Nanoscale Laser Production Of Bi-Sb Alloys From MOFs And Their Sodium Storage Performance

Alloy based materials have extraordinary physical and chemical properties,good mechanical properties,such as low boiling point,high hardness,good stability in acid or alkali solutions and so on.These characteristics are different from their compositional metals.So the alloy materials are widely used in electrochemical energy storage,catalysis,aerospace,transportation and so on.Traditional methods for preparation of alloy based materials mainly include sintering at high temperature,gel injection molding,et al.However,these techniques generally combine multiple consecutive steps,at the cost of complicating the production process and sacrificing the reproducibility.Moreover,they always use expensive equipments or expensive materials,which increase the manufacturing cost.So far,the synthesis method for alloys with nano-sized particles is relatively less.And traditional methods are very hard to get nanoparticles with uniform size.Aiming at these problems,we develop a new method for the preparation of nanosized alloy materials,which is rapid,efficient and low energy consumption.In this method,MOFs are used as precursors,pulsed laser as efficient conversion of heat source,thus the alloy nanoparticles(Bi-Sb alloy)with uniform size are prepared.In recent years,the sodium ion battery becomes an important option for the alternative to lithium ion battery with the advantages of low cost,friendly to environment and so on.In recent years,because alloy based materials usually have high specific capacity,more and more researchers focus on it in the sodium ion battery.In alloy based materials,via synergistically serving as the buffer substrates between alloy components,their stability will be drastically improved.In addition,because of their advantages of high capacity,good stability,etc,Bi-Sb alloys have become very promising anode materials in sodium ion battery.Here,we propose and demonstrate a new approach based on the pulsed laser process and conversion of porous Bi-based metal-organic frameworks(MOFs)to carbon based Bi-Sb alloys architectures,where MOFs are used as the metal containing precursors and laser as the energy source.In this method,MOFs loaded with antimony salts are decomposed into Bi-Sb alloys.By adjusting the amounts of Sb salt in the MOFs,we can continuously adjust the molar ratio of Bi and Sb in the alloys.Precise control in the particle size,uniformity and porosity is achieved by the chemistry of MOFs.In addition,the obtained nanosized alloy particles are uniformly dispersed in the 3D carbon network,which can effectively avoid agglomeration of nanoparticles.At the same time,the conductivity of alloy based materials are increased becaused of carbon.Through a series of material characterization techniques,including:X-ray powder diffraction(XRD),transmission electron microscope(TEM),scanning electron microscopy(SEM),etc,the synthesized carbon-based Bi-Sb alloy's chemical composition,structure and morphology are systematicly studied.Finally,we apply the alloy materials in the sodium ion battery,and study the effect between structure and discharge performance in detail.The research contents and innovative points of this article mainly includes as follows:1.The preparation of new Bi base MOF.A new Bi base MOF,named as MOF-836 is firstly synthesized in which bismuth salts are as metal source and benzenetricarboxylic acid(BTC)as the organic ligand.The crystal structure of MOF-836 is different from the reported CAU-17 which has same metal clusters and organic ligand.The synthesis method of MOF-836 is very simple,especially its production rate is very high,which is very important to the subsequent application.2.The preparation of MOF-836 derived carbon based Bi nanoparticles and their discharge performane for sodium ion battery.For the first time,we us MOF-836 as the precursor,pulsed laser as efficient conversion heat source to synthesize carbon based Bi nanoparticles architectures in which Bi nanoparticles with uniform size are homogeneously dispersed in the 3D carbon network.We study how the laser parameters effect the morphology,structure and electrical conductivity of the materials,and finally successfully synthesize carbon based Bi nanoparticles with high electrical conductivity and uniform size of Bi nanoparticles(about 30±10 nm).Finally,we apply this materials in the sodium ion battery,and study the discharge performance.The carbon based Bi nanoparticles exhibit good cycling performance(98.6 m Ah g^-1 after 500 cycles)at 200 m A g^-1 corresponding to a capacity decay of 0.169%per cycle.3.The preparation of MOF-836 derived carbon based Bi-Sb nanosized alloy and their discharge performanc for sodium ion battery.Antimony salts are loaded in the pores of MOF-836,Sb-in-MOF-836 composites with different loading contents of antimony salts are obtained and are used as precursors to synthesize carbon based Bi-Sb nanosized alloys with different molar ratio of Bi to Sb through pulsed laser process.In the obtained architectures,Bi-Sb alloy nanoparticles with uniform size are homogeneously dispersed in the 3D carbon network.Finally,we apply the materials in the sodium ion battery,and study the discharge performance.The Bi_0.70Sb_0.30(MOF-836)alloys in which the molar ratio of Bi to Sb is0.70:0.30 exhibits the best cycling performance(259.9 m Ah g^-1 after 500 cycles)at 200 m A g^-1,corresponding to a capacity decay of merely 0.128%per cycle.4.CAU-7 derived carbon Bi-Sb preparation of nanometer alloy and its performance study of sodium.In order to increase the percentage of Sb in the Bi-Sb alloys,we changed the ligand type,from BTC to BTB.CAU-7 with high specific surface area(1155 m² g^-1)are successfully synthesized.More antimony salts are loaded in the pores of MOFs,Sb-in-CAU-7 composites with different loading contents of antimony salts are obtained and are used as precursors to synthesize carbon based Bi-Sb nanosized alloys with different molar ratio of Bi to Sb through pulsed laser process.In the obtained architectures,Bi-Sb alloy nanoparticles with uniform size are homogeneously dispersed in the 3D carbon network.Finally,we apply the materials in the sodium ion battery,and study the discharge performance.The Bi_0.50Sb_0.50(CAU-7)alloys in which the molar ratio of Bi to Sb is 0.50:0.50 exhibits the best cycling performance(234.9 m Ah g^-1 after 500 cycles)at 200 m A g^-1,corresponding to a capacity decay of 0.147%per cycle.Therefore,MOF-836 derived Bi-Sb alloy with the molar ratio of Bi to Sb is 0.70:0.30 exhibits the best sodium storage performance.In the Bi-Sb alloys,more Sb in the alloy does not mean the best performance.There is an optimal component in the alloys with the best material stability and performance.To sum up,we use Bi based MOFs and their composites as precursors,pulsed laser as efficient conversion heat source to synthesize carbon based Bi-Sb nanosized alloy with different molar ratio of Bi to Sb.The Bi-Sb alloy nanoparticles with uniform size are homogeneously dispersed in the 3D carbon network.This method is rapid and efficient.And it has high energy utilization rate,the composition of alloy can be easily adjusted continuously.Moreover,the production condition is under room temperature in air,without any protective atmosphere.The discharge performance of Bi-Sb alloy in sodium ion battery is studied,and it shows excellent cycle performance and rate performance.