Controllable Preparation Of Alloy-type Antimony/bismuth-based Anode Materials And Their Sodium/potassium Storage Performanc

According to statistics,in 2021,the total amount of curtailment in China is as high as 26.7billion kilowatt hours,and with the rapid development of renewable energy,the phenomenon of curtailment will continue to exist.In response,it is necessary to quickly build a large number of power energy storage systems.Lithium-ion batteries（LIBs）is the primary choice of chemical energy storage devices today,in addition to the above renewable energy storage field,its application is widely distributed in various types of electronic and electrical equipment.However,as the demand for LIBs keeps rising,the problem of low lithium metal content and unevenly dispersed lithium metal reserves has become a major obstacle to its development.Sodium and potassium,which are more abundant than lithium,have a similar storage mechanism to LIBs,so they have great potential to become a new generation of energy storage devices after LIBs.As the ionic radius of sodium and potassium is larger,the anode materials currently used in commercial LIBs are not fully applicable to sodium ion batteries（SIBs）and potassium ion batteries（PIBs）,so it is necessary to develop a new anode material suitable for SIBs and PIBs.Metal antimony and bismuth as alloying type anode materials have high sodium and potassium storage capacity as well as relatively suitable operating voltage,but their electrochemical performance is poor in practical tests,which is mainly limited by enormous volume changes leading to material pulverization or even detachment from the collector.In response to the above problem,herein,Bi and Sb are modified by different strategies,such as material nanosizing,structural design,introduction of high conductivity or stable substrates,and construct an alloying system.The details are as follows:（1）Using HKUST-1 as the precursor,the octahedral carbon framework with hollow structure was obtained by polydopamine coating and annealing,and the Bi@C@NC material was finally obtained by replacing the copper in the framework with bismuth through replacement reaction.Through testing,it can be seen that Bi@C@NC has better rate performance than Bulk Bi,and it still showed a reversible capacity of 275mAh g^-1 at a high current density of 5 A g^-1 after 180 cycles.The test results show that the internal space formed by the pyrolysis of organic ligands provides a buffer space for the expansion of Bi nanoparticles,and the external nitrogen-doped carbon shell can enhance the electrical conductivity,while the tough carbon shell ensures the material morphology to a certain extent.（2）The intermediate product Cu BTC@PAN NF was obtained by electrostatic spinning,and the final product necklace-like nitrogen-doped carbon nanofibers coated with Sb particles（Sb@C@CNF）was subsequently prepared successfully by high-temperature annealing as well as ion exchange method.Based on the characterization,it can be noticed that the external nitrogen-doped carbon fibers are wrapped around the Sb particles,avoiding the direct contact between Sb and electrolyte.In addition,the network structure composed of carbon nanofibers in Sb@C@CNF can accelerate the charge transfer and reduce the diffusion resistance.In SIBs,Sb@C@CNF can still provide reversible capacities of 202mAh g^-1and 198mAh g^-1after 900and 1000 cycles at 1 Ag^-1and 2 A g^-1 current densities,respectively.In PIBs,after 800 cycles at the current density of 1 A g^-1,the reversible specific capacity still maintained 198mAh g^-1.（3）The final product MXene@Sb/In₂S₃ was successfully prepared by a one-step solvothermal method and annealing which using MXene as a substrate.Low temperature and long time annealing allowed Sb and In₂S₃ to become nanoparticles,while MXene as a substrate avoided the agglomeration of Sb and In₂S₃.Furthermore,the incomplete reversible reaction between In and In₂S₃ makes part of In exist in the form of monomers,which in turn builds an alloying system with Sb in situ.When it is used as anode material for SIBs,it still has a capacity of 320mAh g^-1at a current density of 1 A g^-1 after 1000 cycles.In PIBs,MXene@Sb/In₂S₃retains a reversible capacity of 185mAh g^-1 after 1000 cycles at a constant current of 1 Ag^-1 in cycling tests.