Anode active material particles encapsulated within a thermally decomposed nano-structured metal oxide, and a method for producing and using the same

Abstract

A method for producing a coated active anode material, which comprises dry-mixing a mixed anode material with alumina, titania or a mixture thereof, which is produced by a pyrolysis method, nanostructured and preferably surface-modified, in a mixing unit having a specific power of 0.05 to 1.5 kW per 1 kg of the mixed anode material; a coated mixed anode material obtained by this method; an anode for a lithium-ion battery; and a lithium-ion battery containing such a coated active anode material.

Description

Technical Field

[0001] The present invention relates to a method for producing encapsulated anode active material particles by dry mixing carbon and / or Si-based particles with a fumed nanostructured metal oxide under shear conditions. The present invention further relates to an anode material coated with a fumed metal oxide, as well as a battery cell containing encapsulated carbon and / or Si-based anode particles and their use.

Background Art

[0002] In recent years, various energy storage technologies have attracted attention and have been the focus of intensive research and development in the industry and academia. As energy storage technologies expand to devices such as mobile phones, camcorders, notebook computers, and even electric vehicles, the demand for high-energy density batteries used as power sources for such devices is increasing. Lithium-ion secondary electrons are one of the most important battery types currently in use.

[0003] A lithium-ion secondary battery typically consists of an anode made of a carbon material or a lithium metal alloy, a cathode made of a lithium metal oxide, and an electrolyte in which a lithium salt is dissolved in an organic solvent. The separator of a lithium-ion battery allows lithium ions to pass between the positive and negative electrodes during charging and discharging of the battery.

[0004] U.S. Patent Application Publication No. 2019 / 0393543 describes a lithium metal secondary battery including a cathode, an anode, and a porous separator or electrolyte disposed between the cathode and the anode. The anode includes (a) an anode active layer containing a layer of lithium or a lithium alloy in the form of a foil, coating, or strongly aggregated plurality of particles as an anode active material, and (b) an anode protective layer of a conductive sulfonated elastomer composite disposed between the anode active layer and the separator / electrolyte.

[0005] U.S. Patent Application Publication No. 2019 / 363345 describes forming a protective coating of graphene on the negative electrode lithium electrode of a lithium-containing electrochemical cell such as a lithium-ion battery. The graphene protective coating is said to reduce the formation and growth of dendrites.

[0006] International Publication No. 2019 / 215406 pamphlet describes an anode for a lithium-ion battery that includes at least one anode material that is binder-free, pre-filled with lithium ions, and coated with a protective coating containing a very large number of suitable materials. However, none of the coatings used in the present invention are disclosed in International Publication No. 2019 / 215406 pamphlet.

[0007] Chinese Patent Application Publication No. 106025242 describes a composite anode material for a lithium-ion battery that includes a core layer of porous silicon alloy nanowires having carbon nanotubes and a shell layer made of a conductive polymer film of graphene blended with polypropylene oxide, polyethylene succinate, polyethylene succinate, or polyethylene glycol imine.

[0008] It is known to coat the cathode material of a lithium-ion battery with Al2O3, TiO2, or ZrO2 to improve cycle performance.

[0009] Examples of the use of metal oxides in cathode materials are described in the following papers. In the paper "Mesoporous Carbon Materials as Cathodes for High-Performance Lithium-Ion Capacitors" by Zhang et al., published in Chinese Chemical Letters (2018), 29(4), pages 620 - 623, magnesium citrate was used as a precursor for C mesoporous, and nano-sized metal oxide particles were provided by magnesium citrate as a template.

[0010] In the paper "Improving the Cycle Performance of Lithium-Sulfur Batteries by Using Metal Oxides as Functional Additives to Capture Lithium Polysulfides" by Ponraj et al., published in ACS Applied Material Interfaces in 2016, 8, pages 4000 - 4006, hydrophilic metal oxides were used as additives on the surface of the active sulfur in the cathode to capture polysulfides.

[0011] Elements such as carbon and its allotropes (graphene) are used as anode materials in lithium-ion secondary batteries, but there are some problems with the structural stability of graphene in the anode. In the paper "Electrodes Containing Graphene Nanopowders Inserted into a Sealed Structure within Anodic Aluminum Oxide Coated with PANI Using a Low-Temperature Hydrothermal Method" by Sugam et al., published in the 62nd DAE Solid State Physics Symposium in 2017, 1942, the graphene nanopowders were inserted and confined on anodic aluminum oxide coated with PANI (polyaniline).

[0012] In the paper "Alumina-Coated Fe3O4-Reduced Graphene Oxide Composite Electrodes as Stable Anodes for Lithium-Ion Batteries" by Qi-Hui et al., published in Electrochimica Acta in 2015, 156, pages 147 - 153, an Al2O3 coating is used on the Fe3O4-reduced graphene oxide composite anode material.

[0013] Chinese Patent Application Publication No. 104393258 discloses an Si titanium alloy (graphene nanocomposite material) coated with an oxide.

[0014] Wu Xing et al. described a one-step hydrothermal method for forming a core-shell structure based on MgFe2O4 and TiO2 in the "Electrochemical study of MgFe2O4@TiO2 core-shell nanospheres as anode materials for lithium battery applications" published in Journal of Materials Science: Science in Electronics, Vol. 29, No. 20 (2018), pp. 17872-17880, ISSN: 0957-4522.

[0015] A rather significant general problem with anode materials, especially silicon-based anode materials, is the formation of an uncontrolled solid electrolyte interface (SEI) during the initial charge-discharge process of the battery. Furthermore, due to most of the aging processes of the materials, the performance deteriorates during cycling. This aging phenomenon is particularly related to Si-based anode active materials. During cycling, the negative electrode material is affected by several electrochemical degradation mechanisms that can cause inactivation of the negative electrode material. Due to electrolyte-induced surface changes and unwanted side reactions with lithium species, the thickness of the SEI layer increases, and ultimately, the performance and battery life decrease.

[0016] Surface coating has been proven to be a very important method to address this aging problem by suppressing the direct contact between the active material surface and the liquid electrolyte.

[0017] Nanoscale metal oxide particles have been used as additives in lithium-ion batteries, but their effects are limited due to poor dispersibility. Therefore, practical methods for improving the long life of lithium-ion secondary batteries are often limited. When using commercially available nanoscale metal oxides, in many cases, non-uniform distribution and large weakly aggregated metal oxide particles occur on the surface of the anode material. As a result, the anode material particles are not completely covered by the metal oxide particles, and large undispersed metal oxide particles exist adjacent to the anode particles, which are clearly shown in SEM elemental mapping.

Prior Art Documents

Patent Documents

[0018] [Patent Document 1] U.S. Patent Application Publication No. 2019 / 0393543 [Patent Document 2] U.S. Patent Application Publication No. 2019 / 363345 [Patent Document 3] WO 2019 / 215406 Pamphlet [Patent Document 4] Chinese Patent Application Publication No. 106025242 [Patent Document 5] Chinese Patent Application Publication No. 104393258 [Summary of the Invention] [Problems to be Solved by the Invention]

[0019] The problem to be addressed by the present invention is to provide a uniform coating layer of a metal oxide or a metal oxide mixture around an anode active material containing carbon and / or Si-based particles.

[0020] Surprisingly, during the thorough experimental process, alumina or titania (or a mixed metal oxide of alumina and titania), which are nanostructured metal oxides produced by a thermal decomposition method, can be effectively used for coating an anode material with a metal oxide by using a dry mixing process to coat the anode material containing carbon and / or Si-based particles. Also surprisingly, it was found that further modifying the surface of the nanostructured metal oxide produced by the thermal decomposition method before dry mixing can further significantly improve the coating rate and uniformity of the coating. [Means for Solving the Problems]

[0021] The present invention provides a method for manufacturing a coated active anode material, the coated active anode material, and the use of the coated active anode material in a lithium-ion battery. The lithium-ion battery of the present invention can be used in electronic and electrical devices such as mobile phones, computers (laptop computers, desktop computers, computer pads), electronic watches, key fobs, electrical appliances, power tools, vacuum cleaners, electric lawn mowers, and electric vehicles.

[0022] According to a first aspect of the present invention, a method for manufacturing a coated active anode material is provided. This method is characterized by obtaining a coated active anode material by dry-mixing an active anode material and alumina or titania, which is a metal oxide produced by a thermal decomposition method, in a mixing unit under shear conditions. The coated active anode material is in particulate form, and the metal oxide has a BET surface area of 5 to 300 m 2 / g, and after subjecting a mixture consisting of 5% by weight of the above particles and 95% by weight of an aqueous sodium pyrophosphate solution at 0.5 g / L to ultrasonic treatment at 25°C for 60 seconds, it is characterized by having a unimodal and narrow particle size distribution with an average agglomerate diameter d50 of 5 to 150 nm measured by static light scattering (SLS).

[0023] The metal oxide produced by the thermal decomposition method is hydrophilic. Preferably, in one embodiment, the metal oxide produced by the thermal decomposition method is surface-modified to be hydrophobic.

[0024] In one embodiment, the mixing unit has a specific power of 0.05 to 1.5 kW per 1 kg of the mixed anode material.

[0025] The coated active anode material is in particulate form, and the metal oxide has a BET surface area of 5 to 300 m 2 / g, and a mixture consisting of 5% by weight of the above particles and 95% by weight of an aqueous sodium pyrophosphate solution at 0.5 g / L was subjected to ultrasonic treatment at 25°C for 60 seconds, and the average aggregate diameter d50 measured by static light scattering (SLS) was 5 to 150 nm, more preferably 10 to 120 nm, and even more preferably 20 to 100 nm, having a unimodal and narrow particle size distribution

[0026] SEM-EDX mapping of the coated active anode material shows that the metal oxide completely and uniformly covers substantially all of the anode particles, with no or few large metal oxide weak aggregates

[0027] In one embodiment, the method is characterized in that the specific power of the mixing unit is 0.1 to 1000 kW, the volume of the mixing unit is 0.1 L to 2.5 m 3 and the speed of the mixing tool in the mixing unit is 5 to 30 m / s

[0028] After subjecting a mixture consisting of 5% by weight of particles and 95% by weight of an aqueous sodium pyrophosphate solution at 0.5 g / L to ultrasonic treatment at 25°C for 60 seconds, the span (d 90 -d 10 ) / d50 of the particles of the mixed oxide containing metal oxide and / or aluminum or titanium, measured by static light scattering (SLS), is 0.4 to 1.2

[0029] In one embodiment, the active anode material is in powder form and contains carbon particles, silicon particles, or silicon oxide particles, or all combinations thereof

[0030] The active anode material contains carbon and / or Si-based particles. As used herein, the term Si-based particles means silicon particles (e.g., pure silicon particles), silicon oxide (SiOx) particles, and all combinations of silicon, silicon oxide, and carbon particles (including mixtures and composites thereof). The silicon oxide can be SiO and / or SiO2

[0031] In one embodiment, the coated active anode material is further heat-treated after dry mixing.

[0032] In one embodiment, the proportion of the metal oxide in the coated active anode material is 0.05% to 5% by weight based on the total weight of the coated mixed anode material.

[0033] Another aspect of the present invention relates to a coated active anode material obtained by the above method.

[0034] According to still another aspect of the present invention, there is provided a coated active anode material including an active anode material and a coating of nanostructured metal oxide produced by a pyrolysis method formed on the surface of the mixed anode material. The coated active anode material is particulate, and the metal oxide has a BET surface area (DIN 9277:2014) of 5 to 300 m 2 / g, and has a unimodal and narrow particle size distribution with an average aggregate diameter d50 of 5 to 150 nm obtained by measuring with static light scattering (SLS) after subjecting a mixture consisting of 5% by weight of particles and 95% by weight of an aqueous solution of sodium pyrophosphate at 0.5 g / L to ultrasonic treatment at 25°C for 60 seconds. The nanostructured metal oxide produced by the pyrolysis method is preferably surface-treated to be hydrophobic by reacting the hydroxyl groups of alumina or titania with silane to form -O-Si-R groups. The metal oxide is hydrophilic or hydrophobic, preferably hydrophobic. The active anode material is carbon, silicon, silicon oxide (SiOx), or any combination thereof (including mixtures and / or composites of carbon, silicon, and silicon oxide).

[0035] Other aspects of the present invention relate to an active negative electrode material for a lithium-ion battery including the coated active anode material, a lithium-ion battery including the coated active anode material, and the use of the coated active anode material in an active negative electrode material of a lithium-ion battery.

[0036] Still another aspect of the present invention relates to an apparatus driven by a lithium-ion battery.

[0037] The nanostructured metal oxides produced by the flame process, combined with excellent dispersibility during the dry coating process of the anode material, have a unimodal and narrow particle size distribution. These particles provide excellent interaction and appropriate adhesion to the anode active material.

[0038] Furthermore, by additionally surface-modifying these particles, the interaction and adhesion to the anode active material are further improved. As a result, complete de-aggregation of the metal oxide weak aggregates occurs, and finally, anode active material particles completely and uniformly covered with the fumed nanostructured surface-modified metal oxide are provided.

[0039] It has been found that by using a high-strength dry coating process in combination with the pyrolysis method nanostructured metal oxide particles, the dispersibility of the metal oxide particles is significantly improved and a uniform coating is achieved according to the method of the present invention. During dry mixing, due to the applied shear force (mixing), all metal oxide weak aggregates are decomposed into small strong aggregates and have a very high tendency to deposit on the surface of the anode active material particle powder, resulting in very good interaction and adhesion, and as a result, a uniform coating is obtained. In contrast, conventional metal oxide particles that are not produced by the pyrolysis method and are not nanostructured are composed of isolated spherical particles (the result of grinding coarse metal oxide particles) and do not exhibit such behavior.

[0040] These features and other features and advantages of the present invention will be better understood by reading the following detailed description in conjunction with the following drawings.

Brief Description of the Drawings

[0041]

Figure 1

Figure 2

Figure 3

Figure 4

[0042] Detailed Description of the Invention According to a first aspect of the present invention, there is provided a method for manufacturing encapsulated active anode material particles by dry-mixing an active anode material and a fumed nanostructured metal oxide under shear conditions. The fumed nanostructured metal oxide is preferably surface-modified to be hydrophobic before dry-mixing. A second aspect of the present invention relates to an anode material coated with a fumed metal oxide, and a third aspect of the present invention relates to a battery cell containing encapsulated carbon and / or Si-based anode particles.

[0043] Method for Manufacturing Coated Anode Active Material

[0044] According to a first aspect of the present invention, there is provided a method for manufacturing a coated active anode material. In this method, active anode material particles, such as carbon and / or Si-based anode particles, and a nanostructured oxide produced by a pyrolysis method containing at least two metals and / or a mixed oxide produced by a pyrolysis method are dry-mixed under shear conditions. The Si-based anode particles include silicon particles, silicon oxide particles, and all combinations of silicon, silicon oxide, and carbon particles.

[0045] The fumed nano-structured metal oxide is preferably surface-modified to be hydrophobic before dry mixing.

[0046] The active anode material is also called the core active anode material, or the substrate active anode material or particles. The metal oxide produced by the pyrolysis method, nanostructured, and preferably surface-modified is also called the coating. The coated active anode material refers to the mixed active anode material having the coating formed by dry mixing. When the dry mixing is completed, the carbon and / or Si-based particles are covered with the above metal oxide.

[0047] Dry mixing

[0048] Dry mixing can be carried out, for example, in a mixing unit having a specific power of 0.05 to 1.5 kW per 1 kg of the mixed anode material. Dry mixing is understood to mean that no liquid is added or used during the mixing process, that is, for example, substantially dry powders are mixed together. However, there may be a trace amount of moisture or a liquid other than water in the mixing raw materials, or the mixed material may be water of crystallization.

[0049] When the specific power used is less than 0.05 kW per 1 kg of the mixed anode material, the distribution of the metal oxide on the upper part of the anode active material particles becomes non-uniform, and there is a possibility that it is not firmly bonded to the core material of the anode active material particles. When the specific power per 1 kg of the mixed anode material exceeds 1.5 kW, the electrochemical characteristics deteriorate. Furthermore, the coating becomes brittle and there is a risk of being easily damaged. The nominal power of the mixing unit can be varied widely, for example, from 0.1 kW to 1000 kW. Therefore, it is possible to use a laboratory-scale mixing unit with a nominal power of 0.1 to 5 kW, or a production-scale mixing unit with a nominal power of 10 to 1000 kW. The nominal power is the maximum absolute power stated on the nameplate of the mixing unit.

[0050] The volume of the mixing unit can vary widely. For example, the volume of the mixing unit is 0.1 L to 2.5 m 3is in the range. For example, a laboratory-scale mixing unit has a volume of 0.1 to 10 L, and a production-scale mixing unit has a volume of 0.1 to 2.5 m 3 is.

[0051] Preferably, in the method of the present invention, the forced-action mixer is used in the form of a powerful mixer equipped with a high-speed mixing tool. It has been found that the best results are obtained when the speed of the mixing tool is 5 to 30 m / s, more preferably 10 to 25 m / s. Examples of commercially available mixing units suitable for the method of the present invention include Henschel mixers and Erie mixers. The Erie mixer can be, for example, a high-intensity Erie mixer.

[0052] The mixing time can be variable and is preferably 0.1 to 120 minutes, more preferably 0.2 to 60 minutes, and most preferably 0.5 to 10 minutes.

[0053] After mixing, the mixture may be heat-treated to improve the binding between the coating and the anode active material particles. However, this treatment is optional in the method of the present invention. This is because in this method, the metal oxide produced by the thermal decomposition method, nanostructured and surface-modified, adheres to the core anode active material particles, i.e., carbon and / or Si-based particles, with sufficient hardness. Therefore, in a preferred embodiment of the method of the present invention, heat treatment may not be performed after mixing.

[0054] The best results regarding the adhesion of the metal oxide to the core anode active material particles are obtained when the BET surface area of the metal oxide is 5 m 2 / g to 300 m 2 / g, more preferably 10 m 2 / g to 200 m 2 / g, and most preferably 15 m 2 / g to 150 m 2 / g. The BET surface area can be measured by nitrogen adsorption according to the Brunauer-Emmett-Teller method in accordance with DIN 9277:2014.

[0055] Thermal decomposition method

[0056] According to the present invention, the metal oxides used in the method, namely aluminum oxide or titanium oxide, are produced pyrolytically, i.e., by the pyrolysis method. The pyrolysis method is also called the "fumed" method. Such a "pyrolysis method" or "fumed" method involves reacting the corresponding metal precursor by flame hydrolysis or flame oxidation in an oxyhydrogen flame to form a metal oxide. By this reaction, first, highly dispersed substantially spherical primary metal oxide particles are formed, which combine in a further process of the reaction to form strong aggregates. The strong aggregates can then accumulate as weak aggregates. Weak aggregates can generally be separated into strong aggregates relatively easily by the introduction of energy, but strong aggregates, if broken at all, will not be further broken without the introduction of strong energy. The above metal oxide powder can be partially broken by appropriate grinding and converted into particles in the nanometer (nm) range advantageous for the present invention.

[0057] The preparation of pyrolysis method metal oxides is further described in WO 2004 / 108595 pamphlet. The fumed metal oxides of the present invention include aluminum oxide (Al2O3), also called alumina, and titanium oxide (TiO2), also called titania. Preferably, the fumed alumina and fumed titania are further surface-treated to be hydrophobic. Examples of commercially available fumed alumina include AEROXIDE® Alu C manufactured by Evonik Operations GmbH. Another example of fumed hydrophobic alumina is AEROXIDE® Alu C 805 commercially available from Evonik Operations GmbH. An example of fumed hydrophobic titania is AEROXIDE® TiO2T 805 commercially available from Evonik Operations GmbH. The BET surface area and other properties of these materials are shown in Table 1.

[0058] More specifically, aluminum oxide or titanium oxide powders produced by a pyrolysis method, particularly a flame hydrolysis method, can be produced from metal halides, preferably metal chlorides such as aluminum chloride or titanium chloride respectively. The metal chloride precursor and, where applicable, other metal precursors can be evaporated, and the resulting vapor is mixed, either alone or together with a carrier gas such as nitrogen, in a mixing unit within a burner with other gases, namely air, oxygen, nitrogen, and hydrogen. The gases react with each other in the flame within a sealed combustion chamber to produce metal oxides (or mixed metal oxides) and waste gases. Subsequently, the hot waste gases and the metal oxides are cooled in a heat exchange unit, the waste gases are separated from the metal oxides, and the halide residues adhering to the resulting metal oxides are removed by heat treatment with moist air.

[0059] The flame spray pyrolysis (FSP) method suitable for producing metal oxides can include the following steps. 1) Atomize a solution containing a metal precursor (e.g., aluminum chloride or titanium chloride) with, for example, air or an inert gas, preferably using a multi-substance nozzle. 2) Mix combustion gas, preferably hydrogen and / or methane, with air. 3) Burn the mixture in a flame within a reaction chamber surrounded by a casing. 4) Cool the hot gas and the solid product, and then remove the solid product from the gas.

[0060] Other suitable aluminum oxide or titanium oxide metal precursors for use in producing aluminum oxide or titanium oxide by flame spray pyrolysis may include inorganic compounds such as nitrates, chlorides, or carboxylates of fatty acids having 6 to 9 carbon atoms, such as aluminum 2-ethylhexanoate or titanium 2-ethylhexanoate and other organic compounds. The metal oxide precursor used can be dissolved in water or an organic solvent and atomized. Suitable organic solvents include methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, 2-propanone, 2-butanone, diethyl ether, tert-butyl methyl ether, tetrahydrofuran, C1-C8 carboxylic acids, ethyl acetate, toluene, petroleum, and mixtures thereof.

[0061] The metal oxides produced by pyrolysis, nanostructured, and surface-modified used in the method of the present invention are in the form of strongly aggregated primary particles having an average strongly aggregated particle diameter preferably of 5 to 150 nm, more preferably 10 to 120 nm, still more preferably 20 to 100 nm as measured by transmission electron microscopy (TEM). This number average diameter can be measured by calculating the average size of at least 500 particles analyzed by TEM.

[0062] The average diameter of the weakly aggregated particles is usually 1 to 2 μm. These average numerical values can be measured by static light scattering (SLS) method in a suitable dispersion, such as an aqueous dispersion. The weakly aggregated particles and some strongly aggregated particles can be broken, for example, by grinding or sonicating the particles to form smaller sized particles.

[0063] The average strongly aggregated particle diameter d50 of the metal oxide, obtained by measuring by static light scattering (SLS) after subjecting a mixture consisting of 5 wt% of particles and 95 wt% of an aqueous solution of sodium pyrophosphate at 0.5 g / L to sonication at 25°C for 60 seconds, is 5 to 150 nm, more preferably 10 to 120 nm, still more preferably 20 to 100 nm.

[0064] Therefore, the thermally decomposed, nanostructured, and surface-modified metal oxides used in the method of the present invention are preferably characterized by high dispersibility, i.e., the ability to form relatively small particles under gentle sonication. Dispersion under such gentle conditions is thought to correlate with the conditions during the dry coating process. That is, in the mixing process of the present invention, the weak aggregates of the metal oxide are broken as in the case of sonication, and a uniform coating of the anode active material particles can be formed.

[0065] The span (d 90 -d 10 ) / d 50 of the particles of the mixed oxide containing metal oxides and / or metals, obtained by subjecting a mixture consisting of 5 wt% of particles and 95 wt% of an aqueous solution of sodium pyrophosphate at 0.5 g / L to sonication at 25°C for 60 seconds and measuring by static light scattering (SLS), is preferably 0.4 to 1.2, more preferably 0.5 to 1.1, and even more preferably 0.6 to 1.0.

[0066] Therefore, the nanostructured metal oxides produced by the thermal decomposition method used in the method of the present invention are preferably characterized by a relatively narrow particle size distribution. Thereby, a high-quality metal oxide coating can be realized on the surface of the transition metal oxide.

[0067] The d values of d 10 d 50 d 90 are generally used to characterize the cumulative particle size distribution of a specific sample. For example, the d 10 diameter is the diameter at which 10% of the volume of the sample is composed of particles smaller than d 10 d 50 is the diameter at which 50% of the volume of the sample is composed of particles smaller than d 50 d 50 is also called the "volume median diameter" because it divides the sample into equal volumes. d 90 is the diameter at which 90% of the volume of the sample is composed of particles smaller than d 90 .

[0068] Metal oxides (alumina and / or titania) produced by a thermal decomposition method are hydrophilic. By surface modification of the metal oxides produced by the thermal decomposition method, hydrophobic metal oxides are produced. The surface treatment may include using any of many suitable hydrophobic reagents such as silane. Both hydrophilic and hydrophobic forms of fumed nanostructured metal oxides can be used as coatings by dry mixing with a substrate-active anode material using the method of the present invention. However, fumed nanostructured surface-modified hydrophobic metal oxides are preferred to achieve a more uniform coating of the substrate-active anode material and a complete coating of the substrate-active anode material.

[0069] Surface treatment of metal oxides produced by a thermal decomposition method

[0070] Alumina or titania produced by a thermal decomposition method is hydrophilic because it is naturally covered with hydroxyl (-OH) groups without further surface treatment. However, by surface modification of alumina or titania produced by the thermal decomposition method, hydrophobic alumina or titania can be produced. For example, hydrophobization of alumina or titania can be carried out by reacting hydroxyl groups with silane to form -O-Si-R groups. Therefore, preferably, alumina or titania is surface-modified, which means that the surface of alumina or titania is at least partially covered with silane.

[0071] Alumina or titania produced by the pyrolysis method can be used in hydrophilic and hydrophobic forms. The use of hydrophilic alumina or titania does not require further treatment after synthesis by the pyrolysis method. However, after synthesis by the pyrolysis method, by further treating with a hydrophobic reagent such as silane, the alumina or titania particles can become hydrophobic. For example, in one embodiment, octylsilane is covalently bonded to the surface of the alumina or titania particles. Both hydrophilic and hydrophobic forms of fumed nanostructured alumina or titania can be effectively used as coatings by dry mixing with the substrate-active anode material using the method of the present invention. Fumed nanostructured surface-modified alumina or titania is preferred to achieve a more uniform coating of the substrate-active anode material.

[0072] Therefore, a surface modifier is sprayed onto the alumina or titania produced by the pyrolysis method at room temperature, and then the mixture is heat-treated at a temperature of 50 to 300 °C, preferably 80 to 180 °C, for 0.5 to 3 hours.

[0073] In another embodiment, the surface modification of alumina or titania produced by the pyrolysis method can be carried out by treating the pyrolysis metal oxide with a vaporous surface modifier and then heat-treating the mixture at a temperature of 50 to 800 °C for 0.5 to 6 hours.

[0074] Another method for the surface modification of alumina or titania produced by the pyrolysis method can be carried out by treating the pyrolysis alumina or titania with a vaporous surface modifier and then heat-treating the mixture at a temperature of 50 to 800 °C for 0.5 to 6 hours.

[0075] The heat treatment can be carried out under a protective gas such as nitrogen, for example. The surface treatment can be carried out continuously or batchwise using a heatable mixer and dryer equipped with a spraying device. Suitable devices can be, for example, a paddle mixer or plate, a cyclone, or a fluidized bed dryer.

[0076] The present invention has the advantage that by modifying a metal oxide (i.e., alumina or titania) using commercially available silanes, the properties of alumina or titania can be individually adapted according to the desired properties and the intended purpose.

[0077] As the surface modifier, it is possible to use the following compounds and mixtures of the following compounds: a) (RO)3Si(C n H 2n+1 ) and (RO)3Si(C n H 2n-1 ) type of organosilane, where R is an alkyl such as methyl, ethyl, n-propyl, i-propyl, butyl, etc., and n is from 1 to 20. b) R’ x (RO) y Si(C n H 2n+1 ) and R’ x (RO) y Si(C n H 2n-1 ) type of organosilane, where R is an alkyl such as methyl-, ethyl-, n-propyl-, i-propyl-, butyl-, etc., R’ is an alkyl such as methyl, ethyl, n-propyl, i-propyl, butyl, etc., R’ is cycloalkyl, n is from 1 to 20, x + y is 3, x is 1, 2, y is 1, 2. c) X3Si(C n H 2n+1 ) and X3Si(C n H 2n-1 ) type of halogenated organosilane, where X is Cl, Br, n is from 1 to 20. d) X2(R’)Si(C n H 2n+1 ) and X2(R’)Si(C n H 2n-1 ) type of halogenated organosilane, wherein X is Cl or Br, R’ is, for example, alkyl such as methyl, ethyl, n-propyl, i-propyl, butyl, R’ is cycloalkyl, and n is from 1 to 20. e) Halogenated organosilanes of the type X(R’)2Si(C n H 2n+1 ) and X(R’)2Si(C n H 2n-1 ), wherein X is Cl or Br, R’ is, for example, alkyl such as methyl, ethyl, n-propyl, i-propyl, butyl, R’ is cycloalkyl, and n is from 1 to 20. f) Organosilanes of the type (RO)3Si(CH2) m -R’, wherein R is, for example, alkyl such as methyl, ethyl, propyl, m is from 0.1 to 20, and R’ is methyl-, aryl (for example, -C6H5, substituted phenyl residue), C4F9, OCF2-CHF-CF3, -C6F 13 , -O-CF2-CHF2, -NH2, -N3, -SCN, -CH=CH2, -NH-CH2-CH2-NH2, -N-(CH2-CH2-NH2)2, -OOC(CH3)C=CH2, -OCH2-CH(O)CH2, -NH-CO-N-CO-(CH2)5, -NH-COO-CH3, -NH-COO-CH2-CH3, -NH-(CH2)3Si(OR)3, -S x -(CH2)3Si(OR)3, -SH, -NR’R’’R’’’, wherein R’ is alkyl or aryl, R’’ is H, alkyl or aryl, and R’’’ is H, alkyl, aryl, benzyl, C2H4NR’’’’R’’’’’ (wherein R’’’’ is H or alkyl and R’’’’’ is H or alkyl). g) (R’’) x (RO)y An organosilane of the Si(CH2)m-R’ type, wherein R’’ is alkyl, x + y is 2, R is cycloalkyl, x is 1.2, y is 1.2, m is from 0.1 to 20, R’ is methyl-, aryl (e.g., -C6H5, a substituted phenyl residue), C4F9, OCF2-CHF-CF3, -C6F 13 , -O-CF2-CHF2, -NH2, -N3, -SCN, -CH=CH2, -NH-CH2-CH2-NH2, -N-(CH2-CH2-NH2)2, -OOC(CH3)C=CH2, -OCH2-CH(O)CH2, -NH-CO-N-CO-(CH2)5, -NH-COO-CH3, -NH-COO-CH2-CH3, -NH-(CH2)3Si(OR)3, -S x -(CH2)3Si(OR)3, -SH, -NR’R’’R’’’, wherein R’ is alkyl, aryl, R’’ is H, alkyl, aryl, R’’’ is H, alkyl, aryl, benzyl, C2H4NR’’’’R’’’’’ (wherein R’’’’ is H, alkyl and R’’’’’ is H, alkyl). h) A halogenated organosilane of the X3Si(CH2)m-R’ type, wherein X is Cl, Br, m is from 0.1 to 20, R’ is methyl-, aryl (e.g., -C6H5, a substituted phenyl residue), C4F9, OCF2-CHF-CF3, -C6F 13 , -O-CF2-CHF2, -NH2, -N3, -SCN, -CH=CH2, -NH-CH2-CH2-NH2, -N-(CH2-CH2-NH2)2, -OOC(CH3)C=CH2, -OCH2-CH(O)CH2, -NH-CO-N-CO-(CH2)5, -NH-COO-CH3, -NH-(CH2)3Si(OR)3, -S x -(CH2)3Si(OR)3, -SH. i) A halogenated organosilane of the formula (R)X2Si(CH2)m-R’, wherein X is Cl or Br, R is an alkyl such as methyl, ethyl, propyl, etc., m is from 0.1 to 20, and R’ is methyl-, aryl (e.g., -C6H5, a substituted phenyl residue), C4F9, OCF2-CHF-CF3, -C6F 13 , -O-CF2-CHF2, -NH2, -N3, -SCN, -CH=CH2, -NH-CH2-CH2-NH2, -N-(CH2-CH2-NH2)2, -OOC(CH3)C=CH2, -OCH2-CH(O)CH2, -NH-CO-N-CO-(CH2)5, -NH-COO-CH3, -NH-COO-CH2-CH3, -NH-(CH2)3Si(OR)3, -S x -(CH2)3Si(OR)3, -SH. j) A halogenated organosilane of the formula (R)2XSi(CH2)m-R’, wherein X is Cl or Br, R is an alkyl, m is from 0.1 to 20, and R’ is methyl-, aryl (e.g., -C6H5, a substituted phenyl residue), C4F9, OCF2-CHF-CF3, -C6F 13 , -O-CF2-CHF2, -NH2, -N3, -SCN, -CH=CH2, -NH-CH2-CH2-NH2, -N-(CH2-CH2-NH2)2, -OOC(CH3)C=CH2, -OCH2-CH(O)CH2, -NH-CO-N-CO-(CH2)5, -NH-COO-CH3, -NH-COO-CH2-CH3, -NH-(CH2)3Si(OR)3, -S x -(CH2)3Si(OR)3, -SH.

[0078] Preferably, as the surface modifier, the following silanes are used alone or as a mixture: dimethyldichlorosilane, octyltrimethoxysilane, octyltriethoxysilane, hexamethyldisilazane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, hexadecyltrimethoxysilane, hexadecyltriethoxysilane, dimethylpolysiloxane, glycidyloxypropyltrimethoxysilane, glycidyloxypropyltriethoxysilane, nanofluorohexyltrimethoxysilane, tridecafluorooctyltrimethoxysilane, tridecafluorooctyltriethoxysilane, aminopropyltriethoxysilane. Particularly preferably, octyltrimethoxysilane and octyltriethoxysilane can be used.

[0079] Metal oxide particles produced by the thermal decomposition method usually have a purity of at least 96% by weight, preferably at least 98% by weight, more preferably at least 99% by weight. The metal oxide used in the method of the present invention preferably has a proportion of elements Cd, Ce, Fe, Na, Nb, P of less than 10 ppm, a proportion of elements Ba, Bi, Cr, K, Mn, Sb of less than 5 ppm, and the total proportion of all these elements is less than 100 ppm. The chloride content is preferably less than 0.5% by weight, more preferably 0.01 - 0.3% by weight, based on the mass of the metal oxide powder. The proportion of carbon in the hydrophilic and un-surface-modified metal oxide is preferably less than 0.2% by weight, more preferably 0.005 - 0.2% by weight, even more preferably 0.01 - 0.1% by weight, based on the mass of the metal oxide powder.

[0080] Active anode material

[0081] The substrate anode particles encapsulated or coated with a fumed metal oxide can include any suitable materials used as the anode active material of a lithium-ion secondary battery that enables reversible insertion / extraction of lithium ions and / or reversible reaction with lithium species. Examples thereof include crystalline carbon such as plate-like, flaky, spherical or fibrous natural or artificial graphite; amorphous carbon such as soft carbon, hard carbon, mesophase pitch carbide, calcined coke; or carbonaceous materials including mixtures thereof. Further, Si-based particles can be used as the anode active material. Preferred anode active materials are carbon and / or Si-based particles. The Si-based particles include silicon particles (e.g., pure silicon particles), silicon oxide (SiOx) particles, and all combinations of silicon, silicon oxide, and carbon particles (including mixtures and composites thereof). The silicon oxide can be SiO and / or SiO2. In one embodiment, the active anode material can be a nanostructured porous silicon material. In one embodiment, the anode material is SiOx, and x can vary from 0 to about 2, such as Si, SiO, SiO2, or all combinations thereof.

[0082] Preferred anode active materials are carbon and / or Si-based particles, including composite materials of C and Si-based particles. The "composite material" refers to a composition containing both a carbon material and a silicon material. The carbon and silicon materials can be a mixture of carbon powder and silicon powder of nano-sized particles. In one embodiment, the composite material can include individually chemically bonded carbon and silicon particles. In another embodiment, the composite material can include porous nano-sized silicon particles impregnated with carbon within a silicon porous structure.

[0083] The coated active anode material, when mixed with a metal oxide, may contain carbon and / or Si-based particles. In some embodiments, the active anode material may comprise a composite SiOx / C material. x can vary from 0 to about 2, and is made from 60-99% carbon and 40-1% silicon oxide, preferably 70-95% carbon and 30-5% silicon oxide, more preferably 80-90% carbon and 20-10% silicon oxide. The composite SiOx / C material can be in powder or particle form.

[0084] In one embodiment, the active anode material may comprise a composite SiO / C material made from 60-99% carbon and 40-1% SiO, preferably 70-95% carbon and 30-5% SiO, more preferably 80-90% carbon and 20-10% SiO. The composite SiO / C material can be in powder or particle form.

[0085] In some embodiments, the active anode material may comprise a composite Si / C material made from 60-99% carbon and 40-1% silicon, preferably 70-95% carbon and 30-5% silicon, more preferably 80-90% carbon and 20-10% silicon. The composite Si / C material can be in powder or particle form.

[0086] The coated active anode material has a number average particle size of 1-50 μm, preferably 1-40 μm, more preferably 2-20 μm. The number average particle size can be measured by laser diffraction particle size analysis in accordance with ISO 13320:2009.

[0087] The active anode material may also be referred to as a core active anode material or a substrate active anode material or particles. Titanium oxide or aluminum oxide may also be referred to as a coating, and the mixed active anode material having a coating may also be referred to as a coated active anode material or particles.

[0088] The proportion of the metal oxide in the coated mixed anode material is preferably 0.05 to 5% by weight, more preferably 0.1 to 2% by weight based on the total weight of the coated mixed anode material. When the proportion of the metal oxide is less than 0.05% by weight, the beneficial effects of the coating are usually not yet observable. When it exceeds 5% by weight, usually, the beneficial effects due to the additional amount of the metal coating exceeding 5% by weight are not observed.

[0089] The coated mixed anode material preferably has a coating layer thickness of 10 to 200 nm as measured by TEM analysis.

[0090] The present invention further provides a coated mixed anode material obtained by the method of the present invention. The present invention further provides a coated mixed anode material comprising a metal oxide coating which is produced by a thermal decomposition method, nanostructured, and surface-modified on the surface of anode active material particles.

[0091] In a preferred embodiment of the method according to the present invention, further preferred features of the coated mixed anode material of the metal oxide produced by the above thermal decomposition method, nanostructured, and surface-modified are also preferred features of the coated mixed anode material according to the present invention, regardless of whether it is produced by the method of the present invention.

[0092] The present invention further provides an active negative electrode material for a lithium-ion battery comprising the coated anode material according to the present invention or the coated anode material obtained by the method of the present invention.

[0093] The negative electrode, i.e., the anode of the lithium-ion battery, comprises a current collector and coated active anode material particles formed on or above the current collector. The current collector can be an aluminum foil, a copper foil, a nickel foil, a stainless steel foil, a titanium foil, a polymer substrate coated with a conductive metal, or a combination thereof.

[0094] The present invention also provides a lithium-ion battery comprising a coated anode material, or a coated anode material obtained by the method of the present invention.

[0095] In addition to the anode, the lithium-ion battery of the present invention may include a cathode, a separator if necessary, and an electrolyte containing, for example, a lithium salt or a lithium compound.

[0096] The cathode of the lithium-ion battery may include all suitable materials commonly used in lithium-ion secondary batteries that can reversibly insert / extract lithium ions.

[0097] The cathode material preferably used in the method of the present invention is selected from the group consisting of lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium nickel manganese cobalt oxide, lithium nickel cobalt aluminum oxide, lithium nickel manganese oxide, or mixtures thereof.

[0098] The electrolyte of the lithium-ion battery can be in liquid, gel or solid form. The liquid electrolyte of the lithium-ion battery may include all suitable organic solvents commonly used in lithium-ion batteries, such as anhydrous ethylene carbonate (EC), dimethyl carbonate (DMC), propylene carbonate, methyl ethyl carbonate, diethyl carbonate, gamma-butyrolactone, dimethoxyethane, fluoroethylene carbonate, vinyl ethylene carbonate, or mixtures thereof.

[0099] The gel electrolyte contains a gelling polymer. All suitable gelling polymers can be used.

[0100] The solid electrolyte of the lithium-ion battery may include oxides, such as lithium metal oxides, sulfides, phosphates, or solid polymers.

[0101] The electrolyte of a lithium-ion battery can contain a lithium salt. Examples of such lithium salts include lithium hexafluorophosphate (LiPF6), lithium bis(2-(trifluoromethylsulfonyl)imide) (LiTFSI), lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), Li2SiF6, lithium triflate, LiN(SO2CF2CF3)2, and mixtures thereof.

[0102] The present invention further provides for the use of a coated anode material in an active negative electrode material of a lithium-ion battery.

[0103] Even without further explanation, those skilled in the art are assumed to be able to fully utilize the above description. Therefore, the preferred embodiments and examples are for illustrative purposes only and are in no way limiting.

[0104] Hereinafter, the present invention will be described in more detail using examples. Alternative embodiments of the present invention can also be utilized in a similar manner.

Examples

[0105] Measurement of Physicochemical Property Data

[0106] In the present invention, the following measurement methods were used to evaluate the properties of various materials.

[0107] A) BET surface area For the BET surface area, it was measured using nitrogen in accordance with DIN 9277:2014.

[0108] B) Tapping density Measurement of tapping density in accordance with DIN ISO 787 / XI, Basis of tapping density measurement: The tapping density (formerly tapping volume) is equal to the quotient of the mass and volume of the powder after tapping with a tapping volumeter under predetermined conditions. According to DIN ISO 787 / XI, the tapping density is g / cm 3It is shown by []. However, since the tamping density of the oxide is extremely small, in this case, the value is expressed in g / L. Furthermore, drying, sieving, and repeating the tamping operation are unnecessary.

[0109] Tamping density measuring device: Tamping volumeter Deposition measuring cylinder Laboratory scale (readable up to 0.01 g)

[0110] Conducting tamping density measurement 200 ± 10 mL of the oxide was filled into the volume measuring cylinder of the tamping volumeter so that no pores remained and the surface became flat. The mass of the filled sample was accurately measured up to 0.01 g. The volume measuring cylinder containing the sample was placed in the volume measuring cylinder holder of the tamping volumeter and tamped 1250 times. The volume of the tamped oxide was accurately read once. Evaluating tamping density measurement

[0111]

Number

[0112] C) pH value Regarding the pH value, it was measured with a 4% aqueous dispersion of the hydrophobic oxide in water: methanol (1:1). Reagents for pH value measurement: Distilled water or completely deionized water, pH > 5.5 Methanol, p.a. Multiple buffer solutions pH 7.00, pH 4.66 Device for pH value measurement: Laboratory scale (readable up to 0.1 g) Glass beaker, 250 mL Magnetic stirrer Magnetic rod, 4 cm in length Composite pH electrode pH measuring instrument Dispenser, 100 mL

[0113] Operating Procedure for pH Value Measurement The measurement was carried out in accordance with DIN / ISO 787 / IX. Calibration: Before measuring the pH value, the measuring device was calibrated with a buffer solution. When performing multiple consecutive measurements, one calibration was sufficient. In a 250 mL volumetric glass beaker, using a dispenser, 4 g of hydrophilic oxide was stirred with 96 g (96 mL) of water to form a paste, and while immersing the pH electrode, it was stirred with a magnetic stirrer for 5 minutes (rpm: about 1000 per minute -1 ). In a 250 mL volumetric glass beaker, 4 g of hydrophobic oxide was stirred with 48 g (61 mL) of methanol to form a paste, and the suspension was diluted with 48 g (48 mL) of water, and while immersing the pH electrode, it was stirred with a magnetic stirrer for 5 minutes (rpm: about 1000 per minute -1 ). After turning off the stirrer, it was left for 1 minute and the pH was read. The result was shown to the first decimal place.

[0114] D) Loss on Drying In contrast to the weighing quantity of 10 g described in DIN ISO 787 II, a weighing quantity of 1 g was used for the measurement of loss on drying. The cover was attached before cooling. The second drying was not performed. Approximately 1 g of the sample was accurately weighed to 0.1 mg in a weighing dish with a ground cover dried at 105 °C, taking care not to generate dust, and dried in a drying cabinet at 105 °C for 2 hours. After cooling in a desiccator with the cover on, the sample was weighed again under a blue gel.

[0115]

Number

[0116] The result was shown to the first decimal place. E) Loss on Ignition Measuring device for loss on ignition: Porcelain crucible with crucible cover Muffle furnace Analysis scale (readable up to 0.1 mg) Desiccator Method for measuring loss on ignition: In accordance with DIN 55 921, 0.3 - 1 g of the undried substance was accurately weighed to 0.1 mg into a porcelain crucible with a crucible cover that had been pre-heated to a red-hot state, and heated to a red-hot state at 1000 °C for 2 hours in a muffle furnace. Generation of dust was carefully avoided. It was effective to introduce the weighed sample while the muffle furnace was still cold. When heating the furnace slowly, it was possible to prevent the air turbulence in the porcelain crucible from becoming strong. After reaching 1000 °C, heating was continued in a red-hot state for another 2 hours. Then, the crucible cover was placed, and the weight loss of the crucible was measured on a balance in a desiccator.

[0117] Evaluation of loss on ignition measurement Since the loss on ignition is measured based on the sample dried at 105 °C for 2 hours, the following calculation formula holds.

[0118]

Equation

[0119] m0 = weighed amount (g) TV = loss on drying (%) m1 = weight of the sample after red-hot heating (g) The results were shown to the first decimal place.

[0120] F) Carbon content Regarding the carbon content, it was measured by elemental analysis using a LECO C744 instrument. The measurement principle was to oxidize the carbon in the sample to CO2 and quantify it with an infrared detector.

[0121] G) SEM measurement Energy-dispersive X-ray spectroscopy (EDX) was performed using a SEM. In EDX mapping, a representative area of the sample was used at a magnification of 1000 times, the image width was 2048×1536 pixels (120μm×90.1μm), and the pixel resolution was 0.059μm. The mapping was recorded at an acceleration voltage of 20 kV. After measurement, the elements present in the sample were measured using the total spectrum of the mapping. The threshold value for image analysis was adjusted according to the semi-quantitative mass % value of each element.

[0122] Starting material

[0123] Dry coating additive:

[0124] Fumed alumina (AEROXIDE® Alu C), BET surface area 85 - 115 m2 / g, commercially available from Evonik Operations GmbH. AEROXIDE® Alu C is a particulate material and is pure aluminum oxide (Al2O3) with a large specific surface area.

[0125] Fumed hydrophobic alumina (AEROXIDE® Alu C 805), BET surface area 75 - 105 m 2 / g, commercially available from Evonik Operations GmbH. AEROXIDE® Alu C 805 is highly hydrophobized with an organic silane.

[0126] Fumed hydrophobic titania (AEROXIDE® TiO2T 805), BET surface area 35 - 55 m 2 / g, commercially available from Evonik Operations GmbH. AEROXIDE® TiO2T 805 is particulate fumed titanium dioxide (TiO2) highly hydrophobized with an organic silane.

[0127] Non-fumed alumina (ADMAFINE® AO-802), BET surface area approximately 6 m 2 / g is commercially available from Admatechs Company Limited. ADMAFINE® AO-802 consists of fine spherical aluminum oxide particles with a diameter of 0.2 to 10 μm, which are produced by oxidizing metallic aluminum powder using a proprietary technology called the VMC method.

[0128] Table 1 shows all the properties of these materials.

[0129]

Table 1

[0130] Anode active material A composite Si / C material (DXB8) made of 86% carbon and 14% silicon, purchased from Shandong Gelon Lib Co., Ltd. in China, and artificial graphite powder (SAG20) purchased from MTI Corporation in the United States were used.

[0131] The composite Si / C material made of 86 wt% carbon and 14 wt% silicon is commercially available from Shandong Gelon Lib Co., Ltd. in China under the trademark DXB8, and is hereinafter referred to as Si86 / C14 substrate anode active material (「Si86 / C14_AAM」) powder or particles. As can be seen from SEM analysis, Si86 / C14_AAM is a mixture of SiOx and carbon and has the following properties.

Table 2

[0132] The artificial graphite powder (SAG20) of MTI Corporation in the United States has the following characteristics.

[0133]

Table 3

[0134] Experimental Examples 5 to 10 Two different types of anode active material powders (AAM) were each mixed with 1.0 wt% of a coating additive, namely AEROXIDE® Alu C (Experimental Example 1), AEROXIDE® Alu C 805 (Experimental Example 2), and AEROXIDE® TiO2 T 805 (Experimental Example 3). The mixing was carried out in a high-intensity laboratory mixer (Somakon Mixer MP-GL equipped with a 0.5 L mixing unit). To homogenize the two powders, the speed was increased stepwise: 100 rpm for 1 minute, 200 rpm for 1 minute, and 500 rpm for 1 minute. After homogenization, the mixing speed was further increased to 2000 rpm and processed for 5 minutes to obtain a dry coating of AAM particles with each metal oxide additive. Uniformly coated AAM particles were obtained by using AEROXIDE® Alu C 805 and AEROXIDE® TiO2 T 805 as coating additives to form a fumed metal oxide coating layer with a thickness of 20 - 200 nm on the AAM particles.

[0135] Comparative Example 11 The procedures of Experimental Examples 5 - 10 were exactly repeated, except that non-fumed alumina ADMAFINE® AO-802 was used instead of the fumed metal oxide.

[0136] The particle size distribution of hydrophilic aluminum oxide was measured, and the dispersion behavior when shear force was applied to the alumina weak aggregates was visualized.

[0137] Figure 1 shows the particle size distributions of AEROXIDE® Alu C (a) and ADMAFINE® AO-802 (b) analyzed by a laser diffraction particle size analyzer. The samples were dispersed in distilled water and treated in an external ultrasonic bath (160 W) for 5 minutes.

[0138] In the case of AEROXIDE® Alu C, a very narrow unimodal particle size distribution with small strong aggregate sizes of D10 = 60 nm, D50 = 81 nm, and D90 = 120 nm was detected.

[0139] In the case of ADMAFINE (registered trademark) AO-802, a strongly aggregated size with D10 = 78 nm, D50 = 176 nm, and D90 = 1770 nm was detected, and a partially bimodal distribution that spread more widely and over a wider range was detected, revealing the presence of larger non-dispersed particles.

[0140] Figure 2 shows SEM-EDX mappings of various coating additives on the composite Si / C anode active material DXB8 (a: AEROXIDE (registered trademark) Alu C 805, b: AEROXIDE (registered trademark) Alu C, c: ADMAFINE (registered trademark) AO-802, d: AEROXIDE (registered trademark) TiO2 T 805). On the left side of each of 2a, 2b, 2c, and 2d, Si mappings are shown to visualize the silicon distribution within the anode active material (a mixture of carbon and silicon). This information is useful when comparing with the Al / Ti distribution of the coating additives on the right side, and well shows the interaction between the coating additives and the anode material surface.

[0141] The mappings of DXB8 coated with fumed hydrophobic alumina (a) and fumed hydrophobic titania (d) show that Al / Ti completely and uniformly covers almost all anode particles (rich in silicon and rich in carbon). Larger metal oxide weak aggregates were not detected, indicating the successful dispersion of nanostructured fumed hydrophobic metal oxides. Furthermore, no unattached Al2O3 / TiO2 particles were found next to the anode particles. This indicates a strong interaction between the surface-modified metal oxide particles and the AAM particle surface, that is, excellent adhesion between the coating layer and the substrate.

[0142] Compared with the surface-modified hydrophobic alumina, the hydrophilic material (AEROXIDE (registered trademark) Alu C) also shows excellent dispersibility of weak aggregates, but preferably interacts with silicon-rich particles rather than carbon-rich particles. Therefore, on the surface of silicon-rich particles, the alumina coating becomes more prominent.

[0143] In contrast, when coarser alumina particles (ADMAFINE® AO-802) are used as a coating for AAM particles (case (c)), only a very small portion of the finer-sized Al2O3 particles adhere to the surface of the anode material. The larger, undispersed Al2O3 particles that do not adhere are present next to the anode particles. As a result, the AAM particles are not completely coated by this coarse, non-surface-modified alumina particle.

[0144] Figure 3 shows SEM-EDX mappings of alumina coating additives on artificial graphite SAG20 (a: AEROXIDE® Alu C 805, b: AEROXIDE® Alu C, c: ADMAFINE® AO-802). In each of 3a, 3b, and 3c, the contrast of the material is shown on the left.

[0145] Mapping of graphite coated with fumed hydrophobic alumina AEROXIDE® Alu C 805 shows the best dispersion behavior and the most uniform coating of AAM particles by alumina, in direct comparison to hydrophilic alumina materials. This phenomenon is again related to the excellent interaction between the hydrophobic surface modification of AEROXIDE® Alu C 805 and the surface of the graphite anode particles.

[0146] FIG. 4 shows a lithium-ion battery, generally indicated by the numeral 10, within an apparatus 100 driven by a lithium-ion battery 10 according to an embodiment of the present invention. The apparatus can be any of all electronic devices such as, for example, a mobile phone, an electronic watch, a key fob, a laptop computer, a desktop computer, a computer pad, etc. The apparatus may also be an electrical device such as a power tool, a vacuum cleaner, an electric lawn mower, an electric appliance. The lithium-ion battery 10 is packaged into modules as is well known, and each module includes a plurality of lithium batteries 10 and is used to supply power to an electric vehicle or a hybrid electric vehicle. The lithium-ion battery 10 includes a negative electrode current collector 14 and a positive electrode current collector 12, a cathode 18 adjacent to the positive electrode current collector 12, an anode adjacent to the negative electrode current collector 14, an electrolyte 20, and a separator 22 disposed between the anode 16 and the cathode 18. The anode 16 includes a coated active anode material obtained by dry mixing an active anode material and a nanostructured metal oxide manufactured by a thermal decomposition method of titanium or aluminum in a mixing unit. The active anode material is in powder form and includes carbon particles, silicon particles, silicon oxide particles, or any combination thereof.

[0147] Although the present invention has been described with reference to specific examples, it should be understood that the present invention is not limited to these examples only, and many variations thereof are included within the scope of the present invention defined by the appended claims.

[0148] List of Reference Numerals 10 Battery cell 100 Apparatus driven by the battery cell 12 Positive electrode current collector 14 Negative electrode current collector 16 Anode 18 Cathode 20 Electrolyte 22 Separator

Claims

1. A method for producing a coated active anode material involves dry mixing an active anode material with alumina or titania, or a mixture thereof, which are nanostructured metal oxides produced by thermal decomposition, in a mixing unit under shear conditions to obtain a coated active anode material. The coated active anode material is in particulate form, The aforementioned metal oxide has a BET surface area (DIN 9277:2014) of 5 to 300 m². ２ A method comprising a mixture consisting of 5% by weight of the aforementioned particles and a 95% by weight 0.5 g / L aqueous sodium pyrophosphate solution, wherein the mixture is subjected to sonication at 25°C for 60 seconds, and the average strong aggregate diameter d50 obtained by static light scattering (SLS) is 5 to 150 nm, and the particle size distribution is unimodal and narrow.

2. The alumina or titania, which is a nanostructured metal oxide produced by the aforementioned pyrolysis method, is surface-treated to become hydrophobic by reacting the hydroxyl groups of the alumina or titania with silane to form -O-Si-R groups before the dry mixing, The method according to claim 1, wherein the mixing unit has a specific power of 0.05 to 1.5 kW per 1 kg of the mixed anode material.

3. The method according to claim 1, wherein a mixture comprising 5% by weight of the particles and a 95% by weight 0.5 g / L aqueous solution of sodium pyrophosphate is subjected to sonication at 25°C for 60 seconds, and the average strong aggregate diameter d50 obtained by measurement by static light scattering (SLS) is 10 to 150 nm.

4. The method according to claim 1, wherein a scanning electron microscope equipped with energy-dispersive X-ray mapping as disclosed in the specification of the coated active anode material shows that the metal oxide completely and uniformly coats substantially all anode particles.

5. The specific power of the mixing unit is 0.1 to 1000 kW, and the volume of the mixing unit is 0.1 L to 2.5 m³. ３ The method according to claim 1, wherein the speed of the mixing tool in the mixing unit is 5 to 30 m / second.

6. A mixture consisting of 5% by weight of the aforementioned particles and a 95% by weight 0.5 g / L aqueous solution of sodium pyrophosphate was subjected to sonication at 25°C for 60 seconds, and the span (d) of the particles of the mixed oxide containing the metal oxide and / or aluminum or titanium was measured by static light scattering (SLS). ９０ -d １０ The method according to claim 1, wherein / d50 is 0.4 to 1.

2.

7. The method according to claim 1, wherein the active anode material is in powder form and comprises a powder containing carbon particles, silicon particles, or silicon oxide particles, or a combination thereof.

8. The method according to claim 1, wherein the coated active anode material is subjected to further heat treatment after the dry mixing.

9. The method according to claim 1, wherein the proportion of the metal oxide in the coated active anode material is 0.05% by weight to 5% by weight with respect to the total weight of the coated mixed anode material.

10. A particulate coated active anode material comprising an active anode material containing carbon particles, silicon particles, or silicon oxide particles, or a combination thereof, and a coating formed on the surface of the mixed anode material of alumina, titania, or a mixture thereof, which is a nanostructured metal oxide produced by a pyrolysis method. The aforementioned metal oxide has a BET surface area of ​​5 to 300 m². ２ A mixture consisting of 5% by weight of the aforementioned particles and 95% by weight of a 0.5 g / L sodium pyrophosphate aqueous solution is subjected to sonication at 25°C for 60 seconds, and then measured by static light scattering (SLS) to obtain an average strong aggregate diameter d50 of 5 to 150 nm, which has a unimodal and narrow particle size distribution. The nanostructured metal oxide produced by the aforementioned thermal decomposition method is a coated active anode material that has been surface-treated to become hydrophobic.

11. The coated active anode material according to claim 10, wherein the SEM-EDX mapping of the coated active anode material disclosed in the specification shows that the metal oxide completely and uniformly coats substantially all anode particles.

12. The coated active anode material obtained by the method described in claim 1.

13. An active negative electrode material for a lithium-ion battery comprising the coated active anode material according to claim 10.

14. A lithium-ion battery comprising the coated active anode material according to claim 10.

15. Use of the coated active anode material according to claim 10 in an active anode material of a lithium-ion battery.

16. A device comprising the lithium-ion battery described in claim 14, the device comprising an electrical or electronic device, a mobile phone, an electronic watch, a key fab, a laptop computer, a desktop computer, a computer pad, a power tool, a vacuum cleaner, an electric lawnmower, an electrical appliance, and an electric vehicle.

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