Influence of TiO 2 /TiC composite materials with different crystal structures on the electrochemical properties as sulfur‐loaded matrix for lithium‐sulfur batteries

Abstract

Lithium-sulfur battery is a type of high-performance chemical power supply system, and the structure of composite substrate material will influence on the electrochemical properties of sulfur cathode active materials. In this paper, a TiO2/TiC composite substrate material with the different crystal structure by means of changing sintering temperature is synthesized and its physical properties and electrochemical performances have been researched. Through X-ray diffraction analysis, it can be found that the crystal structures of TiC and TiO2 in the TiO2/TiC composite substrate material sinter at different temperature both have been changed obviously due to the strong interaction between the oxygen atom and titanium and carbon atoms. By comparison, when sintering at 600°C, the composite matrix material has higher crystallinity and they accordingly have some confusion after sintering at 500°C. Raman spectrum information displays that TiO2/TiC composite substrate materials with high crystallinity allow the loaded sulfur to enter the pores and it is easier to form a stable physical adsorption. However, TiO2/TiC composite substrate material with some confusion is easier to form chemical adsorption with sulfur. Electrochemical test results illustrate that the specific discharge capacities of TiO2/TiC composite substrate material with the higher crystallinity loaded 55% sulfur can be achieved to 1247.91 and 834.62 mAh g−1 at 0.1 and 0.5C, respectively. Then, after 300 times charge and discharge cycles at 0.2C, the discharge capacity retention rate of TiO2/TiC composite substrate material with some confusion loaded 45% sulfur can reach 54.40%. To sum up, we can conclude that the TiO2/TiC composite materials with different crystal structures will have a serious impact on the electrochemical performances of sulfur cathode for lithium-sulfur batteries.