Achieving High-Capacity Cathode Presodiation Agent Via Triggering Anionic Oxidation Activity in Sodium Oxide.
basic_science · Level V
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- Record sourced from PubMed, PMID 39032096.
- Also identified by DOI 10.1002/adma.202407720.
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Abstract
Compensating for the irreversible loss of limited active sodium (Na) is crucial for enhancing the energy density of practical sodium-ion batteries (SIBs) full-cell, especially when employing hard carbon anode with initially lower coulombic efficiency. Introducing sacrificial cathode presodiation agents, particularly those that own potential anionic oxidation activity with a high theoretical capacity, can provide additional sodium sources for compensating Na loss. Herein, Ni atoms are precisely implanted at the Na sites within Na<sub>2</sub>O framework, obtaining a (Na<sub>0.89</sub>Ni<sub>0.05</sub>□<sub>0.06</sub>)<sub>2</sub>O (Ni-Na<sub>2</sub>O) presodiation agent. The synergistic interaction between Na vacancies and Ni catalyst effectively tunes the band structure, forming moderate Ni-O covalent bonds, activating the oxidation activity of oxygen anion, reducing the decomposition overpotential to 2.8 V (vs Na/Na<sup>+</sup>), and achieving a high presodiation capacity of 710 mAh/g<sub>≈Na2O</sub> (Na<sub>2</sub>O decomposition rate >80%). Incorporating currently-modified presodiation agent with Na<sub>3</sub>V<sub>2</sub>(PO<sub>4</sub>)<sub>3</sub> and Na<sub>2/3</sub>Ni<sub>2/3</sub>Mn<sub>1/3</sub>O<sub>2</sub> cathodes, the energy density of corresponding Na-ion full-cells presents an essential improvement of 23.9% and 19.3%, respectively. Further, not limited to Ni-Na<sub>2</sub>O, the structure-function relationship between the anionic oxidation mechanism and electrode-electrolyte interface fabrication is revealed as a paradigm for the development of sacrificial cathode presodiation agent.