The stability of P2-layered sodium transition metal oxides in ambient atmospheres.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 32669558.
- Also identified by DOI 10.1038/s41467-020-17290-6 and PMC identifier 7363866.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Air-stability is one of the most important considerations for the practical application of electrode materials in energy-harvesting/storage devices, ranging from solar cells to rechargeable batteries. The promising P2-layered sodium transition metal oxides (P2-Na<sub>x</sub>TmO<sub>2</sub>) often suffer from structural/chemical transformations when contacted with moist air. However, these elaborate transitions and the evaluation rules towards air-stable P2-Na<sub>x</sub>TmO<sub>2</sub> have not yet been clearly elucidated. Herein, taking P2-Na<sub>0.67</sub>MnO<sub>2</sub> and P2-Na<sub>0.67</sub>Ni<sub>0.33</sub>Mn<sub>0.67</sub>O<sub>2</sub> as key examples, we unveil the comprehensive structural/chemical degradation mechanisms of P2-Na<sub>x</sub>TmO<sub>2</sub> in different ambient atmospheres by using various microscopic/spectroscopic characterizations and first-principle calculations. The extent of bulk structural/chemical transformation of P2-Na<sub>x</sub>TmO<sub>2</sub> is determined by the amount of extracted Na<sup>+</sup>, which is mainly compensated by Na<sup>+</sup>/H<sup>+</sup> exchange. By expanding our study to a series of Mn-based oxides, we reveal that the air-stability of P2-Na<sub>x</sub>TmO<sub>2</sub> is highly related to their oxidation features in the first charge process and further propose a practical evaluating rule associated with redox couples for air-stable Na<sub>x</sub>TmO<sub>2</sub> cathodes.