New Insights into Anionic Redox in P2-Type Oxide Cathodes for Sodium-Ion Batteries.
basic_science · Level V
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- Record sourced from PubMed, PMID 39417609.
- Also identified by DOI 10.1021/acs.nanolett.4c03358.
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Abstract
Manganese/nickel-based layered transition metal oxides have caught the attention of studies as promising cathodes for sodium-ion batteries (SIBs). It is reported that utilizing both cationic and anionic redox reactions is a promising method for higher energy density cathodes. However, the anionic redox reaction comes at the expense of irreversible oxygen release. Hence, a Li-Mg cosubstituted P2-Na<sub>0.67</sub>Li<sub>0.07</sub>Mg<sub>0.07</sub>Ni<sub>0.28</sub>Mn<sub>0.58</sub>O<sub>2</sub> material with a honeycomb-ordered superstructure was designed. The Ni<sup>3+</sup>/Ni<sup>4+</sup> redox couple and the anionic redox reaction are proven to have a competitive relationship. Density functional theory calculations reveal the effect of O 2p nonbonding states from Li and prove that Mg-O bonds can stabilize the Ni-O e<sub>g</sub> states. <i>In situ</i> electrochemical impedance spectroscopy measurements and galvanostatic charging/discharging derived d<i>V</i>/d<i>Q</i>, representing resistance changes with time, are obtained to reveal the mechanism of the anionic redox reaction. This study presents the effect and mechanism of the O 2p nonbonding state and Mg-O bonds of manganese/nickel-based layered oxides.