Synthesis and structural properties of lithium titanium oxide powder as-synthesized by two step calcination process

A two-step calcination synthesis, considering the potential for mass production, of lithium titanium oxide powder was carried out to fabricate a single Li₄Ti₅O₁₂ phase, which is useful for anode electrode material of Li-based rechargeable battery as well as an electrode for supercapacitor. The final composition is controlled by adding more TiO₂ powder into powder gained at one calcination process during the two calcination process. We investigated the influence of excess TiO₂ on the structural characteristics of lithium titanium oxide synthesized by the two-step calcination method. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) measurements showed that the as-synthesized powder had a spinel crystal structure as well as A composition of 4: 5: 12. In addition, a high resolution transmission electron microscopy (HRTEM) analysis revealed that the fabricated powder exhibited a single crystalline phase formation. These results indicated that the powder synthesized in the one-step calcination process showed coexistence crystalline phases, which are the Li₄Ti₅O₁₂ and Li_2.39Ti_3.4O₈ phase. However, in the two-step calcination process, the powder synthesized showed the single crystalline Li₄Ti₅O₁₂ phase. A very uniform grain size of the as-synthesized powder was shown in a field emission scanning electron microscopy (FESEM). These results suggested that the two-step calcination process can be used for synthesis of single crystalline Li₄Ti₅O₁₂ powder with uniform grain shape and provide motivation to pursue mass production of lithium titanium based oxide powder for bulk type batteries.