Layered CsTi2NbO7 based anode materials: Effect of interlayered ions on the electrochemical properties

Abstract

Layered anode materials based on aqueous electrolytes have been studied in a three-electrode system. MTi2NbO7 (M = H、Li、Na、K) was prepared by different ion exchange of precursors CsTi2NbO7, and the crystal structures and skeleton structures of the as-prepared materials were characterized by X-ray diffraction (XRD) and laser Raman spectroscopy (LRS). K3[Fe(CN)6] aqueous solution was used as the electrolyte to characterize the electrochemical properties, and the effect of interlayer cation transfer on the performance of the whole process was studied. The results show that NaTi2NbO7 exhibits good electrochemical performance, which can be deduced from the Cyclic voltammetry, Galvanostatic charge–discharge and Electrochemical impedance spectroscopy. It may be caused due to the different hydration radius, electrical conductivity and mobility of interlayer cations. Although K+ has a smaller hydration radius, it is easier to form electric double layer capacitor (EDLC) on the surface of the material to show capacitive properties, rather than all insert the crystal structure and show the battery behavior. Noteworthy, we combine the size of the interlayer channels, the interaction force between the interlayer cations and the laminate, Na+ in such layered materials shows some obvious advantages from relationship between the structure and performance. This work provides an important reference for the future development of layered anode materials in aqueous solution systems or organic battery systems.