Structure and electrochemical properties of CNT-supported Li-Ti-O anode material for Li-ion battery

Abstract

We investigated the structural and electrochemical properties of Li-Ti-O (LTO) and carbon nanotube (CNT)-added LTO for anode material in secondary Li-ion batteries using various techniques. The study focused on elucidating the effects of the microstructural evolution in LTO and the CNT addition on battery functionality. For all the tested compositions of LTO ([Li]/[Ti] = 0.9, 1.0 and 1.22), the system is fully oxidized to comprise a mixed-phase having Li4+2δTi5O12+δ (δ’s are approximately 0.14, 0.25, and 0.65, respectively) and Li2TiO3 structures. The results of the half-cell tests show a decrease in charge/discharge capacity with increasing [Li]/[Ti] ratio, and the detailed structural and chemical analyses unequivocally reveal that the such degradation in the electrochemical property originates mainly from the increase of Li content (δ). Meanwhile, after adding CNT, the Li capacity becomes greatly increased while the LTO composition and the redox kinetics do not change significantly. The origin of the improved specific capacity is associated with the formation of micron-sized structures at the surface of the LTO particles. Thereby we demonstrate that surface engineering via the CNT addition is a promising way to improve the performance of the LTO-based anode material.