Study On ZnSe As An Anode Material For Lithium-ion Batteries

When Zn Se is used as an anode material for lithium-ion batteries,large volume change and structural collapse of electrode materials occur during the cycling process,resulting in severe instability in electrochemical performance.In this article,improvement of Zn Se electrode materials was achieved through the composite and optimization of the nanostructures.H-Zn Se,Zn Se/BN,and Zn Se/CNTs were prepared and characterized through material characterization and electrochemical tests.The research content is mainly divided into the following three parts:（1）A hollow structure of H-Zn Se was prepared using ZIF67 as a precursor using the sacrificial template method.This special hollow structure can well suppress the volume change of the electrode material during cycling,enlarge the specific surface area of the electrode material,and increase the electrochemical reaction active sites,thus improving the rate performance and cycling stability of the cell.At a current density of 0.1 A/g,the specific capacity reached 586.7 m Ah/g after 150 cycles,and the Coulombic efficiency remained above 98%,while that of the Zn Se electrode was only 322.0 m Ah/g.（2）Zn Se/BN composites were obtained by introducing two-dimensional layered boron nitride nanosheets（Boron nitride nanoplates,BNNs）in the synthesis of ZIF8,followed by selenization treatment.The rhombic orthododecahedral structure obtained from ZIF8 as a precursor can provide a large specific surface area and rich pores,and the BNNs encapsulated in the outer layer can buffer the volume change of the electrode material during the charging and discharging process and improve the cycling stability.In the electrochemical tests,the Zn Se/BN electrode exhibited outstanding cycling stability（556.5 m Ah/g after 200 cycles at a current density of 0.1A/g）and great rate performance（225.1 m Ah/g at a current density of 2 A/g）.（3）Using carbon nanotubes（Carbon nanotubes,CNTs）as a template,a layer of Si O₂was first deposited on the outside.Then,a layer of Zn Se was deposited,after which the Si O₂in the interlayer was etched off,and finally a Zn Se/CNTs composite was obtained by high-temperature selenization with CNTs as the inner tube and Zn Se as the outer tube.The tubular structure of the material can also increase the specific surface area and reactive sites.Electrochemical tests show that the Zn Se/CNTs electrode has good cycling stability and rate capability,and the discharge specific capacity can be maintained at 373.7 m Ah/g after 200 cycles at 0.1 A/g and 247.7m Ah/g at high current density of 2 A/g.After 100 cycles at a current density of 0.5A/g for Na-ion batteries,the specific capacity of Zn Se/CNTs electrode is 324.5m Ah/g,and there is no obvious trend of degradation.