Ab initio prediction of the Li5Ge2 Zintl compound

[Display omitted] •We predict the energetics of the experimental ground state phases in the the Li–Ge system.•We perform a crystal structure search using a genetic algorithm.•We identify a new Zintl compound with composition Li5Ge2.•We characterize the electronic and mechanical properties of the Li5Ge2 compound. The lithium–germanium materials system has potential uses in lithium-ion battery devices. An ab initio genetic algorithm search of the system identifies a previously unreported member of the lithium–germanium binary phase diagram with composition Li5Ge2 and space group R3¯m (166) that is stabilized by a Zintl mechanism. We describe the structure of this new phase, investigate its mechanical and electronic properties, and discuss its relationship to other members of the lithium–germanium binary phase diagram.