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Updated: Jan 8, 2026

Characterization of Electrode Materials for Lithium Ion and Sodium Ion Batteries Using Synchrotron Radiation Techniques
Published on: November 11, 2013
Suppressing Fe Migration for Highly Reversible Oxygen Redox of Sodium-Ion Layered Oxide Cathode
Kai Zhang1, Jiawei Zou2,3, Zhenming Xu4
1Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Institute of New Energy, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Fudan University, Shanghai 200433, China.
Abstract:
Sodium-ion batteries are promising energy storage device candidates, yet are limited by low energy density. NaNi0.33Fe0.33Mn0.33O2 (NFM) activates oxygen redox under high voltage and delivers a high capacity, but suffers from irreversible oxygen loss and rapid capacity fading. Moreover, the underlying failure mechanism is still debatable. Herein, we highlight the critical role of Fe migration in NFM electrochemical degradation and develop approaches to suppress Fe migration and facilitate reversible oxygen redox. Incorporating Ca and Sn into NFM mitigates the OP2 phase, alleviates NiO6/FeO6 Jahn-Teller distortions, and deters incoming Fe3+ ions. Consequently, the out-of-plane Fe migration is effectively suppressed, thus minimizing undercoordinated oxygen species formation and achieving highly reversible oxygen redox. As-optimized NFM cathode exhibits a high capacity of 158.3 mAh g-1 and excellent electrochemical stability even under high voltage (4.5 V) and high temperature (50 °C). The pouch cells using this NFM cathode achieve a high capacity retention of 80.7% after 2000 cycles. This interlayer-migration-free cathode offers guidelines for developing long-life sodium-ion layered oxides.
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