Li₄Ti₅O₁₂ electrodes operated under hurdle conditions and SiO₂ incorporation effect

Lithium titanate (Li₄Ti₅O₁₂) and SiO ₂-incorporated Li₄Ti₅O₁₂ are synthesized, using a facile cellulose-assisted combustion technique, as anodes for lithium-ion batteries tested under different conditions, i.e., discharge to an end potential of 1.0 V/0.01 V at room/elevated temperature (55 °C). The particles are characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), nitrogen adsorption-desorption isotherms, X-ray spectrometry (EDX) and transmission electron microscopy (TEM). The results show that silicon element is successfully incorporated with Li ₄Ti₅O₁₂ homogeneously in the forms of Si-doping and SiO₂ separate phase. When discharged in the potential range of 0.01-3.0 V, initial discharge capacities of 260 mA h g^-1 and 298 mA h g^-1 are obtained for the Li₄Ti₅O₁₂ and SiO₂-incorporated Li₄Ti₅O₁₂ electrodes, respectively. Both electrodes show stable cycling performance for 400 cycles (approximately 1.5 months) at room temperature between 0.01 and 3.0 V at a current density of 175 mA g^-1. In addition, the stability of the electrodes under hurdle conditions (0.01-3.0 V at 55 °C) are explored and discussed, and a proposed mechanism for the "decrease-increase- decrease" cycling behavior is confirmed using electrochemical impedance spectroscopy (EIS) and TEM observations. The incorporation of SiO₂ was found to improve the cycling stability under hurdle conditions.