Synchrotron x-ray diffraction studies of the structural properties of electrode materials in operating battery cells

Abstract

Hard x rays from a synchrotron source were utilized in diffraction experiments which probed the bulk of electrode materials while they were operating in situ in battery cells. Two technologically relevant electrode materials were examined; an AB2-type anode in a nickel–metal–hydride cell and a LiMn2O4 cathode in a Li-ion ‘‘rocking chair’’ cell. Structural features such as lattice expansions and contractions, phase transitions, and the formation of multiple phases were easily observed as either hydrogen or lithium was electrochemically intercalated in and out of the electrode materials. The relevance of this technique for future studies of battery electrode materials is discussed.