Spatially Decoupled Bulk-Surface Engineering of Single-Crystal Li-Rich Cathodes via a Rigidified Framework and...

Lithium-rich manganese-based oxides (LRMOs) are attractive next-generation cathodes for lithium-ion batteries (LIBs), owing to their ultrahigh capacity and high operating potential. Although single-crystal LRMOs (SC-LRMOs) mitigate intergranular fractures associated with polycrystalline particles, they still suffer from sluggish Li⁺ transport and intragranular fatigue driven by uncontrolled oxygen release. Herein, a spatially decoupled "rigidified framework-frictionless pathway" strategy integrating bulk Zr⁴⁺ doping with oleic acid (OA)-induced surface reconstruction is proposed. Comprehensive characterizations and density functional theory (DFT) calculations reveal that Zr⁴⁺ substitution rigidifies the bulk lattice by reducing the antibonding orbital occupancy of neighboring Mn─O bonds, suppressing oxygen loss and intragranular microcracking. In contrast, surface-localized OA-induced thermal reduction generates oxygen vacancies (O_v) and triggers a layered-to-spinel reconstruction near the surface, thereby enabling rapid Li⁺ transport. Within the modified framework, the introduced O_v upshifts the O 2p band center and enhances local anionic polarizability, effectively screening Li─O electrostatic repulsion and lowering the Li⁺ migration barrier from 0.548 to 0.405 eV. Hence, the optimized Zr-SC@OA cathode exhibits an initial Coulombic efficiency (ICE) of 86.6% and a reversible capacity of 298.8 mAh g^-1. This bulk-surface decoupling design offers a rational strategy to reconcile thermodynamic stability with transport kinetics in high-energy anionic-redox cathodes.