Synthesis Of Graphdiyne-Coated Sb-Based Anode Materials For Sodium-Ion Batteries

With the development of modern society and industry,the demand for efficient,safe and sustainable clean energy has become increasingly strong,which has also promoted the development of energy storage systems.Due to the sodium-rich resource reserve and the similar chemical reaction mechanism as lithium ion batteries,Sodium ion battery?SIB?is favored by more and more scientific researchers.Antimony,as a new type of negative electrode material for sodium ion batteries,has a moderate voltage platform and high electrical conductivity,making it an ideal material for storing sodium ion electrodes.But it also has its own defects that cannot be ignored.The volume change during the electrochemical cycle is too large,which will cause the powder to fall off from the electrode material,reduce the electron transport between the active ions and the current collector,and cause the capacity to rapidly decay.To solve the existing problems of Sb-based materials,we explored the following:?1?Coaxial tubular?tube-in-tube?Sb@C nanomaterials.Using CuNWs with a diameter of 80-100 nm as a precursor template,a C-shell coating was formed on the surface of CuNWs by hydrothermal synthesis and high-temperature heating,and the conversion between Cu-Sb was completed by electrochemical replacement.Coaxial tubular?tube-in-tube?Sb@C nanomaterial is formed.The internal Sb tube of the material has a hollow structure.The large internal space and the gap between the Sb tube and the C material can well cushion the Sb material due to sodium insertion.Great volume change.Sb material will pulverize due to the drastic volume change,which affects the specific capacity and rate performance of the material.The C shell keeps the Sb tube tightly inside.Even if the metal Sb material is pulverized,it can be stored in the conductive network by the C shell Internally,it does not have to be separated from the conductive network,which improves the electrochemical performance of the material.Cyclic stability test of the electrode at a current density of 0.1 A g^-1.The battery has a discharge capacity of 610 mAh g^-1 at the second turn and a stable cycle of 50 turns at this capacity.When the current density is 1 A g^-1,the battery steadily circulates for 1000 cycles in a state with a specific capacity of 480.4mAh g^-1,which is much higher than the negative electrode material synthesized by commercial Sb powder under the same conditions.It is in the leading position in the same type of Sb materials that have been reported.?2?Sb particles were coated with nanotube-shaped graphite alkyne,with the diameter of 100 nmCuNWs as the precursor template,and the tubular graphite alkyne coating structure was successfully synthesized on the CuNWs surface through cross coupling reaction,with the thickness of graphite alkyne about 20-40 nm.Cu-sb conversion was successfully completed by electrochemical substitution reaction to form hollow tubular Sb nanoparticles.The metal Sb particles exhibit high cyclic stability due to the coated material with graphitic alkyne.And the graphite alkyne itself has a better performance of sodium storage,further improve the specific capacity of the material.The experiment shows that when the current density is 0.1A g^-1,the specific capacity of the material can reach 610.0 mAh g^-1 and stabilize the circulation for 50 cycles.When the current density is 1 A g^-1,the initial capacity of the material is 568.3 mAh g^-1,and it remains 398.3 mAh g^-1 after 1000 cycles,which is in a leading position in the academic reports published in the press.