Enhanced Cycling Performance of Li-Rich Oxide Cathode via a Vaccine Effect

Multi-component incorporation and its inoculated gradient disorder structure can greatly modify the properties of materials. However, the contribution of the inoculated surface gradient disorder structure on the Li-rich cathodeswith distinctive integrated structure of LiMO₂ (M = Ni, Mn, Co) and Li₂MnO₃ has been overlooked. Here, we reveal a vaccine effect of surface gradient disorder structure, demonstrating its significant improvement on the cycling performance of inoculated Li_1.2Mn_0.6Ni_0.2O₂. The inoculated Li_1.2Mn_0.6Ni_0.2O₂ exhibits an initial coulombic efficiency of 85% and maintains ultra-high stability with 100% capacity retention after 500 cycles. Furthermore, it delivers a capacity of 154.5 mAh g^-1 with 84.2% retention after 900 cycles at current density of 200 mA g^-1. Through a combination of electrochemical analysis and theoretical simulations via the basic Nernst equations, we demonstrate that the inoculated gradient disorder structure changes the thermodynamic and kinetic parameters governing the lattice oxygen redox process, which follows three sequential steps O^2-→O₂ ^2-→O^2-→O₂. This structural modification reconstructs the lattice oxygen redox, specially enhancing the electrode potential of the O^2-→O₂ step and reducing the reaction rate of O^2-→O₂ ^2-→O₂ ^- of Li_1.2Mn_0.6Ni_0.2O₂. These findings bring a novel perspective on the conventional foreign element incorporation strategy, providing valuable insights to support the continued development of Li-ion batteries.