The ternary amide KLi3(NH2)4: an important intermediate in the potassium compound-added Li–N–H systems

Abstract

In this paper, the KH-added LiH–NH₃, KH-added LiH–LiNH₂, KH-added LiNH₂, and KNH₂-added LiNH₂ systems were systematically investigated. It was found that the ternary amide KLi₃(NH₂)₄ was an important intermediate that was inclined to be formed in the dehydrogenation and hydrogenation processes of the potassium compound-added Li–N–H system. Further investigations revealed that both the solid state reaction of LiNH₂ with KNH₂ and the solid state reaction of LiNH₂ with KH under mechanical ball milling or heat treatment conditions will lead to the formation of the KLi₃(NH₂)₄ ternary amide. Moreover, the ternary amide KLi₃(NH₂)₄ single phase was successfully synthesized by the mechanical ball milling and its ammonia desorption and hydrogenation properties were investigated. It was observed that the ammonia desorption rate of KLi₃(NH₂)₄ was faster than that of LiNH₂ and the hydrogen absorption kinetics of KLi₃(NH₂)₄ were between those of KNH₂ and LiNH₂.