Activating Reversible Anionic Redox in Layered Oxide Cathodes for Highly Stable Sodium-Ion Batteries by Li/Nb Codoping.
basic_science · Level V
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- Record sourced from PubMed, PMID 42085572.
- Also identified by DOI 10.1021/acsnano.6c00915.
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Abstract
The exploitation of high-capacity, long-cycle cathode materials with reversible anionic redox activity and robust structural stability remains an essential challenge for sodium-ion batteries. Herein, we address these limitations through Na-O-A configuration modulation in P2-Na<sub>0.67</sub>[Ni<sub><i>x</i></sub>Li<sub><i>y</i></sub>Mn<sub>1-<i>x-y</i></sub>]O<sub>2</sub>, which fundamentally enables reversible anionic redox reactions and ensures structural stability. The obtained P2-Na<sub>0.67</sub>Ni<sub>0.23</sub>Mn<sub>0.67</sub>Li<sub>0.08</sub>Nb<sub>0.02</sub>O<sub>2</sub> cathodes deliver a remarkable reversible capacity of 158.4 mAh g<sup>-1</sup> at 0.1C while maintaining extraordinary cycling stability with 98.2% capacity retention after 500 cycles at 5C (a minimal capacity fade of only 0.0036% per cycle). The introduction of the Na-O-Li/Nb configuration enables dual cationic and anionic redox reactions (ARR) to enhance capacity. Meanwhile, the high-valence Nb<sup>5+</sup> species not only suppresses oxygen release through robust Nb-O bonds, thereby improving the reversibility of ARR, but also reinforces the structural rigidity of the transition metal-layer framework. Ultimately, this modulation strategy provides a universal pathway for designing highly stable, high-energy cathodes for next-generation sodium-ion batteries.