Lithium insertion reactions in Li(x)Mo(6)Se(8-y)I(y) structural studies and the absence of triclinic distortions.

The binary Chevrel phase Mo(6)Se(8) forms halogen-chalcogen substitutional solid solution compounds Mo(6)Se(8-y)I(y) (02). This study reports the use of electrochemical insertion of lithium and in situ X-ray diffraction to measure the effects of halogen-chalcogen substitution on the structural properties and distortions found in Li(x)Mo(6)Se(8). The results indicate that halogen-chalcogen substitution stabilizes the Chevrel phase against lattice distortions and that with increased halogen substitution, the entire Li(x)Mo(6)Se(8-y)I(y) phase diagram becomes a single phase solid solution of lithium in Mo(6)Se(8-y)I(y). All changes are reversible in x, and features in the electrochemical behavior are explained from structural considerations.