Application ofin situMössbauer effect methods for the study of electrochemical reactions in lithium-ion battery electrode materials

A method for investigating electrochemical reactions in a Li-ion cell during discharge and recharge using in situ ⁵⁷Fe and ¹¹⁹Sn M\"ossbauer effect measurements is described. An example of the study of a cell utilizing a Sn₂Fe electrode is described, and is discussed in terms of the results of a conventional in situ x-ray diffraction study. It is shown that the x-ray-diffraction method is insensitive for the identification of a number of phases formed in these cells because of their very small crystallite size. The present work demonstrates that M\"ossbauer effect measurements can readily identify these phases and provide important information about grain size effects. This additional information allows for a much more thorough understanding of the reactions that occur during cell discharge and recharge.