Revisiting the Honeycomb-ordered Ni-Sb Layered Oxides and Unraveling the Pivotal Role of Jahn-Teller Effect towards Robust Structure Sodium-ion Batteries

Sodium-ion batteries (SIBs) emerge as the promising candidate for next-generation energy storage facilities especially for grid application. As one of the new emerged cathode materials, honeycomb-ordered layered oxide structures have gradually attracted considerable attention by the virtue of their high redox potential as well as the remarkable structure stability. The representative Ni-Sb honeycomb-ordered structures exhibits high voltage, nevertheless the irreversible phase transition remains the substantial barrier which hinders its application. Herein, systematic studies have been performed for Ni-Sb based honeycomb-ordered O3-NaNi_1/2M_1/6Sb_1/3O₂ (M = Zn, Mg, Cu), with the introducing Zn²⁺, Mg²⁺, and Cu²⁺.substitutionElectrochemical studies show all compounds exhibit high working voltage plateau of approximately 3.35 V, whereas Zn-substituted NaNi_1/2Zn_1/6Sb_1/3O₂ emerges significantly enhance cycling stability with better rate capability. In situ XRD and X-ray absorption fine structure (XAFS) spectrum unambiguously disclose Zn substitution effectively suppress the unfavorable P3-O1 phase transition at high voltages and alleviate the Jahn-Teller effect with slight lattice distortion. Moreover, theoretical study deduces the phase transition and structure evolution process of Zn substitution NaNi_1/2Zn_1/6Sb_1/3O₂ which also confirms the lower Na⁺ diffusion barrier. This study provides valuable insights of honeycomb-ordered layered oxides materials and also inspires an innovative approach for the development of high-performance SIBs cathode materials.