Transition Metal Ordering Optimization for High-Reversible Capacity Positive Electrode Materials in the Li-Ni-Co-Mn Pseudoquaternary System

The phase diagram of the Li-Ni-Co-Mn layered oxide pseudoquaternary system is used as starting point to elucidate the influence of transition metal (TM) ordering on the structures and electrochemistry of positive electrode materials with LiNi1-y-xCoyMnxO2 composition. Whereas our obtained phase diagram shows a comprehensive search of the most suitable target compositions for single-phase layered materials with large structural stability and reversible capacity, a detailed analysis of the transition metal ordering tries to fill the gap existing in the literature between transition metal composition and ordering, showing the effect on the electrochemical performance. Our results demonstrate that, in order to achieve high reversible capacities, control of the TM arrangement at the atomic scale seems to be crucial to enhance both ionic and electronic mobilities, thus maximizing the rate capability and structural stability during cycling.