Method for manufacturing an aggregate of active battery material for electrodes, coated with a binder and having scattered conductors.

Abstract

A method for producing binder-coated active battery material aggregates comprises the step of stirring a predetermined amount of binder-solvent solution with a granular mixture containing active battery material particles in a container over two or more steps. The binder-solvent solution has a solubility limit in the first solvent solution for the binder material particle mixture under a first set of environmental parameters. While holding the granular mixture in the container, the granular mixture is subjected to conditions under a second set of environmental parameters over two or more steps, which reduces the solubility limit and produces a powder mixture of binder-coated active battery material aggregates.

Description

[Technical Field]

[0001] <Cross-reference with related applications> This application claims priority based on U.S. Patent Application No. 18 / 213,873 (Attorney Reference Number: PB23003-US), filed on 25 June 2023 and issued on 7 May 2024 as U.S. Patent No. 11,978,908, with the title "Method for Manufacturing Active Battery Material Aggregates Having Binder-Coated Spotted Conductors for Electrodes."

[0002] This application also claims priority to U.S. Patent Application No. 18 / 655,406 (Attorney Reference Number: PB23003-US1), filed on 6 May 2024 as a continuation of U.S. Patent Application No. 18 / 213,873, with the title "Method for Manufacturing Active Cell Material Aggregates Having Binder-Coated Spotted Conductors for Electrodes." U.S. Patent Applications No. 18 / 213,873 and No. 18 / 655,406 are incorporated herein by reference in their entirety. [Background technology]

[0003] Innovation in portable electronic devices is focused on efficient energy storage as portable systems, as portable devices such as smartphones, laptops, and smart health devices become smaller while their energy demands increase. Electrochemical storage and conversion devices are expanding the potential of these systems in various fields, such as portable electronic devices, aerospace technology, passenger and freight vehicles, and biomedical devices. Electrochemical storage and conversion devices have designs and performance characteristics specifically engineered to suit a wide range of application requirements and operating environments. [Overview of the project] [Means for solving the problem]

[0004] This disclosure can be better understood by referring to the accompanying drawings, and many of its features and advantages will be apparent to those skilled in the art. The use of the same reference numerals in other drawings indicates similar or identical items. [Brief explanation of the drawing]

[0005] [Figure 1] Figure 1 shows a method for manufacturing a subunit of active battery material granules having a binder-coated spotted conductor, according to one embodiment. [Modes for carrying out the invention]

[0006] In the ever-expanding range of applications, there is significant pressure to expand the functionality of energy storage and conversion devices, such as batteries, fuel cells, and electrochemical capacitors. Continuous development has created a demand for mechanically robust, reliable, and high-energy-density electrochemical storage and conversion devices that enable good performance in the useful range of operating environments. Many recent advances in electrochemical storage technology are due to the fabrication and integration of novel materials for device components. Battery technology, for example, continues to evolve rapidly, at least in part, through the development of electrodes and electrode materials for these systems.

[0007] Conventional electrode fabrication often involves a solvent-based approach that includes the step of mixing several key components to form a slurry. These components include active cell material, conductive agent, polymer binder, and solvent. Active cell material is the substance in the battery that participates in the electrochemical reaction that generates electric current. In lithium-ion batteries, for example, the active cell material in the positive electrode (cathode) is often lithium metal oxide, while the active cell material in the negative electrode (anode) is usually graphite. Conductive agents, also known as conductive additives, are materials added to electrodes to improve their electrical conductivity. Common conductive agents include carbon black, graphite, carbon nanotubes, and graphene. Polymer binders are used to hold active cell material particles together and adhere them to the current collector. They impart mechanical strength and flexibility to the electrode. Common polymer binders include polyvinylidene fluoride (PVDF) and carboxymethylcellulose (CMC). Solvents are used to dissolve the polymer binder and form a slurry that can be easily applied to the current collector. After the slurry is applied, the solvent evaporates, leaving a solid electrode. Typical solvents include N-methyl-2-pyrrolidone (NMP) and water. During the mixing process, the polymer binder, which is pre-dissolved in the solvent, flows around the active cell material and conductive particles to partially coat them. The resulting slurry is cast onto a metal current collector and dried to evaporate the solvent, resulting in the formation of a porous electrode. The solvent evaporation step forms a dry porous electrode, but the substantial number of heating and drying steps include the solvent evaporation step and the step of curing and bonding the active cell material on the metal current collector.

[0008] Conventional electrode manufacturing methods include solvent recovery systems to recover evaporated solvent during the drying process, due to the high cost and potential for contamination of conventional solvents. While cheaper and more environmentally friendly solvents, such as aqueous-based slurries, can reduce the costs associated with recovery systems, electrodes may still require a time-consuming and energy-intensive drying process. Furthermore, while the use of water as a solvent for the positive electrode (cathode) or negative electrode (anode) offers many advantages, it also presents significant challenges. In particular, the use of water is limited by its reactivity with electrochemical materials (e.g., lithium metal).

[0009] To address the challenges associated with conventional electrode manufacturing processes, the method described in Figure 1 significantly reduces the amount of solvent required for the binder dispersion and coating of the active cell material particles. In one embodiment, the presented method for producing binder-coated active cell material aggregates comprises the following steps: First, a mixture of binder material particles is dissolved in a solvent solution under a specific set of environmental parameters. These parameters include heating, pressure, and time exceeding standard ambient conditions, resulting in a binder-solvent solution. Next, this binder-solvent solution is stirred with a granular mixture containing active cell material particles while maintaining the aforementioned environmental parameters. Finally, this intermediate solution is placed under a second set of environmental parameters, different from the first set, to produce a powder mixture. This second set of parameters also includes specific temperature, pressure, and time conditions. The resulting powder mixture comprises binder-coated active cell material aggregates, each containing one or more types of active cell material particles partially coated with at least the binder material. Using active battery materials coated with this binder in dry electrode manufacturing provides a more efficient and environmentally friendly approach, reducing the need for solvent recovery systems and the associated costs and potential contamination.

[0010] Figure 1 is a block diagram of a method 100 for manufacturing a subunit of a binder-coated conductor-speckled battery material particulate according to some embodiments. For the purposes of this disclosure, the term “binder-coated conductor-speckled battery material particulate” refers to composite particles comprising battery material particles that are speckled with conductive particles or have conductive particles scattered throughout. These conductive particles enhance the electrical conductivity of the battery material particles, facilitating the flow of current during battery operation. In the context of this application, the term “binder-coated battery material” is used to refer to materials in a battery cell that participate in electrochemical reactions and contribute to the energy storage capacity of the battery. Examples of active battery materials include, but are not limited to, lithium iron phosphate (LFP), lithium nickel manganese cobalt oxide (NMC), lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium titanate (LTO), lithium nickel cobalt aluminum oxide (NCA), synthetic graphite granules, natural graphite granules, Si nanocomposites, silicon graphite composites, silicon porous carbon composites, LiTiO2, and Li4Ti5O2. 12Examples include Sn granules and SiOx / Si granules. This list is not exclusive and should be understood to include other active battery materials known or to be developed in the present technology. For the purposes of this disclosure, the terms: particle, granules, granular subunit, primary particle, microsphere, aggregate and aggregate are used in accordance with the definitions given in the National Institute of Standards and Technology (NIST) publication titled "The Use of Nomenclature in Dispersion Science and Technology," published in August 2001 as NIST Special Publications 945 and 946, which provides guidelines for the use of technical and scientific nomenclature with respect to ceramic dispersions, and the entirety of that disclosure is incorporated herein by reference.

[0011] Method 100 begins with block 102, in which a mixture of binder material particles is dissolved in a solvent solution under the application of a first set of environmental parameters, which includes at least one of heating or pressurizing above ambient conditions, to form a binder-solvent solution. The solubility limit of this solution represents the maximum amount of binder material particles that can be dissolved in the solvent under the environmental conditions of the first set of environmental parameters, but is higher than under standard conditions. Herein, binder material particles include materials that are promising in this application in various embodiments. These materials include polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), polytetrafluoroethylene (PTFE), polyimide, ethylene-propylene-diene monomer (EPDM), poly(acrylic acid-co-maleic acid) (PAA-MA), poly(acrylic acid-co-itaconic acid) (PAA-IA), partially or completely fluorinated polymers and copolymers, poly(acrylic acid) (PAA), lithified poly(acrylic acid) (lithified-PAA), carboxymethylcellulose (CMC), sodium carboxymethylcellulose (NaCMC), and styrene-butadiene rubber (SBR). When multiple types of binders are used, the melting and softening points of each binder in the binder system may be the same or different. In some embodiments, the mixture of binder material particles includes a binder solution which is a commercially available dispersion or emulsion containing binder granules dispersed in a solution.

[0012] The solvent solution, in various embodiments, includes one or more solvents, such as solutions of dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), or dimethylacetamide (DMAc), triethyl phosphate (TEP), dihydrolevoglucocenone (Syrene), tributyl acetylcitrate (ATBC), acetone, tetrahydrofuran (THF), difluoromethane (CH2F2), ethanol, methanol, water, and carbon dioxide.

[0013] As will be apparent to those skilled in the art, in many cases it is difficult to completely dissolve binder material particles in a large amount of solvent under normal room ambient conditions (e.g., a temperature range of 20°C to 25°C and an absolute pressure of 1 bar, as is typical of standard [or normal] temperatures and pressures as usually defined by NIST) without further stirring or increasing the temperature and / or pressure at which the binder material particles and solvent solution are mixed together.

[0014] Accordingly, block 102 includes a step of dissolving a mixture of binder material particles in a solvent solution under the application of a first set of environmental parameters that increase the solubility limit (relative to standard temperature and pressure), thereby enabling an increase in the maximum amount of binder material particles that can be dissolved in the solvent solution. These parameters include heating, pressure, and time above standard ambient conditions, and include at least one of heating or pressurizing above ambient conditions for producing a binder-solvent solution. In one embodiment, the first set of environmental parameters includes a high temperature above standard room temperature. As used herein, the term “solubility limit” refers to the total amount of solute (e.g., binder material) that can be dissolved in a volume of solution such that the solution is completely saturated and the solution does not dissolve any additional solute. For example, in one embodiment, at standard temperature and pressure, only volume X of binder material particles can be dissolved in 1.0 liter of solvent solution. By increasing the temperature and / or pressure, a larger amount of binder material particles, denoted by Y (where Y > X), can be dissolved in the same volume of solvent solution.

[0015] In one embodiment, a mixture of PVDF dissolves completely in a NMP solution at a temperature range of 30°C to 40°C at room atmospheric pressure. In another embodiment, the first set of environmental parameters includes standard room temperature while increasing the pressure in the container in which the binder material particles are mixed with the solvent solution. In yet another embodiment, the first set of environmental parameters includes both a temperature above standard room temperature and a high pressure in the container in which the binder material particles are mixed with the solvent solution. For example, in various embodiments, ethanol is included in the solvent solution of block 102. However, those skilled in the art may recognize that under normal room ambient conditions, ethanol does not dissolve many binder material particles (e.g., PVDF). To counteract this problem, in various embodiments, the operation of block 102 dissolves the PVDF in ethanol by increasing the temperature and pressure of the container (e.g., a closed container) to about 200°C at 100 bar. This process successfully dissolves the binder material particles in the solvent, producing a binder-solvent solution suitable for the next step of the process. Other liquid solvents that enable the dissolution of binder material particles under specific temperature and pressure conditions include, but are not limited to, methanol and acetone.

[0016] In other embodiments, gaseous solvents, such as carbon dioxide, can also be used as supercritical solvents to dissolve binder material particles. Under standard conditions, carbon dioxide exists as a gas. However, when both temperature and pressure rise above their critical points (critical temperature: 31.1°C, critical pressure: 73.8 atm), carbon dioxide transitions to a supercritical fluid state. This state exhibits unique properties, behaving like a gas while filling its container while maintaining a density equivalent to that of a liquid. This supercritical carbon dioxide (sCO2) can effectively dissolve certain binder material particles. For example, PVDF can dissolve in sCO2 under conditions of approximately 170°C and 1650 bar. In other embodiments, the solvent solution includes a subcritical solvent under subcritical conditions of that solvent.

[0017] In some embodiments, the operation of block 102 includes the addition of a co-solvent to the solvent solution, which can effectively reduce the temperature and pressure requirements for dissolving the binder material particles. For example, when a co-solvent of 38% ethanol is added to the solvent solution of pure supercritical CO2 (sCO2), the conditions required to dissolve PVDF are reduced from approximately 170 °C and 1650 bar to approximately 170 °C and 600 bar. It should be noted that in this specification, among other co-solvents, for example, acetone, dimethoxyethane (DME), and water can also be used. Although the use of co-solvents is described in this specification in relation to sCO2, the principle of reducing the temperature and / or pressure requirements by using co-solvents is also applicable to other major solvents, such as N-methyl-2-pyrrolidone (NMP).

[0018] In various embodiments, the binder-solvent solution contains 10 to 30 mass% of dissolved binder material particles. In some embodiments, the binder material particles are at least about 1 mass% of the binder-solvent solution, at least about 5 mass% of the binder-solvent solution, optionally at least about 10 mass% of the binder-solvent solution, optionally at least about 20 mass% of the binder-solvent solution, optionally at least about 30 mass% of the binder-solvent solution, and in some variations, optionally at least about 40 mass% of the binder-solvent solution. As would be recognized by those skilled in the art, the viscosity of the binder-solvent solution increases as the mass percentage of the binder material particles increases. Therefore, there is a certain threshold where it is no longer desirable to further increase the binder material content of the binder-solvent solution because the viscosity becomes too high for further processing. However, this binder-solvent solution still uses significantly less solvent per unit of binder material compared to conventional solvent slurries.

[0019] Referring now to block 104, method 100 continues by agitating a binder-solvent solution with a granular mixture containing active battery material particles while maintaining a first set of environmental parameters. This agitation process can be achieved by methods such as stirring, shaking, or ultrasonic vibration, etc., which helps ensure a uniform dispersion of the active battery material particles in the binder-solvent solution and leads to the formation of an intermediate solution. The active battery material particles can include one or more cathode materials, such as LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi x Mn 2-x O4, LiFePO4, LiMnPO4, LiCoPO4, LiFe x Mn 1-x PO4, LiNi x Mn y Co 1-x-y O2, Li 1+x Ni y Mn z Co 1-x-y-z O2, LiNi x Mn y Co z Al 1-x-y-z O2, and Li 1+x Ni y Mn 1-x Co z O2. In some cases, these active battery material particles may be coated with carbon or otherwise treated to enhance their performance. Alternatively, the active battery material particles can include one or more anode materials, such as synthetic graphite granules, natural graphite granules, Si nanocomposites, LiTiO2, Li4Ti5O 12 , Sn granules, and SiOx / Si granules.

[0020] In some embodiments, the operation of block 104 includes mechanically stirring the active battery material particles in a binder-solvent solution by subjecting the binder-solvent solution to high-shear mixing, sonication, or any other suitable method of uniformly dispersing the active battery material particles in the binder-solvent solution to produce an intermediate solution. In some embodiments, the active battery material particles comprise at least about 10 wt% of the intermediate solution, optionally at least about 20 wt% of the intermediate solution, optionally at least about 30 wt% of the intermediate solution, optionally at least about 40 wt% of the intermediate solution, optionally at least about 50 wt% of the intermediate solution, optionally at least about 60 wt% of the intermediate solution, optionally at least about 70 wt% of the intermediate solution, optionally at least about 80 wt% of the intermediate solution, and in one variation, optionally at least about 90 wt% of the intermediate solution.

[0021] In some embodiments, the active cell material particles include active cell material composite particles or granular subunits having spotted conductors (dispersed conductors). These are produced by stirring a granular mixture containing both active cell material particles and conductive particles, resulting in a mixture of active cell material granular subunits having spotted conductors (dispersed conductors). These subunits consist of one or more types of active cell material particles having spotted conductors (dispersed conductors) and are held together by electrostatic force. Each of these particles enhances the overall electrical conductivity of the structure by containing multiple conductive particles in electrical contact with the active cell material particles. The operation in block 104 includes a step of mechanically stirring the mixture using a method such as high-shear mixing to uniformly disperse the conductive particles among the active cell material particles. The conductive particles may include carbon additives, such as C65 carbon black, C45 carbon black, Super P carbon black, acetylene black, Ketjenblack carbon black, carbon nanotubes, graphene, carbon nanofibers, and carbon fibers. In various embodiments, each active battery material particle having spotted conductors (dispersed conductors) includes a plurality of conductive particles that are in electrical contact with the active battery material particle.

[0022] In one embodiment, the operation of block 104 includes stirring a dry powder mixture of conductive particles and active cell material particles to produce a powder mixture of subunits of active cell material granules having spotted conductors (dispersed conductors). In another embodiment, the operation of block 104 includes stirring a dry powder mixture of active cell material particles in a conductive particle solution in which the solution is a dispersion of conductive particles in a liquid medium. For example, in some embodiments, block 104 includes stirring conductive particles in a solution by any other preferred method of high-shear mixing, sonication, or breaking down conductive particle aggregates into constituent particles or at least smaller aggregates, and / or uniformly dispersing the conductive particles in the solution. In other embodiments, the conductive particle solution is prepared by introducing a wetting agent into a dry powder mixture of conductive particles. After wetting the dry powder mixture of conductive particles, block 104 proceeds with a step of stirring the wet conductive particles in a certain amount of solution (e.g., water, ethanol) by any other suitable method, such as high-shear mixing, sonication, or uniform dispersion of the conductive particles in the solution.

[0023] Next, a dry powder mixture of active cell material particles is introduced into a conductive particle solution. In other embodiments, the operation in block 104 includes stirring together an active cell material solution, in which the solution is a dispersion of active cell material particles in a liquid medium, with a conductive particle solution to produce a mixture of subunits of active cell material granules having spotted conductors (dispersed conductors). Method 100 then follows the step of stirring the active cell material particles and conductive particles in a binder solution. In one embodiment, the binder solution is a commercially available dispersion or emulsion containing binder granules dispersed in a solution. In another embodiment, the binder solution is prepared by introducing a wetting agent into a dry powder mixture of binder granules. After wetting the dry powder mixture of binder granules, block 104 proceeds with a step of stirring the wetted binder granules in a certain amount of solution (e.g., water, ethanol) by any other preferred method, such as high-shear mixing, ultrasonic treatment, or uniform dispersion of the binder granules in the solution.

[0024] The method for preparing the intermediate solution can be achieved by several specific embodiments, each resulting in a solution containing binder material particles, active cell material particles, and uniformly dispersed conductive particles. The first embodiment involves mixing a mixture of active cell material particles having spotted conductors (dispersed conductors) with a binder-solvent solution. The second embodiment involves a two-step process in which a dry mixture of active cell material particles is first stirred in the binder-solvent solution, and then a dry mixture of conductive particles is added. This order prioritizes the dispersion of active cell material particles in the binder-solvent solution before the conductive particles are introduced. The third embodiment also involves a two-step process, but in this case, the dry mixture of conductive particles is stirred in the binder-solvent solution before the dry mixture of active cell material particles is added. This order prioritizes the dispersion of conductive particles in the binder-solvent solution before the active cell material particles are introduced. A fourth embodiment includes a step of mixing the binder material, active cell material, and conductive particles with the solvent solution before applying the first set of environmental parameters. These particular embodiments provide flexibility to the manufacturing process and allow for adjustments based on the specific properties of the materials used and the desired characteristics of the final product.

[0025] In another embodiment, the method involves stirring a dry mixture of active cell material particles in a binder-solvent solution before introducing a solution of conductive particles. This sequence ensures that the active cell material particles are well dispersed in the binder-solvent solution before the conductive particles are added. Alternatively, in some embodiments, the conductive particle solution is stirred in the binder-solvent solution before adding a dry mixture of active cell material particles. This sequence prioritizes the dispersion of the conductive particles in the binder-solvent solution before the active cell material particles are introduced. In some cases, the process may involve bringing the active cell material particles into contact with water. It is important to note that some active cell materials, such as coated LFPs (e.g., carbon-coated LFPs) and lower nickel NMCs (e.g., NMC111, as opposed to the relatively sensitive NMC811 and NMC9055), exhibit greater resistance to potentially harmful effects when exposed to water.

[0026] The method proceeds to step 106, in which the intermediate solution is subjected to a second set of environmental parameters, specifically, temperature, pressure, and time conditions that reduce the solubility limit of a given binder in the intermediate solution, thereby generating a powder mixture of binder-coated active cell material aggregates. This second set of environmental parameters may involve a decrease in pressure while maintaining a constant temperature (a process known as isothermal expansion), a decrease in temperature while maintaining a constant pressure (also called isobaric cooling), or a controlled decrease in both pressure and temperature. For example, in a particular embodiment, the second set of environmental parameters involves an increase in temperature compared to the first set of environmental parameters, facilitating the evaporation of the contained solvent from the intermediate solution. In this particular case, the step of raising the temperature to 180°C at room pressure is sufficient to evaporate almost all of the NMP in the intermediate solution.

[0027] As previously described, in one embodiment, only a maximum amount X of binder material particles dissolves in 1.0 liter of solvent solution at standard temperature and pressure. Any amount Y > X of binder material particles will dissolve in the same 1.0 liter of solvent solution as the temperature and / or pressure are increased. Conversely, decreasing the temperature and / or pressure will decrease the solubility limit of a given binder in the solution. Furthermore, it will be understood that changing the total volume of the solution will not change the solubility limit, but will change the absolute amount of binder that can be dissolved. For example, since the solubility limit of binder per unit volume of solvent is the same under a given set of environmental parameters (e.g., standard room temperature and pressure), halving the amount of solvent from 1.0 liter to 0.5 liter will reduce the maximum amount of binder soluble in the solution from X to X / 2.

[0028] In this method, in another specific embodiment, a second set of environmental parameters may involve a decrease in pressure in a container containing the intermediate solution. In this case, evaporation of the solvent from the intermediate solution is facilitated, for example, under vacuum conditions, when the container is sealed and the pressure is reduced. This pressure reduction allows the liquid solvent to vaporize and evaporate at a temperature lower than the temperature at atmospheric pressure. In yet another specific embodiment, the second set of environmental parameters may involve both a temperature change, e.g., rising above standard room temperature, and a pressure decrease, potentially below atmospheric pressure, in the container containing the intermediate solution. This combination of parameters facilitates the evaporation of the solvent at lower temperatures due to the reduced pressure.

[0029] In certain embodiments, the process includes a step of mechanically stirring the intermediate solution to ensure uniform dispersion of the binder granules and active battery material particles during the evaporation phase. As evaporation reduces the liquid content of the solvent, the viscosity of the remaining intermediate solution increases. As the liquid content decreases, it becomes important to maintain or further increase the level of mechanical stirring in the intermediate solution. This continuous particle movement prevents preferential sedimentation that may occur due to the different densities of the constituent particles.

[0030] In various embodiments, after all remaining solvent has evaporated, the intermediate solution is dried to a powder mixture of binder-coated active cell material aggregates. Each binder-coated active cell material aggregate contains one or more active cell material particles having at least a partial coating of the binder material. Such aggregates can be mechanically processed (e.g., finely ground and pulverized) in various embodiments to produce a finer powder mixture.

[0031] In certain embodiments, method 100 is followed by an optional step in block 108 in which the binder-coated cellular material aggregates are mixed with additional components. This step may be necessary if the cellular material particles having spotted conductors (dispersed conductors) are not mixed with the binder-solvent solution in the operation of block 106. The mixing process in block 108 involves stirring a granular mixture containing the binder-coated cellular material aggregates and conductive particles to produce a mixture of subunits of cellular material granules having binder-coated spotted conductors (dispersed conductors). This process uniformly disperses the conductive particles among the cellular material particles using mechanical stirring, high-shear mixing, or any other preferred method. In various embodiments, each of the cellular material particles having spotted conductors (i.e., cellular material particles with scattered conductors) contains multiple conductive particles that are electrically in contact with the cellular material particles.

[0032] In this technology, it is well known that binder particles tend to form clumps together. The application of pure mechanical force is often insufficient to break these clumps into their constituent particles before heating the binder material to a temperature (e.g., approximately 170°C for PVDF) where it becomes difficult to flex and separate into even smaller particle sizes. However, the process outlined in block 108 produces a powder in which one or more conductive particles are positioned between binder-coated active material particles. The presence of these conductive particle additives reduces the degree of cohesion by weakening the interparticle forces between the binder particles through the introduction of space, resulting in a powder mixture consisting of active cell material aggregates having binder-coated speckled (dispersed) conductors. In one embodiment, the process in block 108 includes a step of cooling the granular mixture during mechanical stirring. This step is important to prevent the binder material from being heated to a temperature where they begin to flex and cohere.

[0033] In some embodiments, the primary particles of the active battery material comprise a powder mixture of subunits of granular active battery material having spotted conductors, comprising approximately 10% by mass or more of the powder mixture aggregate, optionally, possibly approximately 20% by mass or more of the powder mixture aggregate, optionally, possibly approximately 30% by mass or more of the powder mixture aggregate, optionally, possibly approximately 40% by mass or more of the powder mixture aggregate, optionally, possibly approximately 50% by mass or more of the powder mixture aggregate, optionally, possibly approximately 60% by mass or more of the powder mixture aggregate, optionally, possibly approximately 70% by mass or more of the powder mixture aggregate, optionally, possibly approximately 80% by mass or more of the powder mixture aggregate, optionally, possibly approximately 90% by mass or more of the powder mixture aggregate, optionally, possibly approximately 95% by mass or more of the powder mixture aggregate, and in some variations, optionally, possibly approximately 96% by mass or more of the powder mixture aggregate. This flexibility of the composition allows for the optimization of the powder mixture aggregate for various applications.

[0034] In various embodiments, the method also includes an optional step of adding an additional amount of conductive particles to a mixture of active cell material assemblies having speckled conductors (dispersed conductors). This additional step can be performed at any stage of the method, but serves to improve the mass composition and overall conductivity of the mixture. Furthermore, this addition of conductive particles can be performed multiple times at different stages of the method, providing flexibility in optimizing the conductivity of the mixture.

[0035] For the sake of illustration and explanation, Figure 1 is shown above in relation to single-step evaporation; however, those skilled in the art will recognize that the method of Figure 1 may include any number of mixing and evaporation steps without departing from the scope of the disclosure. Active cell material aggregates having spotted conductors (dispersed conductors) can be produced, without departing from the scope of the disclosure, by multi-step evaporation with changes in the amount of solvent solution over any number of mixing and evaporation steps, according to some embodiments.

[0036] For example, in various embodiments, the operation of block 104 includes the step of producing a first intermediate mixture by stirring a first amount of a binder-solvent solution, less than the total amount, in a container with a granular mixture containing active cell material particles. The stirring may include the step of spraying, misting, atomizing, micronizing, or pumping the first amount of binder-solvent solution into the container and onto the granular mixture. For example, in some embodiments, the step of spraying, misting, atomizing, micronizing, or pumping the binder-solvent solution occurs while the granular mixture is being stirred, for example, by rotation or mixing, or otherwise moving around in the container. While holding the first intermediate mixture in the container, the first intermediate mixture is subjected to a second set of environmental parameters (e.g., temperature, pressure, or time) that reduces the solubility limit of a given binder in the first intermediate mixture to produce a second intermediate mixture. This second set of environmental parameters may involve a decrease in pressure while maintaining a constant temperature (a process known as isothermal expansion), a decrease in temperature while maintaining a constant pressure (also called isobaric cooling), or a controlled decrease or increase in both pressure and temperature (either individually or simultaneously). For example, in a particular embodiment, the second set of environmental parameters involves an increase in temperature compared to the first set of environmental parameters, which facilitates the evaporation of the contained solvent from the first intermediate solution. In this particular case, raising the temperature to approximately 180°C at room pressure is sufficient to evaporate almost all of the NMP in the first intermediate solution.

[0037] After the solvent is evaporated from the first intermediate solution, the resulting mixture (i.e., the second intermediate mixture) contains binder granules dispersed among one or more types of active material particles, the binder granules present in the resulting mixture of binder-coated active battery material aggregates in a first mass percentage of the resulting mixture. Next, the resulting mixture (i.e., the second intermediate mixture) is introduced into a second amount, which is at least a portion of the total amount of the remaining binder-solvent solution, by stirring the second amount of binder-solvent solution with the second intermediate mixture while holding the second intermediate mixture in a container, thereby producing a third intermediate mixture.

[0038] While holding the third intermediate mixture in a container, the third intermediate mixture is subjected to a second set of environmental parameters (e.g., temperature, pressure, or time) that reduces the solubility limit of a given binder in the third intermediate mixture, thereby generating a powder mixture of binder-coated active cell material aggregates. After evaporating and removing the solvent from the third intermediate solution, the resulting mixture (i.e., powder mixture) contains binder-coated active cell material aggregates, each containing one or more active cell material particles at least partially coated with the binder material, wherein the binder granules are present in the resulting mixture of binder-coated active cell material aggregates in a second mass percentage of the mixture. As will be understood by those skilled in the art, the second percentage of binder granules is higher than the first mass percentage.

[0039] For example, in one embodiment, multi-step (multi-stage) evaporation is two-stage evaporation, in which activated battery material particles are introduced into the first half of the binder-solvent solution, and that first half is evaporated and removed before the remaining half of the total volume of the binder-solvent solution is introduced. However, those skilled in the art will recognize that the method of Figure 1 may include any number of mixing and evaporation steps without departing from the scope of the present disclosure. Furthermore, it should be recognized that the method of Figure 1 may also include changing the volume of the binder-solvent solution between any number of mixing and evaporation steps without departing from the scope of the present disclosure. For example, in another embodiment, the multi-step evaporation is a three-step evaporation, the first step comprising mixing active battery material particles with 50% of the total volume of the binder-solvent solution and evaporating it; the second step comprising mixing the resulting mixture with 25% of the total volume of the binder-solvent solution and evaporating it; and the third step comprising mixing the mixture obtained from the second step with 25% of the total volume of the binder-solvent solution and evaporating it.

[0040] In another embodiment, multi-step evaporation is a continuous evaporation process in which a small amount of the total amount of binder-solvent solution is mixed with the active cell material particles and evaporated and removed from there approximately simultaneously. Control of the solvent evaporation rate can be achieved by evaporating the solvent from the mixture at a rate that approximately matches the desired rate at which the binder-solvent solution is introduced into the mixture. This evaporation can be carried out using techniques known in the art. Evaporation can be carried out under atmospheric pressure or reduced pressure conditions, and at ambient temperature or higher, but at a temperature that does not decompose the constituent particles. As will be understood, the pressure and / or temperature selected depends on the solvent, polymer, and / or other constituent materials present in the powder mixture and binder solution, as well as the relative amounts of these materials. Therefore, the graph (chart) of the mass percentage of binder granules over time in the resulting mixture of binder-coated active battery material aggregates appears more like a slope or curve (for example, depending on whether the introduction rate and evaporation rate of the binder solution change over time) associated with continuous evaporation, rather than a stepwise shape associated with the batch-type, multi-step evaporation process described above.

[0041] In some embodiments, the conductive particle mixture is dispersed in a first-volume binder-solvent solution and a second-volume binder-solvent solution before stirring with the granular mixture (with or without the use of a dispersant). In other embodiments, the conductive particle mixture is dispersed in a second solvent solution (with or without the use of a dispersant) to produce a conductive dispersion having a certain dispersion limit for the conductive particle mixture in the second solvent solution under a first set of environmental parameters.

[0042] The conductive dispersion is introduced to the active battery material particles by stirring a first amount of the conductive dispersion with the first intermediate mixture while holding the first intermediate mixture in a container, and then, while holding the first intermediate mixture in a container, placing the first intermediate mixture under the conditions of a second set of environmental parameters, and then distillation is performed. In one embodiment, this includes the step of stirring a first amount of conductive dispersion with the granular mixture in a container, and before stirring the first amount of binder-solvent solution and a second amount of binder-solvent solution with the granular mixture, to produce a fourth intermediate mixture. The solvent is distilled off by placing the fourth intermediate mixture under the conditions of a second set of environmental parameters while holding the fourth intermediate mixture in a container.

[0043] In another embodiment, this includes the step of stirring a solution of at least a first amount of binder-solvent, followed by stirring a first amount of conductive dispersion with a third intermediate mixture to produce a fifth intermediate mixture. While holding the fifth intermediate mixture in a container, the solvent is distilled off the fifth intermediate mixture under the conditions of a second set of environmental parameters. In yet another embodiment, a solution of first amount of binder-solvent and a first amount of conductive dispersion are stirred substantially simultaneously in a container with a granular mixture to produce a first intermediate mixture. While holding the first intermediate mixture in a container, the solvent is distilled off the first intermediate mixture under the conditions of a second set of environmental parameters.

[0044] In another embodiment, the step of agitating the first amount includes spraying, misting, atomizing, or pumping the first amount of binder-solvent solution into a container and onto the granular mixture. Instead of the binder-solvent solution, a conductive solvent solution may be used, or a conductive binder-solvent solution may be used. In some embodiments, the spraying, misting, atomizing, or pumping steps are carried out by using a pure hydraulic single-fluid system. In other embodiments, a two-fluid nozzle design may be used to achieve agitation, in which case one of the fluids is a compressed gas or a compressed inert gas, such as argon or nitrogen.

[0045] In some embodiments, activator material aggregates having binder-coated spotted conductors (dispersed conductors) are further reduced in size or compressed to achieve denser aggregates. These additional compaction or compression steps may be separate or sequential processes. Additional grinding or particle size adjustment steps help to further increase the density of the aggregates in some embodiments. In yet another embodiment, hot or cold isostatic pressing (HIP) or cold isostatic pressing (CIP) helps to achieve the same result as denser aggregates. Mechanical mixing steps, with or without specific compression aids or flow enhancers, may help to further increase the density of the aggregates.

[0046] Thus, the various embodiments described herein provide a dry powder-based manufacturing method for producing active cell materials having binder-coated speckled conductors (dispersed conductors). This method significantly reduces the amount of solvent required for binder dispersion and coating around the active cell material particles. This is achieved by eliminating the need for an excess amount of solvent to maintain viscosity, which is associated with the conventional application of solvent slurries onto current collector foil. In other words, this dry electrode manufacturing process eliminates the use of solvent for binder dispersion, which is required for adhesion to the current collector foil. The application of temperature and / or pressure changes during the production of binder-coated active cell material aggregates allows for the use of solvents that were previously unusable for electrode production, such as ethanol, methanol, and environmentally friendly solvents such as supercritical CO2. Furthermore, the production of electrodes using the dry powder mixture of this disclosure results in a more cost-effective process. This is because the slurry is stable over long periods and eliminates the need for equipment to feed the slurry throughout multiple systems for the coating and drying processes. Essentially, this method provides a more efficient, environmentally friendly, and cost-effective approach to the production of active battery materials having binder-coated speckled conductors (dispersed conductors) for use in lithium-ion batteries, for a variety of applications, including but not limited to the following.

[0047] Thus, this disclosure substantially addresses the limitations of conventional electrode formation by introducing a manufacturing process based on dry powder for active cell materials having binder-coated speckled conductors (i.e., conductor-speckled). This process significantly reduces the number of heating and drying cycles characteristic of electrode manufacturing processes, along with the amount of solvent required. Electrodes manufactured by coating a current collector with dry particles, for example, subunits of active cell material granules having binder-coated speckled conductors (conductor-speckled) as described in this disclosure, demonstrate a significant improvement in the manufacturing process. This method not only increases the efficiency of electrode manufacturing but also contributes to the overall performance and long lifespan of the resulting battery components.

[0048] Throughout this disclosure, numerical values ​​represent approximate values ​​or limits of a range, encompassing ranges that include minor deviations from a given value, and embodiments that have the exact value mentioned, as well as embodiments that have the approximate value mentioned. Except for the embodiments shown at the end of the embodiments for carrying out the invention, all numerical values ​​of parameters (e.g., quantities or conditions) described herein (including the appended claims) are understood in all cases to be modified by "about," whether or not the term "about" is actually preceded by the numerical value. "About" means to allow for some degree of inaccuracy in the stated numerical value (i.e., a value that is roughly close to or reasonably approximates the value, approximately the value). Where "about" is not understood in this ordinary sense in the art, "about" in this disclosure means to allow for at least the variation that may occur by the ordinary methods of measuring or using the parameter. For example, "about" may include fluctuations of 5% or less, optionally 4% or less, optionally 3% or less, optionally 2% or less, optionally 1% or less, optionally 0.5% or less, and in certain aspects optionally 0.1% or less. Furthermore, the disclosure of a range includes all values ​​within that entire range and disclosures of further subdivided ranges, including the endpoints and sub-ranges of a given range.

[0049] It should be noted that not all operations and components described in the general description above are mandatory, and that certain operations or parts of the apparatus may be unnecessary. Furthermore, one or more additional operations or components may be performed in addition to those described. Moreover, the order in which the operations are listed does not necessarily indicate the order in which they are performed. Also, the concepts of this disclosure are described based on specific embodiments. However, those skilled in the art will understand that various modifications and alterations are possible without departing from the scope of this disclosure as described in the following claims. Therefore, this specification and the drawings should be understood as illustrative, not restrictive, and all such modifications are intended to be included within the scope of this disclosure.

[0050] Regarding specific embodiments, advantages, other benefits, and solutions to problems have been described above. However, none of these advantages, benefits, solutions to problems, or any features that give rise to or enhance them should be construed as important, essential, or essential in any or all of the claims. Furthermore, the specific embodiments of this disclosure are merely illustrative, and the subject matter of this disclosure can be modified and implemented in different but equivalent ways that will be apparent to those skilled in the art who are interested in the teachings of this specification. Also, except as expressly stated in the claims below, no limitation is intended to the structural or design details shown herein. Accordingly, it is clear that the specific embodiments described above are modifiable, and all such modifications are recognized as falling within the scope of the subject matter of this disclosure. Accordingly, the protections sought in this disclosure are defined as described in the claims below. In addition to the embodiments described herein, examples of certain combinations are also included in the scope of this disclosure, some of which are detailed below.

[0051] In addition to the embodiments described herein, examples of specific combinations are within the scope of this disclosure, some of which are detailed below.

[0052] Example 1. A method for producing an aggregate of active battery material coated with a binder, A step of producing a first intermediate mixture by stirring a first amount of binder-solvent solution with a granular mixture containing activated battery material particles in a container, wherein the binder-solvent solution has a solubility limit in the first solvent solution for the mixture of binder material particles in a first set of environmental parameters. A step of generating a second intermediate mixture by holding the first intermediate mixture in a container and placing the first intermediate mixture under conditions of a second set of environmental parameters that reduce the above-mentioned solubility limit, A step of producing a third intermediate mixture by stirring a second amount of binder-solvent solution with the second intermediate mixture while holding the second intermediate mixture in a container, A step of generating a powder mixture of binder-coated active battery material aggregates by holding the third intermediate mixture in a container and placing the third intermediate mixture under the conditions of a second set of environmental parameters, wherein each binder-coated active battery material aggregate comprises one or more types of active battery material particles having at least a partial coating of the binder material. Methods that include...

[0053] Example 2. The method of Example 1 further comprises the step of dispersing a conductive particle mixture in a binder-solvent solution before stirring the first volume of the binder-solvent solution and the second volume of the binder-solvent solution with the granular mixture.

[0054] Example 3. The method further includes the step of dispersing a conductive particle mixture in a second solvent solution to produce a conductive dispersion, The method of Example 1, wherein the conductive dispersion has a dispersion limit relative to the conductive particle mixture in a second solvent solution under a first set of environmental parameters.

[0055] Example 4. The process involves stirring a first amount of conductive dispersion with the first intermediate mixture while holding the first intermediate mixture in a container, A step of placing the first intermediate mixture under the conditions of a second set of environmental parameters while holding the first intermediate mixture in a container. The method in Example 3 further includes the following.

[0056] Example 5. A step of stirring a first amount of conductive dispersion with a granular mixture in a container, and before stirring a first amount of binder-solvent solution and a second amount of binder-solvent solution with a granular mixture, to produce a fourth intermediate mixture, The steps include: holding the fourth intermediate mixture in a container while placing the fourth intermediate mixture under the conditions of the second set of environmental parameters; The method in Example 3 further includes the above.

[0057] Example 6. After the step of stirring at least a first amount of binder-solvent solution, A step of stirring a first amount of conductive dispersion with a third intermediate mixture to produce a fifth intermediate mixture, The steps include: holding the fifth intermediate mixture in a container while placing the fifth intermediate mixture under the conditions of the second set of environmental parameters; The method in Example 3 further includes the above.

[0058] Example 7. A step of stirring a first amount of binder-solvent solution and a first amount of conductive dispersion with a granular mixture in a container and substantially simultaneously to produce a first intermediate mixture, A step of placing the first intermediate mixture under the conditions of a second set of environmental parameters while holding the first intermediate mixture in a container. The method in Example 3 further includes the above.

[0059] Example 8. The method of Example 1, wherein the rate of introduction of the solvent into the container is substantially equivalent to the rate of evaporation of the solvent from the container.

[0060] Example 9. The method of Example 1, wherein the step of stirring a first amount includes the step of spraying, misting, atomizing, micronizing, or pumping a first amount of binder-solvent solution into a container and onto a granular mixture.

[0061] Example 10. The method of Example 1, wherein the granular mixture comprises one or more types of conductor-speckled active battery material particles held together by electrostatic force, and each conductor-speckled active battery material particle further comprises multiple conductive particles in electrical contact with the active battery material particle.

[0062] Example 11. The method of Example 1, wherein the mixture of binder material particles contains a binder-solvent solution in an amount of 1 to 20% by mass.

[0063] Example 12. The method of Example 1, wherein a first set of environmental parameters includes at least one of heating or pressurizing above ambient conditions, and a second set of environmental parameters includes at least one of reducing pressure or temperature.

[0064] Example 13. The method of Example 1 further includes the step of mechanically stirring the first intermediate mixture while placing the first intermediate mixture under the conditions of a second set of environmental parameters.

[0065] Example 14. The method of Example 1, wherein the binder material particles are selected from the group consisting of polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), polytetrafluoroethylene (PTFE), polyimide, ethylene-propylene-diene monomer (EPDM), poly(acrylic acid-co-maleic acid) (PAA-MA), poly(acrylic acid-co-itaconic acid) (PAA-IA), partially or completely fluorinated polymers and copolymers, poly(acrylic acid) (PAA), lithified poly(acrylic acid) (lithified-PAA), carboxymethylcellulose (CMC), sodium carboxymethylcellulose (NaCMC), and styrene-butadiene rubber (SBR).

[0066] Example 15. The active battery material particles include lithium iron phosphate (LFP), lithium nickel manganese cobalt oxide (NMC), lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium titanate (LTO), lithium nickel cobalt aluminum (NCA) oxide, synthetic graphite granules, natural graphite granules, silicon nanocomposite, silicon graphite composite, silicon porous carbon composite, LiTiO2, and Li4Ti5O2. 12 The method of Example 1, selected from the group consisting of tin granules and SiOx / silicon granules.

[0067] Example 16. The method of Example 1, wherein the first solvent solution and the second solvent solution are selected from the group consisting of dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), triethyl phosphate (TEP), dihydrolevoglucocenone (Syrene), tributyl acetylcitrate (ATBC), acetone, tetrahydrofuran (THF), difluoromethane (CH2F2), ethanol, methanol, water, and carbon dioxide. [Explanation of Symbols]

[0068] 100 ways 102 blocks 104 blocks 106 blocks 108 blocks

Claims

1. A method for producing an aggregate of active battery material coated with a binder, A step of producing a first intermediate mixture by stirring a first amount of binder-solvent solution with a granular mixture containing activated battery material particles in a container, wherein the binder-solvent solution has a solubility limit in the first solvent solution for the mixture of binder material particles in a first set of environmental parameters. A step of generating a second intermediate mixture by holding the first intermediate mixture in the container and placing the first intermediate mixture under conditions of a second set of environmental parameters that reduce the solubility limit, A step of generating a third intermediate mixture by stirring a second amount of binder-solvent solution with the second intermediate mixture while holding the second intermediate mixture in the container, A step of generating a powder mixture of binder-coated active battery material aggregates by holding the third intermediate mixture in the container and placing the third intermediate mixture under the conditions of the second set of environmental parameters, wherein each of the binder-coated active battery material aggregates comprises one or more types of active battery material particles having at least a partial coating of the binder material. Methods that include...

2. The method according to claim 1, further comprising the step of dispersing a conductive particle mixture in the binder-solvent solution before stirring the first amount of the binder-solvent solution and the second amount of the binder-solvent solution with the granular mixture.

3. The method further includes the step of dispersing a conductive particle mixture in a second solvent solution to produce a conductive dispersion, The method according to claim 1, wherein the conductive dispersion has a dispersion limit relative to the conductive particle mixture in the second solvent solution in the first set of environmental parameters.

4. The first intermediate mixture is kept in the container, and a first amount of the conductive dispersion is stirred with the first intermediate mixture. A step of holding the first intermediate mixture in the container while placing the first intermediate mixture under the conditions of the second set of environmental parameters. The method according to claim 3, further comprising:

5. A step of stirring a first amount of the conductive dispersion with the granular mixture in the container, and before stirring the first amount of the binder-solvent solution and the second amount of the binder-solvent solution with the granular mixture, to produce a fourth intermediate mixture, A step of holding the fourth intermediate mixture in the container while placing the fourth intermediate mixture under the conditions of the second set of environmental parameters. The method according to claim 3, further comprising:

6. After the step of stirring at least the first amount of the binder-solvent solution, A step of stirring a first amount of the conductive dispersion with the third intermediate mixture to produce a fifth intermediate mixture, A step of holding the fifth intermediate mixture in the container and placing the fifth intermediate mixture under the conditions of the second set of environmental parameters. The method according to claim 3, further comprising:

7. A step of stirring the first amount of the binder-solvent solution and the first amount of the conductive dispersion with the granular mixture in the container and substantially simultaneously to produce the first intermediate mixture, A step of holding the first intermediate mixture in the container while placing the first intermediate mixture under the conditions of the second set of environmental parameters. The method according to claim 3, further comprising:

8. The method according to claim 1, wherein the rate at which the solvent is introduced into the container is substantially equivalent to the rate at which the solvent evaporates from the container.

9. The method according to claim 1, wherein the step of stirring the first amount includes the step of spraying, misting, atomizing, micronizing, or pumping the first amount of the binder-solvent solution into the container and onto the granular mixture.

10. The method according to claim 1, wherein the granular mixture comprises one or more types of active battery material particles having conductive elements scattered within them, which are held together by electrostatic force, and further comprises a plurality of conductive particles in electrical contact with each of the aforementioned active battery material particles having conductive elements scattered within them.

11. The method according to claim 1, wherein the mixture of binder material particles comprises a binder-solvent solution in an amount of 1 to 20% by mass.

12. The method according to claim 1, wherein the first set of environmental parameters includes at least one of heating or pressurizing above ambient conditions, and the second set of environmental parameters further includes at least one of reducing pressure or temperature.

13. The method according to claim 1, further comprising the step of mechanically stirring the first intermediate mixture during the step of placing the first intermediate mixture under the conditions of the second set of environmental parameters.

14. The method according to claim 1, wherein the binder material particles are selected from the group consisting of polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), polytetrafluoroethylene (PTFE), polyimide, ethylene-propylene-diene monomer (EPDM), poly(acrylic acid-co-maleic acid) (PAA-MA), poly(acrylic acid-co-itaconic acid) (PAA-IA), partially or completely fluorinated polymers and copolymers, poly(acrylic acid) (PAA), lithified poly(acrylic acid) (lithified-PAA), carboxymethylcellulose (CMC), sodium carboxymethylcellulose (NaCMC), and styrene-butadiene rubber (SBR).

15. The active battery material particles include lithium iron phosphate (LFP), lithium nickel manganese cobalt oxide (NMC), lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium titanate (LTO), lithium nickel cobalt aluminum (NCA) oxide, synthetic graphite granules, natural graphite granules, silicon nanocomposite, silicon graphite composite, silicon porous carbon composite, and LiTiO. ２ Li ４ Ti ５ O １２ The method according to claim 1, selected from the group consisting of tin granules and SiOx / silicon granules.

16. The first solvent solution and the second solvent solution are dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), triethyl phosphate (TEP), dihydrolevoglucocenone (Syrene), tributyl acetylcitrate (ATBC), acetone, tetrahydrofuran (THF), difluoromethane (CH4). ２ F ２ The method according to claim 1, wherein a selection is made from the group consisting of ethanol, methanol, water, and carbon dioxide.

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