Preparation, structure and ionic conductivity of lithium phosphide

Lithium phosphides (LiP and Li3P) were synthesized by the exothermic reaction between lithium melt and phosphorus powder in an inert atmosphere. The structure of these compounds was studied using X-ray diffraction and elemental analysis. LiP crystallizes in a monoclinic structure and has a black metallic luster. Li3P crystallizes in a hexagonal structure and has brown color. LiP is an insulator, but Li3P shows ionic conductivity higher than 10−4 (Ω cm)−1 at ambient temperature. Li3P has a good stability in contact with a lithium electrode and acts as a membrane for lithium transport without phase transformation. Lithium phosphide may have potential application as an electrolyte for solid state devices.