Preparation And Lithium/Sodium Storage Performance Of Sn₄P₃ Nanostructured Anode Material

With the gradual development of society and the continuous advancement of technology,the rapid development of portable electronic equipment and power vehicles,people's requirements for energy storage have gradually increased.Lithium-ion batteries and sodium-ion batteries have become the mainstream energy storage methods with their high energy density,long cycle life,low cost and good safety performance.The battery anode material currently widely used is graphite,and its theoretical specific capacity is only 372mAh·g^-1.The low theoretical capacity and energy density of graphite can no longer meet the rapid development of mobile electronic equipment and power automotive industry.The demand for finding materials with higher specific capacity and good cycle performance has become the focus of research on anode materials today.Tin phosphide?Sn₄P₃?is a layered semiconductor material which is formed by alternately stacking a layer of a phosphorus atom and a layer of tin atoms.The material exhibits good electrochemical activity for both Li and Na,and has lithium storage and sodium storage capacity,it also has a high theoretical specific capacity and good cyclic reversibility.The Sn₄P₃ material have a synergistic lithium/sodium mechanism of Sn and P.The high conductivity of Sn compensates for the weak P conductivity.The Li₃P and Na₃P phases generated by the charge and discharge reaction can act as a protective matrix to avoid the aggregation of Sn,this synergistic effect plays an important role in the internal stability of Sn₄P₃ material.The nano-sized Sn₄P₃ has the advantages of small particle size and large specific surface area,shortening the lithium/sodium ion migration path,and improving conductivity and energy density.With these two advantages,the specific research contents of this topic are as follows:?1?Sn nanoparticles were prepared by DC arc plasma method.Then Sn nanoparticles were used as a precursor to generate Sn₄P₃ with red P at 350?by the high temperature solid phase reaction.Through the microscopic characterization methods such as XRD,TEM and SEM,it is proved that the prepared Sn₄P₃ phase is pure and has good crystallinity.The sample is composed of nanosphere particles with a diameter of 5¹0 nm.?2?The Sn₄P₃ nanopowder was assembled into a lithium ion battery and tested for electrochemical performance.At a current density of 100 mA·g^-1,the first discharge capacity is up to 1969 mAh·g^-1,and the coulombic efficiency is 85%.After 100 cycles,the discharge specific capacity can still be maintained at 430 mAh·g-1;At 300 mA·g^-1,the capacity was maintained at 356 mAh·g^-11 after 100 cycles,showing good cycle reversibility.This is mainly due to the fact that the nanosized Sn₄P₃ has a smaller particle size to inhibit volume expansion and a synergistic lithium storage mechanism of Sn and P to maintain the internal stability of the material.In short,when used as a negative electrode material for lithium ion batteries,Sn₄P₃ nanostructures have a high discharge capacity and good cycle stability,and it must be a lithium battery anode material with potential for development.?3?The Sn₄P₃ nanopowder was assembled into a sodium ion battery and tested for electrochemical performance.At a current density of 100 mA·g^-1,the initial discharge capacity is as high as 1463 mAh·g^-1.After 100 cycles,the discharge capacity is 80 mAh·g^-1.When the cycle is cycled to 200 laps,the discharge capacity can also be maintained at 73mAh·g^-1.Compared to the pure phase compound applied to sodium battery anode materials,it exhibits higher discharge capacity and better cycle reversibility.