Effects of Li/Ti ratios on the electrochemical properties of Li4Ti5O12 examined by time-resolved X-ray diffraction

Abstract

Li4Ti5O12 for anodic active material of lithium ion batteries is synthesized using different Li/Ti ratios of 3.5/5.0, 4.0/5.0 and 4.5/5.0 by a solid-state reaction between Li2CO3 and anatase TiO2 at 850 A degrees C. All samples contain a small amount of transformed rutile TiO2 in the final Li4Ti5O12, where the amount of rutile TiO2 decreases with the increase in Li/Ti ratio. A stoichiometric Li4Ti5O12 with Li/Ti = 4.0/5.0 shows a slightly larger particle size and higher charge capacity than those of Li-deficient and Li-excessive particles, while the discharging rate capability is shown to mainly depend on particle size regardless of Li/Ti ratio. According to the time-resolved X-ray diffraction patterns using a synchrotron source, however, no significant difference is found in spite of the difference in Li/Ti ratio, indicating the structural stability of Li4Ti5O12 during the Li insertion and extraction process.