Bismuth-titanium-silicon-based ternary oxide system: A comprehensive analysis and electrochemical utility

Abstract

A novel TiO2-SiO2/Bi2O3 oxide material (TSB) was prepared for a first time via the sol-gel method. The synthesis was performed using titanium(IV) isopropoxide, tetraethoxysilane and bismuth nitrate pentahydrate as oxide precursors, ammonia as hydrolysis promoter and propan-2-ol as solvent. The properties of the synthesized material were comprehensively analyzed, including dispersion characteristics, morphology, crystalline structure, chemical composition and porous structure parameters. Additionally, to confirm the chemical structure and the presence of characteristic surface groups, Fourier transform infrared spectroscopy was applied. The electrochemical properties of a TiO2-SiO2/Bi2O3 anode, operating in 1M LiPF6 in EC/DMC (ethylene carbonate/dimethyl carbonate), were studied. The key point of the investigation was to demonstrate a potential application of TSB material in a Li-ion cell. Electrodes were analyzed with the use of cyclic voltammetry (CV), galvanostatic charging/discharging tests, and scanning electron microscopical (SEM) evaluations were performed. SEM images of both electrodes after charging/discharging processes showed that they to be covered with a film (electrochemical SEI formation). The reversible capacity of the TiO2-SiO2/Bi2O3 anode after 20 cycles at a low current rate was close to the theoretical value of 250 mAh g−1. However, at increasing current rates it decreased to ca. 200 mAh g−1. The reversibility of the process was close to 95%. Moreover after 100 cycle at 50 mA g−1 the value was 198 mAh g−1.