Aqueous method for producing macroparticles

Abstract

A powder mixture comprising multiple particle aggregates. Each of the aggregates contains one or more conductive mottled active material particles bound together by electrostatic force, and each conductive mottled active material particle contains multiple conductive particles in electrical contact with the active material particle. In various embodiments, the active material particles include an anode electroactive material or a cathode electroactive material. A mixture of binder microparticles is scattered over the conductive mottled active material particles. The mixture of binder microparticles is maintained below the softening temperature of the constituent particles, at which point the mixture of binder microparticles becomes flexible and begins to aggregate together. The powder mixture contains less than 3% by mass of the mixture of binder microparticles.

Description

Technical Field

[0001] Efficient energy storage as a transportable system and as a portable device such as a smartphone, a notebook computer, and a smart health device has attracted attention in the development of portable electronic devices while their energy demands are increasing and they are being miniaturized.

Background Art

[0002] Electrochemical storage and conversion devices continue to expand the functions of these systems in various fields including portable electronic devices, aircraft and spacecraft technologies, passenger and freight vehicles, and biomedical devices. Electrochemical storage and conversion devices have specially designed designs and performances, and provide compatibility between a wide range of application requirements and operating environments.

Summary of the Invention

Problems to be Solved by the Invention

[0003] In an expanding range of applications, there is a strong demand for expanding the functionality of energy storage and conversion devices such as batteries, fuel cells, and electrochemical capacitors. Continuous development has created a demand for electrochemical storage and conversion devices that can exhibit good performance in a useful range of operating environments that are mechanically robust, highly reliable, and have a high energy density. Many of the recent advances in electrochemical storage technology are due to the manufacture and integration of new materials for device components. For example, battery technology has continued to develop rapidly, at least in part, through the development of electrode and electrolyte materials for these systems.

[0004] Conventional electrode manufacturing often requires solvent-based methods, which involve mixing active materials, conductive agents, polymer binders, and solvents to form a slurry. A polymer binder, such as polyvinylidene fluoride (PVDF), is pre-dissolved in a solvent, most commonly N-methyl-2-pyrrolidone. During mixing, the polymer binder surrounds and partially coats the particles of the active material and conductive agent. The resulting slurry is poured onto a metal current collector, dried, the solvent is evaporated, and a porous electrode is formed. While the evaporation of the solvent forms a dry porous electrode, the steps of evaporating the solvent and curing / bonding the active material on the metal current collector require considerable heating and drying time.

[0005] Electrode manufacturing technology traditionally involves a solvent recovery system during the drying process to recover evaporated solvent, due to high costs and the potential contamination of conventional solvents. While cheaper and more environmentally friendly solvents such as aqueous slurries have reduced the costs associated with recovery systems, electrodes still require a drying process that is time- and energy-intensive. Furthermore, the use of water as a cathode offers significant advantages but also presents significant challenges. In particular, the use of water limits its reactivity with electroactive materials (e.g., lithium metal). [Means for solving the problem]

[0006] To solve these problems and improve the electrode manufacturing process, Figures 1-5 describe techniques for replacing conventional solvents with water while limiting the exposure of the electroactive material to water. In some embodiments, a method for producing conductive mottled active material particles includes a step of stirring conductive particles in an aqueous binder solution containing a mixture of binder microparticles suspended in an aqueous solvent. An intermediate powder containing conductive particles dispersed in the binder microparticle mixture is produced by evaporating water from the aqueous binder solution. Subsequently, the microparticle mixture containing the active material particles and the intermediate powder are stirred to produce a powder mixture of conductive mottled active material aggregates. Each conductive mottled active material aggregate contains multiple conductive particles in electrical contact with one or more active material particles. Furthermore, the conductive mottled active material aggregates contain binder particles scattered on one or more active material particles. Thus, the various embodiments described herein provide a method for producing a dry powder system of conductive mottled active material that reduces the use of conventional solvents and the heating and drying time from the electrode manufacturing process.

[0007] This description can be better understood by referring to the attached drawings, and many of its features and advantages will become apparent to those skilled in the art. The use of the same reference numerals in different drawings indicates the same or identical item. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 shows powder aggregates of fine particle subunits of conductive mottled active materials according to several embodiments. [Figure 2] Figure 2 is a block diagram of a method for producing aggregates of fine particle subunits of a conductive mottled active material according to several embodiments. [Figure 3] Figure 3 is a block diagram of another method for producing composite particles or microparticle subunits of conductive mottled active material according to several embodiments. [Figure 4]Figure 4 is a block diagram of a method for producing conductive spotted active material particles via multi-step evaporation, according to several embodiments. [Figure 5] Figure 5 is a block diagram of a method for producing fine particle subunits of a conductive mottled active material via multi-step evaporation, according to several embodiments. [Modes for carrying out the invention]

[0009] Figure 1 shows a powder mixture aggregate 100 of fine particle subunits of a conductive mottled active material according to several embodiments. For the purposes of this description, the terms: particle, fine particle, fine particle subunit, primary particle, microsphere, aggregate and aggregate are used according to the definitions provided in the publication entitled "The Use of Nomenclature in Dispersion Science and Technology" of the National Institute of Standards and Technology, formerly published as NIST Special Publications 945 and 946, August 2001, which provides guidelines on the use of technical and scientific nomenclature related to ceramic dispersions, and all descriptions thereof are incorporated herein by reference. As shown, the powder mixture aggregate 100 comprises a plurality of fine particle subunits 102, each containing one or more fine particle subunits 104 of the conductive mottled active material bound together by electrostatic forces.

[0010] In some embodiments, the active material primary particles include one or more cathode materials selected from the group including LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNixMn2-xO4, LiFePO4, LiMnPO4, LiCoPO4, LiFexMn1-xPO4, LiNixMnyCo1-x-yO2, Li1+xNiyMnzCo1-xy-zO2, LiNixMnyCozAl1-xy-zO2, and Li1+xNiyMn1-xCozO2. In some embodiments, the active material primary particles in the above group are coated with carbon, or otherwise treated. In other embodiments, the active material primary particles include one or more anode materials selected from the group including synthetic graphite nanoparticles, natural graphite nanoparticles, Si nanocomposites, LiTiO2, Li4Ti5O12, Sn nanoparticles, and SiOx / Si nanoparticles.

[0011] In some embodiments, the primary particles of the active material constitute the powder mixture aggregate 100 of the fine particle subunits of the conductive mottled active material in an amount of approximately 10% by mass or more of the powder mixture aggregate, optionally approximately 20% by mass or more of the powder mixture aggregate, optionally approximately 30% by mass or more of the powder mixture aggregate, optionally approximately 40% by mass or more of the powder mixture aggregate, optionally approximately 50% by mass or more of the powder mixture aggregate, optionally approximately 60% by mass or more of the powder mixture aggregate, optionally approximately 70% by mass or more of the powder mixture aggregate, optionally approximately 80% by mass or more of the powder mixture aggregate, optionally approximately 90% by mass or more of the powder mixture aggregate, optionally approximately 95% by mass or more of the powder mixture aggregate, and in certain aspects optionally approximately 96% by mass or more of the powder mixture aggregate.

[0012] Each of the conductive mottled active material's microparticle subunits 104 contains a plurality of conductive particles 106 that are electrically in contact with the active material's primary particles 108. Thus, the first conductive particles of the first conductive mottled active material's microparticle subunit are electrically in contact with one or more conductive particles of the second conductive mottled active material's microparticle subunit, thereby forming an electrical circuit that connects to the plurality of active material's primary particles 104. In various embodiments, the conductive particles include one or more 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.

[0013] In some embodiments, the conductive particles 106 constitute the powder mixture aggregate 100 of the fine particle subunits of the conductive mottled active material in an amount of approximately 0.1% by mass or more of the powder mixture aggregate, optionally approximately 0.5% by mass or more of the powder mixture aggregate, optionally approximately 1.0% by mass or more of the powder mixture aggregate, optionally approximately 1.5% by mass or more of the powder mixture aggregate, optionally approximately 2.0% by mass or more of the powder mixture aggregate, optionally approximately 2.5% by mass or more of the powder mixture aggregate, optionally 3.0% by mass or more of the powder mixture aggregate, optionally approximately 3.5% by mass or more of the powder mixture aggregate, optionally approximately 4.0% by mass or more of the powder mixture aggregate, optionally approximately 4.5% by mass or more of the powder mixture aggregate, and in certain aspects, optionally approximately 5.0% by mass or more of the powder mixture aggregate.

[0014] Furthermore, a mixture of binder microparticle subunits 110 is dispersed within the microparticle subunits of the conductive mottled active material. In various embodiments, the binder microparticle subunits are made of one or more polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), polytetrafluoroethylene (PTFE), carboxymethylcellulose (CMC), polyvinyl fluoride (PVF), polyethylene (PE), polypropylene (PP), polyethylene oxide (PEO), polyethylene vinyl acetate (PEVA), polyurethane (PU), polypropylene rubber (PPR), and ethylene propylene rubber (EPR). ), styrene-butadiene rubber (SBR), styrene-ethylene-butylene-styrene rubber (SEBS), acrylonitrile butadiene styrene rubber (ABS), polyisobutylene (PIB), polyvinyl alcohol (PVA), phenoxy resin, polyethylene terephthalate (PET), nylon, polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polyphenylene sulfide (PPS), polystyrene (PS), pitch, tar, asphalt, or bitumen are included in the mixture.

[0015] In some embodiments, the binder microparticle subunit 110 constitutes the powder mixed aggregate 100 of the conductive mottled active material in an amount of approximately 2.0% by mass or more, optionally approximately 3.0% by mass or more, optionally approximately 4.0% by mass or more, optionally approximately 5.0% by mass or more, optionally approximately 6.0% by mass or more, optionally approximately 7.0% by mass or more, optionally approximately 8.0% by mass or more, optionally approximately 9.0% by mass or more, and in certain aspects optionally approximately 10.0% by mass or more of the powder mixed aggregate.

[0016] In some embodiments, the mixture or aggregate of the binder microparticle subunit 110 includes binder microparticle subunits, each of which is an aggregate of binder primary particles. As will be understood by those skilled in the art, binder primary particles, which are individual units of the binder material, are nanoparticle-sized particles that often characteristically aggregate or agglomerate into larger units by adhesion or other weak physical interactions. These aggregates or agglomerates are aggregates of primary particles, including, in some embodiments, joined at corners or edges, so that the total surface area of ​​the aggregates or aggregates does not differ significantly from the sum of the specific surface areas of the primary particles. As a result, the aggregates or aggregates are not fixed units but can change in size and shape. Changes in the conditions of the surrounding solvent (temperature, pressure, pH value, viscosity, etc.) result in a variety of aggregates. Larger aggregates or aggregates may decompose into smaller aggregates or aggregates, and conversely, smaller aggregates or aggregates may re-form larger aggregates. The density of aggregates or agglomerates depends on the particle size distribution of the primary particles.

[0017] As will be understood by those skilled in the art, the various conductive particles and binder particles described herein tend to aggregate and clump together into particle aggregates or aggregates. Therefore, as will be described in more detail below with reference to Figures 2-5, various methods are used to stir the particles and separate the aggregates into smaller sizes closer to the constituent particles in order to achieve good dispersibility within the powder mixture 100.

[0018] Figure 2 is a block diagram of Method 200 for producing aggregates of fine particle subunits of conductive mottled active material according to several embodiments. For ease of illustration and description, Method 200 is described below in an exemplary context with reference to the powder mixture in Figure 1. However, Method 200 is not limited to these exemplary contexts and can rather be applied to any of the various implementable configurations using the guidelines provided herein.

[0019] Method 200 begins in block 202 with the step of stirring conductive particles in an aqueous binder solution. The aqueous binder solution contains a mixture of binder microparticles suspended in an aqueous solvent. In various embodiments, the binder microparticles include polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), polytetrafluoroethylene (PTFE), carboxymethylcellulose (CMC), polyvinyl fluoride (PVF), polyethylene (PE), polypropylene (PP), polyethylene oxide (PEO), polyethylene vinyl acetate (PEVA), polyurethane (PU), polypropylene rubber (PPR), ethylene propylene rubber (EPR), The material comprises a powder mixture of one or more of the following: styrene-butadiene rubber (SBR), styrene-ethylene-butylene-styrene rubber (SEBS), acrylonitrile-butadiene-styrene rubber (ABS), polyisobutylene (PIB), polyvinyl alcohol (PVA), phenoxy resin, polyethylene terephthalate (PET), nylon, polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polyphenylene sulfide (PPS), polystyrene (PS), pitch, tar, asphalt, or bitumen. When multiple binders are used, the melting and softening points of each binder in the binder system may be the same or different.

[0020] In one embodiment, the aqueous binder solution is a commercially available dispersion or emulsion containing binder particles dispersed in an aqueous solution. In another embodiment, the aqueous binder solution is prepared by introducing a wetting agent to a dry powder mixture of binder particles. The wetting agent, in various embodiments, includes surfactants, non-surfactants, organic solvents, and those that reduce the surface tension of the solution, thereby promoting wettability. The presence of a wetting agent allows for the uniform dispersion of powdered materials, such as binder particles and conductive particles, in the aqueous dispersion. Some substances, such as carbon-based materials, do not readily disperse in aqueous dispersions without the assistance of a wetting agent. Useful wetting agents include, but are not limited to, ionic and nonionic surfactants such as isopropanol, and, but are not limited to, organic liquids compatible with aqueous dispersions, such as NMP, DMSO, and acetone. After moistening the dry mixture of binder particles, block 202 continues the process of stirring the moistened binder particles in a volume of aqueous solution (e.g., water) by subjecting the aqueous binder solution to high-shear mixing, sonication, or other suitable method for uniformly dispersing the binder particles in the aqueous solution.

[0021] In some embodiments, the binder fine particles constitute the aqueous binder solution in an amount of 1.0% by mass or more, optionally 5.0% by mass or more, optionally 10.0% by mass or more, optionally 15.0% by mass or more, optionally 20.0% by mass or more, optionally 25.0% by mass or more, optionally 30.0% by mass or more, optionally 35.0% by mass or more, optionally 40.0% by mass or more, and in certain aspects, optionally 45% by mass or more, which constitutes the aqueous binder solution.

[0022] Block 202 includes the step of stirring conductive particles in an aqueous binder solution. In various embodiments, the conductive particles include one or more carbon additives such as C65 carbon black, C45 carbon black, super P carbon black, acetylene black, ketjen black carbon black, carbon nanotubes, graphene, carbon nanofibers, carbon fibers, etc. In some embodiments, dry conductive particles are directly introduced into the aqueous binder solution.

[0023] As will be appreciated by those skilled in the art, conductive particles tend to aggregate and agglomerate into aggregates of conductive particles. Thus, in some embodiments, method 200, in block 204, mechanically separates one or more aggregates of conductive particles into constituent particles in a dispersion in the aqueous binder solution. In some embodiments, in some embodiments, block 204 includes the step of stirring the conductive particles in the aqueous binder solution by subjecting the aqueous binder solution to high-shear mixing, sonication, or any other suitable method of decomposing the conductive particle agglomerates into constituent particles or smaller aggregates and / or uniformly dispersing the conductive particles in the aqueous binder 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 mixture of conductive particles, block 204 continues the step of stirring the wetted conductive particles within the volume of a large amount of aqueous solution by subjecting the aqueous conductive particle solution to high-shear mixing, sonication, or other suitable methods of uniformly dispersing the conductive particles in the aqueous solution. Thereafter, the aqueous conductive particle solution is introduced into the aqueous binder solution and stirred similarly to form an intermediate aqueous solution containing a uniform dispersion of binder microparticles and conductive particles.

[0024] In some embodiments, the conductive particles constitute an aqueous binder solution at 1% by mass or more of the aqueous binder solution, optionally 5% by mass or more of the aqueous binder solution, optionally 10% by mass or more of the aqueous binder solution, optionally 15% by mass or more of the aqueous binder solution, optionally 20% by mass or more of the aqueous binder solution, optionally 25% by mass or more of the aqueous binder solution, optionally 30% by mass or more of the aqueous binder solution, optionally 35% by mass or more of the aqueous binder solution, optionally 40% by mass or more of the aqueous binder solution, and in a further particular aspect, optionally 45% by mass or more of the aqueous binder solution.

[0025] In block 206, method 200 continues the process of evaporating water from the aqueous binder solution to produce an intermediate powder or agglomerate containing conductive particles dispersed in binder microparticles. In some embodiments, the operation of block 206 includes mechanically stirring an intermediate aqueous solution containing a uniform dispersion of binder microparticles and conductive particles during evaporation. The viscosity of the intermediate aqueous solution increases as the water content decreases by evaporation. As the water content of the intermediate aqueous solution decreases, it becomes increasingly important to maintain or further enhance the mechanical stirring of the particles in the intermediate aqueous solution at a conventional level to continuously move the particles and prevent them from selectively precipitating due to density differences or other effects of the constituent particles.

[0026] In various embodiments, after evaporating all remaining water, the intermediate aqueous solution is dried to form aggregates of binder microparticles and conductive particles. In various embodiments, such aggregates can be mechanically processed (e.g., pulverized, crushed, etc.) to produce a finer intermediate powder. As will be understood by those skilled in the art, binder microparticles tend to aggregate. With purely mechanical force, the applied force is insufficient to break down such clumps into their constituent particles before the binder material is heated to a temperature at which the binder material becomes plasticized, for example, 170 Celsius for PVDF. In contrast, the operation of block 206 produces an intermediate powder having one or more conductive particles arranged among the binder microparticles. The presence of this conductive particle additive reduces the interparticle forces between the binder microparticles by introducing space and thus reducing aggregates, resulting in a powdery composition in which the binder microparticles and conductive particles are finely ground to their respective constituent particle sizes.

[0027] In block 208, method 200 continues the step of stirring a fine particle mixture containing active material particles and the intermediate powder or aggregates of block 206 to produce a powder mixture of conductive-spotted active material aggregates or aggregates. In some embodiments, the active material particles include one or more cathode materials selected from the group including LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNixMn2-xO4, LiFePO4, LiMnPO4, LiCoPO4, LiFexMn1-xPO4, LiNixMnyCo1-x-yO2, Li1+xNiyMnzCo1-xy-zO2, LiNixMnyCozAl1-xy-zO2, Li1+xNiyMn1-xCozO2, and LiNi0.8Co0.1Mn0.1O2 (NCM811). In some embodiments, the primary active material particles in the above group are coated with carbon, or otherwise treated. In other embodiments, the active material particles include one or more anode materials selected from the group including, but not limited to, synthetic graphite nanoparticles, natural graphite nanoparticles, Si particle-C fiber nanocomposites, LiTiO2, Li4Ti5O12, Sn nanoparticles, and SiOx / Si nanoparticles. In some embodiments, the operation of block 208 includes a step of cooling the nanoparticle mixture to prevent the above-mentioned problem of heating to a temperature where the binder material becomes flexible and begins to aggregate together.

[0028] In various embodiments, the operation of Method 200 may also include an optional, undescribed step of scattering an additional amount of conductive particles to further increase the mass of the composition and the overall conductivity of the mixture of aggregates of conductive mottled active material. This scattering step may be performed at any point in Method 200, or even in two or more different steps in Method 200.

[0029] The resulting dry mixture or aggregate contains aggregates of conductive mottled active material, such as the fine particle subunit 104 of the conductive mottled active material shown in Figure 1, which comprises one or more active material particles and multiple conductive particles in electrical contact with each other. The aggregates of conductive mottled active material further contain binder fine particles scattered on one or more active material particles. Thus, the composite powder of conductive mottled active material aggregates is produced by an aqueous processing method in which the active material does not come into contact with water. The composite powder can be used in various processing techniques in electrodes and other energy storage devices.

[0030] Figure 3 is a block diagram of another method 300 for producing composite particles or fine particle subunits of conductive-spotted active material according to several embodiments. For ease of illustration and description, the method 300 is described below in an exemplary context with reference to the powder mixture of Figure 1. However, the method 300 is not limited to these exemplary contexts and can rather be applied to any of the various implementable configurations using the guidelines provided herein.

[0031] Method 300 begins with the step of stirring a mixture of fine particles containing active material particles and conductive particles in block 302 to produce a mixture of fine particle subunits of the conductive mottled active material. The operation in block 302 includes mechanical stirring, high-shear mixing and / or any other suitable method for uniformly dispersing the conductive particles in the active material particles. In various embodiments, each of the conductive mottled active material particles contains a plurality of conductive particles in electrical contact with the active material particles.

[0032] In one embodiment, the operation of block 302 includes stirring a dry powder mixture of conductive particles and active material particles to produce a powder mixture of fine particle subunits of the conductive mottled active material. In another embodiment, the operation of block 302 includes stirring a powder mixture of active material particles in an aqueous conductive particle solution. For example, in some embodiments, block 302 includes stirring the conductive particles in the aqueous solution by subjecting the aqueous solution to high-shear mixing, sonication, or other suitable methods to break down aggregates of conductive particles into constituent particles or at least smaller aggregates, and / or uniformly disperse the conductive particles in the aqueous 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 mixture of conductive particles, block 304 continues the process of stirring the wetted conductive particles in a large volume of aqueous solution (e.g., water) by subjecting the aqueous conductive particle solution to high-shear mixing, sonication, or other suitable methods to uniformly disperse the conductive particles in the aqueous solution.

[0033] Subsequently, a dry powder mixture of active material particles is introduced into an aqueous conductive particle solution. In other embodiments, the operation in block 302 includes stirring the aqueous active material solution and the aqueous conductive particle solution together to produce an aqueous mixture of conductive mottled active material fine particle subunits.

[0034] In block 304, method 300 continues the step of stirring the active material particles and conductive particles in the aqueous binder solution. In some embodiments, the aqueous binder solution comprises a mixture of binder microparticles suspended in an aqueous solvent. In one embodiment, the aqueous binder solution is a commercially available dispersion or emulsion comprising binder microparticles dispersed in an aqueous solution. In another embodiment, as shown in detail earlier with respect to Figure 2, the aqueous binder solution is prepared by introducing a wetting agent into a dry powder mixture of binder microparticles. After wetting the dry mixture of binder microparticles, block 304 continues the step of stirring the wetted binder microparticles in a large volume of aqueous solution (e.g., water) by subjecting the aqueous binder solution to high-shear mixing, sonication, or other suitable method for uniformly dispersing the binder microparticles in the aqueous solution.

[0035] In some embodiments, the binder fine particles constitute the aqueous binder solution in an amount of 1.0% by mass or more, optionally 5.0% by mass or more, optionally 10.0% by mass or more, optionally 15.0% by mass or more, optionally 20.0% by mass or more, optionally 25.0% by mass or more, optionally 30.0% by mass or more, optionally 35.0% by mass or more, optionally 40.0% by mass or more, and in certain aspects, optionally 45% by mass or more, which constitutes the aqueous binder solution.

[0036] In one embodiment, an aqueous mixture of conductive mottled active material particles is mixed with an aqueous binder solution so that the resulting solution contains active material particles, conductive particles, and binder fine particles uniformly dispersed in the aqueous binder solution. In another embodiment, the stirring operation of block 304 includes stirring the dry mixture of active material particles in the aqueous binder solution before adding the dry mixture of conductive particles. In yet another embodiment, the stirring operation of block 304 includes stirring the dry mixture of conductive particles in the aqueous binder solution before adding the dry mixture of active material particles.

[0037] In another embodiment, the stirring operation of block 304 includes stirring a dry mixture of active material particles in an aqueous binder solution before adding the aqueous conductive particle solution. In addition, in some embodiments, the stirring operation of block 304 includes stirring a dry mixture of active material particles in an aqueous binder solution before adding the aqueous conductive particle solution. Compared to method 200, the operation of block 304 involves active material particles that come into contact with water. As will be understood by those skilled in the art, some active materials are more resistant to harmful effects in the presence of water. These active materials include, for example, coated LFPs (e.g., carbon-coated LFPs) and lower nickel NMCs (e.g., NMC811 and NMC111, which is more sensitive than NMC9055).

[0038] In block 306, method 300 continues the step of evaporating water from the aqueous binder solution to produce a mixture powder of binder microparticles dispersed in conductive mottled active material microparticle subunits. In some embodiments, the operation in block 306 includes the step of mechanically stirring the aqueous binder solution containing a uniform dispersion of binder microparticles, conductive particles, and active material particles during evaporation. The viscosity of the aqueous binder solution increases as the water content decreases due to evaporation. As the water content of the aqueous binder solution decreases, it becomes increasingly important to maintain or increase the mechanical stirring of the particles in the aqueous binder solution at conventional levels in order to keep the particles moving continuously and prevent selective precipitation, for example, due to density differences of the constituent particles.

[0039] In various embodiments, after evaporating all remaining water, the aqueous binder solution is dried to obtain a powder mixture of aggregates of the conductive mottled active material. In various embodiments, such aggregates may be mechanically processed (e.g., crushed, pulverized, etc.) to produce a finer powder mixture. As will be understood by those skilled in the art, binder microparticles tend to aggregate. With purely mechanical force, the applied force is insufficient to break down such clumps into their constituent particles before the binder material is heated to a temperature at which the binder material becomes plasticized, e.g., 170 Celsius for PVDF, and it becomes even more difficult to separate them into smaller constituent particles. In contrast, the operation of block 306 produces a powder having one or more conductive particles arranged in the binder microparticles. The presence of this conductive particle additive reduces the interparticle forces between the binder microparticles by introducing space, thereby reducing aggregates and producing a powder mixture of aggregates of the conductive mottled active material. In some embodiments, the operation of block 306 includes a step of cooling the particulate mixture during a mechanical stirring step, thereby preventing the above-mentioned problem of the binder material being heated to a temperature at which it becomes flexible and begins to aggregate together.

[0040] In various embodiments, the operation of Method 300 may also include an optional, not-described step of scattering an additional amount of conductive particles to further increase the mass of the composition and the overall conductivity of the mixture of aggregates of conductive mottled active material. This scattering step may be performed at any point in Method 300, or even in two or more different steps in Method 300.

[0041] Figure 4 is a block diagram of Method 400 for producing conductive mottled active material particles via multi-step evaporation, according to several embodiments. For ease of illustration and description, Method 400 is described below in an exemplary context with reference to the powder mixture in Figure 1. However, Method 400 is not limited to these exemplary contexts and can rather be applied to any of the various implementable configurations using the guidelines provided herein.

[0042] Method 400 begins with the step of stirring a dry powder mixture of conductive particles and active material particles in block 402 to produce a powder mixture or aggregate of conductive mottled active material particles. In various embodiments, the operation of block 402 includes mechanical stirring, high-shear mixing and / or any other suitable method for uniformly dispersing the conductive particles in the active material particles.

[0043] In block 404, method 400 continues the process of stirring a powder mixture of conductive mottled active material particles in an aqueous binder solution via multi-step evaporation. In various embodiments, the aqueous binder solution comprises a mixture of binder microparticles suspended in an aqueous solvent as described in detail earlier with respect to Figures 2 and 3. In one embodiment, the aqueous binder solution is a commercially available dispersion (or emulsion) containing binder microparticles dispersed in an aqueous solution. In another embodiment, the aqueous binder solution is prepared by introducing a wetting agent to a dry powder mixture of binder microparticles. After moistening the dry mixture of binder microparticles, the moistened binder microparticles are stirred in a large volume of aqueous solution (e.g., water) by high-shear mixing, sonication, or other suitable method for uniformly dispersing the binder microparticles in the aqueous solution.

[0044] In various embodiments, the multi-step evaporation of block 404 includes the step of introducing a dry powder mixture of conductive mottled active material particles into a first volume of aqueous binder solution, which is less than the total volume of the aqueous binder solution. After evaporating water from the first mixture, the resulting mixture includes aggregates of conductive mottled active material, such as the conductive mottled active material microparticle subunit 104 of Figure 1, which contain multiple conductive particles electrically in contact with one or more active material particles. The aggregates of conductive mottled active material further contain binder microparticles scattered on the active material particles, the binder microparticles present in the resulting mixture of conductive mottled active material aggregates in a first mass% of the resulting mixture.

[0045] Subsequently, a mixture of the resulting conductive mottled active material aggregates, containing a first mass % of binder microparticles, is introduced into a second volume of the aqueous binder solution, which is at least a portion of the total volume of the remaining aqueous binder solution. After evaporating the water from the second mixture, the resulting mixture contains conductive mottled active material aggregates having binder microparticles scattered on one or more active material particles, the binder microparticles present in the resulting mixture of conductive mottled active material aggregates in a second mass % of the mixture. Clearly, the second mass % of binder microparticles is higher than the first mass %.

[0046] For example, in one embodiment, the multi-step evaporation step of block 404 is a two-step evaporation step, which includes introducing a dry powder mixture of conductive mottled active material particles into a first half of the total volume of the aqueous binder solution. After evaporating the water from the first mixture, the resulting mixture comprises a microparticle subunit of the conductive mottled active material having binder microparticles dispersed on one or more active material particles, wherein the binder microparticles are present in the resulting mixture of conductive mottled active material microparticle subunits in a first mass% of the resulting mixture.

[0047] Subsequently, a mixture of the resulting conductive mottled active material particulate subunits, containing a first mass% of binder microparticles, is introduced into the remaining second half of the total volume of the aqueous binder solution. After evaporating the water from the second mixture, the resulting mixture contains the conductive mottled active material particulate subunits, each having binder microparticles dispersed on one or more active material particles, wherein the binder microparticles are present in the resulting mixture of conductive mottled active material particulate subunits in a second mass% of the mixture. Clearly, the second mass% of binder microparticles is approximately twice the first mass%.

[0048] In various embodiments, water is evaporated from an aqueous binder solution to produce a dry powder mixture of aggregates of the conductive mottled active material. In various embodiments of Method 400, such aggregates may be mechanically processed (e.g., pulverized, crushed, etc.) to produce a finer powder mixture. The mechanical processing operation produces a powder having one or more conductive particles arranged in the binder microparticles. The presence of this conductive particle additive reduces interparticle forces between the binder microparticles by introducing space, thereby reducing aggregates and thus producing a powder mixture of aggregates of the conductive mottled active material. In some embodiments, the mechanical processing operation includes a step of cooling the microparticle mixture during a mechanical stirring step to prevent the above-mentioned problem of the binder material being heated to a temperature at which it becomes flexible and begins to aggregate together.

[0049] In various embodiments, the operation of Method 400 may also include an optional, not-described step of scattering an additional amount of conductive particles to further increase the mass of the composition and the overall conductivity of the mixture of aggregates of conductive mottled active material. This scattering step may be performed at any point in Method 400, or even in two or more different steps in Method 400.

[0050] For the sake of ease of explanation and description, it should be noted that Figure 4 is described above in the context of a two-step evaporation using approximately equal amounts of aqueous binder solution. For the sake of ease of explanation and description, it should be noted that Figure 4 is described above in the context of a two-step evaporation using approximately the same amounts of aqueous binder solution. However, those skilled in the art will recognize that the method of Figure 4 may include any number of mixing and evaporation steps without departing from the scope of the disclosure. It should be further noted that the method of Figure 4 may include various amounts of dispersed aqueous binder solution in any number of mixing and evaporation steps without departing from the scope of the disclosure. For example, in another embodiment, the multi-stage evaporation of block 404 is a three-stage evaporation comprising: a first step of mixing and evaporating a dry powder mixture of conductive mottled active material particles in an aqueous binder solution of 50% of the total volume; a second step of mixing and evaporating the obtained fine particle subunits of conductive mottled active material in an aqueous binder solution of 25% of the total volume; and a third step of mixing and evaporating the obtained fine particle subunits of conductive mottled active material in an aqueous binder solution of 25% of the total volume.

[0051] In another embodiment, the multi-stage evaporation of block 404 is a continuous evaporation process in which a small portion of the total volume of the aqueous binder solution is mixed with the dry powder mixture of conductive mottled active material particles and evaporated at approximately the same time. Control of the water evaporation rate can be achieved by evaporating water from the mixture at a rate that matches the rate required for the introduction of the aqueous binder solution into the mixture. This evaporation can be carried out using techniques known to those skilled in the art. Evaporation can be carried out under atmospheric pressure or reduced pressure, and at room temperature or a temperature higher than room temperature that does not decompose the constituent particles. Naturally, the pressure and / or temperature selected depends on the solvent (e.g., water), the polymer and / or the dry mixture and other constituent materials present in the binder solution, and the total amount of these materials. Thus, the chart of the mass % of binder particles over time in the resulting mixture of conductive mottled active material aggregates will be a slope or curve rather than a step shape associated with the batch-type multi-stage evaporation process described above, in a continuous evaporation process (e.g., depending on whether the rates of introduction and evaporation of the binder solution change over time).

[0052] Thus, the batch-type multi-stage evaporation and continuous evaporation processes of Method 400 enable the production of composite powders of conductive mottled active material aggregates, which have an aqueous treatment method that reduces the amount of water and the amount of time the active material particles are in contact with water. This is useful for active materials, which are more tolerant of aqueous environments (e.g., LFP) and are used in processes for producing conductive mottled active material aggregates that strictly avoid contact between the active material particles and water.

[0053] Similarly, Figure 5 is a block diagram of another method 500 for producing a mixture of conductive mottled active material particles via multi-step evaporation, according to several embodiments. For ease of illustration and description, the powder mixture of Figure 1 will be referenced and the method 500 will be described below in an exemplary context. However, the method 500 is not limited to these exemplary contexts and can rather be applied to any of the various implementable configurations using the guidelines provided herein.

[0054] The method begins in block 502 with a step of stirring a dry powder mixture of conductive speckled active material particles in an aqueous binder solution via multi-step evaporation. In various embodiments, the aqueous binder solution contains a mixture of binder microparticles suspended in an aqueous solvent as described in detail earlier with respect to Figures 2-4. In one embodiment, the aqueous binder solution is a commercially available dispersion (or emulsion) containing binder microparticles dispersed in an aqueous solution. In another embodiment, the aqueous binder solution is prepared by introducing a wetting agent to a dry powder mixture of binder microparticles. After moistening the dry mixture of binder microparticles, the moistened binder microparticles are stirred in a large volume of aqueous solution (e.g., water) by high-shear mixing, sonication, or other suitable method for uniformly dispersing the binder microparticles in the aqueous solution. In other embodiments, the aqueous binder solution contains conductive particles uniformly dispersed in an aqueous binder solution, such as an intermediate aqueous solution containing a uniform dispersion of binder microparticles and conductive particles as shown in Figure 2.

[0055] In various embodiments, the multi-step evaporation of block 502 includes the step of introducing a dry powder mixture of active material particles into a first volume of aqueous binder solution, which is less than the total volume of the aqueous binder solution. After evaporating water from the first mixture, the resulting mixture further comprises binder fine particles dispersed among the multiple active material particles, the binder fine particles present in the resulting mixture in a first mass% of the resulting mixture.

[0056] Subsequently, the resulting active material-binder particle mixture, containing a first mass % of binder particles, is introduced into a second volume of the aqueous binder solution, which is at least a portion of the total volume of the remaining aqueous binder solution. After evaporating the water from the second mixture, the resulting active material-binder particle mixture contains binder particles dispersed on one or more active material particles, with the binder particles present in the resulting active material-binder particle mixture at a second mass % of the mixture. As is clear, the second mass % of binder particles is higher than the first mass %.

[0057] For example, in one embodiment, the multi-step evaporation step of block 502 is a two-step evaporation step, which includes introducing a dry powder mixture of active material particles into a first half of the total volume of the aqueous binder solution. After evaporating the water from the first mixture, the resulting active material-binder particle mixture contains binder particles dispersed on one or more active material particles, and the binder particles are present in the resulting active material-binder particle mixture in a first mass% of the mixture.

[0058] Subsequently, the resulting active material-binder particle mixture, containing a first mass % of binder particles, is introduced into the remaining second half of the total volume of the aqueous binder solution. After evaporating the water from the second mixture, the resulting active material-binder particle mixture contains binder particles dispersed on one or more active material particles, and the binder particles are present in the resulting active material-binder particle mixture at a second mass % of the mixture. Clearly, the second mass % of binder particles is approximately twice the first mass %.

[0059] For the sake of ease of explanation and description, it should be noted that Figure 5 is described above in the context of a two-step evaporation using approximately equal amounts of aqueous binder solution. For the sake of ease of explanation and description, it should be noted that Figure 4 is described above in the context of a two-step evaporation using approximately the same amount of aqueous binder solution. However, those skilled in the art will recognize that the method of Figure 4 may include any number of mixing and evaporation steps without departing from the scope of the disclosure. It should be further noted that the method of Figure 5 may include various amounts of dispersed aqueous binder solution in any number of mixing and evaporation steps without departing from the scope of the disclosure. For example, in another embodiment, the multi-stage evaporation of block 502 is a three-stage evaporation, the first step comprising mixing and evaporating a dry powder mixture of active material particles in a total volume of aqueous binder solution, the second step comprising mixing and evaporating the resulting active material-binder fine particle mixture in a total volume of aqueous binder solution, and the third step comprising mixing and evaporating the resulting active material-binder fine particle mixture in a total volume of aqueous binder solution.

[0060] In another embodiment, the multi-stage evaporation of block 502 is a continuous evaporation process in which a small portion of the total volume of the aqueous binder solution is mixed with the dry powder mixture of active material particles and evaporated at approximately the same time. Control of the rate of water evaporation can be achieved by evaporating water from the mixture at a rate that matches the rate required for the introduction of the aqueous binder solution into the mixture. This evaporation can be carried out using techniques known to those skilled in the art. Evaporation can be carried out under atmospheric pressure or reduced pressure, and at room temperature or a temperature higher than room temperature that does not decompose the constituent particles. Naturally, the pressure and / or temperature selected depends on the solvent (e.g., water), the polymer and / or dry mixture and other constituent materials present in the binder solution, and the total amount of these materials. Thus, the chart of the mass % of binder particles over time in the resulting active material-binder particle mixture will be a slope or curve rather than a step shape associated with the batch-type multi-stage evaporation process described above, in a continuous evaporation process (e.g., depending on whether the rates of introduction and evaporation of the binder solution change over time).

[0061] In block 504, the resulting active material-binder microparticle powder mixture is stirred with the dry powder mixture of conductive particles. In various embodiments, the dry powder mixture of conductive particles and the active material-binder microparticle powder mixture are mixed by high-shear mixing, sonication, or any other suitable method for uniformly dispersing the conductive particles in the active material-binder microparticle powder mixture to produce aggregates of conductive mottled active material, such as the conductive mottled active material aggregate 102 shown in Figure 1.

[0062] In various embodiments, water is evaporated from an aqueous binder solution to produce a dry powder mixture of aggregates of the conductive mottled active material. In various embodiments of Method 500, such aggregates may be mechanically processed (e.g., pulverized, crushed, etc.) to produce a finer powder mixture. The mechanical processing operation produces a powder having one or more conductive particles arranged in the binder microparticles. The presence of this conductive particle additive reduces interparticle forces between the binder microparticles by introducing space, thereby reducing aggregates and thus producing a powder mixture of aggregates of the conductive mottled active material. In some embodiments, the mechanical processing operation includes a step of cooling the microparticle mixture during a mechanical stirring step to prevent the above-mentioned problem of the binder material being heated to a temperature at which it becomes flexible and begins to aggregate together.

[0063] In various embodiments, the operation of Method 500 may also include an optional, not-described step of scattering an additional amount of conductive particles to further increase the mass of the composition and the overall conductivity of the mixture of aggregates of conductive mottled active material. This scattering step may be performed at any point in Method 500, or even in two or more different steps in Method 500.

[0064] Thus, the batch-type multi-stage evaporation and continuous evaporation processes of Method 500 enable the production of composite powders of fine particle subunits of conductive mottled active material, which have an aqueous treatment method that reduces the amount of water and the amount of time the active material particles are in contact with water. This is useful for active materials, which can be used in the production process of aggregates of conductive mottled active material that are more tolerant of aqueous environments (e.g., LFP) and, without limitation, strictly avoid contact between the active material particles and water.

[0065] The configuration described herein substantially overcomes the aforementioned drawbacks in conventional electrode formation by providing a dry powder system of conductive mottled active material to reduce the solvent and associated heating and drying time in the electrode manufacturing process. Electrodes manufactured using dry particles, such as fine particle subunits of the conductive mottled active material described herein, coated onto a current collector, demonstrate an improved manufacturing process.

[0066] Throughout this specification, numerical values ​​represent approximate measured values ​​or limit values ​​within a range that includes minor deviations from a given value, and embodiments that have an approximate value, as well as embodiments that have an exact value. Except for the examples described at the end of the detailed description, all numerical values ​​of parameters in this specification, including the appended claims (e.g., numerical values ​​of quantities or conditions), are understood to always be modified by the word “about,” whether or not the word “about” is actually written before the numerical value. “About” indicates that the numerical value tolerates some degree of inaccuracy (to some extent approach the exact value, to be approximate or reasonably close to the value; nearly). Where the inaccuracy provided by “about” is not otherwise understood among those skilled in the art in this ordinary sense, “about” as used herein indicates at least the variation that may arise from the ordinary methods of measuring and using such parameters. For example, “about” may include 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 description of the range includes disclosure of all values ​​within the entire range, as well as the ranges further divided within the range, including the endpoints and subranges given for the range.

[0067] It should be noted that not all of the operations or elements described in the general description above are essential, and that some of the operations or devices may be unnecessary. Furthermore, one or more additional operations may be performed or one or more additional elements may be included in addition to those described. Also, concepts are described with reference to specific embodiments. However, those skilled in the art will understand that various modifications and changes are possible without departing from the scope of this description as described in the following claims. Therefore, this specification and the drawings should be interpreted as illustrative rather than restrictive, and all such modifications are intended to be within the scope of this description.

[0068] Benefits and other advantages, and solutions to problems, relating to specific embodiments, are described above. However, benefits, advantages, solutions to problems, and any features that may result in the implementation or enhancement of any benefit, advantage, or solution should not be construed as essential, required, or essential features in any claim or in all claims. Furthermore, the specific embodiments described above are merely illustrative, and the subject matter described may be modified and implemented in an equivalent manner, though different from what would be apparent to a person skilled in the art who has the benefits described herein. Except as described in the following claims, no limitation is intended on the structural or design details shown herein. It is therefore clear that the specific embodiments described above may be modified or altered, and all such variations are considered to fall within the scope of the subject matter described. Thus, the scope of protection sought herein is as described in the following claims.

[0069] In addition to the embodiments described herein, examples of certain combinations are included in the scope of this description, some of which are detailed below. [Examples]

[0070] Example 1: A powder mixture comprising aggregates of multiple particles, each aggregate of multiple particles comprising one or more conductive spotted active material particles bound together by electrostatic force, each conductive spotted active material particle comprising multiple conductive particles electrically in contact with the active material particle, further comprising conductive spotted active material particles comprising an anode electroactive material or a cathode electroactive material; and a mixture of binder microparticles scattered on the conductive spotted active material particles, the mixture of binder microparticles maintaining a temperature below the softening temperature of the constituent particles at which the mixture of binder microparticles becomes flexible and begins to aggregate together, and further comprising a powder mixture comprising less than 3 mass percent of the mixture of binder microparticles.

[0071] Example 2. The powder mixture of Example 1, wherein the binder fine particle mixture contains a material selected from the group consisting of PVDF, CMC, PMMA, and PTFE.

[0072] Example 3. The powder mixture of Example 1, wherein the content of active material particles in the powder mixture is at least 90% by mass.

[0073] Example 4. The powder mixture of Example 1, wherein the mixture of binder fine particles contains a plurality of binder particle aggregates bound together by electrostatic force, and each of the binder particle aggregates is an aggregate of primary binder particles.

[0074] Example 5. The powder mixture of Example 1, wherein the first conductive particles of the first conductive mottled active material particles are in electrical contact with one or more conductive particles of the second conductive mottled active material particles.

[0075] Example 6. The powder mixture of Example 1, wherein aggregates of multiple particles are produced by stirring active material particles, conductive particles, and binder fine particles in a solvent solution, evaporating the solvent solution, and generating a powder mixture of particle aggregates.

[0076] Example 7. The powder mixture of Example 6, wherein at least a first volume of the solvent solution is introduced into the active material particles, conductive particles and binder microparticles and evaporated before a second volume of the solvent solution is introduced into the active material particles, conductive particles and binder microparticles and evaporated.

[0077] Example 8. A method for producing conductive mottled active material particles, comprising the steps of: stirring a fine particle mixture containing active material particles and conductive particles to produce a mixture of conductive mottled active material particles, wherein each conductive mottled active material particle contains a plurality of conductive particles electrically in contact with the active material particle; stirring active material particles and conductive particles in an aqueous binder solution, wherein the aqueous binder solution contains a mixture of binder fine particles suspended in an aqueous solvent; and evaporating water from the aqueous binder solution to produce a powder containing a mixture of binder fine particles dispersed on conductive mottled active material particles.

[0078] Example 9. The method of Example 8, further comprising the step of stirring a mixture of binder fine particle powders in an aqueous solution to produce an aqueous binder solution.

[0079] Example 10. The method of Example 8, wherein the step of stirring the fine particle mixture includes a step of stirring a dry mixture of active material particles in an aqueous conductive particle solution.

[0080] Example 11. The method of Example 8, further comprising the step of stirring a dry mixture of active material particles in an aqueous binder solution before adding a dry mixture of conductive particles.

[0081] Example 12. The method of Example 8, further comprising the step of stirring a dry mixture of conductive particles in an aqueous binder solution before adding the dry mixture of active material particles.

[0082] Example 13. The method of Example 8, wherein the step of stirring the fine particle mixture includes the step of stirring the aqueous active material solution and the aqueous conductive particle solution.

[0083] Example 14. The method of Example 8, further comprising the step of stirring a dry mixture of active material particles in an aqueous binder solution before adding the aqueous conductive particle solution.

[0084] Example 15. The method of claim 8, further comprising the step of stirring the aqueous conductive particle solution in an aqueous binder solution before adding the dry mixture of active material particles. [Explanation of symbols]

[0085] 100...Powder mixture 102 ···Aggregates of particles 104 ···Conductive mottled active material particles 106...conductive particles 108...Active material particles 110 ···Binder microparticles 200 ···Method for producing aggregates of fine particle subunits of conductive mottled active material 202...block 204...block 206...block 208...blocks 300...Another method for producing composite particles or particulate subunits of conductive-spotted active materials 302...block 304...block 306...block 400 ··Method for producing conductive spotted active material particles via multi-step evaporation 402...block 404 ···Block 500...Another method for producing a mixture of conductive spotted active material particles via multi-step evaporation. 502...block 504...block

Claims

1. A powder mixture (100) containing aggregates (102) of multiple particles, Each of the aggregates (102) of the plurality of particles is One or more conductive mottled active material particles (104) bonded by electrostatic force, each of the conductive mottled active material particles (104) includes a plurality of conductive particles (106) electrically in contact with an active material particle (108), and further, the active material particles include an anode electroactive material or a cathode electroactive material; and A mixture of binder microparticles (110) scattered on conductive mottled active material particles, wherein the binder microparticle mixture maintains a temperature below the softening temperature of the constituent particles at which the binder microparticle mixture becomes flexible and begins to aggregate together, and further comprises less than 3 mass percent of the binder microparticle mixture.

2. The powder mixture according to claim 1, wherein the mixture of binder fine particles comprises a material selected from the group consisting of PVDF, CMC, PMMA, and PTFE.

3. The powder mixture according to claim 1, wherein the content of the active material particles in the powder mixture is at least 90% by mass.

4. The powder mixture according to claim 1, wherein the mixture of binder fine particles comprises a plurality of binder particle aggregates bound together by electrostatic force, and each of the binder particle aggregates is an aggregate of primary binder particles.

5. The powder mixture according to claim 1, wherein the first conductive particles of the first conductive mottled active material particles are in electrical contact with one or more conductive particles of the second conductive mottled active material particles.

6. The powder mixture according to claim 1, wherein the aggregates of the plurality of particles are produced by stirring active material particles, conductive particles, and binder fine particles in a solvent solution, evaporating the solvent solution, and generating the powder mixture of particle aggregates.

7. The powder mixture according to claim 6, wherein at least a first volume of the solvent solution is introduced into the active material particles, conductive particles and binder microparticles and evaporated before a second volume of the solvent solution is introduced into the active material particles, conductive particles and binder microparticles and evaporated.

8. A step (302) of stirring a fine particle mixture containing active material particles and conductive particles to produce a mixture of conductive mottled active material particles, wherein each of the conductive mottled active material particles includes a plurality of conductive particles electrically in contact with the active material particles; A step (304) of stirring the active material particles and conductive particles in an aqueous binder solution, wherein the aqueous binder solution comprises a mixture of binder fine particles suspended in an aqueous solvent; and (306) A step of evaporating water from the aqueous binder solution to produce a powder containing a mixture of the binder fine particles dispersed on conductive spotted active material particles. A method for producing conductive spotted active material particles containing [a specific substance].

9. The method according to claim 8, further comprising the step of stirring a mixture of binder fine particle powders in an aqueous solution to produce the aqueous binder solution.

10. The method according to claim 8, wherein the step of stirring the fine particle mixture includes the step of stirring a dry mixture of active material particles in an aqueous conductive particle solution.

11. The method according to claim 8, further comprising the step of stirring the dry mixture of active material particles in the aqueous binder solution before adding the dry mixture of conductive particles.

12. The method according to claim 8, further comprising the step of stirring the dry mixture of conductive particles in the aqueous binder solution before adding the dry mixture of active material particles.

13. The method according to claim 8, wherein the step of stirring the fine particle mixture includes the step of stirring the aqueous active material solution and the aqueous conductive particle solution.

14. The method according to claim 8, further comprising the step of stirring a dry mixture of active material particles in the aqueous binder solution before adding the aqueous conductive particle solution.

15. The method according to claim 8, further comprising the step of stirring the aqueous conductive particle solution in the aqueous binder solution before adding the dry mixture of active material particles.

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