Boosting the Sodium Storage Performance of O3-Type Layered Oxide Cathode by Dual-Site Doping

O3-type layered oxide materials with inherently sufficient Na content have attracted significant attention for sodium-ion batteries (SIBs). However, they suffer from unsatisfactory electrochemical reaction kinetics, irreversible phase transition, and structural degradation during the electrochemical cycling, resulting in poor sodium storage performance. Herein, we propose a Ca/Sn dual-site doping strategy to boost the electrochemical performance of the O3-type layered oxide cathode materials. The synergistic effect of Ca/Sn dual-site doping can modulate the coordination environment and chemical bonds of transition metal (TM) ions, leading to the fast charge transfer kinetics and highly reversible phase transition with a small volume change. The improved structural stability effectively suppresses TM dissolution and maintains particle integrity during long-term cycling. Therefore, Na_0.98Ca_0.01Ni_0.33Fe_0.33Mn_0.315Sn_0.015O₂ delivers superior cycling stability and excellent rate performance. This work highlights the critical role of dual-site doping in enhancing sodium storage performance and provides significant guidance for the design of high-performance cathode materials.