Influence of Ti(4+) on the electrochemical performance of Li-rich layered oxides - high power and long cycle life of Li2Ru1-xTixO3 cathodes.

Abstract

Li-rich layered oxides are the most attractive cathodes for lithium-ion batteries due to their high capacity (>250 mAh g(-1)). However, their application in electric vehicles is hampered by low power density and poor cycle life. To address these, layered Li2Ru0.75Ti0.25O3 (LRTO) was synthesized and the influence of electroinactive Ti(4+) on the electrochemical performance of Li2RuO3 was investigated. LRTO exhibited a reversible capacity of 240 mAh g(-1) under 14.3 mA g(-1) with 0.11 mol of Li loss after 100 cycles compared to 0.22 mol of Li for Li2Ru0.75Sn0.25O3. More Li(+) can be extracted from LRTO (0.96 mol of Li) even after 250 cycles at 143 mA g(-1) than Li2RuO3 (0.79 mol of Li). High reversible Li extraction and long cycle life were attributed to structural stability of the LiM2 layer in the presence of Ti(4+), facilitating the lithium diffusion kinetics. The versatility of the Li2MO3 structure may initiate exploration of Ti-based Li-rich layered oxides for vehicular applications.