Oxygen redox pathway reconstruction via ZrO polarized layer and transition metal vacancies: a dynamic confinement strategy for high-performance sodium-ion battery

Transition metal layered oxides have emerged as a prominent class of cathode materials for sodium-ion batteries. However, their cycling stability remains a critical limitation impeding further development. Recent studies confirm that lithium incorporation effectively improves the long-term cycling performance of these materials. However, constrained by the inferior initial capacity and rate capability it induces, this approach has never achieved practical and widespread application. Hence, a novel P2-Na 0.67 Li 0.1 Ni 0.23 Mn 0.62 Zr 0.05 O 2 cathode material is proposed. The structural stability of the cathode material is significantly improved through the formation of a surface Zr O polarized layer that effectively suppresses lattice oxygen loss. Simultaneously, the transition metal vacancy concentration was modulated through controlled Zr 4+ doping levels, enabling enhanced initial capacity via optimized cationic/anionic redox participation. The in situ/ex situ characterization of the system demonstrated that it achieved dynamic confinement of anionic redox activity during the entire charge-discharge process, thereby enabling reconstruction of the oxygen reaction pathways. The modified samples exhibited enhanced electrochemical performance with 152.3 mAh g −1 at initial cycling and 99.1 mAh g −1 at 10C. This work presents a novel strategy for transition metal layer optimization and dynamic confinement of lattice oxygen activity, while providing new insights for the development of layered oxide cathode for high-performance SIBs.