Synergistic Bulk and Interface Modification via Lanthanization Enhances Structural Stability and Ion Kinetics in O3-NaNi1/3Fe1/3Mn1/3O2 Cathodes

Abstract

O3-type layered transition metal oxides represent promising cathode materials for sodium-ion batteries (SIBs) due to their high energy density and low cost, yet their practical deployment is limited by sluggish kinetics, complex phase transitions, and interfacial side reactions. We report a surface lanthanation strategy for O3-type NaNi1/3Fe1/3Mn1/3O2 (NFM) that enables gradient lanthanum doping (La 3+ ) via a solid-phase reaction. This dual-modification creates a robust surface layer and broadens sodium ion (Na + ) diffusion pathways, significantly enhancing interfacial and structural stability. Combined experimental and theoretical analyses reveal that the high-bond-energy La-O bonds strengthen the host framework, suppress irreversible phase transitions, and facilitate Na⁺ desolvation. The optimized cathode delivers exceptional rate capability (100.3 mAh g -1 at an ultra-high current density of 1600 mA g -1 ) and cycling stability (79.95% capacity retention after 300 cycles). When configured in full pouch cells, it retains 85.62% capacity after 100 cycles, demonstrating practical viability. This work provides a synergistic interface-to-bulk design strategy for high-performance SIBs with scalable potential.