Synthesis, characterization, and electrochemical performance of spherical nanostructure of Magnéli phase Ti4O7

Abstract

In this paper, the electrically conductive of Magneli phase Ti4O7 was successfully synthesized using TiO(NO3)2 as the precursor of titania in a reductive atmosphere at 1000 °C for 6 h, and characterized by using X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The SEM images clearly show the spherical shape and their average particle size is around 250 nm. The as-prepared Ti4O7 was used as an additive to prepare sulfur/Ti4O7 composite cathode. The cyclic voltammetry tests demonstrated the Ti4O7 can not only contribute to reduce the dissolution of polysulfides into electrolytes, but also improve the electrochemical reaction kinetics during charge–discharge processes. The effect of the Ti4O7 nanospheres heat treatment temperature on the sulfur/Ti4O7 cycling performance was also investigated. As a result, the cathode with nanospheres of Ti4O7 calcined at 1000 °C exhibited 930 mAh g−1 of initial capacity and keeping the remaining capacity of 460 mAh g−1 over 100 cycles, which could be improved due to its high specific surface area and nanosized structure.