Atomic-layer tailored LiNbO₃ coating dual-regulating bulk stability and inorganic-rich interphase construction for lithium-rich layered cathodes

The development of a uniform, electrochemically robust coating capable of reconciling structural integrity with chemical inertness at high voltages is pivotal for unlocking the full potential of layered lithium-rich cathodes (LRNCM). Herein, an atomic-scale LiNbO₃ coating is constructed on LRNCM via atomic layer deposition (ALD), which dual-functionalizes as a chemical passivator and mechanical stabilizer to address concurrent interfacial and bulk degradation. The conformal LiNbO₃ layer suppresses nucleophilic attacks by reactive oxygen species in carbonate electrolytes, redirecting cathode-electrolyte interphase (CEI) evolution toward an inorganic-dominated architecture with high ionic conductivity. This optimized CEI reduces interfacial impedance and charge-transfer polarization. Furthermore, the LiNbO₃ coating functions as a mechanical buffer to suppress anisotropic lattice strain and inhibit phase transitions from layered to spinel structures. The synergistic stabilization enables the LiNbO₃-coated cathode to deliver exceptional cyclability, retaining 84.48 % capacity and 80.27 % energy density after 300 cycles at 1 C, with a voltage decay rate of 0.73 mV/cycle, outperforming the uncoated LRNCM (76.46 %, 71.76 %, and 0.97 mV/cycle). By decoupling anionic redox activity from structural and interfacial degradation, this work establishes ALD-based surface engineering as a scalable paradigm for high-energy LRNCM, offering a materials-design blueprint to harmonize energy density with longevity in next-generation batteries.