Lithium Rich Composition of Li2RuO3 and Li2Ru1-xIrxO3 Layered Materials as Li-Ion Battery Cathode

Li2MO3-based layered structures play an important role in lithium rich composites to realize high energy density cathode for lithium-ion batteries. However, detailed storage mechanism in lithium rich composition is still not clear due to complicated redox chemistry and their synergy effect. In the present work, we report electrochemical property of Li2RuO3 and Li2IrO3 and their solid solution Li2Ru1-xIrxO3 (0 <= x <= 1). Despite having the same structure they differ in space group (C2/c for Li2RuO3 and C2/m for Li2IrO3), however; show the similar electrochemistry against lithium. The solid solution of Li2Ru1-xIrxO3 compositions show a mix behavior depending upon the concentration of the specific phase. Electrochemical performance clarified that specific Li/Li2Ru0.90Ir0.10O3 composition shows better cyclic behavior with 198.30 mAh g(-1) discharge capacity at 40 mA g(-1) current rate. During this study, few underlying points observed here are 1) high voltage oxidation process is mainly due to O-2 removal during de-lithiation, 2) the amount of 02 removal decreases as a function of Jr component in the solid solution increases and more importantly 3) we suspect there will be Ru-Jr bond formation along with Ru-Ru and Jr-Jr bonds. These strong metal-metal bonding in the metal oxide plane shifts the electronic energy levels, as a consequence, oxygen removal is somewhat restricted. Therefore, the objective of this project is to extract knowledge from these two layered materials and use further to design new excellent cathode materials. (C) 2014 The Electrochemical Society