Method for preparing metal powders and uses

Abstract

The present invention provides a method for preparing metal powder, in which ultrasonic vibrations are induced on a perforated membrane in contact with a liquid metal. The metal is a low-melting-point metal or an alloy based on such a metal and having a low melting point. The resulting metal powder is deposited directly on / into a deposition target. The present invention relates to a method for preparing metal powder, in particular a low-melting-point metal (e.g., <450°C). The method is specifically an ultrasonic method in which ultrasonic vibrations are induced on a perforated membrane, which is in contact with a liquid metal. The method allows for on-site generation of the metal powder at the time of use, thereby overcoming the need for its transportation and / or storage. Furthermore, the method according to the present invention allows for the metal powder to be sprayed directly onto / into a deposition target.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of Canadian Patent Application No. CA3,169,823, filed August 5, 2022, the contents of which are incorporated herein by reference in their entirety.

[0002] The present invention relates to a method for preparing metal powders, in particular metals with low melting points (e.g., <450°C). The method is in particular an ultrasonic method in which ultrasonic vibrations of a perforated membrane are induced, the membrane being in contact with a liquid metal. The method allows for the on-site generation of metal powder at the time of use, thereby overcoming the need for its transportation and / or storage. Furthermore, the method according to the invention allows for the direct spraying of metal powder onto / into a deposition target. [Background technology]

[0003] Metallic lithium in powder form contributes to improved performance of lithium rechargeable batteries. However, the preparation of lithium metal is expensive. Furthermore, many safety issues are associated with handling, transportation, and storage. In fact, lithium metal powder is hydrogen-reactive and pyrophoric.

[0004] Generally, the preparation of lithium metal powder is an empirical procedure. In practice, lithium metal is heated to 200°C under a film of light oil. It is then deposited in a preheated bowl (140-150°C) containing enough oil to float the metal. As the metal's temperature drops, the lithium is vigorously stirred, and the fine particles solidify. [1]

[0005] Livent (formerly FMC) has improved this technology to reduce the particle size of the resulting lithium powder. The improved technology also involves passivating the lithium surface with various reagents (CO2, fluoride, wax, phosphorus, polymer). Livent holds several patents and patent applications related to its technology: US 5,567,474, US 5,776,369, US 5,976,403, US 2002 / 119373, US 7,588,623, US 2008 / 283155, US 2011 / 300385, US 2017 / 149052, US 2019 / 097221. The lithium powder is referred to as "stabilized lithium metal powder" (or SLMP) [2,3].

[0006] Similarly, companies such as Albemarle (US2020 / 240020) and TDK (US2016 / 099467) are developing similar technologies.

[0007] In various other fields, techniques for spraying liquids (organic or aqueous) have been developed. For example, the inkjet printing method is a non-contact method in which very small droplets of liquid ink are ejected by a nozzle thanks to electrical intensity and formation points. Drop-on-demand (DOD) methods are generated as needed. In the piezoelectric method, the ink reservoir is in contact with a piezoelectric crystal that converts electrical impulses into mechanical forces. It is the overpressure induced by the piezoelectric element that allows the ejection of the droplets (US Pat. No. 3,683,212).

[0008] Based on the principle of the vibrating screen, many types of nebulizers have been developed for various applications: humidifiers, aromatherapy, medicine dispensers, fuel injection (US 4,533,082, US 4,850,534, EP 0 516 565, US 5,823,428, US 4,153,201, US 4,352,459, US 4,655,393, US 4,723,708, US 4,978,067, US 2007 / 176017, WO 2008 / 058941, US 9,981,090).

[0009] In the field of filtration of dust-containing gases or physical separation of nanomaterials to recover the fine powders produced, specific technologies have been developed, including the use of cyclones, cartridge filters, granular filters, bubble columns, and electrostatic precipitators [4]. Specifically, an electrostatic precipitator consists of a conducting wire connected to a high-tension source and surrounded by a metal cylinder, which acts both as a chimney for the dust-containing gas and as an electrode. Negative ions attach to the dust particles. Electrostatic forces drive them toward the cylinder, where they lose their charge, become neutral particles, and fall into a suitable container (US 895,729).

[0010] There is a need for an efficient and profitable method for preparing lithium metal powder. There is a need for a method for preparing lithium metal powder that allows powder maintenance levels to be kept as low as possible. There is a need for the production of lithium metal powder to be used as an independent source of lithium during the manufacture of electrodes for lithium ion and lithium metal rechargeable batteries. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] U.S. Patent No. 5,567,474 [Patent Document 2] U.S. Patent No. 5,776,369 [Patent Document 3] U.S. Patent No. 5,976,403 [Patent Document 4] US Patent Application Publication No. 2002 / 119373 [Patent Document 5] U.S. Patent No. 7,588,623 [Patent Document 6] US Patent Application Publication No. 2008 / 283155 [Patent Document 7] US Patent Application Publication No. 2011 / 300385 [Patent Document 8] US Patent Application Publication No. 2017 / 149052 [Patent Document 9] US Patent Application Publication No. 2019 / 097221 [Patent Document 10] U.S. Patent Application Publication No. 2020 / 240020 [Patent Document 11] US Patent Application Publication No. 2016 / 099467 [Patent Document 12] U.S. Patent No. 4,533,082 [Patent Document 13] U.S. Patent No. 4,850,534 [Patent Document 14] European Patent Application Publication No. 0516565 [Patent Document 15] U.S. Patent No. 5,823,428 [Patent Document 16] U.S. Patent No. 4,153,201 [Patent Document 17] U.S. Patent No. 4,352,459 [Patent Document 18] U.S. Patent No. 4,655,393 [Patent Document 19] U.S. Patent No. 4,723,708 [Patent Document 20] U.S. Patent No. 4,978,067 [Patent Document 21] US Patent Application Publication No. 2007 / 176017 [Patent Document 22] International Publication No. 2008 / 058941 [Patent Document 23] U.S. Patent No. 9,981,090 [Patent Document 24] U.S. Patent No. 895,729 Summary of the Invention

[0012] The inventors have designed and implemented a method for preparing metal powders. The metals are specifically low-melting metals, e.g., below 450°C. Such metals include lithium, tin, gallium, indium, potassium, sodium, zinc, or alloys of at least one of these metals with a melting point below 450°C. The method is specifically an ultrasonic method in which ultrasonic vibrations of a perforated membrane are induced, the membrane being in contact with a liquid metal. The method allows for on-site generation of the metal powder at the time of its use, thereby overcoming the need for its transportation and / or storage.

[0013] According to one embodiment, the method of the present invention allows for the metal powder to be sprayed directly onto / into the deposition target.

[0014] According to another embodiment, the method allows for the metal powder to be sprayed directly into a liquid to create a suspension.

[0015] According to one embodiment, the method of the present invention provides an independent source of metal powder that is ready to be used in the manufacture of a battery / rechargeable battery electrode (cathode or anode) or other component of a battery / rechargeable battery, for example when the metal powder is lithium powder.

[0016] According to one embodiment, the present invention provides an ultrasonic atomization device adapted to produce metal powder, the device comprising a reservoir adapted to receive liquid metal and comprising a perforated membrane, and a sonotrode or piezoelectric element integrated in the reservoir, wherein ultrasonic vibrations of the perforated membrane are induced to produce metal powder that collects directly on / in a deposition target.

[0017] Consequently, according to one aspect, the present invention relates to: (1) A method for preparing metal powder, in which ultrasonic vibrations are induced on a perforated membrane in contact with a liquid metal. (2) The method according to the above point (1), wherein the metal is a low melting point metal, preferably the metal has a melting point of less than about 450°C. (3) The method according to point (1) or point (2), wherein the metal is lithium, tin, gallium, indium, potassium, sodium, zinc, or an alloy of at least one of these metals having a melting point of less than about 450°C, and preferably the metal is lithium or a lithium-based unalloy. (4) The method according to any one of the above points (1) to (3), wherein the obtained metal powder is in the form of a liquid aerosol, a solid aerosol, or an intermediate liquid-solid aerosol, or a combination of these forms. (5) A method according to any one of the above points (1) to (4), further comprising depositing the resulting metal powder directly onto / into a deposition target. (6) The method according to point (5), wherein the deposition target is a housing containing a liquid, thereby creating a suspension of metal powder in the liquid. (7) The method according to the above point (5), wherein the deposition target is the surface of the anode, the surface of the cathode, the surface of the current collector, or any other component of a rechargeable battery. (8) The method according to any one of the above points (5) to (7), wherein the deposition comprises applying a high voltage between an ultrasonic spray device including a perforated membrane and a deposition target. (9) The method according to point (5), wherein the metal powder is lithium metal powder or a lithium-based alloy, and the deposition target is the surface of an anode, a surface of a cathode, a surface of a current collector, or any other component of a rechargeable battery. (10) The method according to point (9), wherein, prior to the deposition of the layer of lithium metal powder or the layer of the lithium-containing alloy, a layer of a lithiophilic agent and / or a layer of a protective agent that prevents undesired reactions between the deposition target and the lithium layer is applied to the surface of the target, preferably the lithiophilic agent comprises Cu, Zn, Sn, Si, Al, Ag, Sb, Bi, Cr, Fe, Mg, or oxides thereof, or metal fluorides, or combinations thereof, and preferably the protective agent is nickel, chromium, or cobalt. (11) The method according to point (9) or point (10), wherein the layer of lithium metal powder or lithium-based alloy is subsequently subjected to a thermal activation process and / or a passivation process. (12) The method according to point (5), wherein the metal powder is a lithium metal powder or a lithium alloy powder, and the deposition target is a container containing an active electrode material, an aprotic solvent, a non-polar solvent, a hydrocarbon, a mineral oil, a polymer, or an additive, or a combination thereof. (13) The method according to any one of the above points (1) to (8), further comprising the step of mixing the obtained lithium metal powder in a suitable liquid, preferably the liquid being an aprotic solvent, a non-polar solvent, a hydrocarbon, or a mineral oil, or a mixture thereof. (14) The method according to point (12) or point (13), wherein the liquid mixture containing lithium metal powder is used for manufacturing an electrode of a rechargeable battery (cathode or anode) or other rechargeable battery component. (15) A method for preparing metal powder, comprising the use of an ultrasonic atomization device including a perforated membrane, the perforated membrane being in contact with a liquid metal, and ultrasonic vibrations of the perforated membrane being generated by a sonotrode or piezoelectric body immersed in the liquid metal, to produce metal powder that is collected directly on / in a deposition target. (16) A method for preparing a metal powder, comprising: (a) introducing liquid metal into a container associated with an ultrasonic atomization device, the container including a perforated membrane, the liquid metal being in contact with the perforated membrane; (b) ultrasonic vibration of the perforated membrane is induced by a sonotrode or piezoelectric body immersed in the liquid metal to produce metal powder; (c) the metal powder is collected on / in the deposition target. (17) The method according to any one of the above points (1) to (16), which is carried out at the manufacturing site of the electrode of the battery / rechargeable battery or other component of the battery / rechargeable battery, preferably the method is carried out in an enclosure under an inert atmosphere or under vacuum. (18) An ultrasonic atomization device adapted for producing metal powder, comprising: a reservoir adapted to receive liquid metal and having a perforated membrane; and a sonotrode or piezoelectric element integrated into the reservoir; A device in which ultrasonic vibrations of a perforated membrane are induced, causing metal powder to be generated and collected directly on / in a deposition target. (19) An ultrasonic atomization device adapted for producing metal powder, comprising: a reservoir adapted to receive liquid metal and having a perforated membrane; and a sonotrode adapted to be immersed in the liquid metal; a device in which ultrasonic vibrations of a perforated membrane are induced, and metal powder is generated and collected directly on / in a deposition target; Optionally, the sonotrode is spaced from the perforated membrane; Optionally, the device wherein the sonotrode is in contact with the perforated membrane. (20) A metal powder obtained by any one of the methods according to points (1) to (17), wherein the particles of the powder preferably have a diameter of about 0.5 to 100 μm, and preferably have a diameter of about 1 to 50 μm. (21) A liquid mixture containing lithium metal powder obtained by the method according to any one of points (1) to (17), wherein the liquid is preferably an aprotic solvent, a nonpolar solvent, a hydrocarbon, or a mineral oil, or a mixture thereof, and the mixture is preferably a suspension containing lithium particles. (22) An electrode (cathode or anode) or any other component of a battery / rechargeable battery manufactured using lithium metal powder obtained by the method according to any one of points (1) to (17). (23) A battery / rechargeable battery, including an electrode (cathode or anode) or any other component thereof, manufactured using lithium metal powder obtained by the method according to any one of points (1) to (17). (24) An apparatus for the manufacture of electrodes or other components of batteries / rechargeable batteries, incorporating a method according to any one of points (1) to (17) above, wherein the ultrasonic spraying device is fixed or movable, preferably the ultrasonic spraying device is connected to another device that moves according to an XYZ system. (25) An apparatus for manufacturing batteries / rechargeable batteries with electrodes or other components of the batteries / rechargeable batteries, incorporating a method according to any one of points (1) to (17) above, wherein the ultrasonic spraying device is fixed or movable, preferably the ultrasonic spraying device is connected to another device that moves according to an XYZ system. (26) Installation according to point (24) or point (25) above, wherein the deposition target is fixed or movable, preferably the deposition target is connected to a conveyor system or a roll-to-roll type system. (27) A manufacturing site for electrodes or other components of batteries / rechargeable batteries, incorporating a method according to any one of points (1) to (17) above. (28) A manufacturing site for a battery / rechargeable battery comprising an electrode or other component of the battery / rechargeable battery, incorporating a method according to any one of points (1) to (17). (29) A manufacturing site for electrodes or other components of batteries / rechargeable batteries, equipped with a device according to any one of points (24) to (26). (30) Use of an ultrasonic atomization device for the preparation of lithium metal powder.

[0018] Other objects, advantages and features of the present invention will become more apparent from the following description of possible embodiments, given exclusively by way of example, with reference to the following drawings, in which: [Brief explanation of the drawings]

[0019] [Figure 1] Spherical lithium powder according to the present invention and its particle size distribution (Example 2). [Figure 2]Ultrasonic method perforating stainless steel membrane. [Figure 3] Spherical gallium powder according to the present invention (Example 1). [Figure 4] Schematic of the assembly used to produce lithium powder (Example 2). [Figure 5] Schematic diagram of the assembly with the vibrating screen used in Examples 3 and 4. [Figure 6] Schematic diagram of the method for atomization of lithium with a perforated sonotrode. [Figure 7] Spherical lithium powder according to the present invention and its particle size distribution (Example 3). [Figure 8] Presentation of the dispersion of lithium powder in anhydrous toluene. DETAILED DESCRIPTION OF THE INVENTION

[0020] Before further describing the present invention, it should be understood that the present invention is not limited to the specific embodiments described below, as variations of these embodiments may be made and remain within the scope of the appended claims. Likewise, it should be understood that the terminology used is intended to describe the particular embodiments, and is not intended to be limiting. Instead, the scope of the present invention is established by the appended claims.

[0021] In order to provide a clear and consistent understanding of the terms used herein, the following definitions are provided: Furthermore, unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood in the art to which this invention pertains.

[0022] As used herein, the term "metal powder" refers to metal in powder form. It may be in the form of a liquid aerosol, a solid aerosol, or an intermediate liquid-solid aerosol. For example, the term "lithium metal powder" refers to lithium metal in powder form. The particles that make up the powder may be generally spherical. The particles may have diameters on the order of about 0.5 to 100 μm. In the context of this application, the terms "powder" and "aerosol" are used interchangeably. Specifically, the terms "lithium metal powder" and "lithium metal aerosol" are used interchangeably.

[0023] As used herein, the following terms are used interchangeably: "atomizer," "atomizer," "vibrating screen," and "nebulizer." Each of these terms refers to an element of the process by which metal powders are produced. And, as noted above, metal powders or metals in powder form can also be in the form of a liquid aerosol, a solid aerosol, or an intermediate liquid-solid aerosol.

[0024] The present inventors have designed and implemented a method for preparing metal powders. The metals are specifically low-melting metals, e.g., below 450°C. Such metals include lithium, tin, gallium, indium, potassium, sodium, zinc, or alloys of at least one of these metals with a melting point below 450°C. The method is specifically an ultrasonic method in which ultrasonic vibrations of a perforated membrane in contact with the liquid metal are induced. The method allows for on-site generation of metal powders at the time of use, thereby overcoming the need for transport and / or storage. The present inventors have also designed and fabricated an ultrasonic atomization device adapted for producing the metal powders according to the present invention.

[0025] According to one embodiment, the present invention relates to a product and method of atomizing lithium metal liquid to generate liquid or solid aerosols in an inert, reactive, or vacuum environment (FIG. 1). The lithium metal liquid is atomized on demand by an ultrasonic atomization device equipped with a perforated membrane and using ultrasonic methods to form spherical microdroplets. The spherical microdroplets exhibit high electrochemical reactivity due to their surface being free of all contaminants (oxides, nitrides, carbonates, etc.).

[0026] According to one embodiment, the present invention relates to a method for electrostatic collection of liquid or solid droplets. The application of a high voltage between an ultrasonic spraying device and a target generates a strong electric field that directs negatively (-) charged particles toward positively (+) charged particles. The method therefore allows for the collection of escaped particles and efficiently directs them toward the deposition target. The particles can be trapped in an electrostatic precipitator or sprayed directly onto the surface of an electrode during its manufacture.

[0027] According to one embodiment of the present invention, the collected lithium powder is transferred into a non-polar liquid solvent to form a liquid suspension that can be applied to an electrode during fabrication.

[0028] According to one embodiment, the present invention relates to a "standalone" lithium source that can be used in the manufacture of electrodes for lithium-ion (anode or cathode) or solid-state lithium rechargeable batteries. Lithium particles can be used in the electrode mixture (active material, solvent, polymer, additives), directly sprayed, or used in suspension on the surface of a solid electrode. According to one aspect of the present invention, the electrode is then thermally activated to allow diffusion of lithium throughout the material. According to another aspect, the electrode is calendered with a roller, which can be heated or unheated. According to another aspect, a layer of a lithium parent material is applied to the surface of the solid electrode before spraying the lithium metal powder. The lithium parent material can include Cu, Zn, Sn, Si, Al, Ag, Sb, Bi, Cr, Fe, Mg, or oxides or metal fluorides thereof, or combinations thereof. According to another aspect, depending on the nature of the electrode substrate, a protective layer can be applied to the electrode substrate before applying the lithium parent layer to prevent undesired reactions between the electrode substrate and lithium metal. According to another embodiment, the surface passivation of the lithium particles is carried out by using a reactive atmosphere (e.g., Ar / CO2) or a liquid solvent containing a surface-modifying reagent.

[0029] According to one embodiment, the present invention provides an "independent" source of lithium metal, enabling improved performance in lithium and lithium-ion rechargeable batteries. The present invention enables low-cost production of lithium metal powder, which is generated on-demand and on-site, eliminating many safety issues associated with the storage, handling, and transportation of hazardous materials (hydrogen-reactive and pyrophoric powders). According to one aspect, the lithium metal powder according to the present invention generally has a smaller particle size than powders produced in the lithium-ion battery field, making it more attractive for certain applications. Furthermore, because the lithium metal powder is readily incorporated during electrode fabrication, the risk of electrochemical performance degradation over time is reduced.

[0030] The present invention relates to an ultrasonic method using an ultrasonic atomization device containing a perforated membrane. Indeed, the inventors have discovered that by using such a device, it is possible to produce lithium metal aerosol (solid or liquid) or lithium metal powder. In the method according to the invention, no compressed gas is required to generate and transport the aerosol (compare thermal atomization applications). The lithium metal powder produced is fine, light, volatile, and fugitive.

[0031] Many applications of the present invention are possible, some of which are listed below:

[0032] According to one embodiment, the method of the present invention can be applied in a similar manner to lithium metal to all low melting point metals, for example, metals having a melting point below 450° C. Such metals include, for example, lithium, tin, gallium, indium, potassium, sodium, zinc, or alloys of at least one of these metals having a melting point below 450° C. According to another embodiment, solid or liquid co-deposition can be performed.

[0033] According to one aspect of the invention, the ultrasonic spraying device can be fixed or adapted to move according to an XYZ system. The deposition target can be fixed or movable on a conveyor or roll-to-roll type system. In this way, a "lithium printer" is created in a manner similar to additive manufacturing techniques.

[0034] According to one aspect of the invention, the temperature of the substrate and / or its environment may be controlled to deposit solid, liquid, or semi-solid-liquid powders.

[0035] According to one aspect of the present invention, the solid powder can be transported in an aprotic solvent, a hydrocarbon, a mineral oil, or a mixture thereof, thereby creating an independent source of lithium metal powder.

[0036] According to one embodiment, passivation or surface modification of the lithium powder may be performed after depositing the lithium metal powder in an aprotic solvent, a hydrocarbon, a mineral oil, or a mixture thereof.

[0037] According to another aspect, an electrode mix can be formed that can be spread onto a current collector for use in a lithium-ion or lithium rechargeable battery.

[0038] According to one aspect of the invention, the product is a cellulose ester containing an active material (graphite, SiO x , Si, Sn, etc. (see, e.g., US 6,706,447, US 2016 / 164073, US 2018 / 261829, US 2019 / 013513). According to another embodiment, lithium can be sprayed directly onto the electrode or current collector, or spread as a powder in suspension in a volatile solvent [5-12].

[0039] According to one aspect of the invention, the product can be used in an electrode mixture and can be applied by coating on a current collector (US2021 / 280909, US2020 / 083518, US2020 / 014033).

[0040] According to one aspect of the present invention, the product or method can be used to apply lithium onto thin anodes (U.S. Application No. 16 / 458,074, U.S. Application No. 63 / 299,247). According to another aspect, a lithium-loving coating is applied beforehand, and optionally, a protective layer is applied depending on the nature of the thin anode substrate. This improves the quality of the lithium deposition that penetrates therein. This technique is faster than sputtering physical vapor deposition or thermal evaporation techniques (EP 285476), does not require a vacuum process, and uses lower temperatures (200 vs. 600°C) (U.S. Patent No. 5,522,955, WO 2020 / 210913). This is a good alternative to methods of depositing lithium in the molten state (U.S. Patent No. 5,169,446, U.S. Patent No. 3,928,681, EP 0285476).

[0041] Example 1: To implement the method of the present invention in connection with liquid gallium, an ultrasonic atomization device with a perforated membrane was assembled. The device consisted of a ring-shaped piezoelectric element (lead zirconate titanate or PZT) powered by a high-frequency sinusoidal voltage source (AV = 108 V, f = 110 kHz), a 50 μm-thick stainless steel membrane (Figure 2) with 772 orifices with a diameter of approximately 7 μm spaced 90 μm apart, and a reservoir of gallium liquid heated to 50°C. The device was mounted in a fume hood in ambient air (20°C). The piezoelectric element vibrated the perforated stainless steel membrane at a frequency corresponding to ultrasound, causing a jet of liquid gallium to be ejected through the 7 μm orifices. The liquid gallium spray broke down into fine spherical droplets, forming a liquid aerosol in the air, which solidified upon contact with air at room temperature to form a powder with an average particle size (approximately 10 μm) directly proportional to the diameter of the orifices. The resulting gallium powder is shown in Figure 3.

[0042] Example 2: The ultrasonic atomization device of Example 1 (Figure 4) was used, but placed in a glove box (1) under a purified argon atmosphere (HO < 0.1 ppm, O < 0.1 ppm, and N < 0.1 ppm). The argon temperature in the glove box was maintained at 20 °C. This time, battery-grade lithium was used, melted (5) at 220 °C in a heated reservoir (2). The reservoir frame was made of 316L stainless steel, and its temperature was controlled by a heating cartridge and a thermocouple. The system delivered liquid lithium to a perforated membrane (4). An ultrasonic device equipped with a perforated membrane controlled the temperature of the ultrasonic process at 220 °C. Liquid lithium aerosol (6) was generated by ultrasonic vibrations provided by a piezoelectric element or sonotrode (3). The liquid lithium aerosol rapidly solidified upon contact with argon at room temperature. The lithium powder was collected on a substrate (7). This test produced spherical particles with diameters ranging from 0.5 to 25 μm, with an average of 7.5 μm. EDS analysis showed a surface free of any measurable contamination. The resulting lithium metal powder is shown in Figure 1.

[0043] Example 3: An ultrasonic sonotrode device was used to generate the ultrasonic waves necessary to atomize lithium liquid through a screen to produce lithium powder. Figure 5 shows a schematic diagram of the assembly with a vibrating screen used in a glove box under a purified argon atmosphere, similar to Example 2 (1). The sonotrode (3) used was made of titanium (Ti-6AI-4V) and had a sinusoidal vibration frequency of 20 kHz. One hundred and fifty grams (150 g) of liquid lithium (5) was heated to 220 °C in a 316L stainless steel cylinder (2). The controller regulated the temperature of the resistance heating element via a thermocouple immersed in the liquid lithium (5). A woven stainless steel screen (4) with approximately 25 μm (500 mesh) openings was used to retain the lithium at the top of the assembly. The atomization chamber was also designed from 316L stainless steel. A strip (7) was placed at the bottom of the chamber to collect the lithium particles / droplets (6). A 0.5 μm 316L stainless steel filter was attached to the atomization chamber to minimize the pressure difference with the glove box. The sonotrode (3) was immersed in the liquid lithium and positioned a short distance (approximately 3 mm) from the screen (4). The sonotrode (3) could be in contact with the screen (4) or spaced apart from it. Figure 7 shows an electron microscope image of the spherical lithium particles produced by this test. The presented particle size distribution shows that the particles have diameters ranging from approximately 10 to 80 μm, with a mean of approximately 42 μm. Two operating modes were tested: Example 3A: The sonotrode (3) is immersed in the lithium liquid and positioned at a distance of approximately 3 mm from the screen (4). Figure 7 shows an electron microscope image of the spherical lithium particles produced. The particle size distribution shown shows that the particles have diameters between 10 and 80 μm, with a mean of approximately 42 μm. Example 3B: The same device is used. The sonotrode (3) is in contact with the screen (4). A powder similar to that obtained in Example 3A is obtained.

[0044] Example 4: To carry out the coating, spraying was carried out on a preheated strip (7). The test conditions were the same as in Example 3A. The particles were applied to a 60 cm2 strip with a thickness of 5 μm. 2 The lithium powder was sprayed onto a copper strip (7). The strip was covered with a protective layer of electrolytic nickel (approximately 0.5 μm thick) and a lithium-containing tin layer (approximately 40 nm thick). The strip was placed at a distance of approximately 65 mm from the screen (4). The strip was placed at the bottom of the spray chamber (Figure 5) and preheated to 230 °C by a heating element. The lithium powder produced interacted with the lithium-containing tin layer on the surface to form a lithium layer on the strip (7).

[0045] Example 5: The possibility of carrying out a liquid spray on a strip similar to that used in Example 4 was also tested. The assembly and general conditions of Examples 3 and 4 were used, except that the distance between the vibrating screen (4) and the strip (7) was reduced to about 10 mm. In this way, the droplets fell directly onto the strip (7) before solidifying. Each droplet thoroughly wetted the surface of the strip (7). Thus, a (spray-type) liquid coating was carried out.

[0046] Example 6: To demonstrate the feasibility of facilitating the transfer of lithium powder to the next stage of use, direct spraying was performed in a solvent inert to lithium (toluene) to obtain a lithium powder suspension. The test was carried out in a glove box under a purified argon atmosphere using the same conditions and equipment as in Example 2, except that the spray chamber was a 250 mL beaker containing 30 mL of toluene that had previously been dehydrated with a molecular screen to obtain a water concentration of less than 10 ppm. After stirring, a dispersion of lithium powder in the solvent (Figure 8) was obtained, which rapidly separated.

[0047] Example 7: Lithium was partially passivated with polyoxyethylene distearate (POE-200) of molecular weight 200. This allowed for reduced reactivity of the powder during exposure in an anhydrous chamber, facilitating easier handling. Lithium particles were placed in a 1 wt % solution of POE-200 in toluene (HO<10 ppm) that had been previously dehydrated with a molecular screen. It was observed that the presence of POE allowed the lithium particles to disperse better in the solvent and reduced the rate of liquid-solid phase separation. Four milliliters of this solution and the original suspension (Example 6) were then deposited into aluminum dishes and dried at 20°C for 12 hours in a glove box containing purified argon (HO<0.1 ppm, O<0.1 ppm, and N<0.1 ppm). These two dishes were transferred to an anhydrous chamber (dew point -47°C) and placed in a controlled atmosphere chamber containing an aqueous solution saturated with KOH to maintain the assembly atmosphere at a dew point close to -15°C. The plates were weighed over time to determine their mass gain. The unprotected lithium powder showed a weight gain of over 50% compared to the lithium powder treated with the POE solution. The mass gain is associated with the formation of lithium hydroxide. The presence of this compound was confirmed by X-ray diffraction (XRD) analysis of the powder after exposure.

[0048] Referring to Figure 5, a schematic diagram of an ultrasonic device using a sonotrode with a perforated vibrating membrane to generate ultrasonic vibrations that are transmitted to the membrane via a liquid. While housed in an enclosure (1) with an inert, reactive, or partial vacuum atmosphere, the sonotrode (3) is immersed in liquid lithium (or other metal or alloy) (5) contained in a container (2) with a perforated membrane (4). The assembly produces a powder / droplets / aerosol (6) that is collected on a substrate (7).

[0049] Referring to Figure 6, a schematic diagram of an ultrasonic device that includes a perforated vibrating membrane and uses a sonotrode / piezoelectric element to generate ultrasonic vibrations that pulverize lithium (or other metals or alloys). Encased in an enclosure (1) with an inert, reactive, or partial vacuum atmosphere, the end of the sonotrode (3) is perforated (4) and supplied with liquid lithium (5). The assembly produces a powder / droplets / aerosol (6) that is collected on a substrate (7).

[0050] Although the present invention has been described with reference to preferred embodiments, it is understood that this description refers not only to the preferred embodiments but should not be considered as limiting the scope of the invention, which includes various implementations as defined in the following claims. It is understood that several variations, modifications, uses, and adaptations may be added to the embodiments. The present invention is generally intended to encompass such variations, modifications, uses, and adaptations in accordance with the principles of the invention, including any variations of the present description that may be applied to the above elements, which are known or conventional in the field of the invention, consistent with the scope of the following claims.

[0051] The claims should not be limited in scope by the implementations set forth in the examples, but should be accorded the broadest interpretation consistent with the description as a whole.

[0052] This specification makes reference to a number of documents, the contents of each of which are incorporated herein by reference in their entirety.

[0053] References 1.Meyer, JHC, Some practical aspects of handling lithium metal, in Handling and uses of the alkali metals.1957, American Chemical Society, p.9-15. 2. https: / / livent.com / applications-and-innovation / clear-lab / . 3. TDS, LECTRO (registered trademark) MAX POWDER 100, SLMP (registered trademark), Livent. 4. Wildi, T. and G. Sybille, Electrotechnique. Fourth edition ed. 2005, p. 257. 5. Wang, Z., et al., Application of Stabilized Lithium Metal Powder (SLMP (registered trademark)) in graphite anode - A high efficient prelithiation method for lithium-ion batteries. Journal of Power Sources, 2014. 260: p. 57 - 61. 6. Fitch, B. B., et al., An Overview on Stabilized Lithium Metal Powder (SLMP), an Enabling Material for a New Generation of Li-lon Batteries. ECS Transactions, 2007. 3(27): p. 15 - 22. 7. Zhao, H., et al., Toward Practical Application of Functional Conductive Polymer Binder for a High-Energy Lithium-Ion Battery Design. Nano Letters, 2014. 14(11): p. 6704 - 6710. 8. Ai, G., et al., Scalable process for application of stabilized lithium metal powder in Li-ion batteries. Journal of Power Sources, 2016. 309: p. 33 - 41. 9.Fan,K.,et al.,Application of stabilized lithium metal powder and hard carbon in anode of lithium-sulfur battery.Journal of Electroanalytical Chemistry, 2016.760:p.80-84. 10.Pan,Q.,et al.,Improved electrochemical performance of micro-sized SiO-based composite anode by prelithiation of stabilized lithium metal powder.Journal of Power Sources,2017.347:p.170-177. 11.Huang,B.,et al.,Pre-Lithiating SiO Anodes for Lithium-Ion Batteries by a Simple,Effective,and Controllable Strategy Using Stabilized Lithium Metal Powder.ACS Sustainable Chemistry & Engineering, 2021.9(2):p.648-657. 12.Wang,F.,et al.,Construction of air-stable pre-lithiated SiOx anodes for next-generation high-energy-density lithium-ion batteries.Cell Reports Physical Science,2022:p.100872.

Claims

1. A method for preparing metal powder, wherein ultrasonic vibrations are induced on a perforated membrane in contact with a liquid metal.

2. 10. The method of claim 1, wherein the metal is a low melting point metal, preferably the metal has a melting point less than about 450°C.

3. 3. The method according to claim 1 or 2, wherein the metal is lithium, tin, gallium, indium, potassium, sodium, zinc, or an alloy of at least one of these having a melting point of less than about 450°C, preferably the metal is lithium or a lithium-based alloy.

4. The method according to any one of claims 1 to 3, wherein the metal powder obtained is in the form of a liquid aerosol, a solid aerosol, or an intermediate liquid-solid aerosol, or a combination of these forms.

5. The method of any one of claims 1 to 4, further comprising depositing the resulting metal powder directly onto / into a deposition target.

6. The method of claim 5 , wherein the deposition target is a housing containing a liquid, thereby creating a suspension of metal powder in the liquid.

7. 6. The method of claim 5, wherein the deposition target is a surface of an anode, a surface of a cathode, a surface of a current collector, or any other component of a rechargeable battery.

8. The method of any one of claims 5 to 7, wherein the deposition comprises applying a high voltage between an ultrasonic atomization device including the perforated membrane and the deposition target.

9. 6. The method of claim 5, wherein the metal powder is a lithium metal powder or a lithium-based alloy, and the deposition target is the surface of an anode, a surface of a cathode, a surface of a current collector, or any other component of a rechargeable battery.

10. 10. The method of claim 9, wherein prior to deposition of the layer of lithium metal powder or the layer of the alloy comprising lithium, a layer of a lithiophilic agent and / or a layer of a protective agent that prevents undesired reactions between the deposition target and the lithium layer is applied to the surface of the target, preferably the lithiophilic agent comprises Cu, Zn, Sn, Si, Al, Ag, Sb, Bi, Cr, Fe, Mg, or oxides or metal fluorides thereof, or combinations thereof, and preferably the protective agent is nickel, chromium, or cobalt.

11. 11. The method according to claim 9 or 10, wherein the layer of lithium metal powder or the lithium-based alloy is subsequently subjected to a thermal activation process and / or a passivation process.

12. 6. The method of claim 5, wherein the metal powder is a lithium metal powder or a lithium alloy powder, and the deposition target is a container containing an active electrode material, an aprotic solvent, a non-polar solvent, a hydrocarbon, a mineral oil, a polymer, or an additive, or a combination thereof.

13. 9. The method according to any one of claims 1 to 8, further comprising the step of mixing the obtained lithium metal powder in a suitable liquid, preferably the liquid being an aprotic solvent, a non-polar solvent, a hydrocarbon, or a mineral oil, or a mixture thereof.

14. 14. The method of claim 12 or 13, wherein the liquid mixture containing the lithium metal powder is used to manufacture a rechargeable battery electrode (cathode or anode) or other rechargeable battery component.

15. A method for preparing metal powder, comprising the use of an ultrasonic atomization device comprising a perforated membrane, said perforated membrane being in contact with a liquid metal, and ultrasonic vibrations of said perforated membrane being generated by a sonotrode or piezoelectric body immersed in said liquid metal, to produce said metal powder that is collected directly on / in a deposition target.

16. 1. A method for preparing a metal powder, comprising: (a) introducing liquid metal into a container associated with an ultrasonic atomization device, the container comprising a perforated membrane, the liquid metal being in contact with the perforated membrane; (b) ultrasonic vibration of the perforated membrane is induced by a sonotrode or piezoelectric element immersed in the liquid metal to produce the metal powder; (c) the metal powder is collected on / in a deposition target.

17. The method according to any one of claims 1 to 16, which is carried out at the manufacturing site of the electrodes of a battery / rechargeable battery or other components of a battery / rechargeable battery, preferably wherein the method is carried out in an enclosure under an inert atmosphere or under vacuum.

18. 1. An ultrasonic atomization device adapted to produce metal powder, comprising: a reservoir adapted to receive liquid metal and comprising a perforated membrane; and a sonotrode or piezoelectric element integrated into the reservoir; A device wherein, upon induction of ultrasonic vibration of said perforated membrane, said metal powder is generated and collected directly on / in a deposition target.

19. 1. An ultrasonic atomization device adapted for producing metal powder, comprising: a reservoir adapted to receive liquid metal, the reservoir comprising a perforated membrane; and a sonotrode adapted to be immersed in the liquid metal; When ultrasonic vibration of the perforated membrane is induced, the metal powder is generated and collected directly on / in the deposition target; Optionally, the sonotrode is spaced from the perforated membrane; Optionally, the device wherein said sonotrode is in contact with said perforated membrane.

20. 18. A metal powder obtainable by the method according to any one of claims 1 to 17, wherein preferably the particles of the powder have a diameter of about 0.5 to 100 μm, preferably the particles of the powder have a diameter of about 1 to 50 μm.

21. 18. A liquid mixture comprising lithium metal powder obtainable from the method of any one of claims 1 to 17, preferably wherein the liquid is an aprotic solvent, a non-polar solvent, a hydrocarbon, or a mineral oil, or a mixture thereof, preferably wherein the mixture is a suspension comprising lithium particles.

22. An electrode (cathode or anode) or any other component of a battery / rechargeable battery manufactured using the lithium metal powder obtained from the method according to any one of claims 1 to 17.

23. A battery / rechargeable cell comprising an electrode (cathode or anode) or any other component of a battery / rechargeable cell manufactured using lithium metal powder obtained from the method according to any one of claims 1 to 17.

24. Apparatus for the manufacture of electrodes or other components of batteries / rechargeable batteries, incorporating the method of any one of claims 1 to 17, wherein the ultrasonic spraying device is fixed or movable, preferably the ultrasonic spraying device is connected to another device that moves according to an XYZ system.

25. Apparatus for the manufacture of batteries / rechargeable batteries with electrodes or other components of batteries / rechargeable batteries, incorporating the method of any one of claims 1 to 17, wherein the ultrasonic spraying device is fixed or movable, preferably the ultrasonic spraying device is connected to another device that moves according to an XYZ system.

26. 26. Apparatus according to claim 24 or 25, wherein the deposition target is fixed or movable, preferably the deposition target is connected to a conveyor system or a roll-to-roll type system.

27. A manufacturing site for electrodes or other components of batteries / rechargeable batteries, incorporating the method according to any one of claims 1 to 17.

28. A manufacturing site for batteries / rechargeable batteries comprising electrodes or other components of the batteries / rechargeable batteries, said manufacturing site incorporating the method according to any one of claims 1 to 17.

29. A manufacturing site for electrodes or other components of batteries / rechargeable batteries, comprising a device according to any one of claims 24 to 26.

30. The use of an ultrasonic atomization device for the preparation of lithium metal powder.

Images