Carbon-Coated SiO2 Composites as Promising Anode Material for Li-Ion Batteries

Porous silica-based materials are a promising alternative to graphite anodes for Li-ion batteries due to their high theoretical capacity, low discharge potential similar to pure silicon, superior cycling stability compared to silicon, abundance, and environmental friendliness. However, several challenges prevent the practical application of silica anodes, such as low coulombic efficiency and irreversible capacity losses during cycling. The main strategy to tackle the challenges of silica as an anode material has been developed to prepare carbon-coated SiO₂ composites by carbonization in argon atmosphere. A facile and eco-friendly method of preparing carbon-coated SiO₂ composites using sucrose is reported herein. The carbon-coated SiO₂ composites were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetry, transmission and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, cyclic voltammetry, and charge–discharge cycling. A C/SiO₂-0.085 M calendered electrode displays the best cycling stability, capacity of 714.3 mAh·g⁻¹, and coulombic efficiency as well as the lowest charge transfer resistance over 200 cycles without electrode degradation. The electrochemical performance improvement could be attributed to the positive effect of the carbon thin layer that can effectively diminish interfacial impedance.     

DSC investigation of nanocrystalline TiO<Subscript>2</Subscript> powder

The aim of the article is to investigate the influence of particle size on titanium dioxide phase transformations. Nanocrystalline titanium dioxide powder was obtained through a hydrothermal procedure in an aqueous media at high pressure (in the range 25–100 atm) and low temperature (≤200 °C). The as-prepared samples were characterized with respect to their composition by ICP (inductive coupled plasma), structure and morphology by XRD (X-ray diffraction), and TEM (transmission electron microscopy), thermal behavior by TG (thermogravimetry) coupled with DSC (differential scanning calorimetry). Thermal behavior of nanostructured TiO₂ was compared with three commercial TiO₂ samples. The sequence of brookite–anatase–rutile phase transformation in TiO₂ samples was investigated. The heat capacity of anatase and rutile in a large temperature range are reported.