Atomic-scale structural regulation of O3-type cathodes by Li/Zn co-doping

O3-type layered oxide cathode materials have garnered significant attention for sodium-ion battery applications owing to their intrinsically high specific capacity. Nonetheless, their real-world employment is hindered by sluggish reaction kinetics and insufficient interlayer structural robustness. These issues mainly originate from the accumulation of internal stress caused by repeated volume changes and phase transitions during cycling. In this study, we adopt a modification strategy for O3-type layered oxides through the incorporation of Zn 2 + into the transition-metal layers and Li⁺ into the alkali-metal layers to construct Li/Zn codoped NaNi 1/3 Fe 1/3 Mn 1/3 O 2 (NFMLZ, Na 0.93 Li 0.05 Ni 0.33 Fe 0.33 Mn 0.30 Zn 0.03 O 2 ). Theoretical calculations illustrates that the Li/Zn co-doping successfully modulates local electron distribution and boosts the electronic conductivity in NFM. The increased localization around O atoms caused by Li/Zn co-doping is beneficial for stabilizing the crystal framework. Evidence from in-situ XRD further uncovers Li/Zn co-doping dampens severe structural variations. Consequently, the NFMLZ cathode exhibits a high reversible capacity of 70.0 mAh g⁻ 1 at 10 C. What’s more, the full cell based on NFMLZ cathode showcases superior rate performance, realizing a reversible capacity of 68.5 mAh g⁻ 1 at 5 C, and demonstrates strong cycling stability with 77.4% capacity retention after 300 cycles at 1 C as well as high energy density of 372.9 Wh kg⁻ 1 . Overall, this work unravels a cooperative enhancement of ion diffusion and structural stability, providing valuable insights for the rational development of high-performance cathode materials.