Solid⁷Li-NMR andin situXRD studies of the insertion reaction of lithium with tin oxide and tin-based amorphous composite oxide

Abstract

The lithium insertion reactions with tin (II) oxide (SnO) and tin-based composite oxide (abbreviated as TBCO) are studied by solid 7Li-NMR Knight shift, T1 and T1ρ relaxation rate, TEM and in situ XRD methods. By the insertion reaction for SnO, the lithium oxide and β-tin are produced first at Li/Sn = 2; at Li/Sn = 3 to 6 the products are not simple and a mixture of LiSn2, LiSn, Li5Sn2 and Li7Sn2 alloys is detected during the insertion. For the TBCO, which is revealed as amorphous, mainly constituted by randomly distributed very short-range (order of 10-9 m) regions by TEM observation, it is found that electrochemically inserted lithium forms Li2O and produces metallic tin (Sn) in the first step (Li/Sn <2), then the highly ionic lithium-tin alloys, Li7Sn2 (and Li7Si2), are produced in the second step (Li/Sn >2). During the second step, the Li/Sn ratio of formed lithium-tin alloy is kept at almost 4. By the analyses of 7Li NMR Knight shifts, line shape and in situ XRD, the lithium-inserted TBCOs are characterized as almost amorphous and mixtures of highly ionic components.

Preparation of lithium stannide mixtures in organic solvents. A alternate source of lithium in organolithium chemistry

“…The possible explanation might be the decomposition of lithium stannides in the air during the sample preparation. 7 Li solid-state NMR of the lithium stannides mixture using static samples at a field of 7 T, showed poorly resolved spectra that qualitatively resembled those obtained by Furuya et al [8]. However, under MAS, resolution was markedly improved.…”

“…This enhanced resolution allows us to determine that the resonance reported [8] at $38 ppm and assigned to LiSn, is in fact two peaks in a 2:1 ratio, at 42 and 31 ppm. Since these peaks seem to vary in synchrony, it is possible they arise from a single lithium stannide; and while the evidence this species is LiSn is by no means conclusive, there certainly exist other compounds of formula AX with two chemically distinct A and two distinct X atoms, each in a 2:1 ratio.…”

“…Lithium stannides were electrochemically prepared by Furuya et al [8], producing several distinct species, identified by deconvolving poorly resolved 7 Li solidstate NMR spectra; the 7 Li resonances were conjecturally assigned using Knight shifts and T 1 values. We have been able to produce a mixture of lithium stannides as a black slurry by treating preformed lithium naphthalenide with tin (II) chloride or tin powder under stirring for 10 min at 298 K in THF under argon.…”

Electrical Transport and Electronic Structure Calculation of Al-Ga Binary Alloys

“…There are a number of theoretical methods of determining different aspects of the electronic structure of liquid metals among which the density of states and the Fermi energy have significant bearing. The calculations of the Fermi energy E F and the density of states N (E F ) for simple liquid metals have been reported by [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] using various pseudopotentials and the Green function theory. It does not appear that the Harrison first principle pseudopotential has been used for the study of these properties except by Thakur [52] for alkali metals.…”

Electronic Transport and Thermodynamic Properties of Binary Liquid Alloy: Ab Initio Approach

“…There are several theoretical methods to determine different aspects of the electronic structure of liquid metals, among which the DOS and the Fermi energy have significant bearing. The calculations of Fermi energy E F and the DOS N(E F ) for simple liquid metals have been reported by various researchers [5,[26][27][28][29] using various pseudopotential and the Green function theory. It does not appear that the HFP pseudopotential has been used for the study of these properties except by Thakur [29] for alkali metals.…”