Hydro thermal synthesis and electrochemical characterization of (V_1/2Sb_1/2Sn)O₄and (Fe_1/2Sb_1/2Sn)O₄as energy storage materials

This paper reports the hydrothermal synthesis of alloy anode materials (V1/2Sb1/2Sn)O4 and (Fe1/2Sb1/2Sn)O4 and determine the effect of heat treatment on reversible capacities of the two oxides, and evaluation of their electrochemical properties. The compounds were initially prepared using the hydrothermal method at 180°C, and part of the active materials were reheated at 500°C in the air to improve the crystallinity and reduce the impurities. The materials were characterized by X-ray diffraction, scanning electron microscopy (SEM), Raman spectroscopy, and BET surface area. Anodic electrochemical behavior was examined by cyclic voltammetry (CV), galvanostatic cycling, and electrochemical impedance spectroscopy (EIS). Results show that (Fe1/2Sb1/2Sn)O4 reheated at 500°C delivers a better capacity of ∼400 mAh/g at 0.005-1.0 V voltage range up to 60th cycle. When we cycled a higher cut-off voltage of 0.005-3.0V, higher reversible capacity and higher capacity fading were noted due to alloying and conversion reaction of these mixed oxides. Cyclic voltammetry studies show reversible alloying/de-alloying peaks at ∼0.25 and ∼0.5 V vs. Li