Understanding the Stability for Li-Rich Layered Oxide Li2RuO3 Cathode

Lithium-rich layered oxides are considered as promising cathode materials for Li-ion batteries with high energy density due to their higher capacity as compared with the conventional LiMO2 (e.g., LiCoO2, LiNiO2, and LiNi1/3Co1/3Mn O-1/3(2)) layered oxides. However, why lithium-rich layered oxides exhibit high capacities without undergoing a structural collapse for a certain number of cycles has attracted limited attention. Here, based on the model of Li2RuO3, it is uncovered that the mechanism responsible for the structural integrity shown by lithium-rich layered oxides is realized by the fl exible local structure due to the presence of lithium atoms in the transition metal layer, which favors the formation of O-2(2-)-like species, with the aid of in situ extended X-ray absorption fi ne structure (EXAFS), in situ energy loss spectroscopy (EELS), and density functional theory (DFT) calculation. This fi nding will open new scope for the development of high-capacity layered electrodes.