NMR evidence of LiF coating rather than fluorine substitution in Li(Ni0.425Mn0.425Co0.15)O2
Idioma
en
Article de revue
Este ítem está publicado en
Journal of Solid State Chemistry. 2008, vol. 181, n° 12, p. 3303-3307
Elsevier
Resumen en inglés
A series of “Li1+z/2(Ni0.425Mn0.425Co0.15)1−z/2O2−zFz” materials was prepared by a coprecipitation route and their structure was characterized using X-ray diffraction (XRD), as well as 7Li and 19F Magic Angle Spinning (MAS) ...Leer más >
A series of “Li1+z/2(Ni0.425Mn0.425Co0.15)1−z/2O2−zFz” materials was prepared by a coprecipitation route and their structure was characterized using X-ray diffraction (XRD), as well as 7Li and 19F Magic Angle Spinning (MAS) NMR spectroscopy. Two hypotheses were considered: (i) formation of layered oxyfluoride materials and (ii) formation of a mixture between the layered material and LiF. Structural parameters were refined by the Rietveld method, using XRD diffraction data. The refinement results did not allow us to choose between these two hypotheses: no significant change in crystallinity and structural parameters was observed irrespective of the fluorine ratio. 7Li and 19F MAS NMR analyses showed signals with isotropic positions characteristic of LiF, but envelopes characteristic of very strong dipolar interactions with the electron spins of the material, demonstrating that LiF was not incorporated into the layered oxide structure but was instead present as a coating.< Leer menos
Palabras clave en inglés
Lithium-ion battery
Positive electrode material
Layered oxide
Li(Ni
Mn
Co)O2
Fluorine substitution
Coating
X-ray diffraction
NMR spectroscopy
Orígen
Importado de HalCentros de investigación