Formation of amorphous LiCl aggregate regions withinLi+-ion conductingglasses of (LiCl)x(LiPO3)1−x evidenced by 7Li MAS NMR

Abstract

Li+-ion conducting glassesof (LiCl)x(LiPO3)1−x with high LiClcompositions up to x = 0.45 were prepared successfully by using a twin-roller quenching method.7Li magic angle spinning (MAS) NMR spectra of the glasses showed a broadsignal, and a linear dependence of the chemical shift on LiCl composition,x, wasobserved. The chemical shift estimated by extrapolating the linear relation to the LiCl composition limitof x = 1 was very different from that of crystalline LiCl, and was concluded to correspond to that ofamorphous LiCl. A linear relation to the LiCl composition was also observed for thelinewidth of the signal, and quite a sharp signal was expected for amorphous LiClfrom the relation. The glasses with relatively high LiCl compositions of exhibited a sharp signal besides the broad one in the spectra, and the chemical shift ofthe sharp signal corresponded well with that estimated for amorphous LiCl. Thisresult clearly shows the formation of ‘amorphous LiCl aggregate regions’ in the(LiCl)x(LiPO3)1−x glasses with increase of the LiCl composition, and the sharp signal was reasonably attributed to theLi+ ions included in the amorphous LiCl aggregate regions.