Solvent-free process for preparing lithium-ion batteries

Abstract

The solventless process uses multifunctional carbon black to prepare compositions and electrodes for lithium ion batteries. The multifunctional carbon black provides two or more desirable properties, for example, acts as a conductive carbon additive, a fibrillating agent, and / or a mechanical reinforcement. In one example, an electroactive material, for example, graphite or a lithium transition metal compound, a binder, and a multifunctional carbon black are combined in one or more steps. High shear mixing is used to process the binder in the presence of the multifunctional carbon black. The resulting composition can be formed into a film that can be applied onto a suitable substrate to produce an electrode.

Description

[Technical field]

[0001] Government support This invention was made with Government support under Grant No. DE-EE0009109.0000 awarded by the Office of Energy Efficiency and Renewable Energy (EERE) of the U.S. Department of Energy. The Government has certain rights in this invention.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 63 / 322,074, filed March 21, 2022, the entire disclosure of which is incorporated herein by reference. [Background technology]

[0003] Lithium-ion batteries (LIBs) are commonly used as a source of electrical energy for a multitude of applications, ranging from electronic devices to electric vehicles. Lithium-ion batteries typically contain a negative electrode and a positive electrode in an arrangement 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 allows the movement of ions. To prevent direct reaction between the electrodes, a separator is used to physically and electrically insulate the electrodes. 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 anodes that contain 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. Other anode materials that are used in addition to or instead of graphite include lithium titanate, tin oxide, silicon (Si), and SiO x (x is typically 1.04, 1.06, etc.).

[0005] The cathode typically comprises a conductive substrate carrying a mixture containing at least an electrochemically active material and a binder. The electroactive material, such as a lithium transition metal oxide, is capable of accepting and releasing lithium ions. As with the anode, a binder is used to provide mechanical integrity and stability to the electrode.

[0006] The electroactive materials and binders often exhibit poor electrical conductivity or even insulating properties, and the cathodes often contain additive components that increase the electrical conductivity of the electrode. Conductive additives, such as carbon conductive additives, can also be present in LIB anode compositions.

[0007] In manufacturing electrodes, the active electrode material, e.g., 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 binders, but also solvents, plasticizers, conductive additives, etc. During manufacturing, the slurry is coated or extruded onto a conductive substrate. The solvent is removed by drying, as it is detrimental to the final product.

[0008] However, drying operations, especially those aimed at removing the solvent, are time consuming and slow down the overall manufacturing process. They can also pose cost as well as environmental problems, typically due to the toxicity of the solvent, e.g., NMP. With respect to the final product, removal of the solvent during the drying process often results in migration of the binder to the surface of the electrode. Minimal migration may be acceptable in some cases, but problematic in others. For example, high loading (thick, >4.5 mAh / cm2) can result in significant cost savings. 2 ) electrodes, migration worsens, leading to delamination and poor electrode performance.

[0009] As a result, "dry" alternatives have been developed that aim to reduce or eliminate the drying steps associated with slurry technology. Dry processes also produce electrodes that typically contain electroactive materials, binders, and conductive additive components, but do not require the use of solvents.

[0010] Dry techniques that have been proposed include high shear mixing with fibrillizable binders, use of sacrificial binders that are removed during processing of the electrode, dry powder spraying, electrostatic spray deposition, low temperature plasma deposition, sputtering deposition, powder printing, to name a few. In some embodiments, a fibrillation-promoting agent is incorporated into the binder and the resulting formulation is subjected to high shear mixing to fibrillate the binder, thereby producing a web-like structure that better holds the material and can carry 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 shell, 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 ground to a particle size of tens of microns (μm) before activation. Summary of the Invention

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

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

[0014] State-of-the-art fibrillation agents such as AC often contain high impurity levels. Also, 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 reduce battery performance. Furthermore, AC cannot impart sufficient electrical conductivity, necessitating increased amounts of conductive additives in the overall formulation. Even as a simple fibrillation promoter, AC often requires relatively high loadings (often 5-10 wt%), which also in itself limits the amount of active material that can be included.

[0015] Thus, there is a need for compositions and processes that address at least some of the problems associated with existing approaches.

[0016] Broadly, the present invention relates to the use of certain carbon blacks to provide needed improvements in manufacturing methods, product electrodes and / or assembled batteries. More specifically, the present invention relates to the use of these materials during dry or solventless electrode manufacturing processes.

[0017] Carbon blacks can have selected morphologies and / or surface chemistries to serve more than one function during dry (solvent-free) electrode manufacturing processes. For example, the multifunctional carbon blacks described herein can act as fibrillating agents, AC replacements, conductive carbon additives, and / or mechanical reinforcements (or, in other words, as bonding aids, adding mechanical strength and flexibility to the finished electrode).

[0018] In general, a "multifunctional" carbon black (CB) can be defined as a CB that effectively deforms or fibrillates binders used in solventless processes, contributes to the electronic / ionic conductivity of the electrode, and / or provides a mechanical benefit. In certain implementations, a multifunctional CB can be considered capable of fibrillating a fibrillizable binder at loadings of 5 weight percent (wt%) or less. At this loading, the multifunctional CB also acts as a carbon conductive additive and reduces the in-plane resistivity of the electrode. In many cases, mechanical benefits are also obtained.

[0019] In most dry processes, the multifunctional CB is approximately 1600m 2 / g or less BET, for example, about 35 to about 1600m 2 / g and an OAN of about 650 mL / 100 g or less, for example, an OAN in the range of 120 to about 650 mL / 100 g.

[0020] Other desirable CB attributes include high surface roughness (with macroporosity close to the particle surface), good electronic conductivity (0.5 g / cm 3 Examples of the powders include those having a powder resistivity of about 1.0 Ω cm or less, measured at a pressed density of 1.0 Ω cm or less.

[0021] In addition to the BET and OAN properties mentioned above, many multifunctional CBs that can be utilized have the following properties: 2 Surface energy of at least about 17 Å, Raman crystallite plane size (La) of at least about 0.1 cm 3 / g mesopore volume and at least about 0.2 cm3 The total mesopore and macropore volume, characterized by one or more of a macropore volume of at least about 1 cm3 / g, 3 / g.

[0022] For some anode applications, the solventless process requires about 35 to about 1600 m 2 / g, for example, about 55 to about 200 m 2 In a further example, a CB is used having a BET in the range of about 15 mJ / m2 / g and an OAN in the range of about 120 to about 650 mL / 100 g, for example about 130 to about 240 mL / 100 g. 2 0.1 cm 3 / g (for example, about 0.1 to about 0.25 cm 3 ) Raman microcrystal plane size (L a ), and at least about 0.1 cm 3 / g (for example, about 0.1 to about 0.4 cm 3 / g), and a total mesopore volume of at least about 0.2 cm 3 / g (for example, about 0.2 to about 0.8 cm 3 / g).

[0023] In some cathode applications, the solventless process may be performed at a temperature of from about 35 to about 1600, e.g., from about 500 to about 1600 m 2 In a further example, the carbon black employed has a BET in the range of about 15 mJ / m2 / g and an OAN in the range of about 120 to about 650 mL / 100 g, e.g., about 250 to about 650 mL / 100 g. In a further example, the CB has the following properties: 2 surface energy of at least about 17 Å, and a Raman crystallite plane size (L a ), at least about 0.1 cm 3 / g (e.g., at least about 0.35 cm 3 / g) and a mesopore volume of at least about 0.2 cm 3 / g (e.g., at least about 0.4 cm 3 / g) macropore volume. The total mesopore and macropore volume is at least about 1 cm 3 / g.

[0024] In many embodiments, the methods described herein are carried out without the addition of any liquids (typically any solvents).The ingredients are provided as loose particulate materials such as flowable or pourable powders, flakes, beads, granules, pellets, and the like.

[0025] However, in some cases, it is possible to use small amounts of liquid (e.g., solvent) to carry out the methods described herein, typically steps other than the fibrillation step. Generally, when liquid is added, the amount used is about 10% by weight or less of the total amount of ingredients used. In many situations, the liquid, e.g., solvent, is added in an amount of 1% by weight or less.

[0026] One aspect of the invention features a method of preparing an electrode composition. The method includes combining an active electrode material, a binder, and a multifunctional carbon black, such as a multifunctional carbon black described herein, and treating the binder in the presence of the multifunctional carbon black. Many implementations of the method are performed without the addition of a liquid, typically a solvent.

[0027] In general, the binder can be any semi-crystalline polymer. Thus, the method can be practiced with binders that are traditionally considered "fibrillizable," as well as binders that are traditionally considered "non-fibrillizable." Combinations of these can also be utilized.

[0028] In one example, a method for preparing an electrode composition includes mixing an active electrode material, a fibrillizable binder, and a multifunctional carbon black, e.g., about 1600 m 2 / g or less and an OAN of about 650 mL / 100 g or less, and subjecting the binder to a fibrillation operation in the presence of multifunctional carbon black.

[0029] Another aspect of the invention features a method of preparing an electrode composition. The method includes treating a binder (e.g., subjecting the binder to high shear conditions) in the presence of a multifunctional carbon black having the properties described above, and adding an active electrode material before, during, or after binder treatment. The binder can be a fibrillizable binder, a non-fibrillizable binder, or any combination thereof.

[0030] In certain embodiments, the method described herein is carried out without adding any fibrillation aid other than the multifunctional carbon. In such cases, the carbon black used provides the entire binder treatment (e.g., fibrillation) function, completely replacing a conventional fibrillation agent such as, for example, activated carbon. In addition to using a binder treatment (e.g., fibrillation) component consisting of a multifunctional carbon black as described herein, it is also possible to use a binder treatment component consisting essentially of or including a multifunctional carbon black. Thus, in some examples, the multifunctional carbon black is used in combination with various amounts of a conventional fibrillation aid, such as activated carbon. It is also possible to combine the multifunctional CB with another multifunctional CB and / or a conventional conductive carbon additive (CCA).

[0031] The electroactive material, binder, e.g., fibrillizable binder, and multifunctional CB can be combined in a single step, with the binder treatment, e.g., fibrillation operation, occurring thereafter. In other embodiments, the components are combined sequentially. For example, the binder is first treated, e.g., fibrillated, in the presence of the multifunctional additive, and mixed with the electroactive material after this step. Other sequences are possible. A uniform distribution of the components can be obtained using (often milder) conditions than those utilized in the binder treatment, e.g., fibrillation. Low shear mixing techniques can also prevent particle fragmentation and maintain particle size.

[0032] The resulting electrode composition, typically a loose particulate material such as a flowable powder containing the electroactive material, the treated (e.g., fibrillated) binder, the multifunctional CB, and optionally other ingredients, can be further processed. For example, the composition can be formed into a free-standing film that can be applied to a conductive substrate or support to form an electrode. In one approach, the composition is calendered and laminated to a conductive foil substrate. The calendering operation can be performed at room temperature or above, e.g., at a temperature similar to or close to the glass transition temperature of the polymer. The lamination step can be performed while or after the composition is calendered. The resulting product electrodes can be assembled into a LIB battery in which one or both electrodes are prepared by a solventless process. In one example, both electrodes are prepared according to the techniques described herein.

[0033] In a further aspect, the invention features a dry processed film that includes an active electrode material, a binder that is typically processed, e.g., fibrillated, and a multifunctional carbon black. Prior to any drying operation, the dry processed film has a weight that is the same as or within 1% by weight of its theoretical weight. The multifunctional carbon black has a theoretical weight of about 1600 m 2 / g or less and an OAN of about 650 mL / 100 g or less. In some examples, the multifunctional carbon black also has a BET of about 15 mJ / m 2 Surface energy of at least 17 Å, Raman crystallite plane size (La) of at least 0.35 cm 3 and a mesopore volume of at least 0.2 cm 3 / g macropore volume. The total mesopore and micropore volume is at least about 1 cm 3 / g.

[0034] In one embodiment, electrodes prepared by the techniques described herein have an in-plane resistivity equal to or less than that characterizing a reference electrode prepared using AC.

[0035] Implementing embodiments of the present invention has many advantages. Using multifunctional CBs can, for example, reduce the amount of binders and / or traditional processing additives required in the manufacturing process, increasing the potential loading by the active material, resulting in higher energy density electrodes and therefore batteries. The approach described herein can reduce or eliminate the need for AC. In many cases, less additive is needed, increasing the available content allowed for the active electrode material, resulting in batteries with higher energy density and longer life. The CB multifunctional additive can improve the fibrillation of the binder and the material distribution throughout the electrode. Improved adhesion and mechanical stability represent yet other potential advantages. Dry-processed electrodes prepared using the carbon blacks described herein exhibit good charge transfer. The reduction in electrode impedance expected with the multifunctional CB additive can improve cell rate capacity and charging performance, opening opportunities for higher energy density batteries with thicker electrodes and fast charging capabilities.

[0036] While the phenomenon of binder migration is often observed with slurry prepared electrodes, the process and compositions described herein appear to result in a uniform distribution throughout the electrode. The fibrillated binder holds the electroactive particles (along with the conductive additive) together (cohesion) while keeping the electrode film layer attached to the metal substrate (adhesion).

[0037] The solventless technology described herein reduces or eliminates the use of harmful solvents such as N-methyl-2-pyrrolidone (NMP). The ability to bypass the drying steps associated with slurries (or other "wet" processes) can simplify and speed up manufacturing and reduce the footprint of electrode production lines. These benefits, as well as reducing or eliminating the need for solvent recycling or emissions reduction measures, can contribute to overall cost savings.

[0038] In some embodiments, the dry process can be carried out using binders not traditionally considered to be fibrillizable binders, thus expanding manufacturing options.

[0039] The above and other features and advantages of the present invention, including various details of construction and combination of parts, will be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular methods and apparatus for carrying out the invention are illustrative and not limiting of the invention. The principles and features of the invention can be employed in various and numerous embodiments without departing from the scope of the invention.

[0040] In the accompanying drawings, reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale. Instead, emphasis is placed upon illustrating the principles of the invention. The drawings are as follows: [Brief description of the drawings]

[0041] [Figure 1A] 1 shows SEM images (low and high magnification) of the cross section of a reference (comparison) electrode prepared by a dry process using activated carbon (AC). [Figure 1B] 1 shows SEM images (low and high magnification) of the cross section of a reference (comparison) electrode prepared by a dry process using activated carbon (AC). [Figure 1C] FIG. 1B is an elemental fluorine map across the electrode of FIG. 1A. [Figure 1D] 13A-13C are SEM images (low and high magnification) of the cross section of an electrode prepared by a dry process using unmodified CB additive. [Figure 1E] 13A-13C are SEM images (low and high magnification) of the cross section of an electrode prepared by a dry process using unmodified CB additive. [Figure 1F] FIG. 1D is an elemental fluorine map across the electrode of FIG. [Figure 1G]SEM images (low and high magnification) of the cross section of an electrode prepared by a dry process, where the CB used was a heat-treated version of the CB in Figures 1C and 1D. [Figure 1H] SEM images (low and high magnification) of the cross section of an electrode prepared by a dry process, where the CB used was a heat-treated version of the CB in Figures 1C and 1D. [Figure 1I] FIG. 1C is an elemental fluorine map across the electrode of FIG. 1G. [Diagram 2] Figures 1A and 1B (reference) show the in-plane resistivity of the electrodes, Figures 1D and 1E (unmodified CB), and Figures 1G and 1H (heat-treated CB). [Diagram 3] The tensile strength and in-plane resistivity of free-standing graphite electrode films are compared for a reference graphite electrode prepared by a dry process using activated carbon and graphite electrodes prepared by a dry process using several CB specifications classified by BET surface area parameters. [Figure 4] The tensile strength and modulus are compared for a reference free-standing NCM electrode film prepared by a dry process using activated carbon and NCM electrode films prepared by a dry process using several CB specifications at a loading of 5 wt% in the formulation. [Diagram 5] The tensile strength and modulus are compared for free-standing NCM electrode films prepared by a dry process using several CB specifications at 2 wt % loading in the formulation. [Figure 6] The in-plane resistivity of a reference NCM electrode prepared by a dry process using activated carbon and NCM electrodes prepared by a dry process using selected CBs are compared. [Figure 7] The tensile strength and modulus are compared for free-standing NCM electrode films prepared by a dry process using the CB specification at 1 wt % loading in the formulation where the CB material is in fluffy and pelletized form. [Figure 8]1 is a plot showing the 0.2C, 0.5C, 1C, 2C, and 3C discharge capacity of a full coin cell with an NCM622 cathode using a conductive additive disclosed herein. [Figure 9] 1 is a plot showing the C / 20 discharge capacity of a full cell with an NCM622 cathode using a conductive additive disclosed herein. [Figure 10] 1 is a plot showing the first cycle irreversible capacity of a full in cell with an NCM622 cathode using a conductive additive disclosed herein. [Figure 11] 1 is a plot showing the discharge capacity cycling of a half coin cell having an NCM622 cathode using a conductive additive disclosed herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] The present invention will now be described in more detail with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments of the invention set forth herein, but rather these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0043] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Also, all conjunctions used should be understood in the most inclusive sense possible. Thus, the word "or" should be understood as having the definition of "or" logic and not the definition of "exclusive or" logic, unless the context clearly requires otherwise. Furthermore, the singular forms and articles "a", "an" and "the" are intended to include the plural forms unless otherwise indicated. It will be further understood that the terms "includes", "comprises", "including" and / or "comprising", as used herein, specify the presence of at least one of the stated features, integers, steps, operations, elements and components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. Furthermore, when an element, including a component or subsystem, is referred to and / or shown as being connected or coupled to another element, it will be understood that it may be directly connected or coupled to the other element or intervening elements may be present.

[0044] Terms such as "first", "second", etc. are used to describe various components, but these components should not be limited by these terms. These terms are used only to distinguish one element from another. Thus, an element described below may be referred to as a second element, and similarly, the second element may be referred to as a first element without departing from the teachings of the present invention.

[0045] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this invention belongs. Terms as defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and it will be further understood that they are not to be interpreted in an idealized or overly formal sense unless expressly defined in this specification.

[0046] The present invention relates generally to the manufacture of electrodes for electrochemical cells, often for batteries such as LIBs. In one example, the batteries of interest are rechargeable LIBs.

[0047] Typically, LIB batteries are named according to the acronym of the electroactive material, often the intercalation compound, used to form the cathode. The embodiments described herein can be implemented or adapted with various types of lithium ion batteries currently known in the art (such as LCO, LMO, NCM, NCA, LCP, LFP, LFMP, LFSF, or LTS, to name a few) or future developed LIBs.

[0048] Many electrode manufacturing techniques for electrochemical cell applications involve the formation of an electrode (anode or cathode) composition that can be applied (coated, extruded, laminated, etc.) onto a conductive substrate. In the composition, the active electrode materials are mixed (blended) with a binder (e.g., polymer, resin, etc.), which serves to associate and hold the active materials together. Often a liquid is included that is used to dissolve or carry the binder material, plasticizers, and / or other additives.

[0049] Generally, in conventional solvent-based processes, the polymer binder and other ingredients are mixed with a suitable liquid to form a slurry, which can then be applied onto a substrate. The typical amount of liquid used is at least about 40% based on the total weight of the ingredients used. Many wet processes require more solvent. As the solvent is removed (e.g., during drying), the binder becomes increasingly tacky and adheres to the existing particles and / or substrate.

[0050] In contrast to slurry-based techniques, the embodiments described herein include a "solventless" process, also referred to as a "dry" process. In this solventless approach, some, typically all, of the components required to prepare the electrode composition (e.g., active materials, binders, additives, etc.) are provided as loose particulate materials, such as, for example, free-flowing powders, flakes, pellets, beads, etc. The embodiments described herein can 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. Subjecting the binder to certain shear conditions can, for example, result in deformation of the binder, such as, for example, binder elongation, formation of binder strands, entanglement, etc. For some types of binders, this is referred to as binder "fibrillation."

[0051] In many embodiments of the invention, the components are combined and the binder is processed, e.g., fibrillated, without the addition of a liquid, e.g., a solvent.

[0052] Most embodiments are carried out without the addition of liquid and include a completely solvent-free process, but in some cases, a small amount of liquid, e.g., a solvent, can be used to wet at least a portion of the particles to be mixed, for example. This can occur, for example, when forming a preblend, which is then completely dried before performing a subsequent operation. In one embodiment, any solvent used to form the preblend or the like is removed, for example, by drying, before the binder is transformed. The binder processing (e.g., fibrillation) is then carried out under completely solvent-free conditions with the liberated, free-flowing, or pourable particles.

[0053] Suitable solvents can be selected from those typically encountered in LIB manufacturing, including, but not limited to, N-methylpyrrolidone (NMP), acetone, alcohol, and water. The solvent can be removed by standard drying techniques. It is expected that such low solvent levels can be completely or nearly completely removed.

[0054] In many applications, the amount of solvent used is about 1% or less by weight of the total product electrode composition (e.g., a composition containing the electroactive material that has been treated, such as fibrillated, the binder and other components, additive components, etc.), and often less than 1% by weight. In illustrative examples, the amount of solvent used is in the range of about 0 to up to 1% by weight, such as about 0 to about 0.2, to about 0.4, to about 0.6, to about 0.8, or about 0.2 to about 0.4, to about 0.6, to about 0.8, to about 1% by weight, or about 0.2 to about 0.4, to about 0.6, to about 0.8, to about 1% by weight, or about 0.4 to about 0.6, to about 0.8, to about 1% by weight, or about 0.6 to about 0.8, to about 1.0% by weight, or about 0.8 to about 1% by weight, based on the total weight of the components used.

[0055] In other situations, the solvent can be added in an amount in the range of about 0 to about 10% by weight, such as about 0 to about 2, to about 4, to about 6 to about 8% by weight, or about 2 to about 4, to about 6, to about 8, to about 10% by weight, or about 4 to about 6, to about 8, to about 10% by weight, or about 6 to about 8, to about 10% by weight, or about 8 to about 10% by weight.

[0056] Although the components can be mixed and the binder processed, e.g., fibrillated, entirely in the absence of solvent, some electrode manufacturing schemes use small amounts of solvent in post operations (operations performed after the dry electrode composition is formed) to "wet" the product film, e.g., during calendering. Such processes are also referred to herein as "dry" processes.

[0057] Finished products prepared by the solventless or dry processes described herein, such as electrodes, free-standing films, or films laminated onto current collectors, can be recognized by the absence of detectable processing solvents or processing solvent residues. In contrast, products obtained by wet (slurry) techniques typically contain detectable processing solvents and / or processing solvent residues. In a different approach, electrode products or films prepared according to embodiments of the present invention are expected to show uniform or substantially uniform binder distribution throughout the thickness of the electrode or film. Generally, less uniformity is observed with wet techniques, which often results in migration of the binder to the film surface.

[0058] In terms of the components used, the solventless process described herein includes an electroactive component (a material or combination of materials that participates in the electrochemical charge / discharge reaction of the electrochemical cell, such as by absorbing or desorbing lithium), a binder, which may be a fibrillizable or non-fibrillizable binder, and a multifunctional carbon black (CB). In some cases, additional components may be included.

[0059] For many LIB anodes, the electroactive material (also referred to herein as the "active electrode material" or simply the "active material" or "AM") is graphite, e.g., natural graphite, artificial graphite (e.g., agglomerated artificial graphite (MAG)), or a blend of both. Mesocarbon microbeads (MCMB), mesophase pitch-based carbon fibers (MCF), vapor grown carbon fibers (VGCF) can also be used. In other embodiments, the active anode compound is, for example, silicon-graphite composite, graphite-containing nanosilicon (Si) or SiO x The material may comprise, consist essentially of, or consist of silicon, such as particles.

[0060] The principles described herein can also be used with other active anode materials, e.g., those known or currently being investigated, or those developed in the future. Examples include, but are not limited to: (a) intercalation / deintercalation materials (e.g., carbon-based materials, porous carbon, graphene, TiO2, Li4Ti5O 12 etc.), (b) alloyed / de-alloyed materials (e.g., Si, SiO x , doped Si, Ge, Sn, Al, Bi, SnO2, etc.), (c) conversion materials (e.g., transition metal oxides (Mn x O y , NiO, Fe x O y , CuO, Cu2O, MoO2, etc.), formula M x X y (wherein X=S, P, N) are metal sulfides, metal phosphides, and metal nitrides.

[0061] The amount of active anode material can vary depending on the particular type of energy storage device. In an illustrative example, the amount of active anode material (e.g., graphite) is at least 80% by weight, e.g., at least 85, at least 90, at least 95, or at least 99% by weight, based on the total weight of the (dry) electrode composition. The anode active material, e.g., graphite, can be provided in an amount of about 80 to about 85, 90, 93, 96, 99% by weight, or about 85 to about 90, 93, 96, 99% by weight, or about 90 to about 93, 96, 99% by weight, or about 93 to about 96, 99% by weight, or about 96 to about 99% by weight.

[0062] Dry processes for preparing LIB cathodes can use LCO (lithium cobalt oxide), LMO (lithium manganese oxide), NCM (lithium nickel cobalt manganese oxide), NCA (lithium nickel cobalt aluminum oxide), LCP (lithium cobalt phosphate), LFP (lithium iron phosphate), LMFP (lithium iron manganese phosphate), LFSF (lithium iron fluorosulfate), LTS (lithium titanium sulfide). Materials such as these are generally referred to herein as "lithium transition metal compounds", e.g., "lithium transition metal oxides". For example, in addition to cathode materials based on insertion chemistry, which typically involve a chemical reaction that transfers one electron, other types of cathode materials (e.g., having lithium ions inserted into FeF3) can transfer multiple electrons via a more complex mechanism, called a conversion reaction. Other active cathode materials known in the art or developed in the future can be used.

[0063] In some embodiments, the dry processes described herein utilize NCM (also referred to as "NMC") or NCA cathode compositions. These materials are generally known to those skilled in the art. Additionally, many commercially available battery grade formulations (such as, for example, NCM 622) are available in powder form.

[0064] More specifically, the NCM has the formula Li 1+x Ni y Co1-y-z Mn z1-x O2, where x is in the range of 0 to 1, y is in the range of 0 to 1 (e.g., 0.3 to 0.8), and z is in the range of 0 to 1 (e.g., 0.1 to 0.3). Examples of NCMs 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 Li1+x(Ni0.9C0.05Mn0.05)1-xO2.

[0065] NCA is a compound represented by the formula Li 1+x Ni y Co 1-y-z Al z1-xO2, where x ranges from 0 to 1, y ranges from 0 to 1, and z ranges from 0 to 1. An example of an NCA is Li 1+x (Ni 0.8 Co 0.15 Al 0.05 ) 1-x It's O2.

[0066] The amount of electroactive cathode material used can vary depending on the particular type of energy storage device. In illustrative examples, the amount of NCM or NCA is at least 90% by weight, e.g., at least 93%, at least 96%, at least 98%, or at least 99% by weight, based on the total weight of the (dry) electrode composition. The NCM or NCA can be provided in an amount of about 90 to about 93, 96, 99% by weight, or about 93 to about 96, 99% by weight, or about 96 to about 99% by weight.

[0067] In addition to the active materials, the dry processes described herein employ a binder, which generally can be any semi-crystalline polymer.

[0068] In some embodiments, the binder is a fibrillizable binder. The fibrillizable binder can be provided in a binder component that consists of, consists essentially of, or comprises the fibrillizable binder.

[0069] Under certain processing conditions, e.g., high shear mixing in the presence of a fibrillating agent, fibrillizable binders can generate fibrils, forming a network that can connect and support other particles present in the formulation. More specifically, it is believed that the fibrillization of the binder generates a matrix, lattice, or web of fibrils that impart mechanical structure to the electrode. In the product electrode, the fibrillated binder can be detected in SEM images that show the presence of fibrils wrapped around at least some of the particles (e.g., active material particles) present. 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. EDX allows mapping of elemental fluorine distribution throughout a dried electrode and assessing the effectiveness of binder fibrillation. Powder rheology measures the cohesive interactions between particles in a free-flowing electrode powder mixture, and tensile strength testing measures the strength of a free-standing electrode film, both of which are indicative of the degree of binder fibrillation. In some cases, poor or no fibrillation can be inferred for dry product electrode films that crumble or peel off from the substrate.

[0070] In some embodiments, the fibrillizable binder is a fibrillizable fluoropolymer, such as polytetrafluoroethylene or PTFE. Other binders that may be considered to be fibrillizable include, but are not limited to, ultra-high molecular weight polypropylene, polyethylene, and copolymers, and any combination thereof.

[0071] The fibrillizable binder (either alone or as a component of a binder component (e.g., in a polymer blend)) can be provided in an amount of about 1 to about 10 wt%, such as about 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10 wt%. In one example, the fibrillizable binder is provided in an amount of about 5 wt%. In other examples, the fibrillizable binder is provided in an amount within the range of about 1 to about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9 weight percent, or about 2 to about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10 weight percent, or about 3 to: about 4, about 5, about 6, about 7, about 8, about 9, about 10 weight percent, or about 4 to about 5, about 6, about 7, about 8, about 9, about 10 weight percent, or about 5 to: about 6, about 7, about 8, about 9, about 10, or about 6 to about 7, about 8, about 9, about 10 weight percent, or about 7 to about 8, about 9, about 10 weight percent, or about 8 to about 9, about 10 weight percent.

[0072] However, not all situations use fibrillizable binders. Thus, some embodiments of the present invention use binder components that consist of, consist essentially of, or include one or more non-fibrillizable binders. As used herein, the term "non-fibrillizable" binder refers to a binder that is difficult to fibrillize under the same conditions sufficient to fibrillize a "fibrillizable" binder. Nevertheless, even if complete fibrillization is not achieved, by carrying out aspects of the present invention (under the same or substantially the same processing conditions as used for the fibrillizable counterpart), the non-fibrillizable binder can be deformed, often to a significant extent, for example, by stretching, elongating, entangling, etc.

[0073] Without wishing to be bound by any particular interpretation or mechanism, it is believed that fibrillation may be considered an extreme phenomenon in which the binder polymer (which may start as a colloidal particle) is stretched very thin to form very long (high aspect ratio) strands (ribbons) that can bridge across more than two electroactive particles, thereby holding them together. By practicing the embodiments described herein, non-fibrillated binders can also be stretched (elongated) and / or entangled, forming CB-binder complexes, and / or coated with CB. Even if not fully fibrillated, such "treated" non-fibrillizable binders can still function as adhesives, connecting and bonding electroactive particles, providing connectivity of the electroactive particles and adhesion to the current collector. Deformation of non-fibrillizable binders can be observed by at least some of the techniques described above.

[0074] In one example, the 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, cellulose derivatives, and the like. Other possible non-fibrillable binders include polyethylene and polypropylene other than ultra-high molecular weight, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), and fluororubbers, as well as copolymers and mixtures thereof. In one example, the non-fibrillable binder is a cellulose ester, cellulose ether, cellulose nitrate, carboxyalkyl cellulose, cellulose salts, and cellulose salt derivatives. In some embodiments, the non-fibrillizable binder of the microparticles is selected from at least one of cellulose, cellulose acetate, methyl cellulose, ethyl cellulose, hydroxypropyl cellulose (HPC), hydroxyethyl cellulose (HEC), cellulose nitrate, carboxymethyl cellulose (CMC), carboxyethyl cellulose, carboxypropyl cellulose, carboxyisopropyl cellulose, sodium cellulose, sodium cellulose nitrate, and sodium carboxyalkyl cellulose. Another example uses a combination of a non-fibrillizable binder, such as PVDF, and a non-fibrillizable binder, such as PTFE.

[0075] The amount of non-fibrillizable binder that can be used is the same or equivalent to the amount used for the fibrillizable binder. Other suitable amounts can be determined, for example, by routine experimentation.

[0076] A fibrillizable binder may also be used in combination with a non-fibrillizable binder.

[0077] Electrode compositions usually include ingredients such as conductive additives (e.g., conductive carbon additives or CCA), plasticizers, etc. For solventless processes, common techniques also require a binder fibrillation (also known as "fibrillation") agent or aid, typically AC.

[0078] It has been discovered that traditional fibrillation additives (e.g., AC) can be supplemented and in many cases completely replaced by CB materials that offer multiple advantages. For example, certain carbon blacks can act as binder fibrillation (or, in some cases, binder deformation) agents, as conductive additives (creating a conductive network, e.g., long-range electrical conductivity in an electrode), and as mechanical strengthening aids (imparting mechanical support, stability, and / or flexibility to electrode products, often coatings, layers, or films that are typically applied onto conductive substrates to form battery electrodes).

[0079] Generally, CB is a material that exists in the form of aggregates, the aggregates being 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, e.g., about 10 nm to about 15 nm, 10 nm to about 20 nm, 10 nm to about 25 nm, 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 in the art as CB "particles" (not to be confused with the "primary particles" mentioned above).

[0080] Many types of CBs are produced in furnace reactors by pyrolysis of a hydrocarbon feedstock (FS) with hot combustion gases to produce combustion products containing particulate CBs. The properties of a given CB often depend on the production conditions and can be changed or modified by, for example, changes in temperature, pressure, FS, residence time, quench temperature, throughput, and / or other parameters.

[0081] As known in the art, CBs can be described by certain properties determined according to procedures, often standardized protocols, well known in the art. For example, CBs can be characterized by their Brunauer-Emmett-Teller (BET) surface area, measured, for example, according to ASTM D6556-10, their oil adsorption number (OAN), determined, for example, according to ASTM D 2414-16, their statistical thickness surface area (STSA), a property that can be determined by ASTM D 6556-10.

[0082] For a given CB, it may also be important in some cases to specify the ratio of its STSA to its BET surface area (STSA:BET ratio).

[0083] The crystalline domains of CB are determined by Raman spectroscopy. a It can be characterized by its crystallite size. a is defined as 43.5 × (area of ​​G band / area of ​​D band). The crystallite size can give an indication of the degree of graphitization, and the higher the L a The L value correlates with a higher degree of graphitization. a The Raman measurements of carbon blacks are 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 has a band around 1340 cm, which are designated as the "D" and "G" bands, respectively. -1 and 1580cm -1 In general, the D band is the disordered sp 2 Due to carbon, the G band is a graphitic or "ordered" sp 2 It is believed to be due to carbon. Using an empirical approach, the ratio of the G / D bands and the L measured by X-ray diffraction (XRD) a are highly correlated and regression analysis gives the following empirical relationship: La = 43.5 × (area of ​​G band / area of ​​D band) In the formula, L a is calculated in angstroms. Therefore, the higher L a The higher values ​​correspond to more ordered crystal structures.

[0084] The crystalline domain is L c It can be characterized by its crystallite size. c The 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 45 kV, and a tube current of 40 mA. A sample of carbon black particles was loaded into a sample holder (included with the diffractometer) and measurements were performed over an angle (2θ) range of 10° to 80° at a rate of 0.14° / min. Peak positions and full width at half maximum values ​​were calculated using the diffractometer software. For measurement angle calibration, lanthanum hexaboride (LaB6) was used as an X-ray standard. From the measurements obtained, Scherrer's formula: L c (Å)=K * λ / (β * cosθ) to L c Determine the crystallite size, where K is the shape factor constant (0.9) and λ is CuK α1 is the wavelength of the characteristic X-rays (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).

[0085] 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 (e.g., as described in U.S. Pat. No. 10,886,535 (B2), issued to Korchev et al. on January 5, 2021, and incorporated herein by reference).

[0086] The average pore diameter and pore volume can be determined according to the technique described in EP Barrett, LG Joyner, PP Halenda, J. Am. Chem. Soc. 1951, 73, 373-380 (BJH method).

[0087] Other techniques that can be used to study 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 nature 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 about the decomposition and oxidation properties of carbon.

[0088] Tables 1A and 1B below show the physical properties characterizing exemplary CBs, namely CB1-CB17. [Table 1] [Table 2]

[0089] Various CBs have been developed and continue to be developed for carbon conductive additive (CCA) applications. Attractive electrical conductivity is often combined with high specific surface area and extensively developed structure (arrangement of primary CB particles within aggregates) and porosity. CBs that can be added to anode and / or cathode compositions for LIBs prepared by slurry processes are described, for example, in WO 2020 / 197670 (Cabot Corp., published October 1, 2020) and WO 2020 / 197673 (Cabot Corp., published October 1, 2020). Both are incorporated herein by reference in their entirety.

[0090] Examples of commercially available CBs that may be effective CCAs include LITX® 50, LITX® 63, 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.

[0091] In addition to exhibiting desirable electrical conductivity for LIB applications, other properties that may contribute to the multifunctionality of CBs are one, more than one, or all of the following: surface roughness, surface chemistry (surface energy), particle strength, and particle size.

[0092] Typically, CB surface roughness is related to the porosity of a particle, e.g., as described 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 a surface) is known to correlate with surface pore size (e.g., of similar order of magnitude). For example, a 2 nm pore can exhibit an RMS surface roughness of about 1 nm.

[0093] In general, CB porosity can be classified into one or more of the following categories: microporosity, defined by pores with diameters less than 2 nm, mesoporosity, defined by pores with diameters in the range of 2-50 nm, and macroporosity, defined by pores with diameters greater than 50 nm.

[0094] Pore ​​size distribution and pore volume in carbon black can be determined by gas physical adsorption techniques such as nitrogen adsorption porosimetry by measuring nitrogen gas adsorption using BET analysis and then fitting the adsorption isotherms to different models, e.g., DFT (density functional theory) and the BJH (Barrett Joyner Halenda) model, depending on the pore size region of interest. The BJH adsorption model was used to fit the N2 adsorption isotherm and calculate the mesopore and macropore volumes presented herein.

[0095] Without wishing to be bound to a particular interpretation, it is believed that the fibrillation properties in multifunctional CBs may be driven, at least in part, by the macroporosity of the particles, which act as anchoring points to connect the binders on the CB surface and stretch the binders into fibrils when high shear forces are applied.

[0096] Although some carbon blacks are primarily microporous materials, techniques exist to increase the porosity level and / or produce CBs with tailored porosity types.

[0097] For example, contacting the CB starting material with an oxidant stream can increase the porosity, particularly the mesoporous character of the CB product. Increasing the porosity of furnace black can be achieved by increasing the residence time in the carbon black reactor, allowing additional time for the tail gas to attack and etch the carbon surface. Another method relies on the addition of alkaline earth metal ions to the carbon black feedstock, as these ions are known to catalyze the etching of carbon black via 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. Pat. Nos. 8,895,142 (B2) to Kyrlidis et al. and 10,087,330 (B2) to Green et al., which are incorporated herein by reference. Commercially available modified carbon blacks are available from Cabot Corporation. In Tables 1A and 1B above, CB 15 is a steam etched version of CB4.

[0098] Fibrillation properties have also been found to depend on surface chemistry or surface activity, a function that is often related to the manufacturing and / or heating processes used in preparing a particular CB. Often, surface chemistry or surface activity is related to the oxygen-containing groups found on the CB surface. In some embodiments, good fibrillation CB candidates lack or are depleted of oxygen-containing surface groups and tend to be less hydrophilic (more hydrophobic).

[0099] For example, effective fibrillation is believed to be driven, at least in part, by the affinity (adhesion) of the CB to the binder, e.g., a fibrillizable binder. Thus, 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. Oxygen content can be measured by inert gas fusion. Low surface chemistry CBs have an oxygen content in the range of about 10 ppm to about 5000 ppm, e.g., about 100 ppm to about 1000 ppm.

[0100] The presence of oxygen-containing surface groups can be reduced or minimized by techniques such as heat treatment or other surface modification approaches, as known in the art or developed in the future. Surface-modified, e.g., heat-treated, CB can be compared and differentiated from normal carbon black by X-ray scattering, Raman spectroscopy, surface energy measurements by gas adsorption, or other techniques known in the art. In some cases, heat-treated CB and other surface-modified CB also tend to show reduced moisture absorption during processing. In Tables 1A and 1B, CB9 is a heat-treated version of CB11, and CB3 is a heat-treated version of CB4.

[0101] 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). Also believed to play a role in the multifunctional properties of selected CBs is related to CB particle strength (indicated as particle hardness and / or particle agglomeration). Particle strength allows the CB to effectively stretch the polymer binder. This, together with particle roughness, may represent a very important mechanical property to achieve the desired binder fibrillation. Particle strength can be measured by individual pellet crush tests, oscillatory viscoelastic measurements, or other techniques known in the art.

[0102] Initially (before the CB is subjected to mixing, particularly high shear mixing), the D50 particle size of the utilized multifunctional CB may be in the range of about 0.5 to about 20 μm, such as about 1 to about 10, e.g., about 2 to about 5 μm. As a result of binder treatment, e.g., fibrillation (typically under high shear conditions), the starting multifunctional CB particles may break down into smaller particles having particle sizes, e.g., in the range of about 0.05 to about 1 μm, e.g., about 0.1 to about 0.3 μm.

[0103] A multifunctional CB can be combined with a second CB (which may or may not be multifunctional), for example in a CB blend.

[0104] The CB particulate material can be provided in any number of forms. For example, truly fluffy CB-containing powders have been found to work particularly well in some of the drying processes tested. Such powdered materials can be characterized by their particle size, BET, and / or other properties. Often, the powders used have a density of about 100 g / cm. 3 It has the following density:

[0105] Less fluffy CB particles, for example in the form of jet milled pellets, can also be utilized. The powdered CB can be pelletized using techniques and equipment known in the art. In one example, the CB is pelletized with an emulsion solution of the binder utilized to form the electrode composition described herein. Other approaches use emulsion solutions of different binders, for example, binders belonging to the same chemical family or binders with similar functionally active groups that can bind or otherwise interact with the binder used to perform the drying process. As a result, it is believed that the energy interaction between the pelletized CB and the binder used to prepare the electrode composition is increased.

[0106] The pellet size applied for pure CB can be in the range of about 0.1 mm to about 5 mm. In one example, the pellet size is about 0.1 to about 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 mm, or about 0.5 to about 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 mm, or about 1 to about 1.52, 2.5, 3, 3.5, 4, 4.5, 5 mm, or about 1.5 to about 2, 2.5, 3, 3.5, 4, 4.5, 5 mm, or about 2 to about: 2.5, 3, 3.5, 4, 4.5, 5 mm, or about 2.5 to about 33.5, 4, 4.5, 5 mm, or about 3 to about 3.5, 4, 4.5, 5 mm, or about 3.5 to about 4, 4.5, 5 mm, or about 4 to about: 4.5, 5 mm, or about 4.5 to about 5 mm.

[0107] Granules of carbon black may also be useful in some situations. In many cases, CB granules are a densified form of CB with no polymer present in the final product. In general, CB granules can be formed by the conventional pelletizing process associated with CB manufacturing. It is also possible to form CB granules by dispersing fluffy CB in water followed by spray drying.

[0108] In some embodiments, the granules used change their morphology and / or function during the solventless technique described herein. Thus, depending on the initial CB granular material, the polymer binder can be processed, e.g., fibrillated. The size crushing that occurs during this operation can release smaller CB units. In the presence of electroactive materials, the fragmentation of the granules can enhance the distribution of the smaller CB units throughout the electrode composition, resulting in an electrode film with improved electrical conductivity and / or mechanical strength.

[0109] The surface roughness and / or surface energy of the granules are often controlled by selecting the particles that make up the granules. For example, the surface roughness can be selected based on the surface texture produced by the primary particles and / or agglomerates that make up the secondary granules. Such surfaces are rough on the dimensional scale where the roughness is provided by nano / micro-scale hills and valleys on the surface of the CB granules.

[0110] The multifunctional CB in granular form can have a particle size in the micron range, e.g., 1-10 μm, e.g., about 1 to about 2, 3, 4, 5, 6, 7, 8, 9 μm, or about 2 to about 3, 4, 5, 6, 7, 8, 9, 10 μm, or about 3 to about 45, 6, 7, 8, 9, 10 μm, or about 4 to about 5, 6, 7, 8, 9, 10 μm, or about 5 to about 67, 8, 9, 10 μm, or about 6 to about 7, 8, 9, 10 μm, or about 7 to about 8, 9, 10 μm, or about 8 to about 9, 10 μm, or about 9 μm to about 10 μm. In some granules, the initial size can be reduced by grinding to various degrees, e.g., from about 10 microns to less than 1 micron. Some implementations utilize a combination of sizes.

[0111] Granule strength can also be considered. It can be minimized by forming granules in the absence (or with a minimum content) of binder during granule formation. Increasing granule strength can be achieved by using different concentrations of binder and / or different types of binder. In some embodiments, the binder used to form CB granules is the same or similar binder as the binder used in the dry process, for example, a fibrillating binder.

[0112] Some embodiments use granules that are friable under processing, e.g., fibrillation, conditions. In such cases, the strength of the granules can be controlled such that the strength is high enough to fibrillate or deform the polymer binder, but low enough that the granules break apart to release conductive and reinforcing carbon units, e.g., aggregates.

[0113] Granular CB can be used alone as a multifunctional additive or in combination with another form of CB, which may in some cases also be multifunctional.

[0114] The CBs used in the dry processes described herein are selected or tailored to perform two or more functions. In certain embodiments, the various CB attributes are balanced to achieve the best possible combination of electrical conductivity, binder fibrillation, and / or mechanical properties. For example, a CB that is considered to be a good CCA additive is not necessarily a good or even suitable fibrillation aid. Thus, a selection process and sometimes compromises may be required when using a CB that provides good electrical conductivity together with good fibrillation attributes. Achieving or optimizing the multifunctionality of the CB may depend on experimental evaluations testing the performance of films and / or electrodes produced by solventless processes. Suitable CBs can also be selected by considering their properties, for example, in relation to a particular drying process protocol or condition.

[0115] In one example, the CB is selected to combine sufficient surface area (e.g., as measured by BET N2 adsorption) for optimal binder processing, e.g., fibrillation, while ensuring that the particular CB agglomerates used (e.g., CB pellets or jet-milled CB particles) maximizes surface interactions between the CB particles and the binder, and thus allows the binder to break down into particles small enough, e.g., less than 2 microns (μm), to be effectively processed, e.g., fibrillated.

[0116] The CB used in the dry process described herein is approximately 1600 m 2 / g or less, for example, about 1500, 1400, 1300, 1200, 1100, 1000, 900, 800, 700, 600, 500, 400, 300, 200, 100 or 35 m 2The BET can be in the range of about 35 to about 1600, for example, about 35 to about 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, or about 100 to about 200300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, or about 200 to about 300, 400, 500, 6 00, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, or about 300 to about 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, or about 400 to about 500600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, or about 500 to about 600 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, or about 600 to about 700 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, or about 700 to about 800 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, or about 800 to about 900, 1000, 1100, 1200, 1300, 1400, 15 00, 1600, or about 900 to about 1000, 1100, 1200, 1300, 1400, 1500, 1600, or about 1000 to about 1100, 1200, 1300, 1400, 1500, 1600, or about 1100 to about 1200, 1300, 1400, 1500, 1600, or about 1200 to about 1300, 1400, 1500, 1600, or about 1300 to about 1400, 1500, 1600, or about 1400 to about 1500 m 2 / g, 1600, or within the range of about 1500 to about 1600.

[0117] The CB used in the dry processes described herein may have an OAN of about 650 mL / 100 g or less, e.g., about 600 or less, about 500 or less, about 400 or less, about 300 or less, about 250 or less, about 200 or less, about 150 or less, about 120 mL / 100 g or less. The multifunctional CB may have an OAN in the range of about 120 to about 650 mL / 100 g, for example, about 120 to about 200, about 300, about 400, about 500, about 600, about 650 mL / 100 g, or about 200 to about 300, about 400, about 500, about 600, about 650 mL / 100 g, or about 300 to about 400, about 500, about 600, about 650 mL / 100 g, or about 400 to about 500, or about 600 to about 650 mL / 100 g, or about 500 to about 600, about 650 mL / 100 g, or about 600 to about 650 mL / 100 g.

[0118] The LIB anode is approximately 1600m 2 / g or less, for example, about 1500 or less, about 1200 or less, about 000 or less, about 700 or less, about 500 or less, about 200 or less, about 100 or less, or about 35m 2 The CB can be prepared by a dry process utilizing a CB having a BET of 100 to 200 m2 / g or less. The BET can be in the range of about 35 to about 1600 m2 / g. For example, the BET can be in the range of about 35 to about 50, about 75, about 100, about 150, about 200, or about 50 to about 75, about 100, about 150, about 200, or about 75 to about 100, about 150, about 200, or about 100 to about 150, about 200, or about 150 to about 200 m2 / g. 2 In one example, the selected CB may be in the range of about 55 to about 200 m / g. 2 / g.

[0119] For anode applications, the CB used in the solventless processes described herein can have an OAN of about 650 mL / 100 g or less, e.g., about 500 or less, about 400 or less, about 300 or less, about 240 or less, about 200 or less, about 150 or less, about 120 mL / 100 g or less. In one embodiment, the CB selected for preparing the LIB anode by the dry process has an OAN in the range of about 120 to about 650 mL / 100 g, for example, about 120 to about 150, about 200, about 240, about 300 mL / 100 g, or about 120 to about 150, about 200, about 240, about 300 mL / 100 g, or about 120 to about 150 to about 200, about 240, about 300 mL / 100 g, or about 150 to about 200, about 240, about 300 mL / 100 g, or about 200 to about 240, about 300 mL / 100 g, or about 240 to about 300 mL / 100 g. In one example, the selected CB has an OAN in the range of about 130 to about 240 mL / 100 g.

[0120] The LIB cathode is at least about 90m 2 / g, e.g., at least about 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, up to about 1600 m 2 It can be prepared by a dry process utilizing CB having a BET of about 500 to about 1600 m / g. 2 / g, for example, about 800 to about 900, 1000, 1100, 1200, 1300, 1400, 1500, or about 900 to about 10001100, 1200, 1300, 1400, 1500, 1600, or about 1000 to about 1100, 1200, 1300, 1400, 1500, 1600, or about 1100 to about 1200, 1300, 1400, 1500, 1600, or about 1200 to about 1300, 1400, 1500, 1600, or about 1300 to about 1400, 1500, 1600, or about 1400 to about 1500, 1600 m 2 / g, or about 1500 to about 1600m 2 / g. In one example, the selected CB may be in the range of about 1350 to about 1600 m2 In another example, the selected CB has a BET in the range of about 50 to about 190, for example about 90 to about 100 m / g. 2 In a further example, the CB has a BET in the range of 500 to 650 m 2 / g BET.

[0121] In cathode applications, the CB used in the solventless methods described herein can have an OAN of about 650 mL / 100 g or less, e.g., less than about 600, less than about 500, less than about 500, less than about 400, less than about 300, less than about 250, less than about 200, up to about 120 mL / 100 g. The CB can have an OAN in the range of about 120 to about 250, about 350, about 450, about 550, or about 250 to about 350, to about 450, to about 550, to about 650, or about 350 to about 450, to about 550, to about 650 mL / 100 g, or about 550 to about 650 mL / 100 g. In one example, the CB selected has an OAN in the range of about 250 to about 650 mL / 100 g.

[0122] In many cases, the CB that can be used to prepare LIB cathodes by the dry processes described herein ranges from about 80 to about 1600 m 2 Exemplary CBs that can be used to prepare LIB cathodes have a relatively high BET surface area (e.g., about 1350 to about 1600 m) in combination with a relatively low OAN (e.g., in the range of about 120 to about 220 mL / 100 g). 2 Another exemplary CB that can be used to prepare a LIB cathode has a molecular weight in the range of about 80 to about 200 m 2 / g and about 140 to about 280 m 2 A further exemplary CB has an OAN in the range of about 500 to about 1600 mL / 100 g, for example about 240 or less, and in the range of about 140 to about 180 mL / 100 g. 2Yet another exemplary CB that can be used to prepare a LIB cathode has a BET in the range of 650 mL / 100 g and an OAN in the range of about 180 to about 650 mL / 100 g. 2 BET surface area of ​​less than about 500 to about 650 m / g (e.g., 2 / g) and an OAN in the range of about 180 to about 260 mL / 100 g.

[0123] In many cases, the CB that can be used to prepare LIB anodes by the dry processes described herein ranges from about 35 to about 1600 m. 2 Exemplary CBs that can be used to prepare LIB anodes have relatively low BET surface areas (e.g., about 50 to about 200 m2) and OANs (e.g., about 120 to about 650 mL / 100 g). 2 / s) and has an OAN in the range of about 130 to about 240 mL / 100 g.

[0124] In many implementations, the multifunctional CB has an L a For example, CB has a crystallite size of about 17 Å to about 20, about 30, about 40 Å, or about 20 Å to about 30 Å, about 40 Å, about 50 Å, or about 30 Å to about 40, about 50 Å, or about 40 Å to about 50 Å. a It can have a crystallite size.

[0125] The multifunctional CBs described herein have a thermal conductivity of 15 mJ / m 2 For example, about 1 to about 10 mJ / m 2 , for example, about 1 to about 3, about 5, about 7, about 9 mJ / m 2 , or about 3 to about 5, about 7, about 9, or about 10 mJ / m 2 , or about 5 to about 7, about 9, or about 10 mJ / m 2 , or about 7 to about 9, about 10 mJ / m 2 , or about 9 to about 10 mJ / m 2 The surface energy (SEP) of the material may be:

[0126] In terms of porosity, the multifunctional CB must be at least 0.35 cm 3 / g, for example, about 0.35 to about 2 cm 3 / g mesopore volume and at least 1 cm 3 / g, for example, about 1 to about 3 cm 3 In some embodiments, the high surface area CB (e.g., about 800 m 2 / g or more BET), for example, the mesopore volume is about 0.35 to about 0.5, about 1, about 1.5, about 0.5 to about 1, about 1.5 cm 3 / g, about 2, or about 1 to about 1.5, about 2 wt.%, or about 1.5 to about 2 cm 3 / g.

[0127] The multifunctional CB is characterized by a total mesopore and macropore volume of at least 0.2 cm 3 / g, typically higher. In one example, the multifunctional CB used to prepare the anode composition has a molecular weight of about 0.2 to about 0.8 cm 3 / g. Multifunctional CBs suitable for preparing cathode compositions often have a total mesopore and macropore volume of at least 1 cm 3 / g.

[0128] The total mesopore and macropore volume is about 1 to about 1.5, about 2, about 2.5 cm 3 / g, or about 1.5 to about 2.0, about 2.5, about 3 cm 3 / g, or about 2 to about 2.5, about 3 cm 3 / g, or about 2.5 to about 3 cm 3 / g.

[0129] In many implementations, the multifunctional CB has a percent crystallinity of at least 22%, e.g., 23% to 50%, e.g., in the range of about 23 to about 30, 35, 40, 45%, or about 30 to about 35, 40, 45, 50%, or about 35 to about 40, 45, 50%, or about 40 to about 45, 50%, or about 45 to about 50%.

[0130] Examples of suitable CB materials that may be utilized include commercially available specifications such as: Vulcan® series CBs, such as Vulcan® XCmax 22, Black Pearl® series CBs, such as BP 2000 carbon black, PBX® series CBs, such as PBX 51, and LITX® series CBs, such as LITX HP, manufactured by Cabot Corporation.

[0131] Electrode compositions prepared by solventless processes as described herein typically include a multifunctional CB (as described herein), an active electrode material, and a "treated" binder. Some product electrode compositions, especially those prepared with fibrillizable binders, include the post-fibrillation binder (also referred to herein as "fibrillated binder"), often exhibiting high aspect ratio fibrils. Compositions prepared with non-fibrillizable binders still exhibit "treated" binders, i.e., "deformed" (elongated, entangled, etc.) binders, but perhaps to a lesser extent than observed with fibrillizable 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 processing, e.g., fibrillation, is often reflected in the quality of the resulting product, e.g., electrode film. In some cases, electrode compositions prepared with non-fibrillizable binders include "non-deformed" (spherical, rounded, spherical, etc.) binders. Even in such situations, the multifunctional CB can act as a binder and mechanical reinforcement for the electrode while also imparting desirable electrical properties.

[0132] The electrode composition can be employed to form an anode, a cathode, or both an anode and a cathode, for assembly in a device such as, for example, a LIB. One, several, or all of the properties characterizing the multifunctional CB can be evaluated in the product electrode composition (where the binder has been processed, e.g., fibrillated), the product electrode (e.g., a film) typically obtained by further processing the product electrode composition, the assembled electrode (where the product electrode, e.g., a film, is applied to a suitable substrate), and / or the battery described herein. For example, the electrodes can be tested for adhesion (to evaluate the attachment of the electrode film to the substrate), cohesion (to evaluate how well the particles are bonded together), electrode resistivity, and / or other properties by techniques known in the art.

[0133] Based on the total weight of the electrode composition, the multifunctional CB may be provided in an amount ranging from about 0.1 to about 10 wt%, e.g., from about 0.3 to about 5.0 wt%, e.g., from about 0.3 to about 3 wt%. Thus, in one embodiment, the multifunctional CB is present in the composition in an amount ranging from about 0.3 to about 0.5, about 1.0, about 1.5, about 2.0, about 2.5, or from about 0.5 to about 1.0, about 1.5, about 2.0, about 2.5, about 3.0 wt%, or from about 1.5 to about 2.0, about 2.5, about 3.0 wt%, or from about 2.0 to about 2.5, about 3.0, or from about 2.5 to about 3.0. Some embodiments utilize CB in an amount greater than about 3% by weight, such as, for example, 3-5% by weight of the product electrode composition, e.g., 3-3.5, 4 or 4.5%, 3.5-4, 4.5 or 5%, 4-4.5 or 5%, or 4.5-5% by weight. Specific amounts within and outside these ranges can be selected.

[0134] In many cases, this amount is equal to or preferably lower than the amount of AC required to obtain the same or substantially the same electrode performance. In an alternative approach, reaching a performance level established with AC is expected to require a lower amount of multifunctional CB and not take up extra volume for electroactive material.

[0135] In exemplary LIB graphite anode compositions, the loading of the multifunctional CB is about 5 wt% or less, often about 3 wt% or less, e.g., 1 wt% or less. In certain examples, the loading of the multifunctional CB is in the range of about 0.1 wt% to about 1.0 wt%, e.g., about 0.1 to about 0.5 wt%, or about 0.5 to about 1 wt%. Other examples use higher loadings, e.g., in the range of about 1 to about 5, such as at least about 4.5, 4.0, 3.5, 3.0, 2.5, 2.0, or 1.5 wt% loading.

[0136] In exemplary NCM cathode compositions, the loading of the multifunctional CB is about 5 wt% or less, often about 3 wt% or less, e.g., 1 wt% or less. In certain examples, the loading of the multifunctional CB is in the range of about 0.1 wt% to about 1.0 wt%, e.g., about 0.1 to about 0.5 wt%, or about 0.5 to about 1 wt%. Other examples use higher loadings, e.g., in the range of about 1 to about 5, such as loadings of at least about 4.5, 4.0, 3.5, 3.0, 2.5, 2.0, or 1.5 wt%.

[0137] In at least some cases, multifunctional CBs that perform well when added to an anode composition have been found to have different properties than those exhibited by multifunctional CBs that were found to perform well in cathode compositions.

[0138] Thus, in some embodiments, graphite anodes are prepared using CB that has a relatively clean surface (e.g., such as that obtained by heat treatment), relatively low surface area and structure, and little developed meso- and macroporosity.

[0139] In another embodiment, NCM cathodes are prepared using CB that has relatively high surface area and structure and develops meso- and macro-porosity (eg, as obtained by steam etching).

[0140] The relative amount of CB multifunctional additive to fibrillizable binder can be in the range of weight ratios of 5:1 to 0.1:10, e.g., about 1:1 to 0.1:10, 0.5:1 to 0.1:10, 5:1 to 0.5:10, 5:1 to 1:5, 5:1 to 5:10. In certain cases, the weight ratio of CB multifunctional additive to fibrillizable binder is 1:1.

[0141] In one embodiment, the electrode composition contains the active material in an amount of about 90% to about 99% by weight, e.g., 98.0% by weight, the fibrillizable binder in an amount of about 1% to about 5% by weight, and the CB multi-function additive in an amount of about 0.3% to about 5% by weight.

[0142] In many cases, the solventless process described herein is carried out in the absence of any fibrillation aid other than the CB multifunctional additive. In other embodiments, the multifunctional CB can be combined with another, e.g., conventional fibrillation agent such as AC.

[0143] As used herein, the term "fibrillation aid" or "fibrillating agent" refers to a material other than the binder or active electrode material that promotes the fibrillation of a fibrillizable binder. "Additional" or "other" fibrillation aid or "additional" or "other" fibrillating agent refers to a material other than the multifunctional CBs described above (i.e., a material that does not contain or is not a multifunctional CB).

[0144] Further embodiments utilize a substantially non-fibrillating conductive additive, such as a multifunctional CB in combination with a conventional CCA. As used herein, the term "additional conductive additive" refers to a material other than the multifunctional CB as described above (i.e., a material that does not contain or is not a multifunctional CB). Typically, the additional conductive additive lacks or substantially lacks fibrillating functionality.

[0145] Plasticizers and / or other materials conventionally used in electrode compositions may be included as well.

[0146] Some illustrative examples use the multifunctional CB together with another (additional) material, e.g., a conventional fibrillating agent such as AC, hard carbon, graphite, graphene, other non-fibrillating conductive additives, plasticizers, or combinations thereof. In some applications, the multifunctional CB is combined with AC in a ratio ranging from about 95:5 to about 50:50.

[0147] Another example utilizes a carbon-based additive containing at least two carbon blacks that have one or more properties that differ from each other, for example with respect to their BET. Blends of carbon blacks with different structure-OANs and / or blends of different carbon forms are also possible, i.e., blends of activated carbon or graphite with one or more CBs. At least one component in the blend is a multifunctional CB.

[0148] As previously mentioned, many aspects of the present invention relate to methods of making electrode compositions, electrode products (eg, films), electrodes (wherein an electrode product, such as a film, is applied onto a conductive substrate), and / or batteries.

[0149] Turning first to the dry process used to prepare the electrode compositions described above, carrying out this process targets at least two objectives: blending some, typically all, of the components, most often provided in the form of free (e.g., flowable or pourable) particles, and processing the binder in the presence of the multifunctional CB. In some embodiments, each of these two objectives is accomplished by one or more mixing operations carried out under specific shear conditions using appropriate equipment.

[0150] For example, low shear mixing can be selected, for example utilizing a roll mill, to distribute the components as uniformly as possible. As used herein, the term "low shear mixing" refers to mixing performed under conditions that are not sufficient or substantially not sufficient to fibrillate the fibrillizable binder. Relying on low shear mixing conditions can also avoid excessive particle fragmentation, and is often a consideration for some electroactive materials.

[0151] In many embodiments, the treatment of the binder in the presence of the multifunctional CB is carried out under high shear mixing. As used herein, the term "high shear mixing" refers to shear conditions that are vigorous enough to deform (e.g., stretch, entangle) the binder to an extent sufficient to prepare a film electrode by a solvent-free technique. In the case of a fibrillizable binder, high shear mixing refers to mixing under shear conditions sufficient to fibrillize the binder.

[0152] Without wishing to be bound to a particular interpretation, it is believed that in the presence of the multifunctional CB additive and under high shear conditions, the binder polymer becomes deformed, stretched, elongated, and entangled. The surface energy and / or surface roughness attributes that characterize the CB can facilitate the gripping and retention of the binder polymer, and the two (CB and polymer) can become crushed between the electroactive particles, resulting in the binder polymer being elongated. It is believed that the CB particles dispersed in or on the surface of the binder enable the CB 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.

[0153] At the same or substantially the same high shear conditions, these manifestations tend to be more pronounced when the binder used is a fibrillating binder. Surface and other CB properties encourage the polymer to get stuck here and there. When all the particles move under high shear mixing, the polymer gets elongated and forms very long and very thin strands (with high aspect ratios). Typically, these effects are less pronounced with non-fibrillating binders treated at 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 get close to full fibrillation results.

[0154] In addition to the processing contributions mentioned above, multifunctional CBs can improve electrical conductivity and can often act as mechanical reinforcements by holding together fully or to a lesser extent "deformed" (elongated, entangled, etc.) or "non-deformed" (spherical, rounded, spherical, etc.) fibrillizable and non-fibrillizable polymeric binders.

[0155] In some circumstances, high shear mixing can also be relied upon to break down particles into smaller fragments, for example, larger particles or granules of CB, such as CB pellets, can be broken down into smaller particles that become evenly distributed throughout the electrode composition, thereby improving electrical conductivity and / or mechanical properties.

[0156] The particular shear value may depend on the scale of the operation, the materials involved, the type of mixing equipment, and / or other factors. Low or high mixing settings may be determined or optimized based on previous experience, routine experimentation, and the like.

[0157] The components can be combined in any order designed to obtain a mixture, preferably one that is well dispersed, e.g., one that has a uniform distribution of the components, in other words, a homogenous mixture. In one example, the CB is uniformly dispersed on the surface of the electroactive material and binder.

[0158] The binder treatment (eg, fibrillation) can be performed on any mixture or pre-mixture (preblend) that combines the multifunctional CB additive with a binder.

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

[0160] The stepwise sequence may be such that one type of equipment is used to perform a first operation (e.g., preparation of a preblend) and another type of equipment is used in a subsequent operation (e.g., fibrillation), the same applies to shear and / or other mixing parameters.

[0161] In one embodiment, the CB multifunctional additive is first mixed with the binder using a high shear device to process, e.g., fibrillate, the binder. In some cases, this high shear operation also breaks down the CB particles (pelletized granules or other particulates that are prone to shattering under high shear conditions) into smaller pieces. The resulting mixture is then combined with the electroactive material (graphite in one example). Using low shear conditions during this step is advantageous in maintaining particle size (e.g., of the electroactive material).

[0162] In another embodiment, the multifunctional CB is first combined with the electroactive material in a pre-blending step carried out under low shear, for example, to obtain a uniform distribution of the two components. A binder is then added to this pre-blend and processed, for example fibrillated, using high shear conditions.

[0163] In a further embodiment, the electrochemically active material, the binder, and the multifunctional CB are all mixed (e.g., under low shear conditions). The mixture is then subjected to high shear conditions to treat, e.g., fibrillate, the binder.

[0164] Other sequences are possible, for example, the electroactive material can be mixed with the binder first, followed by adding the multifunctional CB additive first, and then treating (e.g., fibrillating) the binder under high shear conditions.

[0165] The 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.) steps or pulses that can last for a suitable period of time, e.g., in the range of about 10 seconds to about 5 minutes, e.g., 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 can be the same or different.

[0166] The pulse may be followed by a rest period or a cooling period. The rest period may be at ambient temperature, e.g., room temperature. The cooling may be to a temperature below ambient temperature, e.g., below room temperature, often below 0°C, e.g., within the range of about -5 to about 5°C.

[0167] The pause or cooling period may depend on the temperature reached during mixing, the amount being handled, etc. In many cases, the cooling lasts for several minutes, for example, 10 to 30 minutes or more. The cooling period may vary in duration and / or temperature conditions.

[0168] By way of example, the binder-containing composition can be subjected to high shear mixing at about 25000 RPM to about 10,000 RPM, optionally about 18000 RPM, for 30 minutes, and then cooled to a subzero temperature for 10 minutes, for example, to about −10° C. Low shear mixing can be performed at about 2000 RPM to about 4000 RPM for 1 minute, followed by cooling at about 0° C. for 10 minutes.

[0169] In one example, a pre-blend of the CB multifunctional additive and the electroactive material is prepared using an acoustic mixer, e.g., at a force of 100 G for several minutes. The resulting blend is mixed with a binder at fibrillation parameters, e.g., using a laboratory-scale jet mill at a pressure rate of 100-90-90-10 psi.

[0170] In another example, all ingredients are mixed in a tube mill (such as an IKA TubeMill 100) at 25000 rpm in a pulsed mode where blending is alternated with rest periods followed by mixing operations of longer duration.

[0171] The mixing and / or processing, e.g., fibrillation steps, can be monitored by visual inspection, hand calendaring, powder rheology, or another suitable technique. For example, small amounts can be manually processed and sheared or passed through a hand calendar. Endpoints can be established based on experience, routine experimentation, visual inspection, and the like. The success of these operations can also be determined by SEM, performance, and / or other techniques typically performed on electrode products, e.g., electrode films.

[0172] The resulting electrode composition (containing, at a minimum, the active electrode material, the multifunctional CB, and the modified, e.g., fibrillated, binder) can be in the form of a pellet, a powder (often a fluffy powder), or other form of free-flowing or loose particulate material.

[0173] In an optional step, the electrode composition can be sieved to remove undesirable agglomerates.

[0174] After mixing and processing, e.g., fibrillation, the composition, optionally sieved, can be formed into a product electrode by any suitable technique known in the art or developed in the future. In one embodiment, the composition is formed into a film by calendering, an operation that can be carried out at room temperature or above, e.g., at a temperature similar to or close to the polymer glass transition temperature. In a typical calendering operation, the electrode composition is subjected to heat and pressure using an extruder. The softened material is passed through a calender roll (e.g., vertically) to prepare a product electrode sheet or film. In many embodiments, the film is self-supporting, a property that can be described using a 150 μm thick film that is self-supporting, and no part of the film is in contact with any type of support, e.g., a substrate.

[0175] The desired film thickness can be obtained by adjusting the gap between the rolls, and in some circumstances, other process parameters.

[0176] The roll temperature can be, for example, from about room temperature (20° C.) to about 200° C. A higher roll temperature can result in a thinner free-standing film on the first pass, while the opposite occurs at a lower temperature. The roll speed can be varied. In an illustrative example, the roll speed is set at about 0.17 meters per minute (m / min) to about 1.3 m / min. A slower roll speed tends to produce a thinner free-standing film on the first pass compared to a faster roll speed. The fluid pressure used can be in the range of about 1,000 psi to about 7000 psi. Again, a higher pressure can result in a thinner free-standing film on the first pass compared to a thicker film obtained at a lower pressure.

[0177] Further passes through a roll mill may be used to reduce the film thickness until the desired thickness and loading is reached. In a specific implementation, the film thickness is in the range of about 40 μm to about 300 μm, for example, about 50 to about 200 μm, about 100 μm to about 150 μm. Film thicknesses in the range of 50 to 100, 50 to 150, 50 to 200, 50 to 250, or 100 to 150, 100 to 200, 100 to 250, 100 to 300, or 150 to 200, 150 to 250, 150 to 300, or 200 to 250, 200 to 300, or 250 to 300 μm are also possible. The desired loading is about 10 mg / cm. 2 ~about 50mg / cm 2 may be also possible.

[0178] Free-standing films prepared using multifunctional CB in a solvent-free process are expected to have good mechanical properties. One reliable mechanical evaluation technique involves tensile strength testing. For example, a graphite anode is expected to have a tensile strength of at least 100 kPa, while the tensile strength of an NCM cathode film is expected to be at least 500 kPa. In one illustrative example, the free-standing 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 produced using AC.

[0179] In an optional operation, the film is thermally activated, for example to soften the binder and prepare the electrode product for application to a substrate. In the laboratory, this can be done using a hot plate at, for example, 100° C. Approaches for larger scale processes include temperature controlled roll-to-roll calenders, convection and / or microwave dryers, etc.

[0180] The film (typically free-standing and containing the active electrode material, the multifunctional CB, and the treated, e.g., fibrillated, binder) can be applied to a conductive substrate or support (e.g., an aluminum or copper current collector). In one embodiment, the film is laminated to a carbon-coated copper foil by calendaring the two together, for example, using a horizontal hot roller at appropriate roll temperature, roll speed, and water pressure.

[0181] The roll temperature can be within the range of about 80 to about 100° C. Too high a temperature can increase blistering and result in poor adhesion, while too low a temperature can prevent adhesion.

[0182] The roll speed can be about 0.17 m / min to about 1.3 m / min, e.g., about 0.5 m / min, and the oil pressure can be set at about 500 psi to about 2000 psi. Other settings can also be used. The pressure can be optimized to be high enough to promote adhesion to the substrate without altering the filling, porosity, or other properties. In some implementations, lamination is performed prior to setting the final thickness and / or porosity of the film electrode.

[0183] Formation of the film and its application to the substrate can in some cases be accomplished in a single step. For example, the powder electrode composition and substrate foil can be fed together through a calender roll under conditions suitable to produce a laminate in which the composition is pressed into a film of thickness and adhered to the foil. This approach eliminates the need to form a free-standing film.

[0184] The laminate structure can be shaped and / or sized for a particular application, such as an electrochemical cell, eg, a LIB, eg, a rechargeable LIB.

[0185] 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 "Lithium Ion Batteries Fundamentals and Applications", by Yuping Wu, CRC press, (2015). In a particular implementation, the battery is a coin cell, such as, for example, a 2032 coin cell, a 18650 cylindrical cell, a pouch cell, etc.

[0186] In an illustrative example, the LIB includes an anode prepared by a dry process. The anode contains the multifunctional CB, for example in an amount of 5 wt% or less, a graphite (e.g., natural graphite, synthetic graphite, or a blend of both, commercially available types of graphite such as MCMB, MCF, VGCF, MAG, etc.) active anode material, and a fibrillating binder. As mentioned above, the graphite active material and the fibrillating binder can be present in the anode in an amount of at least 80 wt% and no more than 5 wt%, respectively.

[0187] The second (opposing) electrode in the battery can also be prepared using a solvent-free process. In one embodiment, both electrodes in the battery comprise the multifunctional CB as described above.

[0188] The second electrode can also be prepared by a conventional dry process (eg, using AC), by a slurry, or by another non-dry technique.

[0189] In addition to the two electrodes, a typical LIB includes a suitable electrolyte. Examples include, for example, ethylene carbonate-dimethyl carbonate-ethyl methyl carbonate (EC-DMC-EMC), vinylene carbonate (VC), LiPF6, ethylene carbonate-diethyl carbonate (EC-DEC, LiPF6, or (EC-DMC), LiPF6. Furthermore, the electrolyte composition may be SiO xOr it may contain special additives known to improve the performance of silicon-containing anodes, such as fluorinated carbonates, such as fluoroethylene carbonate. In the laboratory, the separator that absorbs the electrolyte and prevents electrical contact between the electrodes while allowing the diffusion of Li-ions can be a suitable glass fiber microfilter (e.g., Whatman GF / A). In some cases, polypropylene / polyethylene membrane separators (e.g., Celgard 2300) can also be used.

[0190] The composition or morphology of the electrodes and / or batteries described herein can be characterized by various techniques. Examples include, but are not limited to, electron microscopy, such as 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.

[0191] The amount of solvent or its absence can be assessed by gravimetric testing, which involves drying the wet-cast electrode until the electrode weight reaches a theoretically calculated value based on the known solids loading of the slurry, or until the electrode weight is stable and does not change for a minimum of 3 minutes. Or, stated differently, the weight of the freshly prepared electrode (before any drying operation) is equal to or within ±1% by weight of the theoretical weight (i.e., the weight obtained by adding together the weights of the individual components provided in the process).

[0192] Another approach that can be used to detect solvents (e.g., NMP) relies on attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy (FTIR-ATR) in conjunction with gas chromatography (GC). Dry-processed electrode films can often be distinguished from slurry-based products by very low or undetectable levels of solvent residue. Substantially uniform binder distribution with no binder migration toward the film surface is yet another feature that often characterizes electrode products prepared by solventless processes.

[0193] The flexibility property that characterizes 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 cracks visible to the naked eye. In an illustrative example, the electrode was found to pass a bending test using a pen with a diameter of 8 mm as the rod.

[0194] Electrode performance can be tested by procedures known in the art or techniques adapted or developed. Suitable techniques include, for example, in-plane and through-plane electrode conductivity, electrochemical impedance spectroscopy (EIS), galvanostatic charge / discharge, hybrid pulsed power capability (HPPC), and cycling.

[0195] In many cases, electrodes prepared by solventless processes using multifunctional CBs perform at least as well, and in many cases better (e.g., as measured by in-plane resistivity, initial capacity, or first cycle efficiency) against a comparison (also referred to herein as "reference") electrode containing the same amount of active electrode material (e.g., graphite), binder, and conventional fibrillating agent such as AC. Alternatively, the amount of multifunctional additive required to reach the performance obtained with AC is typically less for electrodes produced according to the embodiments described herein.

[0196] In one example, dry-processed graphite anodes prepared using multifunctional CB at loadings of about 1 wt % or less performed at least as well (as measured by in-plane resistivity, rate capability, and first cycle efficiency) as comparative electrodes containing higher amounts of AC (e.g., 5 wt %).

[0197] Electrodes prepared using multifunctional CB in a solventless process are also expected to have good mechanical properties. 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), to name a few. In many cases, electrodes prepared with multifunctional CB performed at least as well as comparison electrodes made using AC.

[0198] Without wishing to be bound to a particular interpretation, it is believed that the use of multifunctional CBs as described herein can produce ribbon-like binder strands or fibrils that can be long enough to encapsulate and hold together particles of electroactive material.

[0199] Thus, even at relatively low levels, the multifunctional CB appeared to be able to process, e.g., fibrillate, the binder and generate an effective conductive network in the electrode while also contributing to desirable mechanical properties.

[0200] The compositions and methods described herein can also be used (e.g., incorporated into) 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 making such devices are known in the art and are described, for example, in "Battery Reference Book" by TR Crompton, Newness (2000).

[0201] The principles described herein can also be implemented or adapted to semi-dry processes. Such processes often include one step that is a wet (or slurry) step. Other steps are performed without the addition of liquids (e.g., solvents).

[0202] One example of a semi-dry process includes a situation where two or more electrode components (e.g., electroactive material and multifunctional CB) can be mixed together, for example, first in the presence of a liquid (e.g., a solvent), followed by a drying step to remove the solvent. The remaining operations can then be carried out without the addition of a liquid (e.g., a solvent). For example, a dry preblend (containing electroactive material and CB) can be combined with a binder, and the binder can be processed (e.g., fibrillated) in the absence of a liquid, e.g., a solvent.

[0203] The invention is further illustrated by the following non-limiting examples. EXAMPLES

[0204] Materials and Methods Materials used in the solventless electrode process and formulation were graphite BTR 918-2A from Targray, lithium nickel manganese cobalt oxide NCM622 (SNCM03006) from Targray, 1500 cm 2 The carbon blacks used in the examples included: standard activated carbon with a surface area of ​​1000 g / g; conductive CB Ketjenblack EC-600J from Lion; C-NERGY™ Super C65 carbon black from Imerys; and Acetylene Black Li-435 from Denka. All other CB specifications were from Cabot. The fibrillizable binder was polytetrafluoroethylene (PTFE). The physical properties of the carbon blacks used in the examples below are shown in Tables 1A and 1B above.

[0205] Generally, graphite electrodes were prepared in several steps. In the first step (S1), the electrode components were combined and mixed (e.g., by high shear mixing) under conditions suitable to fibrillate the binder. The second step (S2) involved passing the powder blend from S1 through a vertical calender that was preset to an appropriate gap based on the desired film thickness. In the third step (S3), the free-standing film resulting from S2 was laminated onto a current collector.

[0206] A similar sequence of steps was followed to prepare the cathode electrode.

[0207] The thickness of the solvent-free electrodes was measured using a manual drop gauge equipped with a 7.14 mm diameter flat gauge contact head.

[0208] The strength and Young's modulus (elasticity) of the dry films were measured using a Mecmesin MultiTest-dV dynamic force tester with a load of 10 N.

[0209] The sheet resistance of the solvent-free electrodes was measured using a Signatone Pro4-4400 commercial system (SP4 probe head connected to the back of a Keithley 2410-C source meter). Reported values ​​were normalized by electrode thickness and reported as electrode resistivity in ohm-cm.

[0210] Example 1 In this example, a free-standing graphite anode film was prepared in two steps (S1 and S2) using a jet mill as a high-shear mixing device in S1, and then laminated onto a current collector to form an electrode (S3).

[0211] In S1, the electrode components were pre-blended using a Resodyn acoustic mixer (S1-1) and then mixed using a 4 inch jet mill (S1-2). More specifically, the pre-blending step S1-1 was performed to prepare a uniform distribution of the powder components in the blend and included pre-blending the carbon additive and active electrode material (graphite) in the acoustic mixer at 100% intensity and auto frequency for 5 minutes, followed by addition of the polymer and blending for another minute at the same settings. The next mixing step S1-2 included fibrillating the binder and involved passing the pre-blended materials through a laboratory scale jet mill at pressure rates of 100-90-90-10 psi.

[0212] In S2, the powder blend obtained in S1 was passed through a vertical calender at room temperature to obtain a free-standing film with a thickness of 110-190 μm.

[0213] In S3, the free-standing electrode films obtained in S2 were thermally activated on a hot plate set at 100 °C and then laminated onto a carbon-coated 9 μm thick copper foil (MTI Corporation) by calendering them together using a horizontal hot roller calender preheated to 80 °C.

[0214] The compositions of the electrode formulations used (A1 and A2 using CB, A3 using activated carbon, used as reference) are shown in Table A. [Table 3]

[0215] SEM photographs (low and high magnification) of the cross sections of electrode films A1, A2, and A3 (90% graphite, 5% PTFE, and 5% additive) and fluorine elemental mapping are shown in Figures 1A to 1I for reference.

[0216] The binder fibrils can be easily visualized in the formulation using activated carbon (AC), SEM pictures 1A and 1B. Fibrils are also easily observed in electrode A2 (see SEM pictures 1G and 1H). This suggests that the specific CB can function as the sole fibrillation additive, similar to the conventionally used AC, and thus can replace AC in the formulation.

[0217] In SEM photographs 1D and 1E of electrode A1 some fibrils can also be visualized, but to a lesser extent than in A2, supporting the idea that surface chemistry is important and that PTFE is more likely to interact with the cleaner surface of the heat treated material.

[0218] Figures 1C, 1F and 1I show the mapping of elemental fluorine, confirming its homogeneous distribution across the electrode, with no migration phenomena detected (as is very frequent in the case of electrodes prepared with slurries).

[0219] Example 2 Compositions A1-A3 in Table A were further tested for electrical properties of the products. Electrode films were prepared similar to Example 1, except that in addition to the combination of an acoustic mixer and a jet mill in (S1), the blends were further processed using an IKA Tube Mill 100 at 25000 rpm for 15 seconds.

[0220] As seen in Example 1, the fibrillation capabilities of AC and carbon particles CB9 are similar, but CB9 offers the added advantage of lower electrode resistivity when tested at the same loading. As is evident from Figure 2, both CB-containing electrodes, i.e., A1 and A2, showed improved in-plane resistivity compared to the AC-containing reference electrode, i.e., A3.

[0221] Also, because the in-plane resistivity of A2 was nearly as low as that of A1, the improved fibrillation observed in A2 may lead to its overall preference over CB9 (the heat-treated version of CB11) at least in some dry process applications.

[0222] Example 3 The graphite electrode of this example was prepared by the same method as in Example 1, except that the jet mill in (S1) was changed to an IKA Tube Mill 100, where the electrode components were processed with 6 x 15 second blending pulses at 25000 rpm with a 45 second rest, followed by straight blending at 25000 rpm for 2 minutes.

[0223] In S2, the powder blend obtained in S1 was passed through a vertical calender at room temperature to obtain a free-standing film with a thickness of 120–135 μm.

[0224] The electrode formulations used (labeled B1 through B7, with B8 as the reference) are listed in Table B below. [Table 4]

[0225] FIG. 3 compares the tensile strength of the graphite film and the in-plane resistivity of electrodes formulated with various CBs, i.e. additives CB1, CB3, CB4, CB9, CB11, CB14, and CB15 (from Tables 1A and 1B), with graphite electrodes containing AC (see reference electrode composition B8 in Table B). All electrodes were prepared by the dry process and contained 5 wt. % loading of CB additive, graphite (90 wt. %), and PTFE (5 wt. %). As can be seen in FIG. 3, electrodes prepared by the dry process using CBs believed to provide good binder fibrillation properties (see, for example, carbon blacks CB9, CB11, CB14, and CB15) also showed low in-plane resistivity very comparable to or better than the values ​​observed with good CCA additives such as carbon black CB4 (from Table 1). Furthermore, the use of CBs (e.g., carbon blacks CB1, CB3, CB4, CB9, CB11, CB14, and CB15 from Table 1), which were considered to be potentially good fibrillation agents, produced electrodes that exhibited lower in-plane resistivities than those seen with AC.

[0226] In one example, free-standing graphite films containing CB3 showed modest improvements in tensile strength and in-plane resistivity compared to data seen with CB4 (not heat treated), supporting the idea that chemistry matters and that PTFE is more likely to interact with the cleaner surface of the heat treated material, CB3.

[0227] In another example, free-standing graphite films containing CB15 (steam etched) showed significant improvements in tensile strength and in-plane resistivity compared to those seen with CB4 (not steam etched). This supports the idea that chemistry and morphology matter, and that the PTFE is more likely to be fibrillated and more evenly distributed within the poles with CB15 having a cleaner surface, higher surface area, higher structure, and developed meso- and macroporosity in the steam etched material.

[0228] In addition, because lower surface area CBs (e.g., carbon blacks CB1 and CB3) may cause less solid electrolyte interface (SEI) formation (SEI growth is believed to be an important factor in LIB capacity degradation) compared to higher surface area ones (e.g., carbon blacks CB9, CB11, CB14, CB15), the expected improved battery performance of lower surface area CB particles may result in an overall preference for this type of performance additive, at least in some dry process applications.

[0229] Example 4 In this example, free-standing NCM622 cathode films were prepared in two steps (S1 and S2), and an IKA Tube Mill 100 was used as the high shear mixer in S1, and then laminated onto a current collector to fabricate the electrode (S3).

[0230] In S1, the electrode components were pre-blended using a Resodyn acoustic mixer (S1-1) and then mixed using an IKA Tube Mill 100 (S1-2). More specifically, the pre-blending step S1-1 was performed to prepare a uniform distribution of the powder components in the blend and included pre-blending the carbon additive and active electrode material (graphite) in the acoustic mixer at 100% intensity and auto frequency for 5 minutes, followed by addition of the polymer and blending for another minute at the same settings. The next mixing step S1-2 involved fibrillating the binder and included passing the pre-blended material through an IKA Tube Mill 100 at 25000 rpm, 6 x 15 second blending pulses with 45 second pauses in between, followed by straight blending at 5000 rpm for 3 minutes.

[0231] In S2, the powder blend obtained in S1 was passed through a vertical calender at 100 °C to obtain free-standing films with thicknesses of 110–170 μm.

[0232] In S3, the free-standing electrode film obtained in S2 was laminated onto a carbon-coated aluminum foil current collector by calendering them together using a vertical hot roller calender preheated to 100 °C.

[0233] The electrode formulations used (labeled C1-C6 and D1-D6) are shown in Tables C and D, respectively. [Table 5] [Table 6]

[0234] FIG. 4 compares the tensile strength and modulus of free-standing NCM electrode films containing AC (see reference electrode composition C6 in Table C) with electrodes formulated using various CBs, i.e., additives CB1, CB3, CB5, CB9, and CB15 (from Tables 1A and 1B). All electrodes were prepared by the dry process and contained 5 wt% loading of CB additives, NCM622 (90 wt%) and PTFE (5 wt%). As can be seen in FIG. 4, the electrode films prepared by the dry process with CbS showed improved strength compared to the AC-containing reference. In some cases, formulations containing certain CBs, i.e., CB1, CB3, and CB5, showed relatively high modulus (400 N / mm 2 In other cases, formulations containing certain forms of CB, namely CB9 and CB15, had tensile strengths (greater than 1000 kPa) and modulus (400 N / mm 2 The results showed a good balance of 0.1% to 1.0% (less than 0.1%) and formed a flexible, free-standing cathode film that passed quality control and could be laminated onto a current collector.

[0235] FIG. 5 compares the tensile strength and modulus of NCM electrode films (see electrode composition in Table D) formulated with various CBs, namely CB7, CB8, CB10, CB12, CB13, and CB15 (from Tables 1A and 1B). All electrodes were prepared by dry process and contained 2 wt% loading of CB additive, NCM622 (94 wt%), and PTFE (4 wt%). Similar to the data in FIG. 4 reported for the formulations of 5 wt% CB, 90 wt% NCM622, and 5 wt% PTFE, the developed morphology of CBs, namely CB10, CB12, CB13, and CB15, allowed the formation of flexible free-standing electrode films compared to films obtained with less developed morphologies of CBs, namely CB7 and CB8. The results indicate that the relatively high BET, OAN, and pore volume type carbon additives, namely CB9, CB10, CB12, CB13, and CB15, are generally preferred for use as treatment particles in at least some dry process applications.

[0236] As can be seen in Figure 6, the electrode formulation containing carbon black (Formulation C4 in Figure 6) also exhibited lower electrode resistivity compared to the AC-containing reference (i.e., Formulation C6), which is known to be beneficial for battery performance.

[0237] Example 5 The NCM cathode electrode in this example was prepared in three steps via the formation of a free-standing dry-processed film using a twin-screw extruder used as the high-shear mixing device (S1 and S2), followed by its lamination onto a current collector (S3).

[0238] In S1, a three-step operation protocol was followed to prepare the dry electrode powder blend. More specifically, in S1-1, the three electrode components (NCM622, PTFE, and carbon) were first premixed in powder form in a rotating drum for 30 minutes for more uniform distribution. In S1-2, the preblended powder was processed in a twin-screw extruder at a temperature of 100° C., a throughput of 3 kg / h, and a screw speed of 400 rpm to disperse the carbon and fibrillated binder. Finally, the resulting electrode powder blend was in flake shape. In S1-3, the flake-like material obtained in S1-2 was post-processed in an IKA mill at 5000 rpm for 20 seconds with low shear to recover its powder morphology.

[0239] In S2, the powder electrode mixture obtained in S1 was passed through a vertical calender at 100 °C to obtain a free-standing film. The final dry electrode film thickness was in the range of 110–120 μm.

[0240] In S3, the free-standing electrode film obtained in S2 was laminated onto a carbon-coated aluminum foil current collector by calendering them together using a vertical hot roller calender preheated to 100 °C.

[0241] The electrode formulations used (labeled E1 and E2) are listed in Table F below. [Table 7]

[0242] Formulations E1, E2, and E3 produced flakes with a similar appearance to S1-2. Upon calendering (S2), only formulations E2 and E3 produced free-standing cathode films. The tensile strength and modulus for these films are shown in FIG. 7. Formulation E1 was unable to produce a free-standing film; rather, it collapsed before reaching the target thickness of 110 μm. As a result, it was not possible to fabricate a dry process electrode using formulation E1. This may indicate an overall preference for carbon additives such as CB 12, either in fluffy or pellet form, used as the processing particle in at least some dry process applications.

[0243] Example 6 The graphite electrodes in this example were prepared by the same method as in Example 3, except that in step (S2), the calendering was carried out in two steps at different temperatures. In one case, to produce a free-standing film for tensile testing, the powder blend obtained in S1 was first passed through a vertical calender at room temperature, followed by a second pass through a calender machine preheated to 80°C to obtain a free-standing film with a thickness of 250-280 μm. In another case, to prepare a dry-processed electrode for peel strength (adhesion) testing, the powder blend obtained in S1 was passed through a vertical calender preheated to 100°C as the first step, then through a vertical calender preheated to 80°C as the second step, and then the dry film was laminated onto a current collector by passing them together through a vertical calender preheated to 80°C.

[0244] The electrode formulations used (labeled F1-F4) are listed in Table F below. [Table 8]

[0245] All electrodes were prepared by dry process and contained 5 wt% loading of carbon additive, graphite (90 wt%) and binder (5 wt%). As can be seen in Table F, the free-standing electrode films prepared by dry process with fibrillable binder (see, e.g., PTFE), which is expected to stretch easily to form fibrils, also showed higher tensile strength than those in which the fibrillable PTFE binder was partially replaced with a non-fibrillable binder, i.e., PVDF (see, e.g., PTFE / PVDF ratios of 75:25 and 50:50 in formulations F2 and F3, respectively). Furthermore, formulations containing only non-fibrillable binders (see, e.g., PVDF) did not produce free-standing films and failed the first calender pass. On the other hand, partial replacement of PTFE with PVDF in the formulations improved the adhesion of the free-standing films to the current collector (see, e.g., formulations F3 and F1 in Table F for comparison). This supports the idea that while the presence of a fibrillizable binder enables dry process electrode formation, non-fibrillizable binders can be used to improve other electrode properties such as electrode adhesion to the current collector, first cycle irreversibility driven by PTFE performance on the anode side of the battery, to name a few.

[0246] Example 6 NCM electrodes with two different formulations were fabricated by dry and wet (slurry casting) processes and tested in 2032 half-coin cells.

[0247] The dry-processed NCM cathode, namely G1, was prepared by the same method as in Example 4.

[0248] The wet processed NCM cathode, i.e. G2, was fabricated following a two-step mixing process using a Thinky ARE310 planetary centrifugal mixer. The first step involved mixing the carbon conductive additive (CCA) / PVDF / NMP mill base with two small milling tungsten carbide (WC) media for 20 minutes (12 minutes of active mixing). After adding the NCM622 powder to the mill base, the second step involved mixing without media for another 20 minutes (12 minutes of active mixing). Both the NCM and CCA powders were pre-dried at 130°C for 20 minutes. The electrode slurry was coated onto 15 μm thick aluminum foil using an automatic doctor blade coater (Model MSK-AFA-III from MTI Corp.). The NMP was allowed to evaporate in a convection oven set at 80°C for 20 minutes and finally dried in a vacuum oven at approximately 100°C. The dry electrode loading on the Al foil was 24.4 mg / cm. 2 and was calendered on a manual roll press to a density of 3.4 g / cc.

[0249] The electrode formulations used (labeled G1 and G2, with G2 formulation prepared by a slurry (wet) process) and their properties are listed below in Table F. Electrode G2 used an electrode formulation and properties that are standard for NCM cathodes in EV applications and therefore served as the baseline. [Table 9]

[0250] Cathode G1 and G2 (from Table G) were tested in 2032 half coin cells. Disks with a diameter of 15 millimeters were punched for coin cell preparation and dried at 100°C under vacuum for a minimum of 4 hours. Disks were calendered to the desired density (shown in Table G) with a manual roll press and assembled into 2032 coin cells in an argon-filled glove box (M-Braun) for testing against lithium foil. A glass fiber microfilter (Whatman GF / A) was used as the separator. The electrolyte was 100 microliters of ethylene carbonate-dimethyl carbonate-ethyl methyl carbonate (EC-DMC-EMC), vinylene carbonate (VC) 1%, LiPF61M (BASF).

[0251] The reported capacities are normalized in mAh / g of active cathode mass. The room temperature (25° C.) performance of the half coin cells was measured by first forming them using two C / 5-D / 5 charge-discharge cycles, then charging at 1C rate and discharging at C / 5, 1C, 2C, and 3C discharge rates. The results (FIG. 8) showed that the dry processed G1 formulation had better or similar capacity at C-rates up to 1C (0.2C, 0.5C, and 1.0C) compared to the slurry processed benchmark formulation G2.

[0252] Example 7 Two sets of cathodes were prepared by the same dry and wet (slurry casting) processes as in Example 6. The electrode formulations used (labeled H1-H4, with H3 and H4 serving as wet-processed baselines for dry-processed H1 and H2, respectively) and the properties of the resulting cathodes are listed in Table H below. All cathodes were prepared using two different carbons, namely C12 and CB15, each with a carbon content of 3.9±0.2 mg / cm. 2 and 3.8±0.1 mg / cm 2 and contained a 1 wt% loading of carbon additive, NCM622 (96 wt%) and binder (3 wt%). [Table 10]

[0253] The cathodes, namely H1, H2, H3, and H4, were tested in 2032 full coin cells. Disks of 15 millimeter diameter were punched for coin cell preparation and dried at 100°C under vacuum for a minimum of 4 hours. The disks were calendered at the desired electrode density using a manual roll press and assembled into 2032 coin cells in an argon-filled glove box (M-Braun) and tested against a graphite anode containing 3% CB, 5% PVDF, 92% natural graphite. A Celgard filter was used as the separator. The electrolyte was 200 microliters of ethylene carbonate-dimethyl carbonate-ethyl methyl carbonate (EC-DMC-EMC), vinylene carbonate (VC) 1%, LiPF6 1M (BASF).

[0254] Cells of each formulation were fabricated and measured for initial C / 20 capacity and first cycle irreversible loss (FIGS. 9 and 10, respectively). The group of cells whose cathode formulation contained CB12 (from Tables 1A and 1B) and were fabricated by the dry process showed comparable discharge capacity and improved lower first cycle irreversible loss compared to those with wet process cathodes. The group of cells whose cathode formulation contained CB15 (from Tables 1A and 1B) and were fabricated by the dry process showed discharge capacity and first cycle irreversibility comparable to those with wet process cathodes in both cases. In both cases, the performance of the dry processed cathodes remained comparable or better than their wet processed counterparts, indicating that the dry process can replace the traditional slurry process without affecting the electrochemical performance of the battery.

[0255] Example 8 A dry processed NCM cathode containing 2 wt% CB, i.e. CB15 (from Tables 1A and 1B), NCM622 (94 wt%) and PTFE (4 wt%) was prepared by the same method as in Example 4 and tested in 2032 half coin cells as described in Example 6. The dry cathode had a 33.5 mg / cm 2 and 5.6mAh / cm 2 volume and calendered at 3.6 g / cc.

[0256] The cycling performance of the half coin cell was measured by charging at +25°C using a 1C charge rate and discharging at +25°C, using a C / 20 discharge rate for the first 5 cycles and a C / 10 discharge rate for the next 2 cycles, followed by extended cycling at C / 5. The discharge capacity measured during cycling was close to the theoretical capacity of NCM622, as shown in Figure 11.

[0257] While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention as encompassed by the appended claims.

Claims

1. A method for preparing an electrode composition, By combining active electrode material, binder, and multifunctional carbon black, This includes treating the binder in the presence of the carbon black, The above method is carried out without adding a solvent. The aforementioned multi-functional carbon black is 1600 m ２ It has a BET of 650 mL / 100 g or less and an OAN of 650 mL / 100 g or less. The aforementioned multi-functional carbon black has the following characteristics: Surface energy of 15 mJ / m² or less, Raman microcrystal plane size (La) of at least 17 Å, Mesopore volume of at least 0.35 cm³ / g, At least 1.0 cm³ / g total mesopore and macropore volume, and A method having one or more of the following: a % crystallinity of at least 22%.

2. The active electrode material is graphite, and the multifunctional carbon black is 35 to 1600 m ２ The method according to claim 1, wherein the BET is in the range of / g and the OAN is in the range of 120 to 650 mL / 100g.

3. The active electrode material is a lithium transition metal compound, and the carbon black is 80 to 1600 m ２ The method according to claim 1, wherein the BET is in the range of / g and the OAN is in the range of 120 to 650 mL / 100g.

4. The method according to any one of claims 1 to 3, wherein the method is carried out in the presence of the multifunctional carbon black as the sole fibrillation aid.

5. A method for preparing an electrode composition, By combining an active electrode material, a fibrillation-capable binder, and multifunctional carbon black, The method includes subjecting the fibrillable binder to a fibrillation operation in the presence of the multifunctional carbon black, The above method is carried out in the absence of a solvent. The aforementioned multi-functional carbon black is 1600 m ２ It has a BET of 650 mL / 100 g or less and an OAN of 650 mL / 100 g or less. The aforementioned multi-functional carbon black has the following characteristics: Surface energy of 15 mJ / m² or less, Raman microcrystal plane size (La) of at least 17 Å, Mesopore volume of at least 0.35 cm³ / g, At least 1.0 cm³ / g total mesopore and macropore volume, and A method having one or more of the following: a % crystallinity of at least 22%.

6. The active electrode material is graphite, and the multifunctional carbon black is 35 to 1600 m ２ The method according to claim 5, wherein the BET is in the range of / g and the OAN is in the range of 120 to 650 mL / 100g.

7. The active electrode material is a lithium transition metal compound, and the carbon black is 80 to 1600 m ２ The method according to claim 5, wherein the BET is in the range of / g and the OAN is in the range of 120 to 650 mL / 100g.

8. The method according to any one of claims 5 to 7, wherein the electrode composition contains 90% to 98% by weight of the active electrode material, 1% to 5% by weight of the fibrillable binder, and 0.3% to 5% by weight of the multifunctional carbon black.

9. A dry-processed film electrode comprising an active electrode material, a processed binder, and multifunctional carbon black, wherein the film electrode contains a solvent residue of 1% by weight or less relative to the theoretical weight of the film electrode, and the multifunctional carbon black is 1600 m ２ It has a BET of 650 mL / 100 g or less and an OAN of 650 mL / 100 g or less. The aforementioned multi-functional carbon black has the following characteristics: Surface energy of 15 mJ / m² or less, Raman microcrystal plane size (La) of at least 17 Å, Mesopore volume of at least 0.35 cm³ / g, At least 1.0 cm³ / g total mesopore and macropore volume, and A dry-processed film electrode having one or more of the following percentage crystallinity values: at least 22%.

10. The active electrode material is graphite, and the multifunctional carbon black is 35 to 1600 m ２ A dry-processed film electrode according to claim 9, having a BET in the range of / g and an OAN in the range of 120 to 650 mL / 100g.

11. The active electrode material is a lithium transition metal compound, and the carbon black has a BET within the range of 80 to 1600 m ２ / g and an OAN within the range of 120 to 650 mL / 100 g. The dry-processed film electrode according to claim 9.

12. The dry-treated film electrode according to any one of claims 9 to 11, wherein the multifunctional carbon black is the sole fibrillation aid in the film electrode.

13. A method for preparing an electrode composition, (a) Treating the binder by subjecting it to high shear conditions in the presence of multifunctional carbon black, (b) Adding an active electrode material before, during, or after step (a), The aforementioned multi-functional carbon black is 1500m ２ It has a BET of 650 mL / 100 g or less and an OAN of 650 mL / 100 g or less. The above method is carried out without adding a solvent. The aforementioned multi-functional carbon black has the following characteristics: Surface energy of 15 mJ / m² or less, Raman microcrystal plane size (La) of at least 17 Å, Mesopore volume of at least 0.35 cm³ / g, At least 1.0 cm³ / g total mesopore and macropore volume, and A method having one or more of the following: a % crystallinity of at least 22%.

14. The active electrode material is graphite, and the multifunctional carbon black is 35 to 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 120 to 650 mL / 100g.

15. The active electrode material is a lithium transition metal compound, and the carbon black is 80 to 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 120 to 650 mL / 100g.

16. The method according to any one of claims 13 to 15, wherein the method is carried out in the presence of the multifunctional carbon black as the sole fibrillation aid.

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