Lithium-7 NMR investigation of electrochemical reaction of lithium with SnO

Abstract

We report on solid state 7Li NMR measurements of electrochemically lithiated SnO. At low Li contents (Li/SnO≤2), the results are consistent with the formation of amorphous Li 2O. For Li/SnO ratio of 4.3, in addition to the amorphous Li 2O phase, there are at least two distinct Sn/Li alloy environments which are similar to those observed in a reference Li 2.3Sn alloy. However the Li + environments in a sample with Li/SnO ratio equal to 6.4 and an Li 4.4Sn reference alloy differ markedly. The NMR data are thus consistent with the simple model of Li insertion proposed by other groups, involving the formation of Li 2O and Li x Sn alloys (SnO+ xLi→Li 2O+Li x−2 Sn), at low and intermediate Li contents. At high Li content, however, the Li x−2 Sn alloy structure is significantly different in the electrochemically lithiated SnO material, compared to that in the reference alloy.