50% in the particle size distribution of the dispersion.

[0120] CNTs can readily form aggregates, such as bundles, ropes, or clumps, due to strong van der Waals interactions along their length. CNTs can occur as substantially parallel "forests," as randomly entangled clusters of structured clumps ("pillows"), or as other types of aggregates.

[0121] In some embodiments, the aggregates are adjusted to have sufficient strength to fibrillate the binder, but still break down to some extent, generating smaller fragments that spread throughout the composition, resulting in a uniform CNT distribution.

[0122] In many embodiments, the CNT material has a CNT purity of 97% or higher. Typically, anionic, cationic, or metallic impurities are low, for example, in the range of parts per million (ppm). In many cases, the CNTs used herein do not require further additives to counteract van der Waals forces.

[0123] Examples of commercially available CNT materials include, but are not limited to, those available from Cabot Corporation under the trade name ENERMAX® carbon nanotubes, from CNano under the trade name FT, and from LG Chem under the trade name Lucan. Some specific examples include ENERMAX 61, FT2000, and Lucan BT1003M.

[0124] Table 1 below shows the physical properties that characterize exemplary CNTs, namely CNT1 to CNT9. [Table 1]

[0125] Additional processing or modification can further enhance the multifunctionality of CNTs.

[0126] One approach involves pre-milling the CNT material using high-shear mixing equipment such as a jet mill, ball mill, extruder, or homogenizer (milling before mixing with a fibrillable binder and / or electrode active material). Often, the pre-milling operation is dry pre-milling, carried out in a dry state without solvent, as a dry powder. However, in some situations, the pre-milling operation may include a solvent. In this case, the solvent can be removed by heating, freeze-drying, or vacuum. Performing a pre-milling operation before the fibrillation process, optionally together with a drying process (if a solvent is used), can improve electrochemical properties and enhance the fibrillation performance of the CNTs. Pre-milling can also impart a positive mechanical effect to the film and / or electrode product. While we do not wish to be bound by any particular interpretation, it is believed that smaller particles are more uniformly dispersed in the composition, thereby improving the electrical and mechanical properties of the product (film or electrode). In Table 1 above, CNT5 is a pre-milled (minified) version of CNT1, and CNT6, CNT7, and CNT9 are pre-milled (minified) versions of CNT2, CNT3, and CNT4, respectively.

[0127] Another approach involves using carbon nanotubes (CNTs) that contain no oxygen-containing surface groups at all, or only a small number of them. The reduction or absence of oxygen-containing groups such as -OH, -O-, and -COOH increases the hydrophobicity of the additive and, therefore, increases its affinity for hydrophobic, fibrillable binders such as PTFE. One technique for removing oxygen-containing groups from CNTs is heat treatment, which can be carried out, for example, in a vacuum oven.

[0128] In addition to increasing the hydrophobicity of CNTs, heat treatment can also improve their conductivity and reduce or minimize impurities (such as those remaining after CNT production) that may interfere with and adversely affect cycle performance, high-temperature storage, and / or battery safety. Other techniques that can be used to remove impurities include, for example, acid washing, a combination of heat treatment and acid washing, or other techniques. Some approaches involve acid washing, which includes oxidation or graphitization using HNO3, H2SO4, HCl, HF, either alone or in any combination thereof. Another possible approach is to wet MWCNTs with dimethylformamide (DMF), oxidize them first, and then suspend them in nitric acid. In Table 1 above, CNT7 is the acid-washed version of CNT8.

[0129] CNTs can be treated by doping (for example with boron), graphene-winging, or other methods.

[0130] CNTs may be subjected to two or more treatments and / or modifications. For example, CNTs may be subjected to both heat treatment and pre-milling.

[0131] Therefore, generally, the solvent-free processes described herein can use CNT additives as micronized (pre-milled) powders without further processing or modification (e.g., unpulverized (e.g., unfinely pulverized), unheat-treated, unacid-washed, etc.), or as modified CNTs, such as heat-treated CNTs or acid-washed CNTs. In some cases, TEM, radiography, or other techniques can be used to determine the type of CNTs to be used. Good multifunctionality is often reflected in the quality of the resulting film, electrode, or battery product.

[0132] CNTs can be formed or formulated to form mixtures of CNTs having various combinations and distributions of the above-mentioned characteristics (number of layers, diameter, length, morphology, orientation, etc.).

[0133] In some embodiments, one or more types of CNTs are used in combination with one or more types of carbon black (CB).

[0134] As is well known, CB is a material that exists in the form of aggregates, which are formed from CB primary particles. In many cases, the primary particles do not exist independently of the CB aggregates. The primary particles can have an average primary particle size in the range of about 10 nanometers (nm) to about 50 nm, for example, about 10 nm to about 15 nm, about 10 nm to about 20 nm, about 10 nm to about 25 nm, about 10 nm to about 30 nm, or about 10 nm to about 40 nm, and the aggregates can be quite large. CB aggregates have a fractal shape and are often referred to as CB "particles" in the art (these should not be confused with the "primary particles" mentioned above).

[0135] Many types of carbon briquettes (CBs) are produced in a reactor by thermally decomposing hydrocarbon feedstocks (FSs) with high-temperature combustion gases to produce combustion products containing particulate CBs. The properties of a given CB often depend on the manufacturing conditions and can be altered or modified by changes in parameters such as temperature, pressure, FS, residence time, quench temperature, throughput, and other parameters.

[0136] As is known in the art, CB can be described by certain properties determined according to procedures well known in the art, usually standardized protocols. For example, CB can be characterized by the Brunauer-Emmett-Teller (BET) surface area, measured according to ASTM D6556-10, for example; the oil adsorption amount (OAN), determined according to ASTM D2414-16, for example; and the statistical thickness specific surface area (STSA), a property that can be determined by ASTM D6556-10.

[0137] For a given CB, it may be important in some cases to determine its STSA ratio to its BET surface area (STSA:BET ratio).

[0138] The crystalline domain of CB can be characterized by the crystallite size L determined by Raman spectroscopy. a L can be characterized by the crystallite size. a L is defined as 43.5 × (area of the G band / area of the D band). The crystallite size can provide an index of the degree of graphitization, and a higher L a value correlates with a higher degree of graphitization. a The Raman measurement of L is based on Gruber et al., "Raman studies of heat-treated carbon blacks", Carbon Vol.32(7), pp.1377-1382, 1994, which is incorporated herein by reference. The Raman spectrum of carbon shows two main "resonance" bands at approximately 1340 cm -1 and 1580 cm<0​​​​​​​​​​​​​​​​​​​​​​​​Crystallite size was determined by X-ray diffraction using an X-ray diffractometer (PANalytical X'Pert Pro, PANalytical BV) with a copper tube, a tube voltage of 45kV, and a tube current of 40mA. A sample of carbon black particles was packed into a sample holder (an accessory of the diffractometer), and measurements were taken at a rate of 0.14° / min over an angular range of 10° to 80° (2θ). Peak positions and full width at half maximum were calculated using the diffractometer's software. Lanthanum hexaboride (LaB6) was used as an X-ray standard for measurement angle calibration. From the obtained measurements, Scherrer's formula: L c (Å) = K * λ / (β * Using cosθ, L c Determine the crystallite size. In the formula, K is the shape factor constant (0.9) and λ is CuK α1 The characteristic X-ray wavelength is 1.54056 Å, β is the half-maximum peak width in radians, and θ is determined by taking half the measured angular peak position (2θ).

[0140] The cleanliness of the surface can be described by the surface energy (SEP) of the CB, which is a property that can be determined by dynamic vapor (water) adsorption (DVS) or water diffusion pressure (as described, for example, in U.S. Patent No. 10,886,535 (B2), issued to Korchev et al. on January 5, 2021, which is incorporated herein by reference).

[0141] Other techniques that can be used to study carbon-beams (CBs) include Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). FTIR spectroscopy is particularly useful for determining the properties of surface functional groups, while SEM / TEM techniques help visualize particle size and morphology. XPS is often used to determine the elemental composition of materials, and TGA can provide information on carbon decomposition and oxidation properties.

[0142] Various carbon cuboids (CBs) have been and continue to be developed for carbon conductive additive (CCA) applications. Attractive conductivity often combines a high specific surface area and a widely developed structure (arrangement of primary CB particles within aggregates) with porosity. CBs that can be added to anode and / or cathode compositions for LIBs prepared by slurry processes are described, for example, in International Publication No. 2020 / 197670 (Cabot Corp., published October 1, 2020) and International Publication No. 2020 / 197673 (Cabot Corp., published October 1, 2020). Both are incorporated herein by reference in their entirety.

[0143] Examples of commercially available carbon blacks (CBs) that can be effective as CCAs include LITX® 50, LITX® 66, LITX® 200, LITX® 300, LITX® HP, and LITX® MAX 90 carbon black particles from Cabot Corporation; C-NERGY® C45, C-NERGY® C65, and SUPER P® products from Imerys; Li-400, Li-250, Li-100, and Li-435 products from Denka; and EC300 and EC600 products from Ketjen. The physical properties of exemplary CBs that can be used as CCAs are shown in Table 2 below as samples CB1 to CB5. [Table 2]

[0144] Carbon black used in combination with CNTs may have selected morphologies and / or surface chemistry, and may provide two or more functions in dry (solvent-free) electrode manufacturing methods. Generally, "multifunctional" carbon black (CB) can be defined as CB that effectively deforms or fibrillates binders used in solvent-free processes; contributes to the electronic / ionic conductivity of the electrode; and / or provides mechanical benefits. In certain embodiments, multifunctional CB can be considered capable of fibrillating binders at addition amounts of 5 wt% or less. At this addition amount, the multifunctional CB also acts as a carbon conductive additive, reducing the in-plane resistivity of the electrode. In many cases, mechanical benefits are also obtained.

[0145] A multifunctional CB is described, for example, in International Patent Application PCT / US23 / 64614, filed on 17 March 2023 and published on 28 September 2023 as International Publication No. 2023 / 183754(A1), titled Solvent-Free Process for Preparing Lithium-Ion Batteries, which is incorporated herein by reference.

[0146] In addition to exhibiting conductivity desirable for LIB applications, other properties that may contribute to the multifunctionality of CB may include one, more, or all of the following: surface roughness, surface chemistry (surface energy), particle strength, and particle size.

[0147] Typically, CB surface roughness is related to the porosity of the particles, described, for example, by pore volume or pore size distribution. For example, RMS surface roughness (calculated as the root mean square of the measured microscopic peaks and valleys of the surface) is known to correlate with surface pore size (e.g., by approximately the same number of orders of magnitude). For instance, pores of 2 nm may exhibit an RMS surface roughness of about 1 nm.

[0148] Generally, CB porosity can be classified into one or more of the following categories: microporosity, defined by pores with a diameter of less than 2 nm; mesoporosity, defined by pores with a diameter in the range of 2 to 50 nm; and macroporosity, defined by pores with a diameter greater than 50 nm. The average pore diameter and pore volume can be determined according to the technique (BJH method) described in E.P. Barrett, L.G. Joyner, P.P. Halenda, J.Am. Chem. Soc. 1951, 73, 373-380.

[0149] More specifically, the pore size distribution and pore volume in carbon black can be determined by gas physicoadsorption techniques such as nitrogen adsorption porosimetry, by measuring nitrogen gas adsorption using BET analysis, and then fitting the adsorption isotherms to different models, such as DFT (density function theory) and the BJH (Barrett-Joyner-Halenda) model, depending on the pore size range of interest. The BJH adsorption model method was used to fit the N2 adsorption isotherm and calculate the mesopore and macropore volumes presented herein.

[0150] While we do not wish to be bound by any particular interpretation, the fibrillation properties in multifunctional CBs are thought to be driven, at least in part, by the macroporosity of the particles, where the macropores link the binder on the CB surface and act as anchoring points for stretching the binder into fibrils when high shear forces are applied.

[0151] While some carbon blacks are primarily microporous materials, techniques exist to increase the porosity level and / or to produce carbon blacks with controlled porosity types.

[0152] For example, porosity, particularly mesoporosity of the CB product, can be increased by contacting the CB starting material with an oxidizing agent flow. Increasing the porosity of furnace black can be achieved by increasing the residence time in the carbon black reactor, giving the tail gas more time to attack and etch the carbon surface. Another method relies on adding alkaline earth metal ions to the carbon black starting material, as these ions are known to catalyze the etching of carbon black via the tail gas. Both techniques involve etching the CB "in situ," i.e., in the furnace reactor during production, to produce carbon black with internal porosity. Several approaches that can be used to modify carbon black are described, for example, in U.S. Patent No. 8,895,142(B2) granted to Kyrlidis et al. and U.S. Patent No. 10,087,330(B2) granted to Green et al., which are incorporated herein by reference. Commercially available modified carbon black is available from Cabot Corporation. The characteristics of two exemplary CB specifications, namely samples CB2 and CB3, are shown in Table 2 above. CB2 is a vapor-etched version of CB5.

[0153] It has also been found that fibrillation properties depend on surface chemistry or surface activity, which is a feature often associated with the manufacturing and / or heating processes used in preparing specific CBs. Often, surface chemistry or surface activity relates to oxygen-containing groups found on the CB surface. In some embodiments, good fibrillation CB candidates tend to lack or have depleted oxygen-containing surface groups and have low hydrophilicity (high hydrophobicity).

[0154] For example, effective fibrillation is thought to be driven at least in part by the affinity (adhesion) of the CB to the binder, such as a fibrillable binder. Therefore, in one embodiment, a preferred multifunctional CB for successfully fibrillating a binder such as PTFE is a hydrophobic CB (i.e., a CB lacking oxygen-containing surface groups) and / or a low surface energy CB. The oxygen content can be measured by inert gas fusion. Low surface chemical CBs have an oxygen content in the range of about 10 ppm to about 5000 ppm, for example, about 100 ppm to about 1000 ppm.

[0155] The presence of oxygen-containing surface groups can be reduced or minimized by techniques such as heat treatment or other surface modification approaches, which are known in the art or may be developed in the future. Surface-modified carbon black, such as heat-treated carbon black, can be distinguished from ordinary carbon black by X-ray scattering, Raman spectroscopy, surface energy measurement by gas adsorption, or other techniques known in the art. In some cases, heat-treated carbon black and other surface-modified carbon blacks also tend to show reduced moisture absorption during treatment. In Table 2, CB1 is a heat-treated version of CB3, and CB4 is a heat-treated version of CB5.

[0156] Other CB properties to be considered in multifunctional CB candidates relate to their physical morphology. CB particle size is a property that can be determined, for example, by particle size distribution (PSD) techniques and / or scanning electron microscopy (SEM).

[0157] Furthermore, the particle strength of the selected CB (column crystalline structure), which is considered to play a role in the multifunctional properties of the selected CB, is related to the CB particle strength (expressed as particle hardness and / or particle aggregation). Particle strength allows the CB to effectively stretch the polymer binder. This, along with particle roughness, is an important mechanical property for achieving the desired binder fibrillation. Particle strength can be measured by individual pellet crush tests, vibrational viscoelasticity measurements, or other techniques known in the art.

[0158] CB can be supplied as any number of loose particulate materials. For example, truly fluffy CB-containing powders have been found to work particularly well in some of the dry processes tested. Such powdered materials can be characterized by their particle size, BET, and / or other properties. Often, the powder used is about 100 g / cm³. 3 It has the following density:

[0159] For example, less fluffy CB particles can also be used in the form of jet-milled pellets. Powdered CB can be pelletized using techniques and apparatus known in the art. In one example, CB is pelletized using an emulsion solution of a binder used to form the electrode composition described herein. Another approach is to use an emulsion solution of binders that can combine with or otherwise interact with different binders, e.g., binders belonging to the same chemical family, or binders used to carry out a drying process. As a result, it is thought that the energy interaction between the pelletized CB and the binder used to prepare the electrode composition will increase. The pellet size applicable to pure CB and CB-polymer composite materials may be in the range of about 0.1 mm to about 5 mm.

[0160] Carbon black granules can also be useful in several situations. Often, CB granules are a high-density form of CB in which no polymer is present in the final product. Generally, CB granules can be formed by conventional pelletizing processes associated with CB production. It is also possible to form CB granules by dispersing fluffy CB in water and then spray-drying it. Granular CB can also be supplied as a composite material, such as granules encapsulated with a binder, or as a masterbatch.

[0161] In some embodiments, the granules used undergo changes in form and / or function during processing. Therefore, a polymer binder can be processed (e.g., fibrillated) using the initial CB granular material. The sizing that occurs during this operation can release smaller CB units. In the presence of an electrochemical active material, granular fragmentation can enhance the distribution of smaller CB units throughout the electrode composition, resulting in an electrode film with improved conductivity and / or mechanical strength.

[0162] The surface roughness and / or surface energy of granules are often controlled by selecting the particles that make up the granules. For example, surface roughness can be selected based on the surface texture generated by the primary particles and / or aggregates that make up the secondary granules. Such surfaces are rough on a dimensional scale, provided by nanoscale / microscale hills and valleys on the surface of the CB granules.

[0163] The granular multifunctional CBs may have particle sizes in the micron range, for example, 1 to 10 μm, e.g., 1 to 8, 1 to 6, 1 to 4, 1 to 2; or 2 to 10, 2 to 8, 2 to 6, 2 to 4; or 4 to 10, 4 to 8, 4 to 6; or 6 to 10, 6 to 8; or 8 to 10 microns. Some granules can have their initial size reduced by grinding to varying degrees, for example, providing particles ranging from approximately 10 microns to less than 1 micron. Several implementations utilize combinations of multiple sizes.

[0164] The strength of the granules can also be considered. The strength of the granules can be minimized by forming the granules in the absence of (or with minimal) binder during granule formation. Increasing the strength of the granules can be achieved by using binders of various concentrations and / or different types of binders. In some embodiments, the binder used to form the CB granules is the same as or similar to the binder used in the dry process.

[0165] Some embodiments use granules that are easily broken under processing (e.g., fibrillation) conditions. In such cases, the strength of the granules can be controlled to be high enough to fibrillate or deform the polymer binder, and low enough to break apart and release conductive and reinforcing carbon units, such as aggregates.

[0166] In many dry processes, the above CNTs are approximately 1600m 2 It is used in combination with CB having a BET of less than / g and an OAN of approximately 650 mL / 100 g or less.

[0167] CB is approximately 1600m 2 Less than / g, for example, approximately 1500, 1400, 1300, 1200, 1100, 1000, 900, 800, 700, 600, 500, 400, 300, 200, 100, or 50m 2You can have a BET of less than or equal to / g. The BET is in the range of approximately 35 to approximately 1600, for example, approximately 35 to approximately 100, approximately 200, approximately 300, approximately 400, approximately 500, approximately 600, approximately 700, approximately 800, approximately 900, approximately 1000, approximately 1100, approximately 1200, approximately 1300, approximately 1400, approximately 1500; or approximately 100 to approximately 200, approximately 300, approximately 400, approximately 500, approximately 600, approximately 700, approximately 800, approximately 900, approximately 1000, approximately 1100, approximately 1200, approximately 1300, approximately 1400, approximately 1500, approximately 1600; or approximately 200 to approximately 300, approximately 400, approximately 500, approximately 600, approximately 700, approximately 800, approximately 900, approximately 1000, approximately 1100, approximately 1200, approximately 1300, approximately 1400, approximately 1500, approximately 1600; or approximately 300-400, approximately 500, approximately 600, approximately 700, approximately 800, approximately 900, approximately 1000, approximately 1100, approximately 1200, approximately 1300, approximately 1400, approximately 1500, approximately 1600; or approximately 400-500, approximately 600, approximately 700, approximately 800, approximately 900, approximately 1000, approximately 1100, approximately 1200, approximately 1300, approximately 1400, approximately 1500, approximately 1600; or approximately 500-600, approximately 700, Approximately 800, approximately 900, approximately 1000, approximately 1100, approximately 1200, approximately 1300, approximately 1400, approximately 1500, approximately 1600; or approximately 600-700, approximately 800, approximately 900, approximately 1000, approximately 1100, approximately 1200, approximately 1300, approximately 1400, approximately 1500, approximately 1600; or approximately 700-800, approximately 900, approximately 1000, approximately 1100, approximately 1200, approximately 1300, approximately 1400, approximately 1500, approximately 1600; or approximately 800-900, approximately 1000, approximately 1100, approximately 1200, approximately 1300, approximately 1400, approximately 1500, approximately 16 00; or approximately 900-1000, 1100, 1200, 1300, 1400, 1500, 1600; or approximately 1000-1100, 1200, 1300, 1400, 1500, 1600; or approximately 1100-1200, 1300, 1400, 1500, 1600; or approximately 1200-1300, 1400, 1500, 1600; or approximately 1300-1400, 1500, 1600; or approximately 1400-1500, 1600; or approximately 1500-1600m 2 It may be within the range of / g.

[0168] The CB used in the dry process described herein may have an OAN of about 650 mL / 100g or less, for example, about 500 mL / 100g or less, about 400 mL / 100g or less, about 300 mL / 100g or less, about 250 mL / 100g or less, about 200 mL / 100g or less, about 150 mL / 100g or less. Multifunctional CBs may have OANs in the range of approximately 120 to approximately 650 mL / 100g, for example, approximately 120 to approximately 200, approximately 300, approximately 400, approximately 500 / 100g, approximately 600, approximately 650 mL / 100g; or approximately 200 to approximately 300, approximately 400, approximately 500, approximately 600, approximately 650 mL / 100g; or approximately 300 to approximately 400, approximately 500, approximately 600, approximately 650 mL / 100g; or approximately 400 to approximately 500, approximately 600, approximately 650 mL / 100g; or approximately 500 to approximately 600, approximately 650 mL / 100g; or approximately 600 to approximately 650 mL / 100g.

[0169] LIB anodes, for example those containing graphite, contain CNTs at approximately 1600m 2 Less than or equal to / g, for example, approximately 1200 or less, approximately 1000 or less, approximately 700 or less, approximately 500 or less, approximately 200 or less, approximately 100 or less, or approximately 35m 2 It can be prepared by a dry process used in combination with CB having a BET of less than / g. The BET is approximately 35 to 1600 m 2 The range may be approximately 35-50, 75, 100, 150, 200, or 50-75, 100, 150, 200, or 75-100, 150, 200, or 100-150, 200, or 150-200m 2 It may be / g. In one example, the selected CB was approximately 50 to 200m 2 Have a bet within the range of / g

[0170] For anode applications, the CB used in combination with the CNT may have an OAN of approximately 650 mL / 100g or less, for example, approximately 500 mL / 100g or less, approximately 400 mL / 100g or less, approximately 300 mL / 100g or less, for example, approximately 240 mL / 100g or less, approximately 200 mL / 100g or less, approximately 150 mL / 100g or less. In one embodiment, the CB selected for preparing a LIB anode by a dry process has an OAN in the range of approximately 120 to approximately 650 mL / 100g, for example, approximately 120 to approximately 150 mL / 100g, approximately 200 mL / 100g, approximately 240 mL / 100g, approximately 300 mL / 100g; or approximately 150 to approximately 200 mL / 100g, approximately 240 mL / 100g, approximately 300 mL / 100g; or approximately 200 to approximately 240 mL / 100g; or approximately 240 to approximately 300 mL / 100g. In one example, the selected CB has an OAN in the range of approximately 130 to 240 mL / 100g.

[0171] For example, a LIB cathode using a lithium transition metal compound has a minimum length of at least approximately 80 m 2 / g, for example, at least about 100, about 200, about 300, about 400, about 500, about 600, about 700, about 800, about 900, about 1000, about 1100, about 1200, about 1300, about 1400, about 1500, up to about 1600m 2 It can be prepared by a dry process utilizing CNTs in combination with CB having a BET of approximately 500 to 1600 m / g. 2 Within the range of / g, for example, approximately 500-600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500m 2 / g; or approximately 600-700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600m 2 / g; or approximately 700-800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600m 2 / g; or approximately 800-900, 1000, 1100, 1200, 1300, 1400, 1500, 1600m 2 / g; or approximately 900-1000, 1100, 1200, 1300, 1400, 1500, 1600m2 / g; or approximately 1000-1100, 1200, 1300, 1400, 1500, 1600m 2 / g; or approximately 1100-1200, 1300, 1400, 1500, 1600 2 / g; or approximately 1200-1300, 1400, 1500, 1600m 2 / g; or approximately 1300-1400, 1500, 1600m 2 / g; or approximately 1400-1500, 1600m 2 / g; or approximately 1500-1600m 2 It may be within the range of / g. In one example, the selected CB was approximately 1350 to 1600 m 2 The bet is within the range of / g. In another example, the selected CB is in the range of approximately 50 to approximately 190, for example, approximately 90 to approximately 100m 2 The bet is within the range of / g. In a further example, the CB is 500-650m 2 I have a bet of / g.

[0172] For cathode applications, CBs used in combination with CNTs may have an OAN of approximately 650 mL / 100g or less, for example, approximately 600 mL / 100g or less, approximately 500 mL / 100g or less, approximately 500 mL / 100g or less, approximately 400 mL / 100g or less, approximately 300 mL / 100g or less, approximately 250 mL / 100g or less, approximately 200 mL / 100g or less. CBs may have an OAN in the range of approximately 120 to approximately 250 mL / 100g, approximately 350 mL / 100g, approximately 450 mL / 100g, approximately 550 mL / 100g, or approximately 250 to approximately 350 mL / 100g, approximately 450 mL / 100g, approximately 550 mL / 100g, approximately 550 mL / 100g, or approximately 650 mL / 100g. In one example, the selected CB has an OAN in the range of approximately 180 to 650 mL / 100g. In another example, the selected CB has an OAN in the range of approximately 250 to 650 mL / 100g.

[0173] In many cases, the CB that can be used to prepare the LIB cathode by the dry process described herein is approximately 80 to 1600 m 2It has a BET in the range of / g and an OAN in the range of approximately 120 to approximately 650 mL / 100g. An example CB that can be used to prepare a LIB cathode has a relatively high BET surface area (e.g., approximately 1350 to approximately 1600 m²). 2 It has a combination of (in the range of / g) and a relatively low OAN (e.g., in the range of approximately 120 to approximately 220 mL / 100g). Another exemplary CB that can be used to prepare LIB cathodes is approximately 80 to approximately 200 mL 2 It has a BET surface area in the range of / g, and an OAN in the range of approximately 140 to approximately 280 mL / 100g, for example, approximately 240 or less, and approximately 140 to approximately 180 mL / 100g. Further exemplary CBs are approximately 500 to approximately 1600 m 2 It has a BET in the range of / g and an OAN in the range of approximately 180 to approximately 650 mL / 100g. Yet another exemplary CB that can be used to prepare LIB cathodes is 650 mL 2 BET surface area less than / g (for example, approximately 500 to 650 m²) 2 It has an OAN (in the range of / g) and an OAN in the range of approximately 180 to approximately 260 mL / 100g.

[0174] In many cases, the CB that can be used to prepare LIB anodes by the dry process described herein is approximately 35 to 1600 ml. 2 It has a BET in the range of / g and an OAN in the range of approximately 120 to approximately 650 mL / 100g. An example CB that can be used to prepare LIB anodes has a relatively low BET surface area (e.g., approximately 50 to approximately 200 m²). 2 When combined with (within the range of / s), it has an OAN in the range of approximately 130 to approximately 240 mL / 100g.

[0175] Many available CBs have the BET and OAN characteristics mentioned above, plus a 15 mJ / m³ 2 The following surface energies, Raman microcrystal plane size (La) of at least about 17 Å, and at least about 0.1 cm² 3 Mesopore volume per g, at least about 0.2 cm³ 3 Macropore volume of / g, and at least about 1 cm³ 3Characterized by one or more of the total mesopore and macropore volumes per g.

[0176] More specifically, CB is 15 mJ / m 2 For example, approximately 1 to 10 mJ / m³ 2 For example, approximately 1 to 3, 5, 7, and 9 mJ / m³. 2 ; or approximately 3 to 5, 7, 9, or 10 mJ / m 2 ; or approximately 5 to 7, 9, or 10 mJ / m 2 ; or approximately 7 to approximately 9, approximately 10 mJ / m 2 ; or approximately 9 to 10 mJ / m 2 It can have a surface energy (SEP).

[0177] In many implementations, the CB is at least 17 Å, for example, 17 Å to 50 Å. a It has crystallite sizes. For example, CB is approximately 17 Å to approximately 20, 30, 40 Å; or approximately 20 Å to approximately 30 Å, ~ approximately 40 Å, ~ approximately 50 Å; or approximately 30 Å to approximately 40, 50 Å; or approximately 40 Å to approximately 50 Å L a It can have a crystallite size.

[0178] Regarding porosity, multifunctional CB has a minimum of 0.1 cm 3 / g, for example, at least about 0.35cm 3 For example, approximately 0.35 to 2 cm 3 Mesopore volume of / g, and at least 0.2cm 3 / g, for example, approximately 0.2 to 3 cm 3 It can have a total mesopore and macropore volume per g.

[0179] In some embodiments, the mesopore volume is approximately 0.35 to approximately 0.5, approximately 1, approximately 1.5 cm; approximately 0.5 to approximately 1, approximately 1.5 cm. 3 / g, approximately 2; or approximately 1 to approximately 1.5, approximately 2; or approximately 1.5 to approximately 2cm 3 The value is / g. In another embodiment, the mesopore volume is approximately 0.1 to approximately 0.25 cm³. 3 It is within the range of / g.

[0180] Some CBs that can be used to prepare the cathode composition by the dry process described herein are at least 0.2, for example, at least 0.4 cm. 3 It has macroporosity of / g. In the case of an anode composition, some suitable CBs are at least 0.1, for example, at least about 0.1 to about 0.4 cm 3 It has macroporosity within the range of / g.

[0181] The total mesopore and macropore volume characterizing the CB that can be used to prepare electrode compositions by a solvent-free process is at least 0.2 cm³. 3 / g, typically higher than that. In one example, the CB used to prepare the anode composition is about 0.2 to about 0.8 cm 3 It has a total mesopore and macropore volume within the range of / g. In the case of a cathode, CB is at least 1m 3 It can have a total mesoporous and macroporous ratio of / g.

[0182] In some examples, the multifunctional CB has a % crystallinity in the range of at least 22%, for example 23% to 50%, for example about 23% to about 30%, about 35%, about 40%, about 45%; or about 30% to about 35%, about 40%, about 45%, about 50%; or about 35% to about 40%, about 45%, about 50%; or about 40% to about 45%, about 50%; or about 45% to about 50%.

[0183] In one example, the CB is selected to combine a certain CB aggregate used (e.g., CB pellets or jet-milled CB particles) with sufficient surface area (e.g., measured by BET N2 adsorption) for the best binder treatment (e.g., fibrillation), while ensuring that the specific CB aggregate used (e.g., CB pellets or jet-milled CB particles) can be broken down into particles small enough to effectively treat the binder, e.g., fibrillate, e.g., less than 2 microns (μm).

[0184] Two or more types of carbon blacks (CBs) can be used together with the carbon nanotube (CNT) component. In some embodiments, a multifunctional CB is provided in a CB blend, for example, together with a second CB (which may or may not be multifunctional). Other examples utilize, for example, at least two carbon blacks having one or more properties that differ from each other with respect to their BET (Body-Equivalent Tone). Blends of carbon blacks having different structures-OANs and / or blends of different carbon morphologies, i.e., blends of activated carbon or graphite with one or more CBs, are also possible. In certain examples, at least one component in the blend is a multifunctional CB.

[0185] Examples of suitable CB materials that can be used include commercially available specifications such as: Vulcan® series CB such as Vulcan® XCmax 22 from Cabot Corporation; Black Pearls® series CB such as Black Pearls 2000 Carbon Black; PBX® series CB such as PBX 51; and LITX® series CB such as LITX HP and LITX MAX 90.

[0186] The ratio of the CNT component to the CB component can be in the range of approximately 99:1 to approximately 1:99, for example, in the range of approximately 10:90 to approximately 60:40.

[0187] In most cases, the solvent-free processes described herein are carried out in the absence of fibrillation aids other than CNTs or combinations of CNTs and CBs. In some cases, additional fibrillation agents, such as ACs, may be added. As used herein, the terms “fibrillation aid” or “fibrillation agent” refer to materials other than binders or electrode active materials that promote fibrillation of fibrillable binders. “Additional,” “further,” or “other” aids, additives, activators, etc., refer to materials other than the CNT material or CNT-CB combination described above (i.e., materials other than or not of said material). Typically, additional fibrillation aids are not considered multifunctional.

[0188] Several exemplary examples involve using CNTs (or a combination of CNTs and CBs, which may be multifunctional) with other (additional) materials, typically included as separate (separate) components. Examples of such other or additional materials include conventional fibrillating agents such as AC, hard carbon, graphite, graphene, other non-fibrillating conductive additives, plasticizers, or any combination thereof. In some applications, CNTs or blends of CNTs and CBs are combined with AC in a ratio ranging from approximately 95:5 to approximately 50:50.

[0189] In many embodiments, the components described herein (such as CNTs, CBs, AMs, binders, and other optional additives) are provided as loose particulate materials such as flowable or injectable powders, flakes, beads, granules, and pellets.

[0190] As already stated, many aspects of the present invention relate to electrode compositions, electrode products (e.g., films), electrodes (electrode products such as films coated on a conductive substrate), and / or methods for manufacturing batteries.

[0191] First, looking at the dry process used to prepare the electrode composition, carrying out this process targets at least two objectives: namely, blending several, typically all, components, most often in the form of loose (e.g., fluid or injectable) particles; and processing the binder in the presence of CNTs (or a combination of CNTs and at least one CB, e.g., a multifunctional CB). In some embodiments, each of these two objectives is achieved by one or more mixing operations carried out under specific shear conditions using appropriate apparatus.

[0192] For example, to distribute the components as uniformly as possible using a roll mill, low-shear mixing can be selected. As used herein, the term "low-shear mixing" refers to mixing carried out under conditions that are insufficient or substantially insufficient to fibrillate a fibrillable binder. Using low-shear mixing conditions can also avoid excessive particle fragmentation and is often considered for some electrochemically active materials.

[0193] In many embodiments, the treatment of the binder in the presence of CNTs (or CNT-CB combinations) is carried out under high-shear mixing. As used herein, the term “high-shear mixing” refers to shear conditions severe enough to deform (e.g., stretch, entangle) the binder to a degree sufficient to prepare a film electrode by solvent-free techniques. For fibrillable binders, high-shear mixing refers to mixing under shear conditions sufficient to fibrillate the binder.

[0194] While we do not wish to be bound to any particular interpretation, it is thought that in the presence of CNTs (and optionally in combination with CBs, e.g., multifunctional CBs) and under high shear conditions, the binder polymer will deform, stretch, elongate, and entangle. Attributes of surface energy and / or surface roughness can facilitate the gripping of the binder polymer; CNTs, any CBs, and the polymer can become compressed between electroactive particles, resulting in the stretching of the binder polymer. It is thought that CNTs dispersed in or on the surface of the binder, and optionally CB particles, can allow these particles to hold adjacent polymer domains together. Other contributing factors include polymer-polymer interactions (expected to increase with increasing polymer elongation and / or multidirectional shear forces), electroactive particle-polymer binder interactions (which may be related to surface energy), and / or other factors.

[0195] Under the same or substantially the same high-shear conditions, these effects tend to be more pronounced when the binder used is a fibrillating binder. The surface and other properties of CNTs (or CNTs and CBs) can facilitate the polymer from sticking together. As all particles move under high-shear mixing, the polymer elongates, forming very long and very thin strands (with a high aspect ratio). Typically, these effects are less pronounced with non-fibrillating binders treated under the same or substantially the same high-shear conditions. Or, to put it another way, non-fibrillating binders may require high high-shear conditions to achieve results close to complete fibrillation.

[0196] In addition to the processing contributions described above, CNTs or combinations of CNTs and CBs can improve conductivity and, in many cases, act as mechanical reinforcing agents by holding together fibrillable and non-fibrillable polymer binders that are "deformed" (e.g., stretched, entangled) or "undeformed" (e.g., spherical, rounded, or spherical)

[0197] In some situations, high-shear mixing can also be used to break down particles into smaller fragments. Large particles of CNTs and / or CBs, or granules such as pellets, can be ground down to smaller particles so that they spread more uniformly throughout the electrode composition, thereby improving conductivity and / or mechanical properties. In one example, the initial CNTs to be used are subjected to mixing (especially high-shear mixing). 50 The particle size distribution may be in the range of approximately 60 to approximately 500 μm, for example, approximately 70 to approximately 300 μm, or for example, approximately 100 to approximately 200 μm. As a result of subjecting the CNTs to high-shear mixing, the starting CNT particles can be broken down into smaller particles having particle sizes in the range of approximately 5 to approximately 100 μm, or for example, approximately 10 to approximately 30 μm.

[0198] Specific shear values ​​may depend on the scale of the operation, the materials involved, the type of mixing apparatus, and / or other factors. Low or high mixing settings can be determined or optimized based on prior experience, routine experiments, etc.

[0199] The components can be combined in any order designed to obtain a mixture, preferably a well-dispersed mixture, for example, a mixture with a uniform distribution of components, in other words, a homogeneous mixture. In one example, CNTs are uniformly dispersed on the surface of the electrochemical active material and binder. When using CBs, the CBs can be mixed with the CNTs to form a pre-blend. In a different approach, CNTs and CBs may be added individually to one or more other components. This addition may be simultaneous or sequential.

[0200] Binder treatment (e.g., fibrillation) can be performed on any mixture or premixture (preblend) that combines CNTs (optionally, in combination with CBs, e.g., multifunctional CBs) and a binder.

[0201] Suitable techniques that can be used or adapted for mixing and / or binder processing, such as fibrillation, include mechanical stirring, shaking, and agitation, and can rely on equipment such as jet mills, tube mills, acoustic mixers, extruders, planetary mixers, and other mixing devices, such as laboratory-scale mixers, pilot-scale evaluations, and equipment suitable for large-scale industrial production.

[0202] A stepwise procedure allows the use of one type of equipment for the first operation (e.g., preparation of the pre-blend) and another type of equipment for subsequent operations (e.g., fibrillation). The same applies to shear and / or other mixing parameters.

[0203] In one embodiment, CNTs (or a combination of CNTs and CBs) are first combined with a binder using a high-shear apparatus, and the binder is processed (e.g., fibrillated). If used, CBs can be added separately from the CNTs or in a pre-blended mixture with the CNTs. In some cases, this high-shear operation also breaks down multifunctional additive particles (pelletized granules or other fine particles that are easily pulverized under high-shear conditions) into smaller fragments. The resulting mixture is then combined with an electrochemically active material (graphite in one example). Using low-shear conditions during this step is advantageous for maintaining the particle size (e.g., of the electrochemically active material).

[0204] In another embodiment, CNTs (or CNTs and CBs, added individually or in a pre-blended mixture) are first combined with an electrochemical active material in a pre-mixing step, for example, carried out under low shear conditions to obtain a uniform distribution of these components. The resulting mixture is mixed with a binder and subsequently treated (e.g., fibrillation) under high shear conditions.

[0205] In further embodiments, the electrochemical active material, binder, and CNT (or a combination of CNT and CB) are all mixed (e.g., under low shear conditions); and the mixture is then subjected to high shear conditions to treat the binder (e.g., fibrillation).

[0206] Other sequences are also possible. For example, the electrochemical active material can be mixed with the binder first, followed by the addition of CNTs (or CNTs and CBs), and fibrillation can be performed, for example, under high shear conditions.

[0207] Low shear mixing and / or high shear treatment (e.g., fibrillation) can be carried out in one or more (2, 3, 4, 5, 6, etc.) mixing stages or pulses that can be sustained over an appropriate period, which can be, for example, within the range of about 10 seconds to about 5 minutes, such as about 30 seconds to about 1 minute, ~ about 90 seconds, ~ about 2 minutes, ~ about 2.5 minutes, ~ about 3 minutes, ~ about 4 minutes, ~ about 5 minutes; about 1 minute to about 90 seconds, ~ about 2 minutes, ~ about 3 minutes, ~ about 4 minutes, ~ about 5 minutes; about 90 seconds to about 3 minutes, ~ about 4 minutes, ~ about 5 minutes; about 2 minutes to about 3 minutes, ~ about 4 minutes, ~ about 5 minutes; about 3 minutes to about 4 minutes, ~ about 5 minutes; about 4 minutes to about 5 minutes. Different time intervals can also be used. The duration of two, more or all of the pulses may be the same or different.

[0208] After the pulse, a rest period or a cooling period can follow. The rest period can be at ambient temperature, for example, room temperature. Cooling can be at a temperature below ambient temperature, for example, below room temperature, often below 0 °C, for example, within the range of about -5 to about 5 °C.

[0209] The rest or cooling period can vary depending on the temperature reached during mixing, the amount being handled, etc. Often, cooling lasts for several minutes, for example, 10 minutes to 30 minutes or more. The cooling period can vary in duration and / or temperature conditions.

[0210] By way of illustration, a binder-containing composition can be subjected to high shear mixing at about 25,000 RPM to about 10,000 RPM, optionally about 18,000 RPM, for 30 seconds, and then cooled at a sub-freezing temperature, for example, about -10 °C for 10 minutes. Low shear mixing can be carried out at about 2,000 RPM to about 4,000 RPM for 1 minute, followed by cooling at about 0 °C for 10 minutes.

[0211] In one example, a pre-blend of CNT and an electrochemically active material is prepared for several minutes using an acoustic mixer, for example, with a force of 100 G. The resulting blend is combined with a binder using fibrillation parameters, for example, using a laboratory-scale jet mill at a pressure rate of 100 - 90 - 90 - 10 psi.

[0212] In another example, in a pulsed mode where blending is alternated with a resting period, all components are mixed at 25,000 RPM in a tube mill (such as IKA TubeMill 100), followed by a mixing operation with a longer duration.

[0213] The process operations and / or conditions used to form the electrode composition can preserve the integrity of some or all of the initial CNTs used, and the CNTs remain intact. However, in some cases, the initial CNT material may be decomposed into smaller CNT units, for example, generating CNT fragments. Except for their small size, CNT fragments generally share the characteristics 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 a particular interpretation, it is considered that CNTs distributed, for example, uniformly, and pulverized CNTs in the electrode composition can result in electrodes having improved conductivity and / or desirable mechanical properties.

[0214] When the CNT additive is provided in the form of CNT aggregates, bundles or ropes, these can be pulverized or separated into smaller particles under the operations and / or conditions used to form the electrode composition. The resulting smaller particles, thinner bundles, or even individual CNTs are distributed throughout the composition and contribute to the desired mechanical and / or electrical attributes.

[0215] The mixing and / or processing steps, such as fibrillation, can be monitored by visual inspection, hand calendaring, powder rheology, or another suitable technique. For example, a small amount can be handled manually, sheared, or passed through a hand calendar. The endpoints can be established based on experience, routine experimentation, visual inspection, etc. Whether these operations are successful can also be determined by SEM, performance, and / or other techniques typically performed on the electrode product, such as an electrode film.

[0216] The resulting electrode composition may be in the form of a composite material such as pellets, powder (often a fluffy powder), polymer-encapsulated granules (masterbatch), or other forms of free-flowing or loose particulate material.

[0217] In an optional step, the electrode composition can be sieved to remove undesirable clumps.

[0218] Electrode compositions typically include CNTs in combination with optionally CB components, electrode active materials, and “treated” binders. Some product electrode compositions, particularly those prepared with fibrillable binders, contain post-fibrillated binders (also referred to herein as “fibrillated binders”) and often exhibit high-aspect-ratio fibrils. Compositions prepared with non-fibrillable binders still exhibit “deformed” (e.g., stretched, tangled) binders, but probably to a lesser degree than those observed with fibrillable binders under the same or substantially the same fibrillation conditions. Treated (e.g., fibrillated) binders can be detected by the techniques described above. Successful binder treatment (e.g., fibrillation) often reflects in the quality of the resulting electrode (e.g., electrode film). In some cases, electrode compositions prepared with non-fibrillable binders contain “undeformed” (e.g., spherical, rounded, spherical) binders. Even in such cases, CNTs (and optionally CBs) can act as a binder and mechanical reinforcer for the electrodes.

[0219] Based on the total weight of the electrode composition, the multifunctional CNTs may be present in an amount ranging from about 0.1 to about 10% by weight, for example, about 0.3 to about 5.0% by weight, for example, about 0.3 to about 3% by weight. In one embodiment, for example, the CNTs constitute 3 to 5% by weight of the product electrode composition, for example, 3 to 3.5, 4, or 4.5% by weight; 3.5 to 4, 4.5, or 5% by weight; or 4 to 4.5, or 5% by weight; or 4.5 to 5% by weight. In another embodiment, CNTs are present in the composition in amounts ranging from about 0.3 to about 0.5, about 1.0, about 1.5, about 2.0, about 2.5; or about 0.5 to about 1.0, about 1.5, about 2.0, about 2.5, about 3; or about 1.0 to about 1.5, about 2.0, about 2.5, about 3.0; or about 1.5 to about 2.0, about 2.5, about 3.0; or about 2.0 to about 2.5, about 3.0; or about 2.5 to about 3.0. Often, CNTs are provided in amounts of about 5% by weight or less based on the total weight of the electrode composition. Specific amounts within and outside these ranges can be selected. In blends of CNTs and CBs, the same or similar amounts can be used.

[0220] In many cases, the amount of CNTs (or CNT-CB combinations) is equal to, or preferably less than, the amount of AC required to obtain the same or substantially the same electrode performance. In alternative approaches, it is expected that achieving the performance level established with AC will require less CNT (or CNT-CB blend) and will not take up extra volume for the electrochemical active material.

[0221] In exemplary LIB graphite anode compositions, for example, the amount of CNTs added (or the amount of CNTs added in combination with CBs) is about 5% by weight or less, often about 3% by weight or less, for example, 1% by weight or less. In specific examples, the amount added is in the range of about 0.1% to 1.0% by weight, for example, about 0.1% to about 0.5% by weight, or about 0.5% to about 1% by weight. Other examples use amounts added in the range of about 1% to about 5% by weight, for example, at least about 4.5%, 4.0%, 3.5%, 3.0%, 2.5%, 2.0%, or 1.5% by weight.

[0222] In exemplary NCM cathode compositions, CNTs (or CNT-CB combinations) are present in amounts of about 5% by weight or less, for example, about 3% by weight or less, for example, 1% by weight or less. In certain examples, the amount of multifunctional additives added is in the range of about 0.1% to 1.0% by weight, for example, about 0.1% to about 0.5% by weight, or about 0.5% to about 1% by weight. Other examples use amounts in the range of about 1% to about 5% by weight, for example, at least about 4.5%, 4.0%, 3.5%, 3.0%, 2.5%, 2.0%, or 1.5% by weight.

[0223] The relative amount of CNTs (or CNT-CB combinations) to the fibrillable binder can be within the range of 5:1 to 0.1:10 by weight, for example, approximately 1:1 to 0.1:10, 0.5:1 to 0.1:10, 5:1 to 0.5:10, 5:1 to 1:5, or 5:1 to 5:10. In certain cases, the weight ratio is 1:1.

[0224] In one embodiment, the electrode composition contains an active material in an amount of about 90% to about 99% by weight, for example, 98.0% by weight, a fibrillable binder in an amount of about 1% to about 5% by weight, and a combination of CNTs or CNT-CBs in an amount of about 0.3% to about 5% by weight.

[0225] After mixing and processing (e.g., fibrillation), optionally sieved compositions can be formed into product electrodes by any suitable techniques known in the art or to be developed in the future. In one embodiment, the composition is formed into a film by calendering, an operation that can be carried out at a temperature above room temperature, for example, similar to or close to the polymer glass transition temperature. In a typical calendering operation, the composition is subjected to heat and pressure using an extruder. The softened material is passed through a calender roll (e.g., vertical) to prepare a product electrode sheet or film. In many embodiments, the film is freestanding (or self-supporting), a characteristic that can be described using a 150 μm thick film that is self-supporting, and any portion of the film is not in contact with any type of support, e.g., a substrate.

[0226] The desired film thickness can be achieved by adjusting the gap between the rolls and, in some situations, other process parameters.

[0227] The roll temperature can be, for example, approximately room temperature (20°C) to about 200°C. A higher roll temperature may result in a thinner self-supporting film obtained in the first pass, while a lower temperature will have the opposite effect. The roll speed can be varied. In an exemplary example, the roll speed is set to approximately 0.17 meters per minute (m / min) to about 1.3 m / min. Slower roll speeds tend to produce a thinner self-supporting film in the first pass compared to faster roll speeds. The hydraulic pressure used can be in the range of approximately 1,000 psi to about 7,000 psi. Again, higher pressures may result in a thinner self-supporting film in the first pass compared to a thicker film obtained at lower pressures.

[0228] The film may be further passed through a roll mill to reduce its thickness until the desired thickness and amount of additive are reached. In a specific embodiment, the film thickness is in the range of approximately 50 μm to approximately 300 μm, for example, approximately 50 to approximately 200 μm or approximately 100 μm to approximately 150 μm. The film thickness can also be in the range of 50 to 100, 50 to 150, 50 to 200, 50 to 250 μm; or 100 to 150, 100 to 200, 100 to 250, 100 to 300 μm; or 150 to 200, 150 to 250, 150 to 300 μm; or 200 to 250, 200 to 300 μm; or 250 to 300 μm. The desired amount of additive is approximately 10 mg / cm³. 2 ~about 50mg / cm 2 That's fine.

[0229] Self-supporting films prepared by the solvent-free process described herein are expected to have good mechanical properties. One reliable mechanical evaluation technique relates to tensile strength testing. For example, anodes containing CNTs or a combination of CNTs and CBs are expected to have a tensile strength of at least 100 kPa, while the tensile strength of NCM cathode films is expected to be at least 500 kPa. In one exemplary example, the self-supporting film has a tensile strength of at least 0.1 MPa and a thickness in the range of 80 μm to 500 μm. In many cases, the mechanical performance of the film was at least as good as that of a comparative film manufactured using AC.

[0230] In an optional operation, the film is thermally activated, for example, to soften the binder and prepare an electrode product for application to a substrate. In the laboratory, this operation can be performed using, for example, a hot plate at 100°C. Approaches for larger-scale processes include temperature-controlled roll-to-roll calenders, convection and / or microwave dryers, etc.

[0231] A film (typically self-supporting and containing electrode active material, CNTs (or a blend of CNTs and CBs), and a treated, e.g., fibrillated, binder) can be applied to a conductive substrate or support. Available anode substrates include, but are not limited to, copper, nickel, titanium, stainless steel, and carbonaceous materials in the form of foils, meshes, foams, etched, or coated current collectors. Available cathode substrates include, but are not limited to, aluminum, titanium, and carbonaceous materials in the form of foils, meshes, foams, etched, or coated current collectors. In one embodiment, the film is laminated onto a carbon-coated copper foil by calendering the two together using a horizontal hot roller with appropriate roll temperature, roll speed, and water pressure. Another example uses a carbon-coated aluminum current collector.

[0232] In some cases, the film can be applied to the substrate using a conductive adhesive (bonding agent).

[0233] The roll temperature can be in the range of about 60 to about 120 °C. If the temperature is too high, blister formation may increase and adhesion may become insufficient. If the temperature is too low, adhesion may be hindered.

[0234] The roll speed can be about 0.17 m / min to about 1.3 m / min, for example, about 0.5 m / min, and the hydraulic pressure can be set to about 500 psi to about 2,000 psi. Other settings can also be used. The pressure can be optimized to be high enough to promote adhesion to the substrate without changing the addition amount, porosity, or other properties. In some embodiments, the lamination is performed before setting the final thickness and / or porosity of the film electrode.

[0235] The formation of the film and its application to the substrate can also be done in a single step. For example, the powder electrode composition and the substrate foil can be fed together through a calender roll under conditions suitable for manufacturing a laminate, in which the composition is pressed to form a film and adhered to the foil. In this approach, the formation of a self-standing film is not required.

[0236] The laminated structure can be shaped and / or sized for specific applications such as electrochemical cells, for example, LIBs, such as rechargeable LIBs.

[0237] [[ID=2"]]The electrodes prepared as described herein can be incorporated into lithium-ion batteries according to methods known in the art, such as those described in Yuping Wu, "Lithium Ion Batteries Fundamentals and Applications", CRC press (2015). In certain embodiments, the battery is a coin type, such as a 2032 coin cell, a 18650 cylindrical cell, a pouch cell, etc.

[0238] In an exemplary example, the LIB comprises a cathode prepared by a dry process. The cathode contains, for example, 5% by weight or less of CNTs (or a combination of CNTs and CBs), a cathode active material (e.g., NCM), and a fibrillation binder. As described above, the active material and the fibrillation binder may be present in the anode in amounts of at least 80% by weight and 5% by weight or less, respectively.

[0239] The second (opposite) electrode in the battery can also be prepared using a solvent-free process. In one embodiment, both electrodes in the battery contain carbon nanotubes (CNTs). One or both may further include, for example, carbon crystalline polymers (CBs), multifunctional CBs.

[0240] The second electrode can also be prepared by conventional dry processes (e.g., using AC), by slurry, or by other non-dry techniques.

[0241] In addition to the two electrodes, a typical lithium-ion battery (LIB) contains a suitable electrolyte. Examples include, for example, ethylene carbonate-dimethyl carbonate-ethyl methyl carbonate (EC-DMC-EMC), vinylene carbonate (VC), LiPF6; or ethylene carbonate-diethyl carbonate (EC-DEC, LiPF6; or (EC-DMC), LiPF6). In the laboratory, a suitable separator that absorbs the electrolyte and prevents electrical contact between electrodes while allowing the diffusion of Li ions can be a glass fiber microfilter (e.g., Whatman GF / A). In some cases, a polypropylene / polyethylene membrane separator (e.g., Celgard 2300) can also be used.

[0242] The composition or morphology of electrodes and / or batteries described herein can be characterized by a variety of techniques. Examples include, but are not limited to, electron microscopy, e.g., TEM, SEM, X-ray tomography, Raman spectroscopy, and other suitable qualitative or quantitative analytical methods. In one example, SEM data of a graphite electrode prepared by a dry process using the multifunctional additive described herein revealed the presence of ribbon-like binder fibrils, indicating effective fibrillation. The presence of clearly visible strings, along with one or more properties such as elastic modulus, tensile strength, and conductivity, demonstrates the multifunctionality of the additive.

[0243] The amount or absence of solvent can be evaluated by gravimetric testing. This involves drying the wet-cast electrode until the electrode weight reaches a value theoretically calculated based on the known amount of solid added to the slurry, or until the electrode weight stabilizes and does not change for at least 3 minutes. If the electrode was prepared entirely in the absence of solvent, it will maintain the same weight throughout the evaluation period. In other words, the weight of the freshly prepared electrode (before any drying operation) is the same as the theoretical weight (i.e., the weight obtained by adding up the weights of the individual components provided in the process, which are usually loose particulate materials), or within ±1% by weight.

[0244] Another approach that can be used to detect the solvent (e.g., NMP) is to use attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy (FTIR-ATR) 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 binder distribution, where the binder does not migrate toward the film surface, is yet another feature that often characterizes electrode products prepared by solvent-free processes.

[0245] The flexibility characteristics of the electrode (its ability to resist cracking) can be measured by visual inspection when bending the film by hand or using a mandrel bending tester. In a particular embodiment, the electrode is evaluated and expected to pass a 10 mm diameter mandrel bar test without any visible cracks. In an example, the electrode was confirmed to pass a bending test using an 8 mm diameter pen as a rod.

[0246] Electrode performance can be tested by procedures known in the art, or by adapted or developed techniques. Suitable techniques include, for example, in-plane and through-plane electrode conductivity, electrochemical impedance spectroscopy (EIS), constant current charge-discharge rate characteristics, hybrid pulsed power capability (HPPC), and cycle life testing.

[0247] In many cases, electrodes prepared by the solvent-free processes described herein perform at least similarly, and often better (e.g., when measured by in-plane resistivity, initial capacity, or first-cycle efficiency) than comparative electrodes (also referred to herein as "reference") containing the same amounts of electrode active material (e.g., NCM), binder, and conventional fibrillating agents such as AC. Alternatively, the amount of CNTs (or combinations of CNTs and CBs) required to achieve the performance obtained using AC is typically less in electrodes manufactured according to the embodiments described herein.

[0248] In one example, a dry process cathode prepared using CNTs at an additive amount of approximately 1% by weight or less exhibited performance (measured by in-plane resistivity, rate characteristics, and first cycle efficiency) at least as good as a comparative (reference) electrode containing a higher amount (e.g., 5% by weight) of AC.

[0249] Electrodes prepared using the solvent-free processes described herein are also expected to have good mechanical properties. Examples of mechanical evaluation techniques that can be relied upon include peel tests (e.g., 90°, 180°, T-peel, various fixtures), tensile tests, and bending tests (mandrel experiments). In many cases, electrodes prepared using CNTs (or blends of CNTs and CBs) performed at least as well as reference electrodes manufactured using ACs.

[0250] While we do not wish to be bound by any particular interpretation, it is conceivable that by using carbon nanotubes (CNTs) in conjunction with carbon crystalline bands (CBs) at an optional rate, ribbon-like binder strands or fibrils that are long enough to encapsulate and hold electrochemically active particles together can be produced.

[0251] Therefore, even at relatively low levels, CNTs (or a combination of CNTs and CBs) can process the binder (e.g., fibrillation) to create an effective conductive network in the electrode, while simultaneously contributing to desired mechanical properties.

[0252] The electrode compositions and methods described herein can 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 fabricating such devices are known in the art and are described, for example, in "Battery Reference Book" by TR. Crompton, Newness (2000).

[0253] The present invention can be further described by the following non-limiting embodiments. [Examples]

[0254] Materials and methods For use in solvent-free electrode processes and formulations, Targray's lithium nickel manganese cobalt oxide NCM622 (SNCM03006) is used as a reference material with a surface area of ​​1500 cm². 2 Standard activated carbon of / g is mentioned. Polytetrafluoroethylene (PTFE) was used as the fibrillation-capable binder. Other CNT and CB specifications were obtained from Cabot. The physical properties of the CNTs and CBs used in the following examples are shown in Tables 1 and 2 above, respectively.

[0255] The cathode composition contained electrode active materials such as a lithium-ionized transition metal oxide (e.g., NCM622), conductive carbon (e.g., CNTs, CBs, etc.), and a fibrillable binder (e.g., PTFE).

[0256] Generally, the cathode electrode was prepared in several steps. In the first step (S1), the electrode components were combined and mixed under conditions suitable for fibrillating the binder (e.g., by high-shear mixing). The second step (S2) involved passing the powder blend from S1 through a vertical calender pre-set to an appropriate gap based on the desired film thickness. In the third step (S3), the self-supporting film obtained from S2 was laminated onto a current collector.

[0257] A similar series of steps was followed to prepare the anode electrode.

[0258] The thickness of the solvent-free electrode was measured using a manual drop gauge with a 7.14 mm diameter flat gauge contact head. A manual die cutter was used to punch out 15 mm diameter discs for the cathode and 16 mm diameter discs for the anode.

[0259] The mechanical properties of the self-drying film, such as tensile strength and Young's modulus, were tested using a Mecmesin MultiTest-dV electric force tester with a load of 10 N. After calendering the film to the desired thickness, it was cut into 70 × 20 mm strips using a die cutter. These strips were then placed in the apparatus and a test program for tensile testing was executed.

[0260] The sheet resistance of solvent-free electrodes was measured using a Signatone Pro4-4400 commercial system (SP4 probe head connected to the rear of a Keithley 2410-C source meter). The reported values ​​were normalized by electrode thickness and reported as electrode resistivity in ohms-cm (Ω·cm).

[0261] Example 1 In S1, the electrode components were blended using a Resodyn acoustic mixer and an IKA mill according to a two-step operation. More specifically, the first step of S1 was carried out to prepare a uniform distribution of powder components during blending and included a 10-minute pre-blending of carbon additives and electrode active materials in an acoustic mixer at 90% intensity and automatic frequency, followed by the addition of polymers and a further 20-minute blend at the same settings.

[0262] The second stage, which involved fibrillating the blend, was further processed using an IKA Tube Mill 100, consisting of 6 cycles of 15 seconds each at 25,000 rpm and 1 cycle of 3 minutes at 5,000 rpm. In step S2, the powder blend obtained in step S1 was passed through a vertical calender at 100°C to obtain a self-supporting film with a thickness of 30 to 130 μm.

[0263] In step S3, these self-supporting electrode films were then laminated onto a 17 μm thick carbon-coated Al foil by calendering them through a vertical calender at 100°C to obtain electrodes.

[0264] Cathode films were prepared using the carbon additives shown in Tables 1 and 2, according to the formulations shown in Table 3. All electrodes were prepared by a dry process and contained 2% by weight of carbon additives, 94% by weight of NCM622, and 4% by weight of PTFE, with an average thickness in the range of 107–110 μm. [Table 3]

[0265] Compositions A1-A6 in Table 3 were tested for the mechanical properties of self-supporting, dried electrode films. More specifically, Figure 1A compares the tensile strength and modulus of dry electrode films formulated with various CNTs, i.e., additives CNT1, CNT2, CNT3, and CNT4 (from Table 1), at an average film thickness of 107-109 μm. Films prepared with CB1 (from Table 2) and AC were used as references. The fibrillation ability of CNT1, CNT2, and CNT3 was comparable to that of CB1 and far better than that of the AC reference. CNT4 did not appear to fibrillate PTFE well. Electrode films prepared with CNT4 were brittle and rigid and could not be used for tensile strength testing. CNT1 offered the additional benefit of lower electrode resistivity when tested at the same additive amount.

[0266] Figure 1B compares the measured in-plane resistivity of dry cathodes having formulations A1-A5 (from Table 3). Electrodes formulated with CNT1, CNT2, and CNT3 (from Table 1) showed improved in-plane resistivity compared to those prepared with CNT4 and reference CB1. Furthermore, compared to other CNTs, CNT1 yielded the lowest electrode resistivity and characteristics advantageous for battery performance, such as rate characteristics and long cycle life.

[0267] Example 2 The NCM electrode formulations B1 and B2 (Table 4) in this example were prepared according to the procedure described in Example 1. The carbon additives used were CNT5 and CNT1 (from Table 1). CNT5 is a pre-milled (micronized) version of CNT1. Micronization was performed using a mechanical pulverizer (Model: FW177, manufactured by Tianjing Tai Si Te Instrument Co., Ltd.) at a frequency of 50 Hz, output of 1200 W, and speed of 24000 rpm for 80 seconds. The particle size distribution was measured using a laser particle size analyzer (Model: Topsizer, manufactured by Zhuhai OMEC Instruments Co., Ltd.). The particle size distributions of the untreated CNT, i.e., CNT1, and its micronized version, i.e., CNT5, used in this example are summarized in Table 1.

[0268] The electrode formulations used (indicated as B1 and B2) are listed in Table 4 below. All dry electrode films were prepared by a dry process and contained 2% by weight of carbon additives, NCM622 (94% by weight), and PTFE (4% by weight), with an average thickness in the range of 112 ± 1.5 μm. [Table 4]

[0269] Tensile strength and elastic modulus of dry cathode film, and pulverized CNT5(D 50 Formulation B1 and unmicronized CNT1 (D) using approximately 15 μm 50 The electrode resistivity measured with formulation B2 (approximately 140 μm) is shown in Figures 2A and 2B, respectively.

[0270] As can be seen in Figure 2A, micronized CNT5(D 50 The tensile strength of the film electrode prepared with formulation B1 using approximately 15 μm is equal to that of unfinely powdered CNT1 (D 50The tensile strength of the electrode film prepared with formulation B2 (using particles of approximately 140 μm) showed improvement (approximately 30%). The elastic modulus of the film made using pulverized CNT5 was lower than that of the CNT1 film. The results suggest that smaller particle sizes may be important for making the film stronger and more flexible.

[0271] As shown in Figure 2B, electrodes using pulverized CNTs (CNTs) also exhibit improved conductivity, which may be another indicator of the advantages of the selected particle size of the CNTs (in addition to improved interaction with the binder and fibrillation characteristics, this is thought to result in improved distribution of CNT particles throughout the electrode). Improved electrode resistivity (in other words, electrode conductivity) would be beneficial to battery performance.

[0272] Figure 3 shows SEM images (secondary electron images and backscattered electron images) and fluorine element mapping of cross-sections of electrode films containing formulations B1 and B2. In Figures 3A and 3B, the left images (AI and BI) are backscattered electron images, and the right images (A-II and B-II) are secondary electron images. The dispersion of pulverized CNTs, i.e., CNT1 (from Table 1), was higher than that of unpulverized CNTs, i.e., CNT5 (from Table 1). Furthermore, no significant aggregation was observed in films prepared using pulverized CNT5. This was in contrast to the aggregation seen in the red circles in the image of unpulverized CNT1.

[0273] SEM analysis also provided some useful insights into the level of binder fibrillation and how it is affected by CNT PSD. As seen in Figures 3C and 3D, the fibrils appeared to surround the electrode active material and / or carbon. Importantly, the amount of PTFE fibrils seen in Figure 3D with micronized CNT5 was significantly higher than that observed with unmicronized CNT1 (using a scale bar of similar size). This may indicate improved binder fibrillation and appears to be in good agreement with the tensile strength data.

[0274] Figure 4 shows the EDS elemental mapping (scale bar: 100 μm) of fluorine F (Image B) and carbon C (Image C) of dry cathode film B1 prepared from pulverized CNT5. This data confirmed that the carbon additive and polymer were uniformly distributed throughout the electrode. No binder migration was detected (which is very frequent in electrodes prepared with slurry).

[0275] Example 3 The NCM electrode in this example was prepared by the same method as in Example 1. The amount of carbon additive was 1% by weight, the amount of NCM was 96% by weight, and the amount of PTFE added was 3% by weight. The average dry film thickness was 110 ± 2 μm. The formulation used to prepare the electrode film is shown in Table 5. [Table 5]

[0276] Figure 5A compares the tensile strength and modulus of two sets of dry electrode films, B1 and B2 (from Table 4) and C1 and C2 (from Table 5), prepared with two different NCM / CNT / PTFE formulations, namely 94 / 2 / 4 and 96 / 1 / 3, respectively, using pulverized and unpulverized CNTs, i.e., CNT5 and CNT1 (from Table 1). Figure 5B shows a comparison of the in-plane resistivity for the selected formulations. Compared to the 94 / 2 / 4 film, the films prepared with the 96 / 1 / 3 formulation from Table 5 (containing fewer CNTs, less binder, and increased active material) showed decreased tensile strength and modulus. In-plane resistivity was higher with decreasing CNT content.

[0277] At both CNT addition levels, pulverized CNTs showed increased tensile strength compared to unpulverized CNTs. For both 96 / 1 / 3 and 94 / 2 / 4 formulations, the use of pulverized CNTs resulted in a decrease in elastic modulus (compared to unpulverized CNTs), suggesting improved flexibility of the self-supporting film. Compared to unpulverized CNTs, pulverized CNTs reduced the in-plane resistivity of electrodes prepared with both 96 / 1 / 3 and 94 / 2 / 4 formulations, thus benefiting the electrochemical performance of the battery.

[0278] Example 4 The NCM electrodes in this embodiment were prepared according to the procedure described in Example 1. The CNT5, CNT6, CNT7, and CNT9 used in this embodiment are preliminary milled versions of CNT1, CNT2, CNT3, and CNT4 (from Table 1) and were processed by the same milling method as described in Example 2 to achieve a D50 of 15 μm.

[0279] Four types of untreated CNTs were milled, and the same D 50 The following was obtained. The electrode formulations used (labeled D1 to D4) are listed in Table 6 below. All electrodes contained 1% by weight of CNTs, 96% by weight of NCM, and 3% by weight of PTFE, and the average dry film thickness was 75 ± 2 μm. Dry electrode film D4 was too brittle to be manufactured as a self-supporting film. This was because CNTs 5, 6, and 7, which have a large surface area and a small average diameter, had a small surface area (<150 m 2 It demonstrated that CNT9 with a larger diameter (≧30nm) showed better auxiliary processing ability than CNT9. [Table 6]

[0280] Figure 6 compares the in-plane resistivity and through-plane resistivity of dry electrodes for formulations D1, D2, and D3. As can be seen in this figure, formulation D1, which was fabricated using CNT5, exhibited the lowest resistivity.

[0281] Example 5 A cathode-dried self-supporting film and a test electrode were prepared using the same method as in Example 1.

[0282] The electrode formulations used (labeled E1 to E7) are listed in Table 7 below. All electrode films were prepared with a total carbon content of 2 wt% using carbon additives (CB only, CNT only, or a combination of CB and CNT blended at different CB / CNT ratios). The NCM content was 94 wt%, and the PTFE content was 4 wt%. [Table 7]

[0283] Figure 7A compares the tensile strength of an electrode dry film with formulation E1 (NCM electrode film containing only CNT8) with dry electrode films with formulations E2 and E3 (formulated using CB / CNT blended in two different ratios), and dry electrode film with formulation E4 (containing only CB1). As seen in Figure 7A, the dry electrode film prepared with the CB / CNT blend for E3 showed improved tensile strength compared to formulations E1 and E4, which contain CNT and CB as single carbon additives, respectively. This may be due to a synergistic effect. As seen in Figure 7B, a synergistic effect was also observed for CB2 / CNT8, but it appeared at different CB / CNT ratios (see E5 in Table 7), which may be influenced by the difference in surface area between CB1 and CB2.

[0284] As shown in Figure 8, electrodes prepared using the CB1 / CNT8 blend also exhibited lower electrode resistivity compared to electrodes containing pure CB, demonstrating a favorable effect on battery performance.

[0285] Example 6 The selected cathode formulation and test electrode were prepared according to the method described in Example 1.

[0286] Two electrode films were prepared using CB only, i.e., CB3, and a combination of CB and CNT, i.e., CB3 and CNT5 blended in an 80:20 ratio (from Tables 2 and 1, respectively), with a dry film thickness of 110 μm during calendering.

[0287] Table 8 shows the amounts of carbon additive (1 and 2 wt%) and PTFE (1, 2, and 3 wt%) used to produce the self-supporting electrode films, and evaluates the processability of these films. NCM represents the remainder up to 100 wt%. In Table 8, "Pass" indicates that a continuous, flexible film was formed, and "Fail" indicates that a continuous, flexible film could not be formed. [Table 8]

[0288] With 2 wt% total carbon additive, both formulations containing a CB / CNT blend and formulations containing only CB yielded good quality self-supporting films in combination with 4 wt% PTFE. Moving towards lower electrochemically inert material content, for example to 3 wt% PTFE, the presence of a CB3 / CNT5 blend resulted in the formation of a strong and flexible cathode film, while CB3 alone did not result in continuous and flexible film formation under given conditions (indicated as "Fail" in Table 9).

[0289] Films could be prepared using both CB3 alone and a CB3 / CNT5 blend with a carbon additive of 1% by weight. However, the blend significantly increased the flexibility of the film, as shown by the modulus data in Figure 9. (Selected electrode formulations (labeled F1-F4) that allowed for the formation of good quality films are listed in Table 9 below). [Table 9]

[0290] Figure 9 compares the elastic modulus of an NCM dry electrode film containing only CB3 with that containing a CB3 / CNT5 blend. As seen in Figure 9, electrode films prepared by a dry process using the CB / CNT blend (see F2 and F4 in Table 9) showed improved film elasticity compared to the corresponding CB-only formulations (see F1 and F3 in Table 9) when compared with the same NCM-carbon-PTFE addition amount.

[0291] Example 7 The cathode formulation and test electrode were prepared according to the method of Example 1.

[0292] The electrode formulations used (labeled G1 to G6, with A6 serving as a reference for AC content) are listed in Table 10 below. All electrodes were prepared with 2% by weight of carbon additive, 94% by weight of NCM, and 4% by weight of PTFE, either CB alone, CNT alone, or a combination of CB and CNT blended in different ratios (CB / CNT). The average dry film thickness was 110 ± 1.5 μm. [Table 10]

[0293] It was found that continuous, flexible, dry-processed NCM electrode films could not be produced when using carbon dioxide (CB) with a low surface area (SA), such as CB4, as a single conductive additive, or when blended with carbon nanotubes (CNT8) at a CB / CNT ratio higher than 50:50 (see formulations G1, G2, and G3 in Table 10). However, as shown in Figure 10A, blending CB4 and CNT8 at a ratio lower than 50:50, such as 40:60 (see formulation G4), improved processability and enabled the formation of continuous, flexible, self-supporting films. (An "x" indicates no good film formation.)

[0294] Using CNT5 instead of CNT8 in the blend further improved processability by increasing the tensile strength of the electrode film, as demonstrated by a comparison of selected formulations G4 and G6 containing low SA CB4 / CNT8 and CB4 / CNT5 at the same 40:60 ratio and 2% by weight total carbon content (Figure 10B).

[0295] Example 8 The graphite electrode formulations H1-H4 (Table 11) in this example were prepared according to the procedure described in Example 1. The carbon additives used were CNT1, CNT3, and CNT4 (from Table 1), with AC used as a reference. All CNT-containing dry electrode films were prepared by a dry process and contained 1% by weight of carbon additives, NCM622 (94% by weight), and PTFE (5% by weight). [Table 11]

[0296] As shown in Figure 11, formulations containing CNT1, CNT3, and CNT4 showed improvement (at least 80%) in tensile strength compared to the reference anode film prepared using AC, at the same 5% by weight binder addition.

[0297] Example 9 A series of dry cathodes (labeled I1 to I5) were prepared by the same process as in Example 1. The electrode formulations used and the characteristics of the resulting cathodes are shown in Table 12 below. All dry cathodes contained NCM622 (96 wt%), a binder (3 wt%), and 1 wt% CNTs of the selected type (see Table 1 for details). [Table 12]

[0298] Cathodes from Table 12 were tested in 2032 full coin cells. 15 mm diameter discs were punched out for coin cell preparation and dried under vacuum at 100°C for a minimum of 4 hours. The discs were calendered to the desired electrode density using a manual roll press and assembled into 2032 coin cells in an argon-filled glove box (M-Braun). Tested against slurry-treated graphite anodes containing 3% CB, 5% PVDF, and 92% natural graphite at anode access 1.2, measured as the negative electrode to positive electrode volume ratio (N / P). 2325 Celgard film was used as a separator. 1 M lithium hexafluorophosphate (LiPF6) in ethylene carbonate-dimethyl carbonate-ethylmethyl carbonate (EC-DMC-EMC, weight ratio 1:1:1) was used as the electrolyte together with 1 wt% vinylene carbonate (VC) from BASF. The room temperature (25°C) rate performance of full coin cells was measured by first forming them through four C / 20-D / 20 charge-discharge cycles, and then performing four charge-discharge cycles at each rate: C / 10, C / 5, C / 3, C / 2, 1C, and 2C, respectively. The reported capacities are normalized to mAh / g of the active cathode mass. Cycle performance tests were conducted at 25°C using C / 3 charge and C / 3 discharge rates.

[0299] Figure 12 shows the C-rate performance data for cathodes I1 and I2, which were prepared using CNTs of the same type and diameter range but with different average aggregate sizes. 50 Dry-treated cathode I2, fabricated from standard CNT1 of =135μm, is D 50 Compared to dry cathode I1 fabricated with 15μm CNTs, it exhibited comparable capacity at C rates up to C / 3 (C / 20, C / 10, C / 5, C / 3), but the discharge capacity was worse at higher C rates (C / 2 and above). This indicates that the advantages of the latter rate characteristics are driven by smaller aggregate size and improved CNT distribution in the electrode.

[0300] Figure 13 shows the cycle performance tests of the same two cathodes (I1 and I2). These cathodes exhibited very similar specific discharge capacities, retaining over 95% of their initial capacity over 300 cycles. This demonstrates that smaller-sized CNT5s offer the same stable cycle performance benefits as standard CNT1 grades.

[0301] Example 10 Figure 14 shows the C-rate characteristics of cells prepared using the I1, I3, and I4 cathodes of Table 12, and although they are of different types and particle size ranges, they have the same average aggregate size for CNTs (CNT5, CNT6, and CNT7, respectively). 50 The performance of CNTs (=15μm) is compared. See Table 1. Formulation I1, containing CNT5, consistently outperformed other CNTs and showed outstanding rate characteristics. Cathodes using CNT5 and CNT6 also yielded higher capacities than cathodes using CNT7 at C rates up to C / 2, and had a larger surface area (>230m). 2 This suggests that CNTs with a small average diameter (<12nm) perform better than those with a relatively small surface area and a larger diameter.

[0302] Furthermore, as shown in Figure 15, during long-term cycles conducted at 25°C using C / 3 charge and C / 3 discharge rates, CNT5 (composition I1) performed better than CNT6 and CNT7 (compositions I3 and I4, respectively), exhibiting significantly higher discharge capacity. This is likely due to the combination of the robust mechanical properties of the dry cathode film and the improved electronic network provided by the well-distributed and interconnected CNT5.

[0303] Example 11 relatively low D 50 The use of CNTs enabled the production of thinner cathodes with lower active material content. Examples of thin cathodes are listed in Table 12 under electrode ID I5 containing 1 wt% CNT5, with a single-sided coated electrode thickness of 55 μm and an active material content of 15.4 mg / cm². 2 The amount of active material added was measured.

[0304] Figure 16 compares the 2C discharge capacities of two electrodes (ID#I1 and ID#I5), both fabricated from 1 wt% CNT5 but rolled to different thicknesses and therefore measured with different active material additions and electrode densities, as listed in Table 12. As seen in Figure 16, the 55 μm thick, single-sided coated dry cathode I5, with a lower active mass addition and higher density, exhibited a better 2C discharge capacity, twice that of the thicker, lower-density dry electrode I1.

[0305] Example 12 Three cathodes were prepared using the same dry process and tested in a 2032 full coin cell according to the same cell assembly and test protocol as dry cathodes I1-I5 in Example 9. The electrode formulations used and the properties of the resulting cathodes are shown in Table 13 below. All cathodes contained NCM622 (96 wt%) and binder (3 wt%), and an additional 1 wt% carbon additive, either CB3 alone or CB3 / CNT5 blends with two different CB / CNT ratios. A cathode containing 1 wt% CNT5 (see electrode I1 in Table 12) was used for comparison. [Table 13]

[0306] Cells in two groups (electrodes J1 and J2) whose cathode formulation contained a CB / CNT blend showed improved discharge capacity compared to a cathode (electrode J3) made with CB alone, as shown in Figure 17.

[0307] Furthermore, cycle life tests confirmed the good cycle performance of the cathode with the CB / CNT blend (composition J2, Table 13), maintaining 98% capacity retention over 150 cycles, close to that of the one with CNT alone (electrode I1, Table 12), demonstrating comparable structural and electrochemical stability for both dry cathodes (Figure 18).

[0308] While the present invention has been specifically shown and described with reference to its preferred embodiments, it will be understood by those skilled in the art that various modifications in form and detail can be made without departing from the scope of the invention as encompassed by the appended claims.

Claims

1. A method for preparing an electrode composition, The process involves combining the electrode active material, the binder, and the carbon nanotube. A step of treating the binder in the presence of the carbon nanotubes, Includes, The above method is carried out in the absence of a solvent, and the carbon nanotubes are approximately 80 to 500 m ２ Having a BET within the range of / g method.

2. The method according to claim 1, wherein the carbon nanotube is a multilayer multifunctional carbon nanotube.

3. The carbon nanotubes are approximately 200 to 500 m ２ The method according to claim 1, wherein the BET is within the range of / g.

4. The method according to claim 1, wherein the carbon nanotube has a diameter in the range of about 2 to about 50 nanometers.

5. The carbon nanotubes have an average particle size (D) measured by laser diffraction analysis to be in the range of approximately 5 to approximately 500 microns. ５０ The method according to claim 1, having ).

6. The method according to claim 1, wherein the carbon nanotubes are pre-milled as a dry powder.

7. The method according to any one of claims 1 to 6, wherein the electrode active material, the binder, the carbon nanotube, and the electrode composition are loose particulate materials.

8. The method according to any one of claims 1 to 7, wherein the electrode active material is a lithium transition metal compound.

9. The method according to any one of claims 1 to 7, wherein the electrode active material is graphite, a silicon-containing compound, or any combination thereof.

10. The method according to any one of claims 1 to 9, wherein the carbon nanotubes are provided in an amount of about 5% by weight or less based on the total weight of the electrode composition.

11. The method according to any one of claims 1 to 10, wherein the method is carried out in the presence of carbon nanotubes as the sole fibrillating agent.

12. The method according to any one of claims 1 to 10, wherein the carbon nanotube is provided in combination with another fibrillating agent.

13. The method according to any one of claims 1 to 10, wherein the carbon nanotubes are provided in combination with carbon black.

14. The aforementioned carbon black is approximately 1600 m ２ The method according to claim 13, wherein the BET is less than or equal to / g and the OAN is less than or equal to about 650 mL / 100 g.

15. The electrode active material is a lithium transition metal compound, and the carbon black is approximately 80 to approximately 1600 m ２ The method according to claim 13, wherein the BET is in the range of / g and the OAN is in the range of about 120 to about 650 mL / 100g.

16. The electrode active material is a lithium transition metal compound, and the carbon black is approximately 500 to approximately 1600 m ２ The method according to claim 13, wherein the BET is in the range of / g and the OAN is in the range of about 180 to about 650 mL / 100g.

17. The electrode active material is graphite, and the carbon black is approximately 35 to approximately 1600 m ２ The method according to claim 13, wherein the BET is in the range of / g and the OAN is in the range of about 120 to about 650 mL / 100g.

18. The electrode active material is graphite, and the carbon black is approximately 50 to approximately 200 m ２ The method according to claim 13, wherein the BET is in the range of / g and the OAN is in the range of about 130 to about 240 mL / 100g.

19. The carbon black has the following characteristics: Approximately 15 mJ / m ２ The following surface energy, a Raman crystallite planar size (La) of at least about 17 Å, a mesopore volume of at least about 0.35 cm ３ / g, a total mesopore and macropore volume of at least 1.0 cm ３ / g, and a crystallinity of at least 22% The method according to any one of claims 13 to 18, comprising one or more of the above.

20. The method according to any one of claims 13 to 19, wherein the carbon black is multifunctional.

21. The method according to any one of claims 13 to 20, wherein the weight percentage ratio of the carbon black to the carbon nanotubes is in the range of about 99:1 to about 1.

99.

22. The method according to any one of claims 13 to 20, wherein the weight percentage ratio of the carbon black to the carbon nanotubes is in the range of about 60:40 to about 10:

90.

23. The method according to any one of claims 13 to 22, wherein the method is carried out in the presence of the carbon nanotubes and the carbon black as the sole fibrillating agent.

24. The method according to any one of claims 13 to 22, wherein the method is carried out in the presence of the carbon nanotubes, the carbon black, and at least one additional fibrillating agent.

25. The method according to any one of claims 1 to 24, wherein the binder is a fibrillable binder, a non-fibrillable binder, or any combination thereof.

26. The method according to any one of claims 1 to 24, wherein the binder comprises polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), or any combination thereof.

27. The method according to any one of claims 1 to 26, wherein the step of processing the binder includes a high shear operation sufficient to fibrillate the fibrillable binder.

28. The method according to any one of claims 1 to 26, wherein the step of processing the binder includes a high shear operation sufficient to deform the non-fibrillable binder.

29. The method according to any one of claims 1 to 28, wherein the mixing operation of combining two or more components is carried out under shear conditions lower than the shear conditions used in the process of processing the binder.

30. A method further comprising the step of applying an electrode composition prepared according to any one of claims 1 to 29 to a conductive substrate to form a battery electrode.

31. A method further comprising the step of calendering an electrode composition prepared according to any one of claims 1 to 29 to form a film.

32. The method according to claim 31, wherein the film is a self-supporting film having a tensile strength of at least about 0.1 MPa and a thickness in the range of about 30 to about 500 microns.

33. The method according to claim 31 or 32, further comprising the step of applying the film to a conductive substrate to form a battery electrode.

34. A solvent-free method for preparing an electrode composition, A process of combining an electrode active material, a fibrillation-capable binder, and carbon nanotubes, The process includes the step of subjecting the fibrillable binder to a fibrillation operation in the presence of carbon nanotubes, The electrode active material, the fibrillable binder, the carbon nanotube, and the electrode composition are loose particulate materials, and The carbon nanotubes are approximately 80 to 500 m ２ Having a BET within the range of / g method.

35. The solvent-free method according to claim 34, wherein the carbon nanotubes are provided in combination with carbon black.

36. The solvent-free method according to claim 34 or 35, further comprising the step of processing the electrode composition to form a film.

37. A method for preparing an electrode composition, (a) A step of treating the binder by subjecting it to high shear conditions in the presence of carbon nanotubes, (b) A step of adding an electrode active material before, during, or after step (a), Includes, The above method is carried out without adding a solvent, and the carbon nanotubes are approximately 80 to 500 m in length. ２ Having a BET within the range of / g method.

38. The method according to claim 37, wherein the carbon nanotube is a multilayer multifunctional nanotube.

39. The carbon nanotubes are approximately 200 to 500 m ２ The method according to claim 37, wherein the BET is within the range of / g.

40. The method according to claim 37, wherein the carbon nanotube has a diameter in the range of about 2 to about 50 nanometers.

41. The carbon nanotubes have an average particle size (D) measured by laser diffraction analysis to be in the range of approximately 5 to approximately 500 microns. ５０ The method according to claim 37, having ).

42. The method according to claim 37, wherein the carbon nanotubes are pre-milled as a dry powder.

43. The method according to any one of claims 37 to 42, wherein the electrode active material, the binder, the carbon nanotube, and the electrode composition are loose particulate materials.

44. The method according to any one of claims 37 to 43, wherein the electrode active material is a lithium transition metal compound.

45. The method according to any one of claims 37 to 43, wherein the electrode active material is graphite, a silicon-containing compound, or any combination thereof.

46. The method according to any one of claims 37 to 45, wherein the carbon nanotubes are provided in an amount of about 5% by weight or less based on the total weight of the electrode composition.

47. The method according to any one of claims 37 to 46, wherein the method is carried out in the presence of the carbon nanotube as the sole fibrillating agent.

48. The method according to any one of claims 37 to 46, wherein the carbon nanotube is provided in combination with another fibrillating agent.

49. The method according to any one of claims 37 to 46, wherein the carbon nanotubes are provided in combination with carbon black.

50. The aforementioned carbon black is approximately 1600 m ２ The method according to claim 49, wherein the BET is less than or equal to / g and the OAN is less than or equal to about 650 mL / 100 g.

51. The electrode active material is a lithium transition metal compound, and the carbon black is approximately 80 to approximately 1600 m ２ The method according to claim 49, wherein the BET is in the range of / g and the OAN is in the range of about 120 to about 650 mL / 100g.

52. The electrode active material is a lithium transition metal compound, and the carbon black is approximately 500 to approximately 1600 m ２ The method according to claim 49, wherein the BET is in the range of / g and the OAN is in the range of about 180 to about 650 mL / 100g.

53. The electrode active material is graphite, and the carbon black is approximately 35 to approximately 1600 m ２ The method according to claim 49, wherein the BET is in the range of / g and the OAN is in the range of about 120 to about 650 mL / 100g.

54. The electrode active material is graphite, and the carbon black is approximately 50 to approximately 200 m ２ The method according to claim 49, wherein the BET is in the range of / g and the OAN is in the range of about 130 to about 240 mL / 100g.

55. The carbon black has the following characteristics: Approximately 15mJ / m ２ The following surface energies, Raman microcrystal plane size (La) of at least about 17 Å, and at least about 0.35 cm² are required. ３ Mesopore volume per g, at least 1.0 cm ３ Total mesopore and macropore volume per g, and a % crystallinity of at least 22%. The method according to any one of claims 49 to 54, comprising one or more of the above.

56. The method according to any one of claims 49 to 55, wherein the carbon black is multifunctional.

57. The method according to any one of claims 49 to 56, wherein the weight percentage ratio of the carbon black to the carbon nanotubes is in the range of about 99:1 to about 1.

99.

58. The method according to any one of claims 49 to 56, wherein the weight percentage ratio of the carbon black to the carbon nanotubes is in the range of about 60:40 to about 10:

90.

59. The method according to any one of claims 49 to 58, wherein the method is carried out in the presence of the carbon nanotubes and the carbon black as the sole fibrillating agent.

60. The method according to any one of claims 49 to 58, wherein the method is carried out in the presence of the carbon nanotubes, the carbon black, and at least one additional fibrillating agent.

61. The method according to any one of claims 37 to 60, wherein the binder is a fibrillable binder, a non-fibrillable binder, or any combination thereof.

62. The method according to any one of claims 37 to 60, wherein the binder comprises polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), or any combination thereof.

63. The method according to any one of claims 37 to 62, wherein the step of processing the binder includes a high shear operation sufficient to fibrillate the fibrillable binder.

64. The method according to any one of claims 37 to 62, wherein the step of processing the binder includes a high shear operation sufficient to deform the non-fibrillable binder.

65. The method according to any one of claims 37 to 64, wherein the mixing operation of combining two or more components is carried out under shear conditions lower than the shear conditions used in the process of processing the binder.

66. A method further comprising the step of applying an electrode composition prepared according to any one of claims 37 to 65 to a conductive substrate to form a battery electrode.

67. A method further comprising the step of calendering an electrode composition prepared according to any one of claims 37 to 65 to form a film.

68. The method according to claim 67, wherein the film is a self-supporting film having a tensile strength of at least about 1 MPa and a thickness in the range of about 30 to about 500 microns.

69. The method according to claim 67 or 68, further comprising applying the film to a conductive substrate to form a battery electrode.

70. A dry-processed film comprising an electrode active material, a treated binder, and carbon nanotubes, wherein, prior to any drying operation, the film electrode contains a solvent residue of 1% by weight or less relative to the theoretical weight of the film electrode, and the carbon nanotubes are approximately 80 to approximately 500 m ２ A dry-processed film having a BET within the range of / g.

71. The dry-processed film according to claim 70, wherein the dry-processed film is self-supporting or laminated on a substrate.

72. The dry-processed film according to claim 70 or 71, wherein the carbon nanotube is a multi-walled, multi-functional carbon nanotube.

73. The carbon nanotubes are approximately 200 to 500 m ２ A dry-treated film according to claim 70, having a BET in the range of / g.

74. The dry-processed film according to claim 70, wherein the carbon nanotubes have a diameter in the range of about 2 to about 50 nanometers.

75. The carbon nanotubes have an average particle size (D) measured by laser diffraction analysis to be in the range of approximately 5 to approximately 500 microns. ５０ A dry-processed film electrode according to claim 70, having the following characteristics:

76. The dry-processed film according to claim 70, wherein the carbon nanotubes are pre-milled as a dry powder.

77. The dry-processed film according to any one of claims 70 to 76, wherein the electrode active material, the binder, the carbon nanotube, and the electrode composition are particulate materials.

78. The dry-processed film according to any one of claims 70 to 77, wherein the electrode active material is a lithium transition metal compound.

79. The dry-processed film according to any one of claims 70 to 77, wherein the electrode active material is graphite, a silicon-containing compound, or any combination thereof.

80. The dry-processed film according to any one of claims 70 to 79, wherein the carbon nanotubes are present in an additive amount of about 5% by weight or less.

81. The dry-processed film according to any one of claims 70 to 81, wherein the carbon nanotube is the sole fibrillating agent.

82. The method according to any one of claims 70 to 81, wherein the carbon nanotube is provided in combination with another fibrillating agent.

83. The dry-processed film according to any one of claims 70 to 80, wherein the dry-processed film further comprises carbon black.

84. The aforementioned carbon black is approximately 1600 m ２ A dry-processed film according to claim 83, having a BET of 650 mL / 100 g or less and an OAN of approximately 650 mL / 100 g or less.

85. The electrode active material is a lithium transition metal compound, and the carbon black is approximately 80 to approximately 1600 m ２ A dry-processed film according to claim 83, having a BET in the range of / g and an OAN in the range of about 120 to about 650 mL / 100g.

86. The electrode active material is a lithium transition metal compound, and the carbon black is approximately 500 to approximately 1600 m ２ A dry-processed film according to claim 83, having a BET in the range of / g and an OAN in the range of about 180 to about 650 mL / 100g.

87. The electrode active material is graphite, and the carbon black is approximately 35 to approximately 1600 m ２ A dry-processed film according to claim 83, having a BET in the range of / g and an OAN in the range of about 120 to about 650 mL / 100g.

88. The electrode active material is graphite, and the carbon black is approximately 50 to approximately 200 m ２ A dry-processed film according to claim 83, having a BET in the range of / g and an OAN in the range of about 130 to about 240 mL / 100g.

89. The carbon black has the following characteristics: Approximately 15mJ / m ２ The following surface energies, Raman microcrystal plane size (La) of at least about 17 Å, and at least about 0.35 cm² are required. ３ Mesopore volume per g, at least 1.0 cm ３ Total mesopore and macropore volume per g, and a % crystallinity of at least 22%. A dry-processed film according to any one of claims 83 to 88, having one or more of the above.

90. The dry-processed film according to any one of claims 83 to 89, wherein the carbon black is multifunctional.

91. The dry-processed film according to any one of claims 83 to 90, wherein the weight percentage ratio of the carbon black to the carbon nanotubes is in the range of about 99:1 to about 1.

99.

92. The dry-processed film according to any one of claims 83 to 90, wherein the weight percentage ratio of the carbon black to the carbon nanotubes is in the range of about 60:40 to about 10:

90.

93. The dry-processed film according to any one of claims 70 to 92, wherein the binder is a fibrillable binder, a non-fibrillable binder, or any combination thereof.

94. The dry-processed film according to any one of claims 70 to 92, wherein the binder comprises polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), or any combination thereof.

95. The dry-processed film according to any one of claims 70 to 94, wherein the film is a self-supporting film and has a tensile strength of at least about 0.1 MPa and a thickness in the range of about 30 to about 500 microns.

96. An electrode comprising a dry-processed film according to any one of claims 70 to 95.

97. The electrode according to claim 96, wherein the dry-treated film is applied to a substrate.

98. A battery comprising the electrode described in claim 96 or 97.

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