Bismuth powder is a powder of non-ferrous metals, and its appearance is light gray. It has a wide range of uses and is mainly used to prepare bismuth products, bismuth alloys and bismuth compounds. China's bismuth resources rank first in the world, and there are more than 70 bismuth mines in China, making China the world's leading bismuth leader. As a safe "green metal", bismuth is currently not only used in the pharmaceutical industry, but also widely used in semiconductors, superconductors, flame retardants, pigments, cosmetics and other fields. It is expected to replace toxic elements such as lead, antimony, cadmium and mercury. In addition, bismuth is a metal with the strongest diamagnetism. Under the action of a magnetic field, the resistivity increases and the thermal conductivity decreases. It also has good application prospects in thermoelectricity and superconductivity.
The traditional production methods of
bismuth powder include water mist method, gas atomization method and ball milling method; when the water mist method is atomized and dried in water, bismuth is easily oxidized due to the large surface area of bismuth powder; Under normal circumstances, the contact between bismuth and oxygen is also easy to cause a large amount of oxidation; both methods cause many impurities, irregular shape of bismuth powder, and uneven particle distribution. The ball milling method is: artificially hammer bismuth ingots with stainless steel to bismuth grains of ≤10mm, or quench bismuth with water. Then the bismuth particles enter a vacuum environment, and the ball mill lined with ceramic rubber is pulverized. Although this method is ball milled in a vacuum, with less oxidation and low impurities, it is labor-intensive, time-consuming, low in yield, high in cost, and the particles are as coarse as 120 mesh. affect product quality. Invention patent CN201010147094.7 provides a production method of ultrafine bismuth powder, which is produced by wet chemical process, with large production capacity, short contact time between the whole production process and oxygen, low oxidation rate, less impurities, and the oxygen content of bismuth powder is 0< 0.6, uniform particle distribution; particle size -300 mesh.
Technical scheme of the present invention is as follows:
1) Prepare bismuth chloride solution: get the bismuth chloride stock solution with a density of 1.35-1.4g/cm3, add acidified pure aqueous solution containing 4%-6% hydrochloric acid; the volume ratio of acidified pure aqueous solution and bismuth chloride stock solution is 1:1 -2;
2) Synthesis: add zinc ingots whose surface has been cleaned to the prepared bismuth chloride solution; start the displacement reaction; observe the end point of the reaction, when reaching the end point of the reaction, take out the undissolved zinc ingots and precipitate for 2-4 hours; The observation and judging basis of the described reaction end point is: there is bubble to emerge in the solution that participates in reaction;
3) Separation of
bismuth powder: extract the supernatant of the precipitate in step 2) and reclaim zinc by conventional methods; the remaining precipitated bismuth powder is stirred and washed 5-8 times with an acidified pure aqueous solution containing 4%-6% hydrochloric acid, and then washed with pure Rinse the bismuth powder with water to neutrality; after drying the bismuth powder quickly with a centrifuge, immediately soak the bismuth powder with absolute ethanol, and then dry it;
4) Drying: Send the bismuth powder treated in step 3) to a vacuum dryer at a temperature of 60±1°C for drying to obtain a finished bismuth powder of -300 mesh.
According to the bismuth powder produced by the above process, its advantage is that the purity of the obtained product is as high as 99%; the particle size is ultrafine, up to -300 mesh, and the chemical composition of the bismuth powder prepared by the present invention is measured: Bi>99, Fe< 0.1, O<0.5, BiO<0.1, Cr<0.01, Cu<0.01, Si<0.02, other impurities<0.18; at the same time, due to the zinc ingot replacement process, the chemical reaction only involves zinc dissolution and bismuth precipitation, avoiding a large amount of chemical The disadvantages of gas, reduce the pollution of the environment and the harm to the human body. Compared with the prior art, the whole process of the present invention is only in contact with air for a short time in the centrifuge drying, and other processes have reaction liquid or absolute ethanol, or vacuum and oxygen isolation, so the oxidation rate is low.
application [2]
Existing technologies can prepare low-dimensional nano-bismuth materials with different shapes, bismuth nanowires, bismuth nanotubes, etc., but there is no related preparation technology for bismuth two-dimensional ultra-thin material bismuthene. Part of the reason may be that bismuth precursors or Hydrothermal synthesis conditions are difficult to control. Many hexagonal materials are composed of two-dimensional materials stacked to form a macroscopic crystal structure, and the chemical bonds in the plane of two-dimensional materials are very strong, and the van der Waals interaction between layers is very weak, which makes two-dimensional materials overcome layer by various methods. Two-dimensional nanosheets are obtained by exfoliating from their corresponding bulk materials due to the weak interaction force between them. At this stage, the technology of using alloys with high volume specific capacity and stable circulation as negative electrodes has reached the bottleneck. Liquid phase exfoliation of graphene and black phosphorus have been studied. Although phosphorene has a high capacity, phosphorene is very easy to oxidize in the air. Afraid of oxygen and water.
Invention patent CN201710588276 provides a preparation method of two-dimensional bismuthene and a lithium-ion battery. Bismuth powder is added to the stripping solvent and ultrasonically vibrated for a predetermined time to obtain a mixed solvent, and the unstripped bismuth powder in the mixed solvent is removed by centrifugation to obtain The supernatant was obtained, and the two-dimensional bismuthene was prepared by liquid phase exfoliation. The preparation process was simple, and the prepared two-dimensional bismuthene had high volume specific capacity and cycle stability. To achieve the above object, the preparation method comprises the following steps:
(1) Add bismuth powder into the peeling solvent and ultrasonically vibrate for a predetermined time. During the ultrasonic vibration process, the bismuth powder is partially peeled into flakes under the action of the peeling solvent, so as to obtain a mixed bismuthene with flaky shape. solvent;
(2) centrifuging to remove the unstripped bismuth powder in the mixed solvent to obtain a supernatant, which retains the sheet-like bismuthene;
(3) The obtained supernatant is subjected to centrifugal vacuum drying to obtain sheet-like two-dimensional bismuthene.
Generally speaking, compared with the prior art through the above technical solutions conceived by the present invention, the preparation method of two-dimensional bismuthene and the lithium ion battery provided by the present invention mainly have the following beneficial effects:
1. adding bismuth powder into the stripping solvent and ultrasonically vibrating for a predetermined time to obtain a mixed solvent, centrifuging to remove the unstripped bismuth powder in the mixed solvent to obtain a supernatant, and preparing two-dimensional bismuthene by liquid phase stripping, The preparation process is simple, and the prepared two-dimensional bismuthene has high volume specific capacity and cycle stability;
2. A lithium-ion battery using two-dimensional bismuthene as an electrode material is charged and discharged at a constant current at a current density of 0.5C (1883mA/cm3, 190mA/g). After 150 cycles, it still maintains about 90% of its initial capacity. Good cycle characteristics;
3. The thickness of two-dimensional bismuthene is 3 nanometers to 5 nanometers. Experiments have proved that the volume capacity of two-dimensional bismuthene has almost no obvious attenuation under different current densities, and has good rate performance.
