Lithium iodide

Lithium iodide, or LiI, is a compound of lithium and iodine. When exposed to air, it becomes yellow in color, due to the liberation of the iodine.

Applications
Lithium iodide is used as an electrolyte for high temperature batteries. It is also used for long life batteries as required, for example, by artificial pacemakers. The solid is used as a phosphor for neutron detection.