Layered-to-rocksalt atomic reconfiguration on O3-type cathodes surface for high-energy and durable sodium-ion batteries

High-energy O3-type cathode materials have been intensively pursued due to the immense potential of sodium-ion batteries as a scalable and economic energy storage solution. However, their intrinsic sensitivity of surface to humid air inevitably triggers detrimental bulk degradation and the formation of ionically/electronically insulating surface residuals, severely impairing their battery performance and commercialization efforts. Here, we present a transformative layered-to-rocksalt atomic reconfiguration strategy that achieves dual breakthroughs, the elimination of residual alkalis and the in-situ construction of a robust layered-rocksalt heterostructure surface in the prototypical O3-NaNi_1/3Fe_1/3Mn_1/3O₂ cathode. This ingenious design defies conventional trade-offs, simultaneously preserving rapid Na⁺ diffusion kinetics, ensuring exceptional electrochemical reversibility and reinforcing structural stability. Consequently, the engineered cathode demonstrates a superior initial Coulombic efficiency of 97.6 %, a high cycling durability with capacity retention of 80.1 % after 300 cycles at 1 C and a new benchmark for rate capability with 78.9 % capacity retention at a high rate of 10 C. The proposed surface layered-to-rocksalt atomic reconfiguration strategy exemplifies a groundbreaking electrode design concept and opens up a wide of compositional possibilities for future development of high-power and high-energy cathodes, marking a significant step forward in the evolution of sodium-ion battery technology.