Method for producing metal powder and use

Abstract

The present invention provides a method for preparing a metal powder in which ultrasonic vibrations are induced on a perforated film, the perforated film being in contact with a liquid metal. The metal is a low melting point metal or an alloy based on this metal and having a low melting point. The resulting metal powder is deposited directly onto / into the deposition target.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Canadian Patent Application No. CA 3,169,823, filed on August 5, 2022. The contents of this Canadian application are incorporated herein by reference in their entirety. Technical Field

[0003] The present invention relates to a method for preparing a metal powder. The metal is in particular a low melting point metal (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 the liquid metal. The method enables the metal powder to be produced on site when it is used, thereby overcoming the need to transport and / or store the metal powder. The method according to the invention further enables the metal powder to be sprayed directly onto / into a deposition target. Background Art

[0004] Lithium metal in powder form helps improve the performance of lithium rechargeable batteries. However, the preparation of lithium metal does require high costs. In addition, many safety challenges are associated with handling, transportation and storage. In fact, lithium metal powder is hydrogen-reactive and pyrophoric.

[0005] In general, the preparation of lithium metal powder is an empirical operation. In practice, lithium metal is heated to 200°C under a thin film of light oil. The lithium metal is then deposited in a preheated bowl (140°C to 150°C) containing an amount of oil sufficient to float the metal. As the temperature of the metal drops, the lithium is vigorously agitated and the fine particles solidify. [1]

[0007] Livent Corporation (Livent) (formerly known as FMC) has refined this technology to reduce the size of the lithium powder particles obtained. The refined technology also involves the use of various reagents (CO 2 , fluoride, wax, phosphorus, polymer) to passivate the surface of lithium. Livent has a number of 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; US2011 / 300385; US2017 / 149052; US2019 / 097221. The lithium powder is named "stable lithium metal powder" (or SLMP) [2,3].

[0008] Companies such as Albemarle (US2020 / 240020) and TDK (US2016 / 099467) have also developed similar technologies.

[0009] In various other fields, technologies have been developed for atomizing liquids (organic or aqueous solvents). For example, the inkjet printing method is a non-contact method in which very small drops of liquid ink are pushed through a nozzle by means of electrical intensity and a forming point. Drop-on-demand or DOD is produced every time it is desired. For the piezoelectric method, the ink reservoir is in contact with a piezoelectric crystal, which converts the electrical pulses into mechanical force. The overpressure induced by the piezoelectric element allows the droplets to be discharged (US 3,683.212).

[0010] Based on the principle of vibrating screens, many types of atomizers have been developed for different applications: humidifiers, aromatherapy, dispensers of pharmaceutical products, fuel injection ( US 4,533,082 ; US 4,850,534 ; EP 0516565 ; 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 ).

[0011] In the field of filtering dusty gases or physically separating nanomaterials to recover the fine powders produced, certain technologies have been developed, including: the use of cyclones, cartridge filters, particle filters, bubble columns and electrostatic precipitators [4]. In particular, the latter consists of a conductive wire connected to a high tension source and surrounded by a metal cylinder, which acts as both a chimney and an electrode for the dusty gas. Negative ions attach to the dust particles. The electrostatic force carries the dust particles towards the cylinder, where they lose their charge and become neutral particles that fall into a suitable container (US 895,729).

[0012] There is a need for an efficient and advantageous method of preparing lithium metal powders. There is a need for a method for preparing lithium metal powders which allows the level of maintenance powder to be kept as low as possible.

[0013] There is also a need to produce lithium metal powders for use as an independent source of lithium during the manufacture of electrodes for lithium-ion rechargeable batteries and lithium metal rechargeable batteries. Summary of the invention

[0014] The inventors have designed and implemented a method for preparing metal powder. The metal is specifically a low melting point metal, for example 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 the liquid metal. The method enables the metal powder to be produced on site when it is used, thereby overcoming the need to transport and / or store the metal powder.

[0015] According to one embodiment, the method of the present invention enables spraying of the metal powder directly onto / into a deposition target.

[0016] According to another embodiment, the method enables spraying the metal powder directly into a liquid to produce a suspension.

[0017] According to one embodiment, the method of the present invention provides an independent source of metal powder, which, when the metal powder is lithium powder, is ready for use, for example, in the manufacture of electrodes (cathode or anode) of batteries / rechargeable batteries or other components of batteries / rechargeable batteries.

[0018] According to one embodiment, the present invention provides an ultrasonic spraying device suitable for producing metal powder. The device comprises: a reservoir, the reservoir is suitable for receiving liquid metal and comprises a perforated membrane; and a sonotrode or a piezoelectric body, the sonotrode or the piezoelectric body is integrated into the reservoir. When the ultrasonic vibration of the perforated membrane is induced, the metal powder is generated and is directly gathered onto / in a deposition target.

[0019] Thus, according to one aspect, the present invention relates to:

[0020] (1). A method for preparing metal powder, in which ultrasonic vibration is induced on a perforated membrane, the perforated membrane being in contact with liquid metal.

[0021] (2) The method according to the above point (1), wherein the metal is a low melting point metal; preferably, the melting point of the metal is lower than about 450°C.

[0022] (3) The method according to the above point (1) or (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 below about 450°C; preferably, the metal is lithium or a lithium-based alloy.

[0023] (4) The method according to any one of the above items (1) to (3), wherein the metal powder produced is in the form of liquid aerosol, solid aerosol or intermediate liquid-solid aerosol or a combination of these forms.

[0024] (5) The method according to any one of the above points (1) to (4), further comprising depositing the produced metal powder directly onto / into a deposition target.

[0025] (6) The method according to item (5) above, wherein the deposition target is a shell containing a liquid, thereby generating a suspension of metal powder in the liquid.

[0026] (7) The method according to item (5) above, wherein the deposition target is the surface of an anode, a cathode, a current collector or any other component of a rechargeable battery.

[0027] (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 the perforated membrane and the deposition target.

[0028] (9) The method according to the above point (5), wherein the metal powder is lithium metal powder or lithium-based alloy; and the deposition target is the surface of the anode, cathode, current collector or any other component of the rechargeable battery.

[0029] (10) A method according to item (9) above, wherein before the deposition of a layer of lithium metal powder or a layer of an alloy containing lithium, a layer of a lithium-philic agent and / or a layer of a protective agent for preventing undesirable reactions between the deposited target and the lithium layer is applied to the surface of the target; wherein preferably, the lithium-philic agent comprises Cu, Zn, Sn, Si, Al, Ag, Sb, Bi, Cr, Fe, Mg or oxides of these metals, or metal fluorides, or combinations thereof; wherein preferably, the protective agent is nickel, chromium or cobalt.

[0030] (11) The method according to the above point (9) or (10), wherein the lithium metal powder layer or the lithium-based alloy is subsequently subjected to a thermal activation process and / or a passivation treatment process.

[0031] (12) A method according to the above point (5), wherein the metal powder is lithium metal powder or lithium alloy powder; and the deposition target is a container, which contains active electrode materials, aprotic solvents, non-polar solvents, hydrocarbons, mineral oils, polymers or additives or a combination of these.

[0032] (13) A method according to any one of points (1) to (8) above, which further comprises the step of mixing the obtained lithium metal powder in a suitable liquid; wherein preferably, the liquid is a non-protonic solvent, a non-polar solvent, a hydrocarbon, or a mineral oil or a mixture of these.

[0033] (14) A method according to point (12) or (13) above, wherein a liquid mixture containing the lithium metal powder is used in the manufacture of an electrode (cathode or anode) of a rechargeable battery or other rechargeable battery component.

[0034] (15). A method for preparing metal powder, the method comprising using an ultrasonic spray device, the ultrasonic spray device comprising a perforated membrane, wherein the perforated membrane is in contact with liquid metal, and ultrasonic vibration of the perforated membrane is generated by a sonar probe or a piezoelectric body immersed in the liquid metal, thereby producing the metal powder, and the metal powder is directly collected on / in a deposition target.

[0035] (16) A method for preparing a metal powder, the method comprising the following steps:

[0036] (a) introducing liquid metal into a container, the container being associated with an ultrasonic spray device, wherein the container comprises a perforated membrane, wherein the liquid metal is in contact with the perforated membrane;

[0037] (b) inducing ultrasonic vibration of the perforated membrane by immersing a sonar probe or a piezoelectric body in the liquid metal, thereby producing the metal powder; and

[0038] (c) collecting the metal powder on / in a deposition target.

[0039] (17) A method according to any one of points (1) to (16) above, which is carried out at a manufacturing site of an electrode of a battery / rechargeable battery or other component of a battery / rechargeable battery; wherein preferably, the method is carried out in an enclosure under an inert atmosphere or under vacuum.

[0040] (18) An ultrasonic spraying device, which is suitable for producing metal powder, comprising: a reservoir, the reservoir is suitable for receiving liquid metal and comprises a perforated membrane; and a sonar probe or a piezoelectric body, the sonar probe or the piezoelectric body is integrated in the reservoir, wherein

[0041] Upon inducing ultrasonic vibrations of the perforated membrane, the metal powder is generated and collected directly onto / into a deposition target.

[0042] (19) An ultrasonic spraying device suitable for producing metal powder, the ultrasonic spraying device comprising: a reservoir suitable for receiving liquid metal and comprising a perforated membrane; and a sonar probe suitable for being immersed in the liquid metal, wherein

[0043] Upon inducing ultrasonic vibrations of the perforated membrane, the metal powder is generated and collected directly onto / into a deposition target,

[0044] Optionally, the sonar probe is spaced apart from the perforated membrane,

[0045] Optionally, the sonar probe is in contact with the perforated membrane.

[0046] (20). A metal powder obtained by a method according to any one of points (1) to (17); wherein preferably, the diameter of the powder particles is between about 0.5 μm and 100 μm; wherein preferably, the diameter of the powder particles is between about 1 μm and 50 μm.

[0047] (21). A liquid mixture comprising lithium metal powder, wherein the lithium metal powder is produced by a method according to any one of points (1) to (17); wherein preferably, the liquid is a non-protonic solvent, a non-polar solvent, a hydrocarbon or a mineral oil, or a mixture of these; wherein preferably, the mixture is a suspension comprising lithium particles.

[0048] (22). An electrode (cathode or anode) or any other component of a battery / rechargeable battery, which is manufactured using lithium metal powder, wherein the lithium metal powder is produced by the method described in any one of points (1) to (17).

[0049] (23). A battery / rechargeable battery comprising an electrode (cathode or anode) or any other component of a battery / rechargeable battery manufactured using lithium metal powder, wherein the lithium metal powder is produced by a method according to any one of points (1) to (17).

[0050] (24). A facility for manufacturing electrodes or other components of a battery / rechargeable battery, the facility incorporating a method according to any one of the above points (1) to (17), and wherein the ultrasonic spray device is fixed or mobile; wherein preferably, the ultrasonic spray device is connected to another device that moves according to an XYZ system.

[0051] (25) A facility for manufacturing a battery / rechargeable battery, wherein the battery / rechargeable battery comprises an electrode or other component of a battery / rechargeable battery, wherein the facility incorporates a method according to any one of the above points (1) to (17), and wherein the ultrasonic spray device is fixed or mobile; wherein preferably, the ultrasonic spray device is connected to another device that moves according to an XYZ system.

[0052] (26) The facility according to point (24) or (25) above, wherein the deposition target is fixed or mobile; wherein preferably, the deposition target is connected to a conveyor system or a roll-to-roll system.

[0053] (27) A manufacturing site for electrodes or other components of batteries / rechargeable batteries, the manufacturing site incorporating a method according to any one of the above points (1) to (17).

[0054] (28). A manufacturing site for a battery / rechargeable battery, wherein the battery / rechargeable battery comprises an electrode or other component of a battery / rechargeable battery, wherein the manufacturing site incorporates a method according to any one of points (1) to (17).

[0055] (29) A manufacturing site for electrodes or other components of batteries / rechargeable batteries, the manufacturing site comprising a facility according to any one of points (24) to (26).

[0056] (30). Use of an ultrasonic spraying device for preparing lithium metal powder.

[0057] Other objects, advantages and features of the present invention will become apparent from the following description of possible embodiments which are provided exclusively by way of example with reference to the following drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 : Spherical lithium powder according to the present invention and its particle size distribution (Example 2).

[0059] Figure 2 : Perforated stainless steel membrane by ultrasonic method.

[0060] Figure 3 : Spherical gallium powder according to the present invention (Example 1).

[0061] Figure 4 : Schematic diagram of the assembly used to produce lithium powder (Example 2).

[0062] Figure 5 : Schematic diagram of the assembly with a vibrating screen used in Examples 3 and 4.

[0063] Figure 6 : Schematic representation of the method used to spray lithium at a perforating sonar probe.

[0064] Figure 7 : Spherical lithium powder according to the present invention and its particle size distribution (Example 3).

[0065] Figure 8 : Presentation of dispersion of lithium powder in anhydrous toluene. DETAILED DESCRIPTION

[0066] Before further describing the present invention, it is to be understood that the present invention is not limited to the specific embodiments described below, as variations of these embodiments can be created and still be within the scope of the appended claims. It is also to be understood that the terms used are intended to describe specific embodiments and are not intended to be limiting. Instead, the scope of the present invention will be determined by the appended claims.

[0067] In order to provide a clear and consistent understanding of the terms used in this specification, some definitions are provided below. In addition, unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood in the technical field related to the present invention.

[0068] In this document, the term "metal powder" refers to a metal in powder form. It can 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 constituting the powder can be in a roughly spherical form. The diameter of the particles can be about 0.5-100 μm. In the text of this application, the terms "powder" and "aerosol" are used interchangeably. Specifically, the terms "lithium metal powder" and "lithium metal aerosol" are used interchangeably.

[0069] As used in this document, the following terms are used interchangeably: "sprayer", "atomizer", "screen vibrator", "nebulizer". Each of these terms refers to an element that produces a metal powder. Moreover, as noted above, the metal powder or metal in powder form may also be in the form of a liquid aerosol, a solid aerosol, or an intermediate liquid-solid aerosol.

[0070] The inventors have designed and implemented a method for preparing metal powder. The metal is specifically a low melting point metal, for example 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 perforated membrane being in contact with liquid metal. The method enables the metal powder to be produced on site when the metal powder is used, thereby overcoming the need to transport and / or store the metal powder. The inventors have also designed and produced an ultrasonic spraying device suitable for producing metal powder according to the present invention.

[0071] According to one embodiment, the present invention relates to a product and atomization method for producing a lithium metal liquid in an inert, reactive environment or under vacuum as a liquid aerosol or a solid aerosol. Figure 1 ). The lithium metal liquid is sprayed as required by an ultrasonic spray device, which includes a perforated membrane and uses an ultrasonic method to form spherical microdroplets. The lithium metal liquid exhibits high electrochemical reactivity because its surface does not contain any contaminants (oxides, nitrides, carbonates, etc.).

[0072] According to one embodiment, the present invention relates to a method for electrostatically recovering liquid droplets or solid droplets. Applying a high voltage between an ultrasonic spray device and a target generates a strong electric field that guides negatively (-) charged particles toward positively (+) charged particles. Therefore, the method enables the recovery of fugitive particles and efficiently guides the fugitive particles to a deposition target. The particles can be captured in an electrostatic precipitator or sprayed directly on the surface of an electrode during electrode manufacturing.

[0073] According to one embodiment of the present invention, the collected lithium powder is transferred in a non-polar liquid solvent to form a liquid suspension liquid that can be applied to an electrode during electrode manufacturing.

[0074] According to one embodiment, the present invention relates to an "independent" source of lithium that can be used to make electrodes for lithium-ion batteries (anodes or cathodes) or solid-state lithium rechargeable batteries. Lithium particles can be used in the electrode mixture (active materials, solvents, polymers, additives), or can be sprayed or suspended directly on the surface of the solid electrode. According to one aspect of the invention, the electrode is then thermally activated to enable the lithium to diffuse in the material. According to another aspect, the electrode is rolled by rollers, which can be heated or non-heated. According to another aspect, a layer of a lithiophile is applied to the surface of the solid electrode before spraying with lithium metal powder. The lithiophile can contain Cu, Zn, Sn, Si, Al, Ag, Sb, Bi, Cr, Fe, Mg or their oxides, or metal fluorides or combinations of these. 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 lithiophile layer to prevent undesirable reactions between the electrode substrate and the lithium metal. According to another aspect, the lithium metal is heated by a reactive atmosphere (e.g., Ar / CO 2 ) or use a liquid solvent containing a surface modification agent to passivate the surface of the lithium particles.

[0075] According to one embodiment, the present invention provides an "independent" source of lithium metal that enables the performance of lithium batteries and lithium-ion rechargeable batteries to be improved. The present invention enables the low-cost manufacture of lithium metal powder and enables the resolution of many safety issues associated with the storage, handling and transportation of hazardous materials (hydrogen-reactive powders and pyrophoric powders) because the materials are produced on-site on demand. According to one aspect, the particle size of the lithium metal powder according to the present invention is smaller than the particle size of the powder commonly produced in the le field, and is therefore of greater concern for certain applications. In addition, since the lithium metal powder is immediately incorporated during electrode manufacture, the risk of electrochemical performance degradation over time is reduced.

[0076] The present invention relates to an ultrasonic method using an ultrasonic spraying device comprising a perforated membrane. In fact, the inventors have found that by using this device, lithium metal aerosols (solid or liquid) or lithium metal powders can be produced. In the method according to the invention, no compressed gas is required to produce and transport the aerosol (compared to thermal spraying applications). The lithium metal powder produced is fine, light, volatile and fugitive.

[0077] Many applications of the invention are possible. Some applications are indicated below.

[0078] According to one aspect, the method of the present invention can be applied to all low melting point metals, such as metals with a melting point below 450° C., in a manner similar to that of lithium metal. Such metals include, for example, lithium, tin, gallium, indium, potassium, sodium, zinc, or alloys of at least one of these metals with a melting point below 450° C. According to another aspect, solid or liquid co-deposition can be performed.

[0079] 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 system. In this way, a "lithium printer" is created in a manner similar to that of additive manufacturing technology.

[0080] According to one aspect of the invention, the temperature of the substrate and / or its environment may be controlled to allow deposition of solid powder, liquid powder or semi-solid-liquid powder.

[0081] According to one aspect of the invention, the solid powder may be transferred in an aprotic solvent, a hydrocarbon, a mineral oil, or a mixture of these. Thus, an independent source of lithium metal powder may be produced.

[0082] According to one aspect, after the lithium metal powder is deposited in an aprotic solvent, hydrocarbon, mineral oil, or a mixture of these, the lithium powder may be passivated or surface modified.

[0083] According to another aspect, an electrode mixture may be formed that may be spread on a current collector used in a lithium ion rechargeable battery or a lithium rechargeable battery.

[0084] According to one aspect of the present invention, the product can be used as a catalyst for active materials (graphite, SiO x In another aspect, lithium can be directly sprayed onto the electrode or current collector, or a powder suspended in a volatile solvent can be diffused [5-12].

[0085] According to one aspect of the present invention, the product can be used in an electrode mix, and it can be applied by coating on a current collector (US2021 / 280909; US2020 / 083518; US2020 / 014033).

[0086] According to one aspect of the invention, the product or method can be used to apply lithium to a thin anode (U.S. Application No. 16 / 458,074; U.S. Application No. 63 / 299,247). According to another aspect, a lithium-philic coating is applied in advance, and a protective layer is applied if necessary according to the properties of the substrate of the thin anode. This improves the deposition quality of the lithium infiltrated therein. This technology is faster than sputtering physical vapor deposition or thermal evaporation technology (EP 285476), does not require a vacuum process, and has a lower temperature (200°C vs. 600°C) (US 5,522,955; WO 2020 / 210913). It is an alternative to the deposition method of lithium in a molten state (US 5,169,446; US 3,928,681; EP 0285476).

[0087] Example 1: Assemble an ultrasonic spraying device containing a perforated membrane to implement the method according to the present invention in relation to liquid gallium. The device consists of: a ring-shaped piezoelectric element (lead zirconate titanate or PZT) powered by a high-frequency sinusoidal voltage source (ΔV=108V, f=110kHz); a 50 μm thick stainless steel membrane containing 772 pores ( Figure 2 ); and a reservoir of gallium liquid, which is heated to 50°C. The apparatus is installed in a fume hood in ambient air (20°C). The piezoelectric element causes the perforated stainless steel membrane to vibrate at a frequency corresponding to the frequency of the ultrasound and excites the liquid gallium to spray through a 7μm orifice. The spray of liquid gallium breaks up into fine spherical droplets, forming a liquid aerosol in the air, which solidifies at room temperature on contact with air to form a powder with an average particle size directly proportional to the diameter of the orifice (about 10μm). Figure 3 The obtained gallium powder is shown.

[0088] Example 2: Using Example 1 ( Figure 4 ) ultrasonic spray coating device, but the device was placed in a glove box in a purified argon atmosphere (H 2 O<0.1ppm, O 2 <0.1ppm, and N 2<0.1ppm) (1). The argon temperature in the glove box was maintained at 20°C. Battery-grade lithium was used this time, which was melted at 220°C in a heated reservoir (2) (5). The frame of the reservoir was made of 316L stainless steel, and its temperature was controlled by a heating cylinder and a thermocouple. This system provides liquid lithium to a perforated membrane (4). This ultrasonic device with a perforated membrane controls the temperature of the ultrasonic method at 220°C. Liquid lithium aerosol (6) is generated by ultrasonic vibrations provided by a piezoelectric or sonar probe (3), which rapidly solidifies when in contact with argon at room temperature. The lithium powder is collected on a substrate (7). This test produced spherical particles with diameters between 0.5μm and 25μm, with an average of 7.5μm. EDS analysis showed that the surface did not contain any measurable contamination. Figure 1 The obtained lithium metal powder is shown.

[0089] Example 3: An apparatus using an ultrasonic sonar probe was employed to generate the ultrasonic waves required to spray lithium liquid through a screen to produce lithium powder. Figure 5 A schematic diagram of an assembly with a vibrating screen is presented, which is employed in a glove box under a purified argon atmosphere as in Example 2 (1). The sonar probe (3) used is made of titanium (Ti-6AI-4V) and has a sinusoidal oscillation frequency of 20 kHz. One hundred and fifty grams (150 g) of liquid lithium (5) is heated to 220° C. in a 316L stainless steel cylinder (2). The controller regulates the temperature of the resistive heating element via a thermocouple immersed in the liquid lithium (5). A woven stainless steel screen (4) with a pore size of approximately 25 μm (500 mesh) is used to hold the lithium in the upper half of the assembly. The spray chamber is also designed as 316L stainless steel. A strip (7) is placed at the bottom of the chamber to collect lithium particles / droplets (6). A 0.5 μm 316L stainless steel filter is installed on the spray chamber to minimize the pressure difference with the glove box. The sonar probe (3) is immersed in the liquid lithium and positioned at a short distance (about 3 mm) from the screen (4). The sonar probe (3) can be in contact with the screen (4) or spaced apart. Figure 7 An electron micrograph of spherical lithium particles produced by this test is shown. The particle size distribution presented shows that the diameter of the particles ranged between about 10 μm and 80 μm, with an average of about 42 μm. The following two modes of operation were tested.

[0090] Example 3A: The sonar probe (3) was immersed in lithium liquid and placed at a distance of about 3 mm from the sieve (4). Figure 7 An electron micrograph of the produced spherical lithium particles is shown. The particle size distribution presented shows that the diameter of the particles ranges between 10 μm and 80 μm, with an average of about 42 μm.

[0091] Example 3B: The same apparatus was used. The sonar probe (3) was brought into contact with the sieve (4). A powder similar to that obtained in Example 3A was obtained.

[0092] Example 4: For coating, spraying was carried out on a preheated strip (7). The test conditions were the same as those of Example 3A. The particles were sprayed on a 60 cm 2 The strip is placed on a copper strip (7). The latter is covered by a protective layer of electrolytic nickel (about 0.5 μm thick) and a lithium-philic tin layer (about 40 nm thick). The strip is located at a distance of about 65 mm from the sieve (4). The latter is placed at the bottom of the spray chamber ( Figure 5 ) and has been preheated to 230° C. by a heating element. The resulting lithium powder interacts with the lithiophilic tin layer on the surface to form a lithium layer (7) on the strip.

[0093] Example 5: The possibility of spraying liquid 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, but with the difference that the distance between the vibrating screen (4) and the strip (7) was reduced by about 10 mm. In this way, the droplets dripped directly onto the strip (7) before solidification. Each droplet wetted the surface of the strip (7) thoroughly. Thus, liquid coating (spraying) was performed.

[0094] Example 6: In order to demonstrate the feasibility of promoting the transfer of lithium powder to the next stage of use, spraying was performed directly in a solvent inert to lithium (toluene) to obtain a lithium powder suspension. The test was performed in a glove box under a purified argon atmosphere using the same conditions and equipment as in Example 2, but the difference was that the spray chamber was a 250 mL beaker containing 30 mL of toluene, which had previously been dehydrated with molecular sieves to obtain a water concentration of less than 10 ppm. After stirring, a dispersion of lithium powder in a solvent ( Figure 8 ), the dispersion separates quickly.

[0095] Example 7: Lithium was partially passivated with polyoxyethylene distearate (POE-200) with a molecular weight of 200. This reduced the reactivity of the powder during exposure to the anhydrous chamber and facilitated handling. Lithium particles were placed in POE-200 in toluene (H 2 O<10ppm). It was observed that the presence of POE allowed better dispersion of lithium particles in the solvent and reduced the rate of liquid-solid phase separation. Subsequently, 4 mL of this solution and the original suspension (Example 6) were deposited in an aluminum petri dish and heated in a glove box at 20°C with purified argon (H 2 O<0.1ppm, O 2 <0.1ppm, and N 2<0.1ppm) for 12 hours. The two petri dishes were transferred to an anhydrous space (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. Over time, the petri dishes were weighed to determine their mass gain. The unprotected lithium powder showed a weight gain of more than 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 exposed powder.

[0096] refer to Figure 5 , a schematic representation of an ultrasonic device comprising a perforated vibrating membrane and using a sonar probe to generate ultrasonic vibrations which are transmitted to the membrane through the intermediary of a liquid. The sonar probe (3) is immersed in liquid lithium (or other metal or alloy) (5) contained in a container (2) comprising a perforated membrane (4) when contained in an enclosure (1) having an inert, reactive or partial vacuum atmosphere. The assembly produces an aerosol / droplets / powder (6) which is collected on a substrate (7).

[0097] refer to Figure 6 , schematic representation of an ultrasonic device comprising a perforated diaphragm and using a sonar probe / piezoelectric to generate ultrasonic vibrations which pulverize lithium (or other metals or alloys). Contained in a housing (1) having an inert, reactive or partial vacuum atmosphere, the end of the sonar probe (3) is pierced (4) and supplied with liquid lithium (5). The assembly produces an aerosol / droplets / powder (6) which is collected on a substrate (7).

[0098] Even though the present invention is described with reference to preferred embodiments, it should be understood that this description refers not only to preferred embodiments and should not be considered as limiting the scope of the present invention, which includes the various embodiments defined in the following claims. It should be understood that several changes, modifications, uses and adaptations may be added to the described embodiments. The present invention is intended to cover such changes, modifications, uses and adaptations that generally follow the principles of the present invention and include any changes in this specification that would become known or conventional in the field of the present invention and consistent with the scope of the claims below, which may be applied to the above-mentioned elements.

[0099] The scope of the claims should not be limited by the implementations set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.

[0100] This specification refers to several documents. The contents of each of these documents are incorporated into this specification by reference in their entirety.

[0101] References

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Claims

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

2. The method according to claim 1, wherein the metal is a low melting point metal; wherein preferably, the melting point of the metal is lower than about 450°C.

3. The method according to claim 1 or claim 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 below about 450°C; wherein preferably, the metal is lithium or an alloy having a lithium base.

4. The method according to any one of claims 1 to 3, wherein the metal powder produced 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 according to any one of claims 1 to 4, comprising further depositing the produced metal powder directly onto / into a deposition target.

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

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

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

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

10. The method according to claim 9, wherein before the deposition of the layer of lithium metal powder or the layer of an alloy containing lithium, a layer of a lithium-philic agent and / or a layer of a protective agent which prevents undesired reactions between the deposited target and the lithium layer is applied on the surface of the target; wherein preferably, the lithium-philic agent comprises Cu, Zn, Sn, Si, Al, Ag, Sb, Bi, Cr, Fe, Mg or oxides of these metals, or metal fluorides, or combinations of these; wherein preferably, the protective agent is nickel, chromium or cobalt.

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

12. The method according to claim 5, wherein the metal powder is lithium metal powder or powder of a lithium alloy; 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 of these.

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

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

15. A method for preparing metal powder, the method comprising using an ultrasonic spray device, the ultrasonic spray device comprising a perforated membrane, wherein the perforated membrane is in contact with liquid metal, and ultrasonic vibration of the perforated membrane is generated by a sonar probe (sonotrode) or a piezoelectric body immersed in the liquid metal, thereby producing the metal powder, and the metal powder is directly collected on / in a deposition target.

16. A method for preparing a metal powder, the method comprising the following steps: (a) introducing liquid metal into a container, the container being associated with an ultrasonic spray device, wherein the container comprises a perforated membrane, wherein the liquid metal is in contact with the perforated membrane; (b) inducing ultrasonic vibration of the perforated membrane by immersing a sonar probe or a piezoelectric body in the liquid metal, thereby producing the metal powder; and (c) collecting the metal powder on / in a deposition target.

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

18. An ultrasonic spraying device, which is suitable for producing metal powder, comprising: a reservoir, the reservoir is suitable for receiving liquid metal and comprises a perforated membrane; and a sonar probe or a piezoelectric body, the sonar probe or the piezoelectric body is integrated in the reservoir, wherein Upon inducing ultrasonic vibrations of the perforated membrane, the metal powder is generated and collected directly onto / into a deposition target.

19. An ultrasonic spraying device, which is suitable for producing metal powder, comprising: a reservoir, the reservoir is suitable for receiving liquid metal and comprises a perforated membrane; and a sonar probe, the sonar probe is suitable for being immersed in the liquid metal, wherein Upon inducing ultrasonic vibrations of the perforated membrane, the metal powder is generated and collected directly onto / into a deposition target, Optionally, the sonar probe is spaced apart from the perforated membrane, Optionally, the sonar probe is in contact with the perforated membrane.

20. A metal powder obtained by the method according to any one of claims 1 to 17; wherein preferably, the diameter of the powder particles is between about 0.5 μm and 100 μm; wherein preferably, the diameter of the powder particles is between about 1 μm and 50 μm.

21. A liquid mixture comprising lithium metal powder produced by a method according to any one of claims 1 to 17; wherein preferably, the liquid is an aprotic solvent, a non-polar solvent, a hydrocarbon or a mineral oil, or a mixture of these; wherein preferably, 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 lithium metal powder produced by the method according to any one of claims 1 to 17.

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

24. A facility for making other components of an electrode or battery / rechargeable battery, wherein the facility is incorporated into a method according to any one of claims 1 to 17, and wherein the ultrasonic spraying device is fixed or mobile; wherein preferably, the ultrasonic spraying device is connected to another device that moves according to an XYZ system.

25. A facility for the manufacture of a battery / rechargeable battery, wherein the battery / rechargeable battery comprises an electrode or other components of a battery / rechargeable battery, wherein the facility is incorporated into a method according to any one of claims 1 to 17, and wherein the ultrasonic spraying device is fixed or mobile; wherein preferably, the ultrasonic spraying device is connected to another device that moves according to an XYZ system.

26. The plant of claim 24 or claim 25, wherein the deposition target is fixed or mobile; wherein preferably the deposition target is connected to a conveyor system or a roll-to-roll system.

27. A manufacturing site for an electrode or other component of a battery / rechargeable battery incorporating a method according to any one of claims 1 to 17.

28. A manufacturing site for a battery / rechargeable battery comprising an electrode or other component of a battery / rechargeable battery, the manufacturing site incorporating a method according to any one of claims 1 to 17.

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

30. Use of an ultrasonic spraying device for preparing lithium metal powder.

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