Method for preparing a metal powder, and applications

Abstract

The invention provides a method for preparing a metal powder, in which an ultrasonic vibration is induced on a perforated membrane that is in contact with a liquid metal. The metal is a low-melting-point metal or an alloy based on such a metal and which has a low melting point. The resulting metal powder is deposited directly onto / into a deposition target.

Description

PROCESS FOR PREPARING A METAL POWDER, AND APPLICATIONS CROSS REFERENCE TO RELATED REQUESTS

[0001] This application claims the benefit of Canadian patent application CA 3,169,823 filed on August 5, 2022. The contents of that Canadian application are incorporated herein in their entirety by reference. FIELD OF THE INVENTION

[0002] The present invention relates to a method for preparing a metal powder. The metal is in particular a metal with a low melting point (for example < 450°C). The method is in particular an ultrasonic method in which an ultrasonic vibration is induced of a perforated membrane which is in contact with the liquid metal. The method allows the production of the metal powder on site at the time of its use, thus overcoming the need to transport and / or store it. In addition, the method according to the invention allows the spraying of the metal powder directly onto / into the deposition target. CONTEXT OF THE INVENTION

[0003] Metallic lithium powder contributes to improving the performance of lithium batteries. However, its preparation is expensive. In addition, there are numerous safety challenges associated with its handling, transportation, and storage. Lithium metal powder is hydroreactive and pyrophoric.

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

[0005] Livent (formerly FMC) has refined this technique to reduce the particle size of the resulting lithium powder. The refined technique also includes passivation of the lithium surface using various reagents (CO2, fluoride, wax, phosphorus, polymer). Livent has several patents and patent applications in in relation to its technique: 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 called “Stabilized Lithium Metal Powder” (or SLMP) [2,3],

[0006] Companies such as Albemarle (US 2020 / 240020) and TDK (US 2016 / 099467) have also developed similar techniques.

[0007] In various other fields, techniques for atomizing liquids (organic or aqueous solvents) have been developed. For example, the inkjet printing process is a non-contact process in which very small drops of liquid ink are projected by nozzles using electrical current and forming dots. The drop-on-demand (DOD) process is generated each time it is desired. For the piezoelectric process, the ink reservoir is in contact with a piezoelectric crystal that will convert the electrical pulses into mechanical forces. It is the overpressure induced by the piezoelectric element that allows the expulsion of the droplet (US 3,683,212).

[0008] Based on the principle of vibrating sieve, several types of nebulizers have been developed for different applications: humidifiers, aromatherapy, drug dispensers, 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).

[0009] In the field of filtration of dusty gases or physical separation of nanomaterials in order to recover the fine powder produced, some techniques have been developed including: the use of cyclones, cartridge filters, granular filters, bubble columns and electrostatic precipitators [4]. In particular, the latter is composed of a conductive wire connected to a high voltage source, and surrounded by a metal cylinder, the latter serving both as a chimney for the dusty gases and as an electrode. The negative ions attach themselves to the dust particles. The electrostatic force brings them towards the cylinder where they lose their charge and, becoming neutral particles, fall into suitable containers (US 895,729).

[0010] There is a need for efficient and cost-effective lithium metal powder preparation processes. There is a need for lithium metal powder preparation processes that keep powder handling levels as low as possible.

[0011] There is also a need for the production of powdered lithium metal, used as an independent source of lithium during the manufacture of lithium-ion battery electrodes and lithium metal batteries. SUMMARY OF THE INVENTION

[0012] The inventors have designed and implemented a method for preparing a metal powder. The metal is in particular a metal with a low melting point, for example below 450°C. Such metals include lithium, tin, gallium, indium, potassium, sodium, zinc, or an alloy of at least one of these metals with a melting point below 450°C. The method is in particular an ultrasonic method in which an ultrasonic vibration is induced of a perforated membrane which is in contact with the liquid metal. The method allows the production of the metal powder on site at the time of its use, thus avoiding the need to transport and / or store it.

[0013] According to one embodiment, the method of the invention makes it possible to spray the metal powder directly onto / into the deposition target.

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

[0015] According to one embodiment, the method of the invention provides an independent source of metal powder ready for use, for example in the manufacture of cell / battery electrodes (cathodes or anodes) or other cell / battery components when the metal powder is a lithium powder.

[0016] According to one embodiment, the invention provides an ultrasonic spraying device suitable for producing a metal powder. The device comprises: a reservoir adapted to receive a liquid metal and comprises a perforated membrane; and a sonotrode or piezoelectric integrated with the reservoir. When ultrasonic vibration of the perforated membrane is induced, the metal powder is produced and collected directly on / in a deposition target.

[0017] Therefore, in one aspect, the invention relates to: (1). A method of preparing a metal powder, in which an ultrasonic vibration is induced in a perforated membrane which is in contact with a liquid metal. (2). A method according to point (1) above, wherein the metal is a low melting point metal; preferably the metal has a melting point below about 450°C. (3). A method according to point (1) or (2) above, wherein the metal is lithium, tin, gallium, indium, potassium, sodium, zinc, or an alloy of at least one of these having a melting point below about 450°C; preferably the metal is lithium or an alloy based thereon. (4). A method according to any one of (1) to (3) above, wherein the prepared metal powder is in the form of a liquid, solid, or liquid-solid intermediate aerosol, or a combination of these forms. (5). A method according to any one of points (1) to (4) above, further comprising depositing the prepared metal powder directly onto / into a deposition target. (6). Method according to point (5) above, in which the deposition target is an enclosure comprising a liquid, thus creating a suspension of metal powder in the liquid. (7). A method according to point (5) above, wherein the deposition target is the surface of an anode, a cathode, a current collector, or any other battery component. (8). A method according to any one of points (5) to (7) above, wherein the deposition comprises applying a high voltage between an ultrasonic sputtering device comprising the perforated membrane and the deposition target. (9). The method of (5) above, 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 cathode, a current collector, or any other battery component. (10). A method according to point (9) above, wherein a layer of a lithiophilic agent and / or a layer of a protective agent preventing undesirable reactions between the deposition target and the lithium layer is applied to the surface of the target before the deposition of the layer of lithium metal powder or lithium-comprising alloy; preferably the lithiophilic agent comprises Cu, Zn, Sn, Si, Al, Ag, Sb, Bi, Cr, Fe, Mg, or an oxide thereof, or a metal fluoride, or a combination thereof; preferably the protective agent is nickel, chromium, or cobalt. (11). Method according to point (9) or (10) above, in which the deposited 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 of item (5) above, wherein the metal powder is a lithium metal powder or a lithium alloy powder; and the deposition target is a container that contains an electrode active material, an aprotic solvent, a non-polar solvent, a hydrocarbon, a mineral oil, a polymer, or an additive, or a combination thereof. (13). A method according to any one of points (1) to (8) above, further comprising a step of mixing the obtained lithium metal powder in a suitable liquid; preferably the liquid is an aprotic solvent, a non-polar solvent, a hydrocarbon, or a mineral oil, or a mixture thereof. (14). Method according to point (12) or (13) above, in which the liquid mixture containing the metallic lithium powder is used in the manufacture of battery electrodes (cathode or anode) or other battery components. (15). A method of preparing a metal powder, comprising using an ultrasonic spraying device comprising a perforated membrane, wherein the perforated membrane is in contact with a liquid metal and the ultrasonic vibration of the perforated membrane is generated through a sonotrode immersed in the liquid metal or a piezoelectric producing the metal powder which is collected directly on / in a deposition target. (16). A method of preparing a metal powder, comprising the following steps: (a) introducing a liquid metal into a container associated with an ultrasonic spraying device, the container comprising a perforated membrane, the liquid metal being in contact with the perforated membrane; (b) inducing an ultrasonic vibration of the perforated membrane through a sonotrode immersed in the liquid metal or a piezoelectric, producing the metal powder; and (c) the metal powder is collected on / in a deposition target. (17). A method according to any one of points (1) to (16) above, being carried out on the site of manufacture of cell / battery electrodes or other cell / battery components; preferably the method is carried out in an enclosure under an inert atmosphere or under vacuum. (18). An ultrasonic spraying device adapted for producing a metal powder, comprising: a reservoir adapted to receive a liquid metal and comprising a perforated membrane; and a sonotrode or piezoelectric integrated with the reservoir, wherein when ultrasonic vibration of the perforated membrane is induced, the metal powder is produced and collected directly on / in a deposition target. (19). Ultrasonic spraying device adapted for producing a metal powder, comprising: a reservoir adapted to receive a liquid metal and comprising a perforated membrane; and a sonotrode adapted to be immersed in the liquid metal, wherein when ultrasonic vibration of the perforated membrane is induced, the metal powder is produced and collected directly on / in a deposition target, optionally the sonotrode is spaced from the perforated membrane, optionally the sonotrode is in contact with the perforated membrane. (20). Metal powder obtained by the method according to any one of points (1) to (17); preferably the particles of the powder have a diameter between about 0.5 and 100 pm; preferably the particles of the powder have a diameter between about 1 and 50 pm. (21). A liquid mixture comprising a lithium metal powder prepared by the process according to any one of points (1) to (17); preferably the liquid is an aprotic solvent, a non-polar solvent, a hydrocarbon, or a mineral oil, or a mixture thereof; preferably the mixture is a suspension comprising lithium particles. (22). Electrode (cathode or anode) or any other cell / battery component, manufactured using a lithium metal powder prepared by the process according to any one of points (1) to (17). (23). Battery / cell comprising an electrode (cathode or anode) or any other cell / cell component, manufactured using a lithium metal powder prepared by the process according to any one of points (1) to (17). (24). Installation for the manufacture of electrodes or other battery components, incorporating the method according to any one of points (1) to (17) above, and in which the ultrasonic spraying device is fixed or mobile; preferably the ultrasonic spraying device is linked to another device which moves according to the XYZ system. (25). Installation for the manufacture of a battery / cell comprising electrodes or other cell / cell components, incorporating the method according to any one of points (1) to (17) above, and in which the ultrasonic spraying device is fixed or mobile; preferably the ultrasonic spraying device is linked to another device which moves according to the XYZ system. (26). Installation according to point (24) or (25) above, in which the deposit target is fixed or mobile; preferably the deposit target is linked to a conveyor system or a “roll-to-roll” type system. (27). Manufacturing site for electrodes or other battery components, incorporating the process according to any one of points (1) to (17) above. (28). Battery / cell manufacturing site comprising electrodes or other cell / cell components, incorporating the method according to any one of points (1) to (17). (29). Site for manufacturing electrodes or other battery components, comprising the installation according to any one of points (24) to (26). (30). Use of an ultrasonic spraying device for the preparation of a metallic lithium powder.

[0018] Other objects, advantages and functions of the present invention will become more apparent from the following description of possible embodiments, given by way of example only, in relation to the following figures. BRIEF DESCRIPTION OF THE FIGURES

[0019] Figure 1: Spherical lithium powder and its particle size distribution according to the invention (Example 2).

[0020] Figure 2: Perforated stainless steel membrane of the ultrasonic process.

[0021] Figure 3: Spherical gallium powder according to the invention (Example 1).

[0022] Figure 4: Diagram of the assembly used to produce the lithium powder (Example 2).

[0023] Figure 5: Schematic of the vibrating screen assembly used for Examples 3 and 4.

[0024] Figure 6: Schematic of the lithium sputtering process using a perforated sonotrode.

[0025] Figure 7: Spherical lithium powder and its particle size distribution according to the invention (Example 3).

[0026] Figure 8: Presentation of the dispersion of lithium powder in anhydrous toluene. DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0027] Before the present invention is further described, it should be understood that the invention is not limited to the particular embodiments described below, as variations of these embodiments may be made and remain within the scope of the appended claims. It should also be understood that the terminology used is for the purpose of describing particular embodiments and is not intended to be limiting. Instead, the scope of the present invention will be established by the appended claims.

[0028] In order to provide a clear and consistent understanding of the terms used in this specification, a number of definitions are provided below. In addition, unless otherwise indicated, all technical and scientific terms as used herein have the same meaning as commonly understood in the technical field to which the invention relates.

[0029] As used herein, the term "metal powder" refers to a metal in powder form. It may be in the form of a liquid, solid, or liquid-solid intermediate aerosol. For example, the term "lithium metal powder" refers to lithium metal in powder form. The particles constituting the powder may be generally spherical in shape. The particles may have a diameter in the range of about 0.5-100 μm. In the text of this application, the terms "powder" and "aerosol" are used interchangeably. In particular, the terms "lithium metal powder" and "lithium metal aerosol" are used interchangeably.

[0030] As used herein, the following terms are used interchangeably: "pulverizer," "atomizer," "vibrating screen," "nebulizer." Each of these terms refers to an element by which the metal powder is produced. And as indicated above, the metal powder or metal in powder form may also be in the form of a liquid, solid, or liquid-solid intermediate aerosol.

[0031] The inventors have designed and implemented a method for preparing a metal powder. The metal is in particular a metal with a low melting point, for example below 450°C. Such metals include lithium, tin, gallium, indium, potassium, sodium, zinc, or an alloy of at least one of these metals with a melting point below 450°C. The method is in particular an ultrasonic method in which an ultrasonic vibration is induced of a perforated membrane which is in contact with the liquid metal. The method allows the production of the metal powder on site at the time of its use, thus avoiding the need to transport and / or store it. The inventors have also designed and produced an ultrasonic spraying device suitable for the production of a metal powder according to the invention.

[0032] According to one embodiment, the invention relates to a product and a method for atomizing liquid metallic lithium to produce a liquid or solid aerosol in an inert, reactive atmosphere, or under vacuum (Figure 1). The liquid metallic lithium is sprayed, on demand, using an ultrasonic spraying device comprising a perforated membrane and which uses an ultrasonic process to form spherical microdroplets. These have a high electrochemical reactivity since their surface is free of any contaminants (oxides, nitrides, carbonates, etc.).

[0033] According to one embodiment, the invention relates to a method for electrostatic recovery of liquid or solid droplets. The application of a high voltage between the ultrasonic spraying device and a target produces an intense electric field which directs the negatively charged particles (-) towards the positively charged target (+). The method thus makes it possible to recover the fugitive particles and efficiently direct them towards the deposition target. The particles can be captured in an electrostatic precipitator or sprayed directly onto the surface of an electrode during its manufacture.

[0034] According to one embodiment of the invention, the collected lithium powder is transferred into a non-polar liquid solvent in order to form a liquid suspension which can be applied to an electrode during its manufacture.

[0035] According to one embodiment, the invention relates to an "independent" lithium source that can be used in the manufacture of lithium-ion battery electrodes (anode or cathode) or "all-solid" lithium. The lithium particles can be used in an electrode mixture (active material, solvent, polymer, additives), or sprayed directly, or in a suspension on the surface of a solid electrode. According to one aspect of the invention, the electrodes are then thermally activated to allow the diffusion of lithium into the materials. According to another aspect, the electrodes are calendered using rollers which may be heated or non-heated. According to another aspect, a layer of a lithiophilic agent is applied to the surface of the solid electrode before spraying with the lithium metal powder. The lithiophilic agent may comprise Cu, Zn, Sn, Si, Al, Ag, Sb, Bi, Cr, Fe, Mg, or their oxides, or a metal fluoride, or a combination thereof. According to another aspect, depending on the nature of the electrode substrate, a protective layer may be applied to the electrode substrate before the application of the lithiophilic layer in order to prevent unwanted reactions between the electrode substrate and the lithium metal layer.In another aspect, the passivation of the surface of the lithium particles is carried out using a reactive atmosphere (e.g. Ar / CO2), or using a liquid solvent containing a surface modification reagent.

[0036] According to one embodiment, the invention provides an "independent" source of metallic lithium allowing the improvement of the performance of lithium and lithium-ion batteries. The invention allows the manufacture of metallic lithium powder at low cost, and makes it possible to solve several safety problems regarding the storage, handling, and transport of hazardous materials (hydro-reactive and pyrophoric powder) since it is produced on site, on demand. According to one aspect, the metallic lithium powder according to the invention has a smaller particle size compared to that of powders generally produced in the field, and is therefore more attractive for certain applications. In addition, since the metallic lithium powder is incorporated immediately during electrode manufacture, the risks of degradation of electrochemical performance over time are reduced.

[0037] The present invention relates to an ultrasonic process that uses an ultrasonic spraying device comprising a perforated membrane. Indeed, the inventors have discovered that it is possible to produce an aerosol of metallic lithium (solid or liquid) or metallic lithium powder, by using such a device. In the process according to the invention, no compressed gas is necessary to generate and transport the aerosol (vs. "thermal spray" application). The metallic lithium powder produced is fine, light, volatile, and fugitive.

[0038] Several applications of the invention are possible. Some are indicated below.

[0039] In one aspect, the method of the invention can be applied, similarly to metallic lithium, to any low melting point metal, for example a metal having a melting point melting below 450°C. Such metals include, for example, lithium, tin, gallium, indium, potassium, sodium, zinc, or an alloy of at least one of these metals having a melting point below 450°C. According to another aspect, solid or liquid codepositions can be carried out.

[0040] According to one aspect of the invention, the ultrasonic spraying device may be fixed or adapted to an XYZ movement system. The deposition target may be fixed or movable on a conveyor or roll-to-roll system. A "lithium printer" is thus manufactured in a manner similar to the additive manufacturing technique.

[0041] According to one aspect of the invention, the temperature of the substrate and / or its environment can be controlled in order to deposit a solid, liquid, or semi-solid-liquid powder.

[0042] According to one aspect of the invention, the solid powder can be transferred into an aprotic solvent, a hydrocarbon, a mineral oil, or a mixture thereof. Thus, an independent source of lithium metal powder can be produced.

[0043] In one aspect, after deposition of the lithium metal powder in an aprotic solvent, a hydrocarbon, a mineral oil, or a mixture thereof, passivation or surface modification of the lithium powders may be performed.

[0044] In another aspect, an electrode mixture may be formed that may be spread on a current collector used in a lithium-ion battery or a lithium battery.

[0045] According to one aspect of the invention, the product can be used as an independent source of lithium for the pre-lithiation of active materials (graphite, SiO x, Si, Sn, etc.) (see e.g. US 6,706,447; US 2016 / 164073; US 2018 / 261829; US 2019 / 013513). In another aspect, lithium can be sprayed directly onto an electrode or current collector or the powder can be spread suspended in a volatile solvent [5-12],

[0046] According to one aspect of the invention, the product can be used in an electrode mixture and coated onto a current collector (US 2021 / 280909; US 2020 / 083518; US 2020 / 014033).

[0047] According to one aspect of the invention, the product and method can be used to apply lithium to a thin anode (US Appl. No. 16 / 458,074, US Appl. No. 63 / 299,247). According to another aspect, a lithiophilic coating and, if necessary, a protective layer are first applied depending on the nature of the substrate of the thin anode. This improves the quality of the lithium deposit that infiltrates inside it. This technique is faster than the PVD "sputtering" technique or thermal evaporation (EP 285476), does not require a vacuum process, and the temperature is lower (200 vs. 600°C) (US 5,522,955; WO 2020 / 210913). It is a good alternative to the method of deposition of lithium in the molten state (US 5,169,446; US 3,928,681, EP 0285476).

[0048] Example 1: An ultrasonic spraying device comprising a perforated membrane is assembled in order to practice the method according to the invention in relation to liquid gallium. The device is composed of a ring-shaped piezoelectric element (lead zirconate titanate PZT) supplied with a high-frequency sinusoidal voltage source (AV = 108 V, f = 110 kHz), a 50 μm thick stainless steel membrane having 772 openings having a diameter of approximately 7 μm spaced 90 μm apart (Figure 2) and a reservoir of liquid gallium heated to 50°C. The device is installed under a laboratory hood in ambient air (20°C). The piezoelectric element causes the vibration of the perforated stainless steel membrane at a frequency which corresponds to the ultrasonic waves and causes the ejection of liquid gallium through the 7 μm orifices.The liquid gallium jets break into fine spherical droplets, forming a liquid aerosol in the air that solidifies upon contact with air at room temperature to form a powder with an average particle size directly proportional to the diameter of the orifices (approximately 10 pm). Figure 3 shows the resulting gallium powder.

[0049] Example 2: The ultrasonic spraying device of Example 1 (Figure 4) is used, but it is placed in a glove box under a purified argon atmosphere (H2O < 0.1 ppm, O2 < 0.1 ppm and N2 < 0.1 ppm) (1). The temperature of the argon in the glove box is maintained at 20°C. This time, battery-grade lithium is used, which is melted (5) at 220°C in the heated tank (2). The frame of the latter is made of 316 L stainless steel and its temperature is controlled using a heating cartridge and a thermocouple. This system supplies liquid lithium to the perforated membrane (4). This ultrasonic device with a perforated membrane controls the temperature of the ultrasonic process at 220°C. Using the ultrasonic vibration provided by the piezoelectric or sonotrode (3), an aerosol of liquid lithium (6) is produced which solidifies rapidly on contact with argon at room temperature. The lithium powder is collected on the substrate (7).This test produced spherical particles with a diameter between 0.5 and 25 pm with an average of 7.5 pm. EDS analyses show a surface free of any measurable contamination. Figure 1 shows the resulting metallic lithium powder.

[0050] Example 3: A device using an ultrasonic sonotrode was used to generate the ultrasonic wave necessary to spray liquid lithium through a sieve to produce lithium powders. Figure 5 shows a schematic of the vibrating sieve setup which was used in a glove box under a purified argon atmosphere as for Example 2 (1). The sonotrode (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) are heated to 220°C in a 316L stainless steel cylinder (2). A controller regulates the temperature of the resistive heating element using a thermocouple immersed in the liquid lithium (5). A stainless steel woven screen with openings of approximately 25 μm (500 mesh) (4) is used to keep the lithium in the upper part of the assembly. The sputtering chamber is also made of 316 L stainless steel. A strip (7) was placed at the bottom of the chamber to collect the lithium particles / droplets (6). A 0.5 pm 316 L stainless steel filter is installed on the spray chamber to minimize the pressure difference with that of the glove box.The sonotrode (3) is immersed in liquid lithium and is placed at a short distance (about 3 mm) from the sieve (4). The sonotrode (3) can be in contact or spaced from the sieve (4). Figure 7 shows an electron micrograph of the spherical lithium particles that were produced by this test. The particle size distribution presented shows that the particles have a diameter between about 10 and 80 pm with an average of about 42 pm. The two operating modes below were tested. • Example 3A: The sonotrode (3) is immersed in liquid lithium and placed at a distance of about 3 mm from the sieve (4). Figure 7 shows an electron micrograph of the spherical lithium particles that were produced. The particle size distribution presented shows that the particles have a diameter between 10 and 80 pm with an average of about 42 pm. • Example 3B: The same device is used. The sonotrode (3) is in contact with the sieve (4). A powder similar to that obtained in Example 3A is obtained.

[0051] Example 4: In order to carry out a coating, spraying on a preheated strip (7) was carried out. The test conditions are the same as for Example 3A. The particles were projected onto a 60 cm copper strip (7) 2 having a thickness of 5 μm. The latter is covered with a protective layer of electrolytic nickel (approximately 0.5 μm thick) and a lithiophilic layer of tin (approximately 40 nm thick). The strip is located at a distance of approximately 65 mm from the sieve (4). The latter was placed at the bottom of the sputtering chamber (Figure 5) and was preheated to 230°C by a heating element. The lithium powders produced interacted with the lithiophilic layer of tin on the surface to form a lithium layer on the strip (7).

[0052] Example 5: The possibility of carrying out liquid spraying on a strip similar to that used in Example 4 was also tested. By using the assembly and the general conditions of Example 3 and Example 4, except that the distance between the vibrating screen (4) and the strip (7) was reduced to approximately 10 mm. In doing so, the droplets were deposited directly on the strip (7) before they had solidified. Each of the droplets wetted the surface of the strip (7) well. Therefore, a liquid coating (spray type) was produced.

[0053] Example 6: In order to demonstrate the feasibility of facilitating the transfer of lithium powder to the next stage of its use, a spray was directly carried out in a solvent inert to lithium (toluene) in order to obtain a suspension of the lithium powder. The test was carried out in a glove box under a purified argon atmosphere with the same conditions and equipment presented in Example 2; with the difference that the spray chamber was a 250 ml beaker containing 30 ml of toluene previously dehydrated with a molecular sieve in order to obtain a water concentration lower than 10 ppm. Following stirring, we obtain a dispersion of lithium powders in a solvent (Figure 8) which separates quickly.

[0054] Example 7: Partial passivation of lithium with polyoxyethylene distearate with a molecular weight of 200 (POE-200) was carried out. This reduces the reactivity of the powder when exposed in an anhydrous chamber and facilitates handling. The lithium particles were placed in a 1% wt. solution of POE-200 in toluene previously dehydrated with a molecular sieve (H2O < 10 ppm). It was observed that the presence of POE allows the lithium particles to be better dispersed in the solvent and reduces the liquid-solid phase separation rate. Subsequently, 4 ml of this solution as well as the original suspension (Example 6) were placed in aluminum boats and dried at 20°C for 12 hours in a glove box with purified argon (H2O < 0.1 ppm, O2 < 0.1 ppm, and N2 < 0.1 ppm).These two boats were transferred to an anhydrous room (dew point of -47°C) and placed in a controlled atmosphere chamber containing a saturated aqueous solution of KOH which allows to maintain the atmosphere of the assembly at a dew point around -15°C. The boats were weighed over time to determine their mass gain. The unprotected lithium powder shows a weight gain of more than 50% compared to the lithium powder which had the treatment with the POE solution. The mass gain is linked to the formation of lithium hydroxide. The presence of this compound was confirmed using X-ray diffraction (XRD) analysis of the powders after their exposure.

[0055] Referring to Figure 5, a schematic representation of the ultrasonic device comprising a perforated vibrating membrane and using a sonotrode for the generation of ultrasonic vibrations which are transmitted to the membrane through the liquid. Contents in an enclosure with an inert, reactive atmosphere, or under partial vacuum (1), the sonotrode (3) is immersed in liquid lithium (or other metals or alloys) (5) contained in a container (2) comprising a perforated membrane (4). The assembly produces an aerosol / droplets / powders (6) which are collected on a substrate (7).

[0056] Referring to Figure 6, a schematic representation of the ultrasonic device comprising a perforated vibrating membrane and using a sonotrode / piezoelectric to generate the ultrasonic vibration which atomizes the lithium (or other metals or alloys). Contained in an enclosure with an inert, reactive, or partial vacuum atmosphere (1), the end of the sonotrode (3) is pierced (4) and supplied with liquid lithium (5). The arrangement produces an aerosol / droplets / powders (6) which are collected on a substrate (7).

[0057] Although the present invention is described with reference to preferred embodiments, it is understood that the present description refers only to preferred embodiments and should not be considered as limiting the scope of the invention which includes different implementations as defined in the claims below. It is understood that several variations, modifications, uses, and adaptations may be grafted onto said implementations. The present invention is intended to cover such variations, modifications, uses, and adaptations, following in general, the principles of the invention and including any variation of the present description which will become known or conventional in the field of the invention, and which can be applied to the elements mentioned above, in accordance with the scope of the claims below.

[0058] The claims are not to be limited in scope by the embodiments illustrated in the examples, but are to be given the broadest interpretation consistent with the description as a whole.

[0059] This description refers to a number of documents. The contents of each of these documents are incorporated into this description by reference in their entirety. 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® MAX POWDER 100, SLMP®, Livent. 4. Wildi, T. and G. Sybille, Electrotechnics. Fourth edition ed. 2005, p. 257. 5. Wang, Z., et al., Application of Stabilized Lithium Metal Powder (SLMP®) 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 ofLi-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

CLAIMS 1. A process for preparing a metal powder, in which an ultrasonic vibration is induced in a perforated membrane which is in contact with a liquid metal.

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

3. The method of claim 1 or 2, wherein the metal is lithium, tin, gallium, indium, potassium, sodium, zinc, or an alloy of at least one thereof having a melting point below about 450°C; preferably the metal is lithium or an alloy thereof.

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

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

6. Method according to claim 5, in which the deposition target is an enclosure comprising a liquid, thus creating a suspension of metal powder in the liquid.

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

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

9. 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 cathode, a current collector, or any other battery component.

10. The method of claim 9, wherein a layer of a lithiophilic agent and / or a layer of a protective agent preventing undesirable reactions between the deposition target and the lithium layer is applied to the surface of the target before the deposition of the powder layer. of metallic lithium or an alloy comprising lithium; preferably the lithiophilic agent comprises Cu, Zn, Sn, Si, Al, Ag, Sb, Bi, Cr, Fe, Mg, or an oxide thereof, or a metallic fluoride, or a combination thereof; preferably the protective agent is nickel, chromium, or cobalt.

11. A method according to claim 9 or 10, wherein the deposited 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 of claim 5, wherein the metal powder is a lithium metal or lithium alloy powder; and the deposition target is a container that contains an electrode active material, an aprotic solvent, a non-polar solvent, a hydrocarbon, a mineral oil, a polymer, or an additive, or a combination thereof.

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

14. A method according to claim 12 or 13, wherein the liquid mixture containing the metallic lithium powder is used in the manufacture of battery electrodes (cathode or anode) or other battery components.

15. A method of preparing a metal powder, comprising the use of an ultrasonic spraying device comprising a perforated membrane, wherein the perforated membrane is in contact with a liquid metal and the ultrasonic vibration of the perforated membrane is generated through a sonotrode immersed in the liquid metal or a piezoelectric producing the metal powder which is collected directly on / in a deposition target.

16. Process for preparing a metal powder, comprising the following steps: (a) introducing a liquid metal into a container associated with an ultrasonic spraying device, the container comprising a perforated membrane, the liquid metal being in contact with the perforated membrane; (b) inducing an ultrasonic vibration of the perforated membrane through a sonotrode immersed in the liquid metal or a piezoelectric, producing the metal powder; and (c) the metal powder is collected on / in a deposition target.

17. Method according to any one of claims 1 to 16, being carried out on the site of manufacture of cell / battery electrodes or other cell / battery components; preferably the method is carried out in an enclosure under an inert atmosphere or under vacuum.

18. An ultrasonic spraying device adapted for producing a metal powder, comprising: a reservoir adapted to receive a liquid metal and comprising a perforated membrane; and a sonotrode or piezoelectric integrated with the reservoir, wherein when an ultrasonic vibration of the perforated membrane is induced, the metal powder is produced and collected directly on / in a deposition target.

19. Ultrasonic spraying device adapted for producing a metal powder, comprising: a reservoir adapted to receive a liquid metal and comprising a perforated membrane; and a sonotrode adapted to be immersed in the liquid metal, wherein when an ultrasonic vibration of the perforated membrane is induced, the metal powder is produced and collected directly on / in a deposition target, optionally the sonotrode is spaced from the perforated membrane, optionally the sonotrode is in contact with the perforated membrane.

20. Metal powder obtained by the process according to any one of claims 1 to 17; preferably the particles of the powder have a diameter between about 0.5 and 100 pm; preferably the particles of the powder have a diameter between about 1 and 50 pm.

21. A liquid mixture comprising a lithium metal powder prepared by the process according to any one of claims 1 to 17; preferably the liquid is an aprotic solvent, a non-polar solvent, a hydrocarbon, or a mineral oil, or a mixture thereof; preferably the mixture is a suspension comprising lithium particles.

22. Electrode (cathode or anode) or any other cell / battery component, manufactured using a lithium metal powder prepared by the process according to any one of claims 1 to 17.

23. Battery / cell comprising an electrode (cathode or anode) or any other cell / cell component, manufactured using a lithium metal powder prepared by the process according to any one of claims 1 to 17.

24. Installation for the manufacture of electrodes or other battery components, incorporating the method according to any one of claims 1 to 17, and in which the ultrasonic spraying device is fixed or mobile; preferably the ultrasonic spraying device is linked to another device which moves according to the XYZ system.

25. Installation for the manufacture of a battery / cell comprising electrodes or other cell / cell components, incorporating the method according to any one of claims 1 to 17, and in which the ultrasonic spraying device is fixed or mobile; preferably the ultrasonic spraying device is linked to another device which moves according to the XYZ system.

26. Installation according to claim 24 or 25, in which the deposition target is fixed or mobile; preferably the deposition target is linked to a conveyor system or a “roll-to-roll” type system.

27. Site for manufacturing electrodes or other battery components, incorporating the method according to any one of claims 1 to 17.

28. Battery / cell manufacturing site comprising electrodes or other cell / cell components, incorporating the method according to any one of claims 1 to 17.

29. Site for manufacturing electrodes or other battery components, comprising the installation according to any one of claims 24 to 26.

30. Use of an ultrasonic spraying device for the preparation of metallic lithium powder.

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