Robust Surface Reconstruction Induced by Subsurface Ni/Li Antisites in Ni-Rich Cathodes

Loss of active materials is a critical problem of layered oxide cathodes for lithium-ion batteries and undermines their long-term electrochemical performance. However, the atomic-scale outward migration mechanism of transition metals and oxygen remains elusive due to a highly localized environment at surface. Here, the robust surface reconstruction of LiNi0.8Mn0.1Co0.1O2 (NMC811) induced by artificially introduced Ni/Li antisites is reported. Using scanning transmission electron microscopy, the outward co-migration process of nickel and oxygen ions is directly revealed at the atomic scale, finally resulting in a stable surface structure. The robust nature of this surface structure originates from the strong linear superexchange interaction between subsurface Ni-Li and surface Ni as supported by first-principles calculations. An idealized subsurface structure with 13 Ni-Li is designed to suppress the outward migration of transition metal and oxygen ions and provide a universal lattice-coherent surface protection strategy for layered lithium transition metal oxide cathodes.

Automated summary

The study reports that surface reconstruction induced by specific antisites can suppress the outward migration of transition metals and oxygen ions, achieving a stable surface structure for layered oxide cathodes of lithium-ion batteries.