Influence of Li Content on the Topological Inhibition of Oxygen Loss in Li-Rich Cathode Materials

Lithium-rich layer oxide cathodes are promising energy storage materials due to their high energy densities. However, the oxygen loss during cycling limits their practical applications. Here, the essential role of Li content on the topological inhibition of oxygen loss in lithium-rich cathode materials and the relationship between the migration network of oxygen ions and the transition metal (TM) component are revealed. Utilizing first-principles calculations in combination with percolation theory and Monte Carlo simulations, it is found that TM ions can effectively encage the oxidized oxygen species when the TM concentration in TM layer exceeds 5/6, which hinders the formation of a percolating oxygen migration network. This study demonstrates the significance of rational compositional design in lithium-rich cathodes for effectively suppressing irreversible oxygen release and enhancing cathode cycling performance. In Li-rich layered oxide cathodes, the formation of a migration network of redox-active oxygen ions can be prevented when the transition metal ions occupy over 5/6 of the sites in the transition metal layer, and thereby, the oxidized oxygen species can be encaged in the lattice, leading to topological inhibition of oxygen loss during cycling. image