We developed a mass production method that simultaneously controls the phase transformation and crystal size of TiO 2 coatings on multiwalled carbon nanotubes (MWCNTs). Initially, MWCNTs were successfully coated with amorphous 15-20-nm-thick TiO 2 by an in-situ sol-gel method. As the calcination temperature increased in both air and argon atmospheres, the amorphous TiO 2 was gradually transformed into the fully anatase phase at approximately 600°C, a mixture of the anatase and rutile phases at approximately 700°C, and the fully rutile phase above approximately 800°C. The crystal size increased with increasing calcination temperature. Moreover, above 600°C, the size of crystals formed in air was approximately twice that of crystals formed in argon. The reason is thought to be that MWCNTs, which continuously supported the stresses associated with the reconstructive phase transformation, disappeared owing to complete oxidation in air at these high temperatures.

In this study, we investigated the electrochemical effects of morphological changes using BaSnO3 (BSO) of various shapes (columns, hollow rods, spheres) as anode materials for Li-ion batteries. The BSOs were prepared by hydrothermal method and their electrochemical properties were evaluated using galvanostataic charge/discharge and CV test. As a results, columnar BSO exhibits the best electrochemical properties, as an inert material, BaO can contribute to Li storage because of higher electrical conductivity. This results suggest that the formation of column shape can lead to improved electrochemical properties as anode materials of secondary battery.

The phase stability of electrolyte matrix was improved by metal dopant materials which are Ni and Mn. The Ni-, Mn-doped LiAlO2 and dopant-free LiAlO2 were prepared by the mechanochemical process (MCP). The effects of dopant material, molar ratio and type of precursor were investigated after heat treatment at 700 and 800 °C. As a results, the Mn-doped LiAlO2 prevents phase transition even at higher operating temperature. Also, the stability was increased when Mn4+ ion was adapted as a precursor source than Mn3+ ion and the minimum Mn content to maintain the α-phase after heat treatment at 800 °C is found to be LiAl0.75Mn0.25O2. This result suggested that the formation of nano-sized particles confirmed the applicability as a matrix material with excellent electrolyte impregnation.