Synthesis and structural properties of lithium titanium oxide powder

Recently, lithium titanium oxide material has gained renewed interest in electrodes for lithium ion rechargeable batteries. We investigated the influence of excess Li on the structural characteristics of lithium titanium oxide synthesized by the conventional powder calcination method, considering the potential for mass production. The lithium excess ratio is controlled by using different weight of Li₂CO₃ powder during calcination. X-ray diffraction (XRD) measurement for the synthesized powder showed that the lithium titanium oxide material with excess lithium content had a spinel crystal structure as well as a different crystal one. In addition, high resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM) measurement revealed that the lithium titanium oxide powders with a lithium excess ratio of 5–20% exhibited a two phase formation. Inductively coupled plasma — atomic emission spectrometer (ICP-AES) and energy dispersive x-ray spectroscopy (EDX) measurements were used to analyze composition of the lithium titanium oxide powder. These results suggested that the conventional calcination method, considering the potential for mass production, formed two phases according to the Li excess amount in initial raw materials.     

Further insights into thermoelectric properties of nonstoichiometric titanium oxide fabricated by high pressure and high temperature

The present work explores the feasibility of advancing the thermoelectric properties of nonstoichiometric TiO_2?x through introducing more and more oxygen deficiencies. Compared with previous work, it is found that this compositional manipulation induces phase transition; in addition, the scattering mechanisms of both carrier and phonon have changed, resulting in the temperature-independent electrical resistivity, inferior electrical performance and an unexpected high thermal conductivity. As a consequence, a moderate zT value of 0.13 is obtained in TiO_1.72 at 600?℃. Through this work, we understand deeply about thermoelectric properties of nonstoichiometric titanium oxide by high pressure and high temperature, and further investigations about this system have been directed.