A uniaxial length-variable lithium particle and a preparation method thereof

Abstract

The application discloses a single-axis length-variable lithium particle and a preparation method thereof. The shape of the lithium particle is controllable in the range from a sphere to an ellipsoid, the radius Ra in the a-axis direction of the ellipsoid lithium particle is the same as the radius Rb in the b-axis direction, and the length Lc in the c-axis direction is in the range from 2*Ra to 20*Ra. According to the application, the shape of the lithium particle is controllable and variable, and continuous production can be realized; and on the other hand, the size of the lithium particle is controllable and the process is simple.

Description

Technical Field

[0001] This invention belongs to the field of lithium metal processing, and particularly relates to a lithium particle with variable uniaxial length and its preparation method. Background Technology

[0002] Lithium metal, as an energy material, has always attracted great attention. Currently, due to limitations in processing technology, the most widely used form of lithium metal in the new energy industry is mainly in the form of lithium strip. Driven by requirements for research diversity and ease of use, new demands have been placed on the form of lithium metal, such as the preparation of lithium particles with smaller particle sizes. FMC has successfully prepared lithium metal particles using a solution method, but the resulting particles have a relatively large diameter (D50) of approximately 45 micrometers, and exhibit a wide range of size variation. The lithium powder particle size distribution follows a normal distribution, with the difference between the largest and smallest particles reaching 100 micrometers. Further preparation of smaller lithium metal particles with a smaller size variation range is extremely difficult.

[0003] As can be seen from the above, it is indeed necessary to provide a method for preparing lithium metal particles with controllable size and morphology. Summary of the Invention

[0004] This invention provides a lithium particle with variable uniaxial length and its preparation method. The process is simple, the shape of the prepared lithium metal particles is controllable and variable, the size of the lithium metal particles is controllable, and continuous production can be achieved.

[0005] The principle of this invention is to use an inert gas flow to divide molten lithium metal particles of the desired shape and size by controlling the flow rate of molten lithium and the pressure and flow rate of inert gas in a Y-shaped mold.

[0006] To achieve the objective of this invention, according to one aspect of the invention, a lithium particle with uniaxial variable length is provided. The shape of the lithium particle is controllable within the range of spherical to elongated spherical. The elongated spherical shape refers to the shape formed by extending a spherical particle in one direction. The three directions in the orthogonal coordinate system are divided into the a-axis direction, the b-axis direction, and the c-axis direction. Then, the radius Ra of the elongated spherical lithium particle in the a-axis direction is the same as the radius Rb in the b-axis direction, and the length Lc in the c-axis direction is in the range of 2×Ra to 20×Ra (the equivalent spherical radius Rc is in the range of Ra to 10×Ra).

[0007] In some implementations, Lc is a value in the range of 2Ra to 20×Ra, such as 2Ra (which is approximately spherical), 3Ra, 4Ra, 5Ra, 10Ra, 15Ra, or 20Ra.

[0008] In some embodiments, the lithium particles are metallic lithium or an alloy of lithium with at least one selected from the following: Ag, Al, Au, Ba, Be, Bi, B, C, Ca, Cd, Co, Cr, Cs, Fe, Ga, Ge, Hf, Hg, In, Ir, K, Mg, Mn, Mo, N, Na, Nb, Ni, Pt, Pu, Rb, Rh, S, Se, Si, Sn, Sr, Ta, Te, Ti, V, Y, Zn, Zr, Pb, Pd, Sb, and Cu.

[0009] In some implementations, Ra or R is in the range of 1 micrometer to 10 micrometers, Lc is in the range of 2 micrometers to 200 micrometers, or Rc is in the range of 1 micrometer to 100 micrometers.

[0010] According to another aspect of the present invention, a method for preparing lithium particles with variable uniaxial length is provided, comprising the following steps:

[0011] Step 1: In an inert atmosphere, molten lithium is introduced into one branch of a Y-shaped mold;

[0012] Step two: Inert gas or a high-temperature resistant solution is introduced from another branch of the Y-shaped mold to separate the molten lithium;

[0013] Step 3: Cool the molten lithium after it has been divided to obtain lithium particles.

[0014] In some implementations, the feed rate of molten lithium and the pressure and flow rate of the inert gas or high-temperature resistant solution are adjusted to control the Lc(Rc) of the lithium particles.

[0015] In some embodiments, the molten lithium feed rate ranges from 10 μL / h to 50 mL / h, preferably from 0.1 mL / h to 10 mL / h, and more preferably from 1 mL / h to 5 mL / h.

[0016] In some embodiments, the pressure range of the inert gas or high-temperature resistant solution is 0.1 MPa to 0.5 MPa, where the pressure is relative to the inert atmosphere.

[0017] In some embodiments, the flow rate of the inert gas or high-temperature resistant solution ranges from 10 μL / h to 1 L / h, preferably from 0.1 mL / h to 100 mL / h, and more preferably from 1 mL / h to 10 mL / h.

[0018] In some embodiments, the inert atmosphere and inert gas may be selected from argon, helium, and neon; the inert atmosphere and inert gas may be the same or different gases.

[0019] In some embodiments, the high-temperature resistant solution includes a solvent phase, a solute, and optionally an ionic surfactant.

[0020] In some embodiments, the solvent phase includes liquid paraffin; the solute includes octadecyl phosphate, oleic acid, etc.; the ionic surfactant includes R-OSO3Na, R-OPO3Na, ammonium salt surfactants, etc., where R is an aliphatic or aromatic hydrocarbon group.

[0021] In some embodiments, the mass fraction ratio of solvent phase, solute and ionic surfactant in the high-temperature resistant solution is (85%-95%):(5%-15%):(0-5%).

[0022] In some embodiments, the channel diameter of the Y-shaped mold is in the range of 2 micrometers to 20 micrometers.

[0023] In some embodiments, the Y-shaped mold includes, in sequence, a heat preservation unit, a cooling unit, and an outlet unit.

[0024] In some embodiments, the insulation temperature range of the insulation unit is 180°C to 500°C.

[0025] In some embodiments, the tiered cooling unit includes at least two tiers: a 180°C temperature zone and a normal temperature zone.

[0026] In some embodiments, the Y-shaped mold is made of one of the following materials: stainless steel, copper, high-temperature resistant plastics (including polyimide, polyaryletherketone, etc.), or ceramic materials.

[0027] In some implementations, the method employs multiple sets of Y-shaped molds connected in parallel.

[0028] The technical advantages of this invention are mainly reflected in the following aspects:

[0029] 1. The process is simple and can produce small-sized lithium particles, such as lithium particles with a diameter of 10 micrometers or less than 5 micrometers.

[0030] 2. The shape of the prepared lithium particles is controllable and variable.

[0031] 3. The size of the prepared lithium particles is controllable, and the size variation can be controlled within ±5 micrometers.

[0032] 4. This method can achieve continuous production. Attached Figure Description

[0033] Figure 1 A schematic diagram of elongated spherical lithium particles;

[0034] Figure 2 This is a schematic diagram of a Y-shaped mold;

[0035] Figure 3 A schematic diagram of a continuous flow of molten lithium to produce lithium metal rope;

[0036] Figure 4 This is a schematic diagram of molten lithium being broken down into individual particles.

[0037] Figure 5 Electron micrograph of the spherical lithium metal particles prepared in Example 2.

[0038] Figure 6 Electron micrograph of the spherical lithium metal particles prepared in Example 4. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0040] In order to overcome the limitations of lithium particle production and processing and achieve continuous production with controllable lithium particle shape and size, the inventors have conducted in-depth and extensive research and have pioneered a new method for preparing lithium particles with variable uniaxial length.

[0041] Figure 1 This is a schematic side view of the elongated spherical lithium particle prepared according to the present invention. The c-axis is the major axis of the elongated sphere, and the a-axis and b-axis are the minor axes. The radius Ra along the a-axis of the elongated spherical lithium particle is approximately the same as the radius Rb along the b-axis, while the length Lc along the c-axis can range from 2Ra to 20 × Ra (the equivalent sphere radius Rc ranges from Ra to 10 × Ra).

[0042] To achieve the above objectives, this invention uses a Y-shaped mold. Figure 2This is a schematic diagram of a Y-shaped mold. The Y-shaped mold includes a handle and two forked sections, wherein the handle is horizontally positioned, and the two forked sections can be horizontally positioned or vertically positioned (i.e., in the direction of gravity). The handle and forked sections each have channels that communicate with each other. The two channels of the forked sections are used to introduce molten lithium and an inert gas, respectively. The handle channel and the forked section channel can be substantially the same size, with a channel diameter ranging from 1 micrometer to 100 micrometers, preferably from 5 micrometers to 50 micrometers. The end of the handle opposite to the forked section can be flared to facilitate material discharge from the mold. In some embodiments, the two forked sections can have different channel sizes; one forked section may have a channel the same size as the handle channel for introducing molten lithium, while the other forked section may have a different channel (smaller or larger diameter) for introducing an inert gas or a high-temperature resistant solution.

[0043] like Figure 2 As shown, the Y-shaped mold includes: a molten lithium inlet 1 corresponding to the two bifurcated sections and an inert gas or high-temperature resistant solution inlet 2; a lithium particle forming area 3 located at the handle; and a lithium particle outlet 4 located at the end of the handle opposite to the bifurcated sections. In some embodiments, the Y-shaped mold can also be divided into a mold insulation unit, a stepped cooling unit, and a material outlet unit. The mold insulation unit is used to maintain the temperature at the same level as the feed temperature and includes the first half of the bifurcated section and the lithium particle forming area. In this area, the process of dividing molten lithium into small droplets by pressurized inert gas or high-temperature resistant solution is mainly carried out. The stepped cooling unit is used to gradually cool the divided droplets to room temperature. This area includes the second half of the lithium particle forming area. The material outlet unit is mainly for facilitating the discharge and collection of lithium particles. This area is the lithium particle outlet 4.

[0044] The method for preparing lithium particles according to the present invention may include the following steps: Molten lithium enters through inlet 1, and inert gas or a high-temperature resistant solution enters through inlet 2. After the molten lithium and the inert gas or high-temperature resistant solution meet, the molten lithium is separated by the inert gas or high-temperature resistant solution. The separated molten lithium enters the lithium particle forming zone 3, where it undergoes a stepped cooling process to obtain lithium particles. The lithium particles pass through the lithium metal particle forming zone 3 and are collected from the lithium metal particle outlet 4. The entire process is carried out under an inert atmosphere. Note: The pressure of the inert gas input through inlet 2 is higher than the pressure of the inert atmosphere. In this document, the pressure of the inert gas refers to the pressure relative to the inert atmosphere, typically in the range of 0.1 MPa to 0.5 MPa.

[0045] The shape and size of lithium particles are controlled by adjusting the flow rate of molten lithium and the flow rate and pressure of the inert gas or high-temperature resistant solution. When the flow rate or pressure of the inert gas or high-temperature resistant solution is low, the molten lithium will not be broken into single particles but will remain continuous, ultimately resulting in a lithium metal rope, such as... Figure 3As shown. When the flow rate of the inert gas or the high-temperature resistant solution is increased, or the pressure of the inert gas or the high-temperature resistant solution is increased, the molten lithium is broken into single particles, such as... Figure 4 As shown. By controlling the flow rate of molten lithium and the flow rate and pressure of inert gas or high-temperature resistant solution, lithium particles of various shapes can be obtained, including spherical, elongated, and rod-shaped particles. The size of the lithium particles can also be controlled by the channel diameter of the lithium metal forming zone.

[0046] The present invention will be illustrated below with reference to specific embodiments.

[0047] Example 1

[0048] A Y-shaped mold was made of stainless steel, with a Y-shaped channel diameter of 25 micrometers. Molten lithium and inert gas were introduced into the prepared Y-shaped mold under an inert atmosphere. The flow rate of molten lithium was controlled at 40 microliters / hour, the flow rate of inert gas was controlled at 20 microliters / hour, and the inert gas pressure was controlled at 0.1 MPa. At this time, the metallic lithium formed a continuous line, and single particles of metallic lithium could not be obtained.

[0049] Example 2

[0050] Other conditions were the same as in Example 1, except that the flow rate of molten lithium was changed to 10 μL / h, resulting in monodisperse lithium metal particles, such as... Figure 5 As shown.

[0051] Example 3

[0052] Other conditions were the same as in Example 1, except that the flow rate of the inert gas was changed to 60 μL / h, resulting in monodisperse lithium metal particles with the same particle shape as in Example 2.

[0053] Example 4

[0054] Other conditions were the same as in Example 1, except that the flow rate of the inert gas was changed to 40 μL / h, resulting in monodisperse lithium metal particles with an elongated spherical shape. Figure 6 As shown.

[0055] Example 5

[0056] The other conditions were the same as in Example 1, except that the inert gas was changed to liquid paraffin containing octadecyl phosphate and quaternary ammonium salt surfactants, wherein the mass fraction of octadecyl phosphate and quaternary ammonium salt surfactants was 2.5%, resulting in monodisperse lithium metal particles.

[0057] While specific embodiments of the present invention have been described in detail, they are not intended to limit the invention. Any modifications, substitutions, and improvements made to those details within the spirit and principles of the invention should be included within the scope of protection of the invention. The full scope of the invention is given by the appended claims and any equivalents.

Claims

1. A method for preparing elongated spherical lithium particles with variable uniaxial length, characterized in that... The method includes the following steps: Step 1: Provide a Y-shaped mold. The channel diameter of the Y-shaped mold is in the range of 2 micrometers to 20 micrometers. The Y-shaped mold includes two forked parts and a handle. The handle is placed horizontally. The Y-shaped mold includes a heat preservation unit, a cooling unit and an outlet unit in sequence. Molten lithium is introduced into one of the forked parts of the Y-shaped mold in an inert atmosphere. Step two: Inert gas or a high-temperature resistant solution is introduced from another branch of the Y-shaped mold to separate the molten lithium; Step 3: Cool the molten lithium after segmentation to obtain lithium particles. By adjusting the feed rate of molten lithium and the pressure and flow rate of inert gas or high-temperature resistant solution, the Lc of lithium particles is controlled to obtain elongated spherical lithium particles with variable uniaxial length. The elongated spherical shape refers to the shape formed by extending the spherical particle in one direction. The three directions in the orthogonal coordinate system are divided into the a-axis direction, the b-axis direction, and the c-axis direction. The radius Ra of the elongated spherical lithium particle in the a-axis direction is the same as the radius Rb in the b-axis direction. The length Lc in the c-axis direction is in the range of 2×Ra to 20×Ra, where Ra or Rb ranges from 1 micrometer to 10 micrometers; the length Lc ranges from 2 micrometers to 200 micrometers, and the size variation of the lithium particle is within ±5 micrometers.

2. The method according to claim 1, characterized in that... The lithium particles are metallic lithium or an alloy of lithium with at least one of the following: Ag, Al, Au, Ba, Be, Bi, B, C, Ca, Cd, Co, Cr, Cs, Fe, Ga, Ge, Hf, Hg, In, Ir, K, Mg, Mn, Mo, N, Na, Nb, Ni, Pt, Pu, Rb, Rh, S, Se, Si, Sn, Sr, Ta, Te, Ti, V, Y, Zn, Zr, Pb, Pd, Sb, and Cu.

3. The method according to claim 1, characterized in that... The feed rate of the molten lithium ranges from 10 μL / h to 50 mL / h; The pressure range of the inert gas or high-temperature resistant solution is 0.1 MPa to 0.5 MPa; The flow rate of the inert gas or high-temperature resistant solution ranges from 10 μL / hour to 1 L / hour.

4. The method according to claim 1, characterized in that... The method employs multiple sets of Y-shaped molds connected in parallel.

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