A method for preparing nano-powder by expanding and crushing

Abstract

The application discloses a kind of nanometer powder's expansion breaking preparation method, S1, dry micron powder is pressed into the sheet of thickness 0.1-0.5cm, as working electrode, in glove box, detachable lithium, sodium ion battery is assembled, electrode is lithium, sodium foil, battery constant current is discharged to cut-off potential.S2, disassemble battery, remove working electrode, it is washed in anhydrous solvent, centrifuged and dried.The application presses micron powder into sheet, assembles detachable lithium, sodium ion battery, electrode material is pre-discharged to cut-off voltage, by the excessive expansion of electrode material in the process of discharging, then put in anhydrous solvent and make it broken into nanometer particles.The method breaks micron particles into nanometer particles by pre-discharge technology, does not introduce extra material, has high purity, the uniformity of particle size obtained is good, can be prepared at normal temperature and pressure, has low requirement to production environment, and step is simple, easy to operate, low cost.

Description

Technical Field

[0001] The invention discloses an expansion and crushing preparation method for nano powders, and relates to the technical field of expansion and crushing preparation. Background Art

[0002] Nanomaterials generally refer to materials whose structural unit sizes range from 1 to 100 nm. When macroscopic objects are subdivided into ultrafine particles (nanoscale), their dimensions approach the wavelength of light. Combined with special surface effects, small size effects, and macroscopic quantum tunneling, their optical, thermal, electrical, magnetic, mechanical, and chemical properties differ significantly from those of bulk solids. Among nanomaterials, nanopowders have the longest development history and the most mature technology, forming the foundation for the production of other nanomaterials. They can be used in high-density magnetic recording materials; wave-absorbing stealth materials; magnetic fluid materials; radiation shielding materials; polishing materials for single-crystal silicon and precision optical devices; thermally conductive substrates and wiring materials for microchips; microelectronic packaging materials; optoelectronic materials; advanced battery electrode materials; solar cell materials; high-efficiency catalysts; high-efficiency combustion aids; sensitive components; high-toughness ceramic materials; human body repair materials; and anti-cancer agents.

[0003] Methods for preparing nanomaterials include hydrothermal, sol-gel, chemical precipitation, mechanical ball milling, and chemical vapor deposition. Materials prepared by the hydrothermal method offer advantages such as high purity, good dispersibility, complete crystal form, and controllable grain size. However, it requires a high temperature and high pressure preparation environment, placing high demands on the production environment and making the preparation method more complex. Products prepared by the sol-gel method have advantages such as good chemical uniformity and high purity. However, the reaction cycle is long, and the calcination process is prone to agglomeration. Chemical precipitation offers advantages such as lower reaction temperature, simple operation, and low cost, but also has disadvantages such as poor product uniformity and prone to agglomeration. Mechanical ball milling offers low cost, simple operation, and the ability to meet industrial mass production requirements, but the finished material has poor consistency and high impurity content. Nanomaterials prepared by the chemical vapor deposition method have controllable particle size and high purity. However, its disadvantages are high production costs and low yields.

[0004] SUMMARY OF THE INVENTION

[0005] The object of the present invention is to provide a method for preparing nanopowders by expansion and crushing.

[0006] In order to achieve the above technical objectives and effects, the invention is implemented through the following technical solutions:

[0007] A method for preparing nanopowders by expansion and crushing, S1, pressing dried micron-sized powder into thin sheets with a thickness of 0.1-0.5 cm as working electrodes, assembling detachable lithium-ion and sodium-ion batteries in a glove box, with lithium and sodium foils as counter electrodes, and discharging the batteries at a constant current to a cutoff potential.

[0008] S2, disassemble the battery, take out the working electrode, put it into anhydrous solvent for washing, centrifugation and drying.

[0009] Further, the micro-sized powder is one of silicon, silicon monoxide, germanium, tin and bismuth.

[0010] Further, the constant current discharge current density is 1-100 mA / g.

[0011] Further, the discharge cut-off potential is 0.01-1 V vs. Li + / Li or vs. Na + / Na.

[0012] Further, the anhydrous solvent is one or several of acetonitrile, formamide, N-methyl pyrrolidone, N,N-dimethylformamide, methyl ethyl carbonate, dimethyl carbonate and ethylene carbonate.

[0013] Beneficial effects:

[0014] The micro-sized powder is pressed into a sheet, and the detachable lithium and sodium ion battery is assembled. The electrode material is pre-discharged to a cut-off voltage. Through the over-expansion of the electrode material during the discharging process, it is then put into an anhydrous solvent to break it into nano-sized particles. The excess electrolyte is washed away, and the nano-powder is obtained after drying. Different micro-sized powders can be pre-discharged to different cut-off voltages by using different current densities, which has universal applicability. The method breaks the micro-sized particles into nano-sized particles through pre-discharge technology, does not introduce excess substances, has high purity, and the particle size uniformity is good. It can be prepared at normal temperature and pressure, has low requirements on the production environment, and the steps are simple, easy to operate and low in cost.

[0015] Of course, implementing any product of the present application does not necessarily require achieving all the advantages described above at the same time. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 SEM image of the original micro-sized silicon monoxide particles of Example 1 of the present application

[0017] Figure 2 SEM image of the nano-sized silicon monoxide after pre-discharge breaking of Example 1 of the present application. DETAILED DESCRIPTION

[0018] In order to more clearly illustrate the technical solutions of the present application, the present application will be described in detail below with reference to the examples.

[0019] Example 1

[0020] (1) Dry micron-sized silicon dioxide was pressed into a 0.1 cm thick sheet and used as the working electrode to assemble a removable lithium-ion battery in a glove box. The counter electrode was lithium foil. The battery was discharged at a constant current density of 10 mA / g to a cutoff potential of 0.01 V.

[0021] (2) Disassemble the cell, remove the working electrode, wash it in N-methylpyrrolidone, and then centrifuge and dry it.

[0022] Example 2

[0023] (1) Dried micron-sized bismuth was pressed into a 0.2 cm thick sheet and used as the working electrode to assemble a removable lithium-ion battery in a glove box. The counter electrode was lithium foil. The battery was discharged at a current density of 20 mA / g to a cutoff potential of 0.1 V.

[0024] (2) Disassemble the cell, remove the working electrode, wash it in N,N-dimethylformamide, and then centrifuge and dry it.

[0025] Example 3

[0026] (1) Dry micron-sized silicon dioxide was pressed into a 0.1 cm thick sheet and used as the working electrode to assemble a detachable sodium ion battery in a glove box. The counter electrode was sodium foil. The battery was discharged at a constant current density of 50 mA / g to a cutoff potential of 0.05 V.

[0027] (2) Disassemble the cell, remove the working electrode, wash it in formamide, and then centrifuge and dry it.

[0028] Example 4

[0029] (1) Dry micron-sized silicon was pressed into a 0.2 cm thick sheet and used as the working electrode to assemble a removable lithium-ion battery in a glove box. The counter electrode was lithium foil. The battery was discharged at a constant current density of 20 mA / g to a cutoff potential of 0.01 V.

[0030] (2) Disassemble the cell, remove the working electrode, wash it in ethyl methyl carbonate, and then centrifuge and dry it.

[0031] Example 5

[0032] (1) Dry micron-sized silicon was pressed into a 0.2 cm thick sheet and used as the working electrode to assemble a detachable sodium-ion battery in a glove box. The counter electrode was sodium foil. The battery was discharged at a constant current density of 30 mA / g to a cutoff potential of 0.1 V.

[0033] (2) Disassemble the cell, remove the working electrode, wash it in N,N-dimethylformamide, and then centrifuge and dry it.

[0034] Example 6

[0035] (1) Dry micron-sized germanium was pressed into a thin sheet with a thickness of 0.3 cm, and used as a working electrode to assemble a detachable lithium-ion battery in a glove box. A lithium foil was used as a counter electrode, and the battery was discharged at a current density of 50 mA / g to a cutoff potential of 0.3 V.

[0036] (2) The battery was disassembled, and the working electrode was removed and washed in ethylene carbonate, then centrifuged and dried.

[0037] Example 7

[0038] (1) Dry micron-sized germanium was pressed into a thin sheet with a thickness of 0.4 cm, and used as a working electrode to assemble a detachable sodium-ion battery in a glove box. A sodium foil was used as a counter electrode, and the battery was discharged at a current density of 50 mA / g to a cutoff potential of 0.1 V.

[0039] (2) The battery was disassembled, and the working electrode was removed and washed in acetonitrile, then centrifuged and dried.

[0040] Example 8

[0041] (1) Dry micron-sized tin was pressed into a thin sheet with a thickness of 0.5 cm, and used as a working electrode to assemble a detachable lithium-ion battery in a glove box. A lithium foil was used as a counter electrode, and the battery was discharged at a current density of 100 mA / g to a cutoff potential of 0.5 V.

[0042] (2) The battery was disassembled, and the working electrode was removed and washed in formamide, then centrifuged and dried.

[0043] Example 9

[0044] (1) Dry micron-sized tin was pressed into a thin sheet with a thickness of 0.2 cm, and used as a working electrode to assemble a detachable sodium-ion battery in a glove box. A sodium foil was used as a counter electrode, and the battery was discharged at a current density of 10 mA / g to a cutoff potential of 1 V.

[0045] (2) The battery was disassembled, and the working electrode was removed and washed in dimethyl carbonate, then centrifuged and dried.

[0046] Example 10

[0047] (1) Dry micron-sized bismuth was pressed into a thin sheet with a thickness of 0.5 cm, and used as a working electrode to assemble a detachable lithium-ion battery in a glove box. A lithium foil was used as a counter electrode, and the battery was discharged at a current density of 10 mA / g to a cutoff potential of 0.01 V.

[0048] The above are only part of the embodiments of the present application and do not limit the present application in any form. Any simple modification, equivalent change and modification made to the above embodiments still belongs to the protection scope of the technical scheme of the present application.

Claims

1. A method for preparing nanopowder by expansion and crushing, characterized in that: The steps include: S1. Press the dried micron-sized powder into a sheet with a thickness of 0.1-0.5 cm as the working electrode. Assemble a detachable lithium-ion battery and a sodium-ion battery in a glove box with lithium and sodium foil as the counter electrode. Discharge the battery at a constant current to the cutoff potential. S2. Disassemble the battery, remove the working electrode, wash it in an anhydrous solvent, centrifuge and dry it; The micron-sized powder is one of silicon, silicon oxide, germanium, tin and bismuth; The constant current discharge current density is 1-100mA / g; The discharge cut-off potential is 0.01-1V vs. Li + / Li or vs. Na + / Na; The anhydrous solvent is one or more of acetonitrile, formamide, N-methylpyrrolidone, N,N-dimethylformamide, ethyl methyl carbonate, dimethyl carbonate, and ethylene carbonate.

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