Preparation And Sodium Ion Storage Research Of Transition Metal Selenide Anode Materials

Lithium ion batteries have been widely used as a secondary energy system,but the cost issues have limited its further application.As an alternative to lithium ion batteries,the current problem for sodium ion batteries lies in the lack of suitable sodium storage electrode materials.Transition metal selenide has attracted great attention due to its abundant resources,good conductivity and simple preparation.However,problems such as volume expansion and side reactions under low voltage conditions still need to be resolved.In the background,this paper through construction of a binder-free electrode material based on carbon cloth reduces the resistance of the electrode,and provides a new idea for the preparation of a electrode material for sodium ion battery.Using a combination of arrayed nanostructure design,metal ion doping and carbon composition to enhance the sodium storage performance of the material.First,using the hydrothermal method,the Fe-doped Co precursor nanoarray was controllably loaded on the surface-activated carbon cloth substrate,and the Fe-doped Co-Se array was obtained by the liquid-phase ion exchange method.The iron ion doping can enhance the conductivity of electrode,facilitating the rapid diffusion of sodium ions in the crystal lattice.At the same time,the FeCo-Se array with the best doping ratio is selected for polydopamine coating,and carbonized to form the final FeCo-Se@NC array.The nitrogen-doped carbon layer can be used as a buffer layer to relieve the volume expansion of the active material due to sodium insertion and further provides more electroactive sites for sodium ion storage,which can improve electrode conductivity.The unique structural design and composition optimization make the FeCo-Se@NC array show excellent electrochemical performance in the sodium-ion half-cell.When the current density is increased from 0.05 to 5.0 A g^?1,is stable The reversible capacities for the FeCo-Se@NC are532.1 and 193.3 m Ah g^?1,after 150 cycles,FeCo-Se@NC can still maintain a reversible capacity of 386.1 m Ah g^?1.Through the selection of cathode materials and electrolyte,and the optimization of the device assembly process,sodium ion full battery and sodium ion capacitor with possible practical use are obtained.For FeCo-Se@NC//NVP/C full battery,when the current density is 0.1 A g^?1,it can provide a reversible capacity of 350.6 m Ah g^?1;and the reversible capacity of 252.3 m Ah g^?1 can be maintained after 50 cycles at a current density of 0.5 A g^?1.In addition,the assembled FeCo-Se@NC//AC sodium ion capacitor combined with different charge storage mechanisms can reach90.1 Wh kg^?1 at a power density of 91.7 W kg^?1.Finally,a systematic summary of the research content and results of this article is carried out,and the current problems and future research directions are analyzed and prospected.