Influence of Mn/Fe ratio on electrochemical and structural properties of P2-NaxMn1–yFeyO2 phases as positive electrode material for Na-Ion batteries
Idioma
en
Article de revue
Este ítem está publicado en
Chemistry of Materials. 2018, vol. 30, n° 21, p. 7672-7681
American Chemical Society
Resumen en inglés
The comparative structural, Mössbauer, and electrochemical studies of the NaxMn2/3Fe1/3O2 and NaxMn1/2Fe1/2O2 systems show that the change in the Mn/Fe ratio has a significant influence on the overlap between the Mn3+/4+ ...Leer más >
The comparative structural, Mössbauer, and electrochemical studies of the NaxMn2/3Fe1/3O2 and NaxMn1/2Fe1/2O2 systems show that the change in the Mn/Fe ratio has a significant influence on the overlap between the Mn3+/4+ and Fe3+/4+ redox couples. The P2-type structure is maintained in the 0.3 < x < 0.8 domain. For the highest intercalation amount, structural distortions occur due to the Jahn–Teller effect of the Mn3+ ions. The macroscopic distortion results from a competition between the opposite effects of Mn3+ and Fe3+: the isotropic character of Fe3+ tends to prevent the macroscopic distortion. For the lower sodium amounts, the instability of the interstitial trigonal prismatic space leads to the formation, by slab gliding, of a very disordered structure. Even if this structural transition is reversible, a strong capacity fading is observed if the cell is charged above 4 V verus Na/Na+.< Leer menos
Orígen
Importado de HalCentros de investigación