Anion-Cation Dual-Ion Multisite Doping Stabilizes the Crystal Structure of Li-Rich Layered Oxides

Li-rich layered oxide (LLOs) cathode materials are gainingincreasingattention as lithium-ion batteries (LIBs) pursue greater energy density.However, LLOs still suffer from severe capacity fading and voltagedecay due to their unstable crystal structure. Hence, the anion-cationdual-ion multisite doping strategy based on Mg and S atoms is usedto stabilize the crystal structures of LLOs. Mg substitutes Li atomsin the Li and transition-metal (TM) layers, while S atoms occupy tetrahedralinterstitial sites and lattice O sites, all of which contribute tothe crystal structure stability of LLOs. Theoretical calculationsshow that Mg/S dual-ion multisite doping successfully reduces theenergy levels of the TM 3d-O 2p and isolated O 2p orbitals,which effectively stabilizes the lattice oxygen. Therefore, multisite-dopedsamples exhibit promising electrochemical performance. This strategyprovides a new approach to enhance the crystal structure stabilityof LLOs for the design of high-energy-density Li-ion batteries.