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

We report on solid state Li-7 NMR measurements of electrochemically lithiated SnO. At low Li contents (Li/SnO less than or equal to 2), the results are consistent with the formation of amorphous Li2O. For Li/SnO ratio of 4.3, in addition to the amorphous Li2O phase, there are at least two distinct Sn/Li alloy environments which are similar to those observed in a reference Li2.3Sn alloy. However the Li+ environments in a sample with Li/SnO ratio equal to 6.4 and an Li4.4Sn 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 Li2O and LixSn alloys (SnO + xLi --> Li2O + Lix-2Sn), at low and intermediate Li contents. At high Li content however, the Lix-2Sn alloy structure is significantly different in the electrochemically lithiated SnO material, compared to that in the reference alloy. (C) 1998 Elsevier Science B.V. All rights reserved.