Lithium metal powder, preparation method thereof and lithium ion battery

Abstract

The invention relates to lithium metal powder and a preparation method thereof and a lithium ion battery, and the preparation method comprises the following steps: in an inert atmosphere, carrying out crushing treatment on a lithium foil, or mixing the lithium foil and functional powder and then carrying out crushing treatment to obtain crushed powder, and carrying out annealing treatment on the crushed powder to obtain the lithium metal powder, the functional powder includes a non-lithium powder. The preparation of the lithium metal powder can be realized by adopting a simple crushing method under the conditions of normal temperature and no solvent, especially no organic solvent, the obtained lithium metal powder is spherical powder with uniform morphology and high sphericity degree, and non-lithium powder can be added as functional powder in the crushing process, so that the lithium metal powder can be used as functional powder. Compact coating of the surface is also realized during crushing, and the surface-functionalized lithium metal powder obtained after coating of different functional powder has different characteristics and is convenient to use in different scenes.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and particularly to a lithium metal powder, a preparation method thereof, and a lithium-ion battery. Background Art

[0002] At present, vigorously developing new energy devices such as lithium-ion batteries is one of the directions to achieve low carbon, and the development of new energy devices has also greatly promoted the progress of lithium-ion battery technology. However, in the lithium-ion battery system, a solid electrolyte interphase (SEI) film will be formed on the surface of the negative electrode during the first charging process of the battery, which will lead to a part of irreversible capacity loss in the battery, resulting in a decrease in the energy density of the battery. The pre-lithiation technology can well make up for this part of irreversible capacity loss, thereby improving the energy density of the lithium-ion battery.

[0003] Lithium metal powder is a relatively good lithium supplement in the pre-lithiation technology. As the energy density of lithium-ion batteries gradually approaches its theoretical capacity, in order to meet the use of more devices, it is urgent to develop lithium metal batteries with higher energy density. However, the commercial lithium foil used in lithium metal batteries is relatively thick (thickness > 20 μm) at present, which makes the amount of lithium metal greatly excessive, increases the weight and volume of the lithium metal battery, thus reducing the specific energy and volumetric energy density of the battery. In addition, too much lithium metal may also lead to the growth of lithium dendrites, causing safety problems, and at the same time reducing the Coulombic efficiency and shortening the cycle life of the battery.

[0004] To effectively control the thickness of the lithium metal negative electrode, lithium metal powder is usually used for slurry coating to prepare the lithium metal negative electrode, so as to improve the energy density of the lithium metal battery. At present, there are generally two drawbacks in the conventional lithium metal powder preparation technology. One is that the preparation process is cumbersome and often requires reaction in organic solvents. The other is that it needs to be carried out under high-temperature conditions, heated above the melting point of metallic lithium, and the preparation risk will increase at high temperatures.

[0005] CN117673292A discloses a preparation method of lithium metal powder. By mixing a lithium metal material and an oscillating solution (a metal salt and a solvent of ethers, carbonates or a combination of the two), a mixed solution is formed; then the mixed solution is ultrasonically oscillated to react to form lithium metal powder, and the lithium metal powder is also coated with a protective layer. It realizes the preparation of lithium metal powder by means of ultrasonic oscillation. It can be seen that it adopts a preparation method in organic solvents, the process is relatively cumbersome, and it will inevitably cause harm to the environment.

[0006] CN106299240A discloses a method for preparing stabilized lithium metal powder, wherein lithium metal is added to molten asphalt and stirred, so that lithium metal and lithium ion good conductor are wrapped in the molten low-temperature solid asphalt, and then heated to 2500℃-3500℃ to graphitize the asphalt to obtain stabilized lithium metal powder. The whole method is simple and easy to implement, with high yield and low cost. However, 2500℃-3500℃ is a relatively high temperature, which will cause the metal lithium to melt, increase the danger of the whole process, and significantly increase energy consumption.

[0007] CN1868639A discloses a nano-sized lithium metal powder and a preparation method thereof, wherein lithium flakes react with naphthalene in an organic solvent to generate a metal organic intermediate, which is then pyrolyzed in vacuum at 40-150°C to obtain a nano-sized lithium metal powder. Due to the high activity of lithium metal, it also needs to react in an organic solvent, and also needs to be pyrolyzed by chemical reaction with naphthalene, which makes the entire preparation process more complicated, greatly reduces the preparation efficiency, and is not conducive to batch preparation.

[0008] Therefore, how to provide a simple, efficient and large-scale preparation process for spherical lithium metal powder, which can be carried out at room temperature and under solvent-free conditions, has become a problem that needs to be solved urgently. Summary of the invention

[0009] In order to solve the above technical problems, the present invention provides a lithium metal powder and a preparation method thereof and a lithium ion battery. The present invention adopts a simple crushing method, and can realize the preparation of lithium metal powder at room temperature and without solvent, especially without organic solvent. The obtained lithium metal powder is a spherical powder with uniform morphology and high sphericity. In addition, non-lithium powder can be added as functional powder during the crushing process. During the crushing process, dense coating of the surface is also achieved. The surface functionalized lithium metal powder obtained after coating with different functional powders has different characteristics, which is convenient for use in different scenarios.

[0010] To achieve this object, the present invention adopts the following technical solutions:

[0011] In a first aspect, the present invention provides a method for preparing lithium metal powder, the preparation method comprising the following steps:

[0012] Under an inert atmosphere, the lithium foil is crushed, or the lithium foil and the functional powder are mixed and crushed to obtain crushed powder, and the crushed powder is annealed to obtain lithium metal powder;

[0013] The functional powder includes non-lithium powder.

[0014] The method for preparing lithium metal powder adopted in the present invention is simple. By means of crushing, under the shear stress of a high-speed rotating blade group, the lithium foil is cut and torn through the edge of the blade, realizing the preliminary deconstruction of the lithium foil from a sheet to irregular fragments. The circumferentially uniformly distributed impact force forces the particles to reconstruct along the path of the minimum surface energy, resulting in a relatively high sphericity of the obtained powder, with the sphericity ≥ 0.92. In addition, large-scale preparation can be achieved, and no organic solvent is required during the whole process, nor is it necessary to carry out the process at high temperature, avoiding the danger brought by the over-activity of lithium metal at high temperature. The preparation of lithium metal powder can be realized only through a simple crushing method. Among them, the raw material can also include non-lithium powder as a functional powder. When no functional powder is added, the lithium foil can be directly crushed to obtain pure lithium metal powder; when a functional powder is added, dense coating on the surface is also realized while crushing the lithium foil. The surface-functionalized lithium metal powders obtained after coating with different functional powders have different characteristics, which is convenient for use in different scenarios.

[0015] It should be noted that the crushing treatment of the present invention is carried out in a shear crusher, and no specific requirements or special limitations are imposed on the specific crusher equipment used for the crushing treatment, as long as it is based on the same principle of shear crushing as the present invention. Those skilled in the art can make an adaptive selection according to the actual situation.

[0016] As a preferred technical solution of the present invention, the lithium metal powder includes pure lithium metal powder or surface-functionalized lithium metal powder.

[0017] Preferably, the functional powder includes any one or a combination of at least two of metal elementary powder, metal compound powder, non-metal compound powder, inorganic non-metal elementary powder or polymer material powder.

[0018] It should be noted that the present invention does not make specific requirements or special limitations on the specific types of the metal elementary powder, metal compound powder, non-metal compound powder, inorganic non-metal elementary powder and polymer material powder. Those skilled in the art can make an adaptive selection and adjustment according to the actual situation. For example, the metal elementary powder can be Ag powder, Mg powder or Zn powder, etc.; the metal compound powder can be LiF powder, MgO powder or ZnS powder, etc.; the non-metal compound powder can be BN powder, C3N4 powder or SiO2 powder, etc.; the inorganic non-metal elementary powder can be carbon powder, sulfur powder, boron powder or silicon powder, etc., among which the carbon powder can be Super P and / or CNT, etc.; the polymer material powder can be PEO (polyethylene oxide) powder, PEGMA (polyethylene glycol monomethyl acrylate) powder, PBO (poly(p-phenylene terephthalamide)) powder or PP (polypropylene) powder, etc.

[0019] In the present invention, using toner as the functional powder can achieve the dispersion of current density and the increase of conductivity during use; using sulfur powder, non-metal compound powder, metal elemental powder, and metal compound powder as the functional powder can improve the ionic conductivity, chemical stability, and mechanical properties of the solid electrolyte interface film for the negative electrode, thereby improving the electrochemical performance of the battery; using polymer material powder as the functional powder can isolate air and prevent pure lithium metal powder from being corroded, etc.

[0020] Preferably, the particle size of the functional powder is 1 nm - 400 μm, such as 1 nm, 10 nm, 50 nm, 100 nm, 500 nm, 1 μm, 10 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, or 400 μm, etc.

[0021] In the present invention, by controlling the particle size of the functional powder to be 1 nm - 400 μm, it is suitable for use in most cases and can improve the electrochemical performance of the corresponding battery.

[0022] Preferably, the addition amount of the functional powder is 1 wt% - 20 wt% of the mass of the lithium foil, such as 1 wt%, 3 wt%, 5 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%, or 20 wt%, etc.

[0023] Preferably, the thickness of the lithium foil is 5 μm - 200 μm, such as 5 μm, 30 μm, 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm, or 200 μm, etc.

[0024] It should be noted that the present invention uses lithium foil, rather than lithium metal in the form of a massive block that is not easy to break; the present invention does not make specific requirements and special limitations on the length and width of the lithium foil, and those skilled in the art can make adaptive selections and adjustments according to the actual situation.

[0025] As a preferred technical solution of the present invention, the crushing speed of the crushing treatment is 2000 rpm - 30000 rpm, such as 2000 rpm, 5000 rpm, 8000 rpm, 10000 rpm, 12000 rpm, 15000 rpm, 18000 rpm, 20000 rpm, 22000 rpm, 25000 rpm, 28000 rpm, or 30000 rpm.

[0026] Preferably, the crushing time for the crushing treatment is 30 s - 10800 s, such as 30 s, 50 s, 80 s, 100 s, 150 s, 200 s, 500 s, 800 s, 1000 s, 3000 s, 5000 s, 8000 s, 10000 s, or 10800 s, etc.

[0027] Preferably, the gas used for the inert atmosphere includes argon.

[0028] In the present invention, by regulating the crushing speed and time of the crushing treatment, lithium metal powders with different particle sizes can be obtained. Meanwhile, if functional powders are added, the coating effect can be better, and the coating uniformity can be improved, thereby meeting the usage requirements in different scenarios.

[0029] As a preferred technical solution of the present invention, the temperature for the annealing treatment is 150 °C - 175 °C, such as 150 °C, 152 °C, 155 °C, 158 °C, 160 °C, 162 °C, 165 °C, 168 °C, 170 °C, 172 °C, or 175 °C, etc.

[0030] In the present invention, by regulating the temperature of the annealing treatment to 150 °C - 175 °C, stress can be further eliminated, the sphericity of the powder can be improved, the coating uniformity and densification of the functional powder can be enhanced, and metal defects can be reduced. If the annealing temperature is too high, the pure lithium metal powder will completely melt; if the annealing temperature is too low, no improvement effect will be achieved, and the sphericity cannot be further improved and the coating density cannot be increased.

[0031] Preferably, the time for the annealing treatment is 1 h - 3 h, such as 1 h, 1.5 h, 2 h, 2.5 h, or 3 h, etc.

[0032] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0033] Under an argon atmosphere, a lithium foil with a thickness of 50 μm - 200 μm and functional powder accounting for 1 wt% - 20 wt% of the mass of the lithium foil are mixed, and then crushed at 2000 rpm - 30000 rpm for 30 s - 10800 s in a crusher to perform the crushing treatment to obtain a crushed powder body. After annealing the crushed powder body at 150 °C - 175 °C for 1 h - 3 h, lithium metal powder is obtained;

[0034] The functional powder includes non-lithium powder.

[0035] In the second aspect, the present invention also provides a lithium metal powder, which is prepared according to the preparation method described in the first aspect.

[0036] As a preferred technical solution of the present invention, the average particle size D50 of the lithium metal powder is 1 μm - 10,000 μm, such as 1 μm, 20 μm, 50 μm, 80 μm, 100 μm, 220 μm, 350 μm, 480 μm, 600 μm, 720 μm, 850 μm, 980 μm, 1000 μm, 5000 μm, 7000 μm or 10,000 μm, etc.

[0037] As a preferred technical solution of the present invention, the lithium metal powder includes pure lithium metal powder or surface-functionalized lithium metal powder.

[0038] Preferably, the surface-functionalized lithium metal powder includes the pure lithium metal powder and a functionalized coating layer coated on the surface of the pure lithium metal powder.

[0039] Preferably, the raw material of the functionalized coating layer includes non-lithium powder.

[0040] Preferably, the non-lithium powder includes any one or a combination of at least two of metal elemental powder, metal compound powder, non-metal compound powder, inorganic non-metal elemental powder or polymer material powder.

[0041] In a third aspect, the present invention also provides a lithium-ion battery, which includes a lithium supplement material, and the lithium supplement material includes the lithium metal powder prepared by the preparation method as described in the first aspect, or the lithium metal powder as described in the second aspect.

[0042] In a fourth aspect, the present invention also provides a lithium-ion battery, which includes a negative electrode material, and the negative electrode material includes the lithium metal powder prepared by the preparation method as described in the first aspect, or the lithium metal powder as described in the second aspect.

[0043] Compared with the prior art, the present invention has at least the following beneficial effects:

[0044] 1) The present invention uses a simple crushing method to prepare lithium metal powder under normal temperature and without organic solvents, and the prepared lithium metal powder has a spherical morphology and a high sphericity.

[0045] 2) In the process of crushing, non-lithium powder can also be added as a functional powder, and dense coating on the surface is achieved while crushing. The surface-functionalized lithium metal powders obtained by coating with different functional powders have different characteristics, which is convenient for use in different scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic diagram of the preparation process of the pure lithium metal powder provided in Example 1 of the present invention.

[0047] Figure 2 It is a schematic diagram of the preparation process of the surface-functionalized lithium metal powder provided in Embodiment 5 of the present invention.

[0048] Figure 3 It is the SEM image of the pure lithium metal powder provided in Embodiment 1 of the present invention.

[0049] Figure 4 It is the SEM image of the surface-functionalized lithium metal powder provided in Embodiment 5 of the present invention.

[0050] Figure 5 It is the distribution map of C element in the surface-functionalized lithium metal powder provided in Embodiment 5 of the present invention.

[0051] Figure 6 It is the SEM image of the surface-functionalized lithium metal powder provided in Embodiment 10 of the present invention.

[0052] Figure 7 It is the distribution map of Ag element in the surface-functionalized lithium metal powder provided in Embodiment 10 of the present invention.

[0053] Figure 8 It is the SEM image of the surface-functionalized lithium metal powder provided in Embodiment 11 of the present invention.

[0054] Figure 9 It is the distribution map of Zn element in the surface-functionalized lithium metal powder provided in Embodiment 11 of the present invention.

[0055] Figure 10 It is the distribution map of O element in the surface-functionalized lithium metal powder provided in Embodiment 11 of the present invention.

[0056] Figure 11 It is the SEM image of the surface-functionalized lithium metal powder provided in Embodiment 12 of the present invention.

[0057] Figure 12 It is the distribution map of Si element in the surface-functionalized lithium metal powder provided in Embodiment 12 of the present invention.

[0058] Figure 13 It is the SEM image of the surface-functionalized lithium metal powder provided in Embodiment 13 of the present invention.

[0059] Figure 14 It is the distribution map of C element in the surface-functionalized lithium metal powder provided in Embodiment 13 of the present invention. Detailed implementation manners

[0060] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and through specific implementation manners. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0061] Unless otherwise specified, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods.

[0062] The shearing crusher used in the specific implementation part of the present invention is from Changzhou Surui Instruments Co., Ltd., and the model is YXA-2000.

[0063] Example 1

[0064] This example provides a method for preparing lithium metal powder. Figure 1 The schematic flow chart of the preparation of the lithium metal powder provided in Example 1 of the present invention is shown. The preparation method includes the following steps:

[0065] Take a 10 cm long and 60 μm thick lithium foil and place it in the crusher. Set the crushing speed to 6000 rpm and the crushing time to 60 s, and start crushing. Then anneal the crushed powder at 170 °C for 2 h. After cooling to room temperature, a pure lithium metal powder with an average particle size D50 of 318 μm is obtained. This preparation process is carried out entirely in a glove box filled with high-purity argon.

[0066] Example 2

[0067] This example provides a method for preparing lithium metal powder. The preparation method includes the following steps:

[0068] Take a 10 cm long and 60 μm thick lithium foil and place it in the crusher. Set the crushing speed to 10000 rpm and the crushing time to 30 s, and start crushing. Then anneal the crushed powder at 170 °C for 2 h. After cooling to room temperature, a pure lithium metal powder with an average particle size D50 of 210 μm is obtained. This preparation process is carried out entirely in a glove box filled with high-purity argon.

[0069] Example 3

[0070] This example provides a method for preparing lithium metal powder. The preparation method includes the following steps:

[0071] Take a 10 cm long and 100 μm thick lithium foil and place it in the crusher. Set the crushing speed to 6000 rpm and the crushing time to 60 s, and start crushing. Then anneal the crushed powder at 170 °C for 2 h. After cooling to room temperature, a pure lithium metal powder with an average particle size D50 of 513 μm is obtained. This preparation process is carried out entirely in a glove box filled with high-purity argon.

[0072] Example 4

[0073] This example provides a method for preparing lithium metal powder. The preparation method includes the following steps:

[0074] A 10 cm long and 100 μm thick lithium foil was placed in a crusher. The crushing rotation speed was set at 10,000 rpm, and the crushing time was 30 s. Crushing was started. Subsequently, the crushed powder was annealed at 170 °C for 2 h. After cooling to room temperature, pure lithium metal powder with an average particle size D50 of 459 μm was obtained. This preparation process was carried out entirely in a glove box filled with high-purity argon gas.

[0075] Example 5

[0076] This example provides a method for preparing lithium metal powder. Figure 2 The schematic diagram of the preparation process of the surface-functionalized lithium metal powder provided in Example 5 of the present invention is shown. The preparation method includes the following steps:

[0077] A 10 cm long and 60 μm thick lithium foil and 10 wt% of Super P (particle size 40 nm) based on the mass of the lithium foil were placed in a crusher. The crushing rotation speed was set at 6,000 rpm, and the crushing time was 60 s. Crushing was started. Subsequently, the crushed powder was annealed at 170 °C for 2 h. After cooling to room temperature, surface-functionalized lithium metal powder with an average particle size D50 of 325 μm was obtained. This preparation process was carried out entirely in a glove box filled with high-purity argon gas.

[0078] Figure 3 The SEM image of the pure lithium metal powder provided in Example 1 of the present invention is shown. Figure 4 The SEM image of the surface-functionalized lithium metal powder provided in Example 5 of the present invention is shown. Figure 5 The C element distribution map of the surface-functionalized lithium metal powder provided in Example 5 of the present invention is shown. It can be seen from the figure that both the pure lithium metal powder and the surface-functionalized lithium metal powder are spherical in morphology and have a high sphericity. When Super P was not added, the average particle size D50 of the pure lithium metal powder was 318 μm, there were no obvious small particles on the surface and no carbon element was detected by EDS. When Super P was added, the powder could still maintain a spherical morphology with a high sphericity. The average particle size D50 of the surface-functionalized lithium metal powder was 325 μm, there were many fine particles on the surface and C element was detected by EDS. Furthermore, it was shown that Super P could be uniformly and densely coated on the surface of the spherical pure lithium metal powder while the lithium foil was being crushed.

[0079] Example 6

[0080] This embodiment provides a method for preparing lithium metal powder. The difference between this preparation method and that of Example 1 is that a 10 cm long and 60 μm thick lithium foil and 20 wt% of Super P (particle size 40 nm) based on the mass of the lithium foil are placed in a crusher to obtain surface-functionalized lithium metal powder with an average particle size D50 of 343 μm. The remaining preparation methods and parameters are the same as those in Example 1.

[0081] Example 7

[0082] This embodiment provides a method for preparing lithium metal powder. The difference between this preparation method and that of Example 1 is that a 10 cm long and 200 μm thick lithium foil and 20 wt% of Super P (particle size 40 nm) based on the mass of the lithium foil are placed in a crusher to obtain surface-functionalized lithium metal powder with an average particle size D50 of 1755 μm. The remaining preparation methods and parameters are the same as those in Example 1.

[0083] Example 8

[0084] This embodiment provides a method for preparing lithium metal powder. The difference between this preparation method and that of Example 1 is that a 10 cm long and 200 μm thick lithium foil and 15 wt% of Super P (particle size 40 nm) based on the mass of the lithium foil are placed in a crusher to obtain surface-functionalized lithium metal powder with an average particle size D50 of 1675 μm. The remaining preparation methods and parameters are the same as those in Example 1.

[0085] Example 9

[0086] This embodiment provides a method for preparing lithium metal powder. The difference between this preparation method and that of Example 1 is that a 10 cm long and 200 μm thick lithium foil and 10 wt% of Super P (particle size about 40 nm) based on the mass of the lithium foil are placed in a crusher to obtain surface-functionalized lithium metal powder with an average particle size D50 of 1605 μm. The remaining preparation methods and parameters are the same as those in Example 1.

[0087] Example 10

[0088] This embodiment provides a method for preparing lithium metal powder. The difference between this preparation method and that of Example 1 is that 10 wt% of Ag powder (particle size 100 nm) based on the mass of the lithium foil is added to the lithium foil and placed in a crusher to obtain surface-functionalized lithium metal powder with an average particle size D50 of 327 μm. The remaining preparation methods and parameters are the same as those in Example 1.

[0089] Figure 6 The SEM image of the surface-functionalized lithium metal powder provided in Example 10 of the present invention is shown. Figure 7Shows the distribution map of Ag element in the surface-functionalized lithium metal powder provided in Example 10 of the present invention. As can be seen from the figure, the powder has a spherical morphology with a high sphericity, and the Ag element is evenly distributed on the surface of the powder.

[0090] Example 11

[0091] This example provides a preparation method of lithium metal powder. The difference between this preparation method and that of Example 1 is that 10 wt% of ZnO powder (particle size 30 nm) based on the mass of the lithium foil is added to the lithium foil in a crusher to obtain a surface-functionalized lithium metal powder with an average particle size D50 of 323 μm, and the remaining preparation methods and parameters are the same as those in Example 1.

[0092] Figure 8 Shows the SEM image of the surface-functionalized lithium metal powder provided in Example 11 of the present invention. Figure 9 Shows the distribution map of Zn element in the surface-functionalized lithium metal powder provided in Example 11 of the present invention. Figure 10 Shows the distribution map of O element in the surface-functionalized lithium metal powder provided in Example 11 of the present invention. As can be seen from the figure, the powder has a spherical morphology with a high sphericity, and the Zn and O elements are evenly distributed on the surface of the powder.

[0093] Example 12

[0094] This example provides a preparation method of lithium metal powder. The difference between this preparation method and that of Example 1 is that 10 wt% of Si powder (particle size 100 nm) based on the mass of the lithium foil is added to the lithium foil in a crusher to obtain a surface-functionalized lithium metal powder with an average particle size D50 of 337 μm, and the remaining preparation methods and parameters are the same as those in Example 1.

[0095] Figure 11 Shows the SEM image of the surface-functionalized lithium metal powder provided in Example 12 of the present invention. Figure 12 Shows the distribution map of Si element in the surface-functionalized lithium metal powder provided in Example 12 of the present invention. As can be seen from the figure, the powder has a spherical morphology with a high sphericity, and the Si element is evenly distributed on the surface of the powder.

[0096] Example 13

[0097] This example provides a preparation method of lithium metal powder. The difference between this preparation method and that of Example 1 is that 10 wt% of PP powder (particle size 6.5 μm) based on the mass of the lithium foil is added to the lithium foil in a crusher to obtain a lithium metal powder with an average particle size D50 of 336 μm, and the remaining preparation methods and parameters are the same as those in Example 1.

[0098] Figure 13The SEM image of the surface-functionalized lithium metal powder provided in Embodiment 13 of the present invention is shown. Figure 14 The distribution map of C element in the surface-functionalized lithium metal powder provided in Embodiment 13 of the present invention is shown. It can be seen from the figure that the powder has a spherical morphology with a high sphericity, and the C element is evenly distributed on the surface of the powder.

[0099] Embodiment 14

[0100] This embodiment provides a preparation method of lithium metal powder. The preparation method includes the following steps:

[0101] Take a 10 cm long and 60 μm thick lithium foil and place it in a crusher. Set the crushing speed to 2000 rpm and the crushing time to 3600 s, and start crushing. Then anneal the crushed powder at 150 °C for 3 h. After cooling to room temperature, pure lithium metal powder with an average particle size D50 of 306 μm is obtained. This preparation process is carried out entirely in a glove box filled with high-purity argon.

[0102] Embodiment 15

[0103] This embodiment provides a preparation method of lithium metal powder. The preparation method includes the following steps:

[0104] Take a 10 cm long and 60 μm thick lithium foil and place it in a crusher. Set the crushing speed to 30000 rpm and the crushing time to 30 s, and start crushing. Then anneal the crushed powder at 175 °C for 1 h. After cooling to room temperature, pure lithium metal powder with an average particle size D50 of 294 μm is obtained. This preparation process is carried out entirely in a glove box filled with high-purity argon.

[0105] Embodiment 16

[0106] This embodiment provides a preparation method of lithium metal powder. The difference between this preparation method and that of Embodiment 5 is that the annealing temperature is 145 °C, and surface-functionalized lithium metal powder with an average particle size D50 of 325 μm is obtained. The rest of the preparation methods and parameters are the same as those in Embodiment 5.

[0107] Comparative Example 1

[0108] This comparative example provides a preparation method of lithium metal powder. The preparation method used is the one disclosed in CN117673292A, and the obtained pure lithium metal powder has an average particle size D50 of 72 μm.

[0109] Application Examples 1-15

[0110] The pure lithium metal powder / surface-functionalized lithium metal powder provided in Examples 1-15 was pressed onto the surface of copper foam with a diameter of 12 mm and a thickness of 300 μm to obtain a negative electrode sheet (the thickness of the pure lithium metal powder / surface-functionalized lithium metal powder layer was 50 μm). Then, using the above negative electrode sheet and a lithium sheet as the counter electrode, a battery was assembled with an electrolyte of 1 M LiTFSI in DOL / DME (1:1 volume ratio) added with 2% LiNO3, corresponding to Application Examples 1-15 respectively.

[0111] The batteries of Application Examples 1-15 were subjected to performance tests, and the test voltage was 0-3V. The specific test results are shown in Table 1.

[0112] Table 1

[0113]

[0114] It can be seen from the test results that:

[0115] (1) It can be seen from Examples 1-15 and Application Examples 1-15 that the present invention adopts a simple crushing method to prepare spherical lithium metal powder under normal temperature and without organic solvents. During the crushing process, non-lithium powder can be added as functional powder, and at the same time of crushing, the surface of the pure lithium metal powder is densely coated, obtaining spherical surface-functionalized lithium metal powder, and the lithium metal powder coated with different functional powders has different characteristics, which is convenient for use in different scenarios. After assembling the obtained pure lithium metal powder and surface-functionalized lithium metal powder into a battery, both have a high specific capacity, and compared with using graphite (theoretical capacity 372 mAh / g), the capacity is nearly 10 times higher.

[0116] (2) It can be seen from Example 16 that by regulating the annealing temperature to 150°C - 175°C, the present invention can further eliminate stress, improve the sphericity of the powder, improve the uniformity and density of the functional powder coating, and reduce metal defects. If the annealing temperature is too high, the pure lithium metal powder will completely melt; if the annealing temperature is too low, it will not play any improvement role and cannot further improve the sphericity and increase the coating density.

[0117] (3) It can be seen from Examples 1-15 and Comparative Example 1 that the crushing method provided by the present invention can, on the basis of realizing the preparation of spherical pure lithium metal powder / surface-functionalized lithium metal powder, also achieve the purpose of high-efficiency and batch preparation, improve the output. If the conventional solvent method, such as the preparation method disclosed in CN117673292A, is used for preparation, the amount prepared each time is less and the time consumed for each preparation is longer, and high-efficiency large-scale production cannot be achieved.

[0118] In summary, the present invention adopts a simple crushing method to prepare lithium metal powder under normal temperature and solvent-free conditions, especially without organic solvents. The obtained lithium metal powder is a spherical powder with uniform morphology and high sphericity. Moreover, non-lithium powder can be added as functional powder during the crushing process, and dense coating on the surface is achieved simultaneously during crushing. The surface-functionalized lithium metal powders obtained by coating with different functional powders have different characteristics, which are convenient for use in different scenarios.

[0119] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A method for preparing lithium metal powder, characterized in that, The preparation method includes the following steps: Under an inert atmosphere, the lithium foil is crushed, or the lithium foil and the functional powder are mixed and then crushed to obtain a crushed powder. After annealing the crushed powder, lithium metal powder is obtained; The functional powder includes non-lithium powder.

2. The preparation method according to claim 1, characterized in that, The lithium metal powder includes pure lithium metal powder or surface-functionalized lithium metal powder; Preferably, the functional powder includes any one or a combination of at least two of elemental metal powder, metal compound powder, non-metal compound powder, inorganic non-metal elemental powder, or polymer material powder; Preferably, the particle size of the functional powder is 1 nm - 400 μm; Preferably, the addition amount of the functional powder is 1 wt% - 20 wt% of the mass of the lithium foil; Preferably, the thickness of the lithium foil is 5 μm - 200 μm.

3. The preparation method according to claim 1 or 2, characterized in that, The crushing speed of the crushing treatment is 2000 rpm - 30000 rpm; Preferably, the crushing time of the crushing treatment is 30 s - 10800 s; Preferably, the gas used for the inert atmosphere includes argon.

4. The preparation method according to any one of claims 1-3, characterized in that, The temperature of the annealing treatment is 150 °C - 175 °C; Preferably, the time of the annealing treatment is 1 h - 3 h.

5. The preparation method according to claim 1, wherein The preparation method includes the following steps: Under an argon atmosphere, a lithium foil with a thickness of 50 μm - 200 μm and 1 wt% - 20 wt% of the functional powder based on the mass of the lithium foil are mixed, and then crushed at 2000 rpm - 30000 rpm for 30 s - 10800 s in a crusher to obtain a crushed powder. After annealing the crushed powder at 150 °C - 175 °C for 1 h - 3 h, lithium metal powder is obtained; The functional powder includes non-lithium powder.

6. A lithium metal powder, characterized in that, The lithium metal powder is prepared by the preparation method according to any one of claims 1 - 5.

7. The lithium metal powder according to claim 6, characterized in that, The average particle size D50 of the lithium metal powder is 1 μm - 10000 μm.

8. The lithium metal powder according to claim 6 or 7, characterized in that, The lithium metal powder includes pure lithium metal powder or surface-functionalized lithium metal powder; Preferably, the surface-functionalized lithium metal powder includes the pure lithium metal powder and a functionalized coating layer coated on the surface of the pure lithium metal powder; Preferably, the raw material of the functionalized coating layer includes non-lithium powder; Preferably, the non-lithium powder includes any one or a combination of at least two of elemental metal powder, metal compound powder, non-metal compound powder, inorganic non-metal elemental powder, or polymer material powder.

9. A lithium-ion battery, characterized in that, The lithium-ion battery includes a lithium supplement material, and the lithium supplement material includes lithium metal powder prepared by the preparation method according to any one of claims 1 - 5, or lithium metal powder according to any one of claims 6 - 9.

10. A lithium-ion battery, characterized in that, The lithium-ion battery includes a negative electrode material, and the negative electrode material includes lithium metal powder prepared by the preparation method according to any one of claims 1 - 5, or lithium metal powder according to any one of claims 6 - 9.

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