Li4Ti5O12 electrodes operated under hurdle conditions and SiO2 incorporation effect

Abstract

Lithium titanate (Li4Ti5O12) and SiO2-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 Li4Ti5O12 homogeneously in the forms of Si-doping and SiO2 separate phase. When discharged in the potential range of 0.01e3.0 V, initial discharge capacities of 260 mA h g1 and 298 mA h g1 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 (0.01e3.0 V at 55 degrees Celcius) areexplored and discussed, and a proposed mechanism for the “decrease-increase-decrease” cyclingbehavior is confirmed using electrochemical impedance spectroscopy (EIS) and TEM observations. The incorporation of SiO2 was found to improve the cycling stability under hurdle conditions.