Thermodynamically Guided Antisite Ordering Stabilizes Cobalt-Free Ultrahigh-Ni Cathodes

Eliminating Co from ultrahigh-Ni layered cathodes often exacerbates Li/Ni mixing, impeding Li⁺ transport, amplifying reaction heterogeneity, and accelerating structural degradation. Most strategies focus on minimizing the overall degree of cation mixing, whereas thermodynamic control of antisite spatial organization remains underexplored. Here, we address this central stability challenge by developing a thermodynamics-guided defect-engineering strategy that stabilizes spatially correlated Li/Ni antisite configurations in cobalt-free ultrahigh-Ni cathodes. Density functional theory screening of high-valence dopants reveals that Te⁶⁺ exhibits the strongest energetic preference for spatially correlated antisite configurations. This prediction guides the synthesis of LiNi_0.948Al_0.045Te_0.007O₂ containing coherent local antisite-ordered superlattice domains. These ordered domains persist after prolonged cycling, strengthen interlayer coupling, suppress H2-H3 phase separation and c-axis contraction, and preserve low-barrier Li⁺ migration pathways. Local Te-O coordination further stabilizes lattice oxygen and mitigates oxygen-loss-induced surface reconstruction. Consequently, the cathode delivers 185 mAh g^-1 at 10 C, retains 96.7% of its initial capacity after 200 cycles at 1 C with a 4.4 V cutoff, and retains 92% of its initial capacity after 100 cycles with a 4.6 V cutoff. These findings establish the spatial organization of defects as a critical design variable for mitigating the stability-transport trade-off in cobalt-free ultrahigh-Ni layered cathodes.